Summary of biological doctoral thesis: Research on mangrove vegetation which have biological activities in Xuan Thuy National Park and propose sustainable usage

This dissertation contributed to implement data on the diversification of vascular plants, structure, biomass of some typical mangrove vegetation communities, chemical compositions, and biological activities of mangrove vegetation in Xuan Thuy National Park.

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY - PHAN THI THANH HUONG RESEARCH ON MANGROVE VEGETATION WHICH HAVE BIOLOGICAL ACTIVITIES IN XUAN THUY NATIONAL PARK AND PROPOSE SUSTAINABLE USAGE Major: Botany Code : 42 01 11 SUMMARY OF BIOLOGICAL DOCTORAL THESIS HANOI - 2018 This thesis was fulfilled at Graduate University of Science and Technology Supervisor 1: Assoc.Prof Dr Tran Huy Thai Supervisor 2: Dr Nguyen Hoai Nam Reviewer 1: Assoc.Prof Dr Nguyen Trung Thanh Reviewer 2: Assoc.Prof Dr Trinh Thi Thuy Reviewer 3: Assoc.Prof Dr Nguyen Khac Khoi The thesis will be defended in the Graduate University of Science and Technology (GUST) council at Vietnam Academy of Science and Technology (VAST) at …… on… 2018 This thesis may be found at: - The library of GUST - National Library of Vietnam INTRODUCTION The urgency of this dissertation Mangroves are important to not only ecology but also socio-economic Mangroves are considered as a center of tropical marine biology, one of the world’s most biodiversity and genetic ecosystems About 90% of marine organisms live in mangroves, and 80% of the world’s fisheries depend on mangroves (S Sandilyan, 2012) However, the mangrove ecosystem is vulnerable to human impacts and climate change There have been several hitherto report that mangroves in the world are severely degraded (FAO, 2007) In an effort to protect this particularly valuable ecosystem, scientists have been researching in a variety of aspects in order to exploit, converse and develop these resources in a scientific and effective way Vietnam, with more than 3,000 km of coastline, has a rich mangrove forest system stretching from north to south Mangroves not only act as a major role in ensuring the livelihoods of the coastal residential but also play an extremely important role in ensuring environmentalism, reducing nature’s impacts and overcoming the phenomena of rising sea level, saline intrusion, etc Xuan Thuy National Park, which belongs to the Northern mangrove system, is located in the southeast of Giao Thuy district, Nam Dinh province, at the Ba Lat estuary of the Red River According to previously punlished documents, the total area of the park is approximately 7,100 hectares, including 3,100 hectares of land and roughly 4,000 hectares of mangrove forest Xuan Thuy National Park is the 50th Ramsar Site of the World, the first of Southeast Asian and the only of Vietnam from 1989 to 2005 In accordance with the report of Xuan Thuy National Park, it is preserving the precious ecological value, such as thousands of hectares of mangroves, rich aquatic resources including algae which have economic value The resources of Xuan Thuy National Park are likely to exploit bioactive substances, including: 1) Mangroves species; 2) Mollusca; 3) Botany that live in mangrove conditions; 4) Microalgae and microorganisms of mangroves In particular, mangrove plants play the central role of the mangrove ecosystem This biological resource has not been researched, exploited and used effectively, along with the risk of recession due to the impact of emphatic climate change and human activities However, nowadays, there are insubstantial and comprehensive studies on mangrove plant in Xuan Thuy National Park towards biological activity have shown To contribute to researches related to the mangrove system, the Ph.D student conducted a research project “Research on mangrove vegetation which have biological activities in Xuan Thuy National Park and propose sustainable usage” The meaning of dissertation topic  Scientific significance This dissertation contributed to implement data on the diversification of vascular plants, structure, biomass of some typical mangrove vegetation communities, chemical compositions, and biological activities of mangrove vegetation in Xuan Thuy National Park  Practical significance Based on the results of the research, the thesis has selected mangrove species with biological activity and proposed sustainable use of some valuable medicinal species in order to conserve and develop mangrove plants in Xuan Thuy National Park Structure of the dissertation The dissertation consists of 146 pages, including: Introduction (2 pages); Chapter 1: Overview (28 pages); Chapter 2: Subjects, scope, content and methods (14 pages); Chapter 3: Research result and discussion (83 pages); Chapter 4: Conclusion and request (3 pages); New contributions of the thesis (1 page); List of published works (1 page); Reference (14 pages) CHAPTER OVERVIEW 1.1 Mangrove definition The term ‘mangrove’ cannot be definite in the exact way Saeger’s definition of mangrove is a type of tall plant (trees, shrubs, herbs or ferns) which dominate in semi-tropical coastal tide, subtropical, showing a distinct level of tolerance to anaerobic conditions and high salinity, and blume can live in marine dispersal condition (P Saenger, 2002) 1.2 Geographic distribution, mangrove area 1.2.1 Mangrove area and distribution in the world Mangrove is distributed mainly in the equatorial and tropical area of two hemispheres (between latitudes 23oN and 23oS), at coastline, island chains, warm Gulf Stream spreading offset from the abundant mangrove to cooler areas Mangrove in the world is distributed in 124 countries and regions Mangrove accounts for approximately % of the world’s forest area and appear in about 75% of the tropical coasts of the world (P Saenger, 2002) 1.2.2 Mangrove area and distribution in Vietnam According to Phan Nguyen Hong et al (1999), mangroves in Vietnam are divided into four zones and 12 sub-zones: Zone I: Northeast Coast, from Ngoc headland to Do Son headland; Zone II: Northern Delta Coast, from Do Son headland to Lac Truong headland; Zone III: Central Coast, from Lach Truong headland to Vung Tau headland, Zone IV: South Coast, from Vung Tau headland to Nai headland, Ha Tien 1.3 Value, role of mangrove Mangroves are important ecosystems that provide a variety of goods and services to the coastal citizens The profit of mangrove includes timber and non-timber forest products, aquatic product resources, biofiltration, coastal protection, carbon storage and absorption, recreation and ecotourism 1.4 Mangrove plants 1.4.1 Mangrove plants diversity in the world The total number of species of vegetation in the world is 23 genera and 53 species belonging to 16 families According to Saenger et al (1983), the total number of mangrove species is 60 species The exact number of mangroves in the world so far has been debated and discussed among taxonomists The official number of mangrove vegetative species ranging from 50 to 70 following the different classification systems 1.4.2 Mangrove plants diversity in Vietnam It can be said Phan Nguyen Hong, who has many monographs, articles on mangrove has been published, is a leading author in the study of mangroves in Vietnam In 1993, Phan Nguyen Hong published the list of 77 species of mangroves in two groups divided into different environmental and life forms: Group 1, referred to as true mangrove, has 35 species belonging to 20 genera of 16 families; Group 2, has 42 species belonging to 36 genera of 28 families, including species live in mangrove, which usually grow in secondary and planted forests on high ground Nowadays, there are 69 mangrove species in the South, and 34 species in the North 1.5 Structure, biomass of true mangrove vegetative communities in Xuan Thuy National Park The study of the structural and biomass characteristics of plant communities, especially mangrove communities is very important The results of this research help researchers understand the ecological succession of biome, assess the natural reserves which is the basis for effective management and exploitation of vegetative resources Normally, studies on mangrove structure and biomass are conducted in parallel 1.6 Research on the chemistry and biological activity of mangrove plants 1.6.1 Research on the chemistry of mangrove plants 1.6.1.1 Research situation in the world These days, there are more than 40 plant species have been chemically studied, 349 compounds have been isolated from mangrove plants and 200 compounds from semimangrove plants, in which 200 secondary metabolite compounds are reported to be present in only real mangrove species, and 80 compounds are found only in semi-mangrove plants, LP Jayatissa et al., 2006 1.6.1.2 Research situation in Vietnam In Vietnam, the research on the chemical composition of mangrove species is quite poor and not really comprehensive Nguyen Thi Hoai Thu et al studied the chemical composition of Sonneratia alba collected in Can Gio Mangrove The results showed that six compounds are isolated from petroleum ether fraction of leaves of Sonneratia alba including oleanolic acid, betulin, betulinic acid, alphitolic acid, methyl gallate and 5hydroxymethylfurfural (Nguyen Thi Hoai Thu et al 2011) 1.6.2 Research on biological activity of mangrove plants 1.6.2.1 Researches in the world Mangrove forests are rich in chemical compounds such as steroids, triterpenes, saponins, flavonoids, alkaloids and tannins Extracts from mangrove species are thought to have a variety of medicinal properties Studies on biological activity have shown that mangrove plant species have antimicrobial activity, antioxidant, cytotoxic, anti-cancer, anti-fungal, antimalarial and antimicrobial activity assay 1.6.2.2 Researches in Vietnam As well as studies on the chemical composition, studies on the biological activity of mangrove species in Vietnam are few and far from comprehensive Pham Van Ngot et al studied on the antimicrobial activity of some mangrove species in Can Gio Mangrove Biosphere Reserve The results show that the methanol fraction from 10 species of mangrove: S alba, D trifoliate, L racemosa, R apiculata, R mucronata, Pluchea indica (L.) Lees., Dolichandrone spathacea (L.f.) Seem., Wedelia biflora (L.) DC., B gymnorhiza, X granatum are resistant to pathogens such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa (Pham Van Ngot et al., 2015) CHAPTER SUBJECTS, CONTENTS AND RESEARCH METHODS 2.1 Subjects and research scope The study subjects are tracheophyta vascular plants and some mangrove floristic composition conditions in high tide and sand dunes in the core and buffer zone of Xuan Thuy National Park Plant species in agricultural ecosystem, artificial ecosystems are not mentioned in this study - Study period: years: 2014 - 2016 2.2 Research contents - Research diversity in vascular plants at Xuan Thuy National Park, Nam Dinh + Definition of scientific name, establish vascular plants species list + Diversity in vascular plants taxon-level at Xuan Thuy National Park + Diversity of life forms, botanical geography + Assess value in use of plants species + Rare species plants have conservation value - Research on structure, biomass from a few feature plants communities in Xuan Thuy National Park - Sampling, bioactivity screening of some mangrove for the next study - Research on chemical constituents and biological activity of Sonneratia caseolaris (L.) Engl and Rhizophora stylosa Griff from Xuan Thuy National Park - Propose sustainable usage on mangrove vegetation which have biological activities in Xuan Thuy National Park 2.3 Research methods 2.3.1 Research methods of diversity in vascular plants 2.3.1.1 Methods of inheritance 2.3.1.2 Methods of plants investigation by routes Research methods of diversity in plants using scientific documents of N.N.Thin (1997, 2004 …) combined results from the study of the world’s research 2.3.1.3 Analysis of collected information and data a) Definition of scientific name, establish plants species list Definition of scientific name: The scientific names of mangrove species was determined by morphological comparison methods The main documents used are FAO (1994), Vietnamese Herbs (P.H.Ho, 1999-2000), List of Vietnamese Plants (Nguyen Hoang Tri, 1996) Establish plants species list based on the system opinion A.L.Takhtazan (1973), N.T.Ban (2003, 2005) for the branches and classes Families and species in families are arranged in alphabetical order of the scientific names (Brummit, 1992) b) Diversity assessment in plants taxon-level Assessment of diversity in plants at the level of branches and classes: Statistics of number of families, genera, species with each branches, classes, families and genera Identify genera index (species average number of a genera), families index (species average number of a families), and genera/families index as the average genera per families Assess the diversity in a species in families and genera: Statistics of 10 families and 10 genera to determine the diversity in a species in families and genera c) Diversity assessment in plant life-form The plant life-form is determined by Raunkiaer system (1934) d) Diversity assessment in botanical geography Based on the distribution of species in the world and Vietnam to identify botanical geography factors according to Pocs Tamas, 1965 and Le Tran Chan, 1999 e) Assessment value in use of plants species The value in use of plant species is determined by the following key documents: Vietnam Forest Tree Name (Ministry of agriculture and rural development, 2000), 1900 useful plant species in Vietnam (T.D Ly, 1993), Useful plants in Vietnam (V.V Chi & Tran Hop, 1999) Vietnamese medicinal plants and herbs (D.T Loi, 1995), Dictionary of medicinal plants in Vietnam (V.V Chi, 2012), Vietnam Plant Resources (T.M Hoi, 2013)… And based on the study that gathered by local usage experiences f) Assessment of the conservation value of plants Vietnam Red Book (2007), Decree 32/2006 / ND-CP (2006) of the Government 2.3.2 Research methods of the structure of mangrove plants communities 2.3.2.1 Field research methods Methods of vegetation research based on the method of plants research by Nguyen Nghia Thin (2007) 2.3.2.2 Methods of analysis information, data processing Summarize all data collected from the phase report, measurement at plot to calculate, analyze and process data Data is processed and analyzed by Microsoft Excel 2007 Determine biomass of species in plant communities according to the formula of Komiyama (2005) 2.2.3 Methods of chemical research and biological activity 2.3.3.1 Methods of isolation of compounds a) Thin layer chromatography (TLC) b) Preparative thin layer chromatography (Prep TLC) c) Column chromatography (CC) 2.3.3.2 Methods of determining the structure of compounds The general method for determining the chemical structure of compounds is to combine the determination of physical properties with modern spectroscopic methods including: a) Mass spectrometry (ESI-MS) b) Nuclear Magnetic Resonance Spectrum (NMR) c) Melting point (Mp) 2.3.3.3 Methods of biological activity research a) Evaluation of antimicrobial activity assay Antimicrobial activity assay: evaluatation of the antibiotic activity of the fractions proceeded on 96 well microtiter plates by methods Vander Bergher and Vlietlinck (1991) and McKane & Kandel (1996) b) Evaluation of cytotoxic activity assay The in vitro cytotoxicity assay was approved by the National Cancer Institute (NCI) as the standard cytotoxicity test for screening, detecting compounds that inhibit growth or kill cancer cells This test is performed according to the method of Monks (1991) CHAPTER RESEARCH RESULTS AND DISCUSSION 3.1 Diversity in vascular plants at Xuan Thuy National Park 3.1.1 Definition of scientific name, establish plants species list Based on the collected samples, the scientific name has been determined and established vascular plants species list According to the results, Xuan Thuy National Park has recorded 116 species (including mangrove plants, species involved in mangroves, species from inland and adapted to Xuan Thuy National Park) belonging to 101 genera, 42 families of Pteridophyta and Magnoliophyta Magnoliophyta is divided into two classes: Magnoliopsida include 32 families, 73 genera, 112 species, Liliopsida include families, 21 genera, 26 species of vascular plants Xuan Thuy National Park has 18 mangrove plants, 88 species involved in mangroves, 10 species from coastal inland 3.1.2 Diversity in plants in the Xuan Thuy National Park 3.1.2.1 Diversity in branches Diversity in branches at Xuan Thuy National Park has only branches and very different in number of species Magnoliophyta has 109 species, 93.97% of total species; 94 genera, 93.07% of total genera and 37 families, 88.1% of total families in the study area Families and genera of Magnoliophyta have a high percentage compared to the rest Polypodiophyta, only species, has 6.03% of total species; genera, 6.93% of total genera and families, 11.9% of total families in the study area Diversity index of families, genera and average diversity index genera and families: - Diversity index of families is 2.76 - Diversity index of genera is 1.15 - Average diversity index genera and families is 2.4 3.1.2.2 Diversity in families Of the 42 vascular plants branches at Xuan Thuy National Park, 20 families has only one species; 10 families has species and families has species There are 32 families has the least number of species The 10 most diverse families are from to 15 species, including one family have 15 species (Poaceae), followed by a family of 14 species (Asteraceae), a family of species (Verbenaceae), a family of species (Cyperaceae), two families of five species (Rhizophoraceae, Malvaceae) and four families of four species (Amaranthaceae, Euphorbiaceae, Fabaceae, Solanaceae) 3.1.2.3 Diversity in genera Plants at Xuan Thuy National Park has 10 large families (9.9%) with 24 species (23.76%) The most abundant species are Cyperus with species (3.96%); Bruguiera and Sonneratia has species (2.97%); the remaining genera are Acanthus, Achyranthes, Pluchea, Solanum, Vitex, Pandanus and Paspalum has species (1.98%) 3.1.3 Diversity of life forms In Xuan Thuy National Park, 115 species (99.13% of total species) have been identified, one species has not been identified Of the species identified, the upper shoot group (Ph) was dominant with 66 species (55.65%); followed by group of trees near the soil (Ch) has 17 species (14.78%), group of trees a year (Th) has 17 species (14.78%); group of hiddenshot tree (Cr) has species (7.82%) and semi-hollowed tree (Hm) has species (6.95%) were the lowest Set up a live spectrum for plants at Xuan Thuy National Park as follows: SB = 55.65 Ph + 14.78 Ch + 6.95 Hm + 7.82 Cr + 14.78 Th So the upper shoot group (Ph) has the largest number of species, playing a dominant role in comparison to other life forms Group Ph spectrum as follows: Ph = 7.25 Mg + 10.93 Me + 4.69 Mi + 46.87 Na + 12.5 Lp + 18.75 Hp 3.1.4 Diversity of botanical geography Botanical geography factors of 113 plant species (97.41%) have been identified, while species have not identified (2.59%) Among the botanical geography factors of Xuan Thuy National Park, the Asia tropical factors is the highest proportion (32.76%); followed by newtropical and inter-tropical factors has 16.38%; Indochina factor has 7.76%; Hainan - Taiwan - Philippines has the lowest rate of only species (0.86%) 3.1.5 Value in use of plants species Of the 116 species of plants in Xuan Thuy National Park, 108 species have been used (93.1%) and the remaining species (6.9%) have not been identified Number of medicinal plants (THU) with 101 turns (46.76%), accounting for the most; followed by eatable tree (DNA) with 32 turns (13.42%), other uses such as fuel, land improvement tree (CDK) has 18 turns (8.33%); tree for the oil (CTD) and tree for tanin, tobacco (TAN) has 16 turns (7.4%); ornamental plants (CAN) has turns (4.17%); wood tree (LGO) and tree for fiber (SOI) have turns (3.24%), poisonous plants (DOC) have turns (2.8%); fodder plants (AGS) has turns (2.31%); the lowest is handicraft plants (DTC) only two (0.92%) 3.1.6 Rare species plants have conservation value In Xuan Thuy National Park have only one rare, threatened, valuable species (0.86%) is Scirpus kimsonnensis N.K Khoi, both is endemic to Vietnam in the coastal waters, and listed in the Vietnam Red Book (2007) as threatened with extinction This species is valuable for cattle feed 3.2 Research on structure, biomass of some typical mangrove communities in Xuan Thuy National Park 3.2.1 Classification of carpet mangroves in Xuan Thuy National Park According to T.V Trung (1978) and N.N Thin (2004), typical carpet mangroves in Xuan Thuy National Park is in the system: group of plant types at altitude less than 700 m in the North and less than 1000 m in the South; closed forest types; tropical evergreen forest types; forest on mangrove land types This carpet type have communities: - The K candel community - The K candel, S caseolaris, A corniculata, R stylosa community - The mangrove community of K candel, A corniculata participate but have not advantage - The mangrove community of A corniculata, K candel participate but have not advantage - The A corniculata, S caseolaris, K candel community - The community of A corniculata, S caseolaris, K candel participate in low density 3.2.2 Describe the structure and biomass identification of six typical mangrove communities in Xuan Thuy National Park 3.2.2.1 The K candel community (Plot 01)  Describe the structure: This type of community is located in the core zone of the park, Con Ngan area To study this type of community, we installed a plot at coordinates N: 20013’12.8”, E: 106032’57.1”, the plot dimension was 20 x 20 m (400 m2) Plot 01 have only K candel 20 years old was planted in 1997 Stratification: The canopy stage has only a single stage with K candel, the height of the tops is relatively equal - 4.2 m Shrubs and regenerated trees only have regenerated K candel has height less than 10 cm The number of K candel in phase (4/2015) decreased sharply compared to phase (6/2014) (from 770 trees to 375 trees) because 395 K candel trees died Phase (4/2016), the number of dead K candel has decreased significantly, only 24 more, the density of trees decreased to 8,775 trees/ha Most of the K candel trees in this plot are leafy and dry Death trees occur in small groups or scattered The dead trees have been decayed, broken, fallen The sharp decline in the density of K candel in this plot was identified by storms and poor soil At the end of the study (4/2016), K candel in this plot had a density of 8,775 trees/ha Groups of trees with the diameter of 3.1 - 3.5 cm and 3.6 - cm have 60-70%, in addition to the distance between the smallest diameter trees (2 cm) and the largest diameter trees (4.5 cm) is not too far It shows K candel in this plot have relatively equal diameters The number of regenerated K candel is poor, scattered in this plot, height from 10 to 20 cm, normal growth, but the potentiality to grow into mature trees is not very good because the ground in this area is bad, subsidence, low regeneration density  Biomass Biomass of wood trees in plot 01 is declining At the end of the study, the average biomass of wood mangroves in plot 01 was 61.25 tons/ha, become the lowest biomass plot 3.2.2.2 The K candel, S caseolaris, A corniculata, R stylosa community (Plot 02)  Describe the structure: A corniculata, K candel in plot 04 are not similar stem diameter A corniculata in this plot has stem diameter about 2.6 – 3.5 cm The stem diameter has grown through the phase report In this plot, only K candel can regenerated, the new tree grows normally  Biomass The biomass of both A corniculata and K candel increased slightly through the phase report The average biomass of A corniculata plants in the first stage was 95.95 tons/ha, the second was 98 tons/ha, the third was 100.5 tons/ha Biomass of K candel in the first phase is 18.675 tons/ha, the second phase is 19.275 tons / ha, the third phase is 19.325 tons/ha At the end of the study, wood mangrove trees in plot 04 had an average biomass of 119.82 tons/ha 3.2.2.5 The A corniculata, S caseolaris, K candel community (Plot 05)  Describe the structure: This type of community is located in the core zone of national park, Con Ngan area (Bong Trang) For this type of community study, we established a plot at the coordinates N:20015’14.1”, E: 106034’13.8”, plot size 20 x 20 m (400 m2) In this type of community, there are three species of mangrove: A corniculata, S caseolaris, K candel The bush stage is O ro plants Stratification: The cross of canopy stage is made up of S caseolaris species with a height of - m The canopy stage consists of A corniculata and K candel A corniculata has height of 1.3 - 2.7 m K candel has height of - m The bushes, regenerated trees have the appearance of O ro plants with the height of 0.5 - 0.7 m The regenerated tree consists of A corniculata and K candel with the height of 10 - 20 cm In this type of community, A corniculata and K candel are well-grown and welldeveloped The young S caseolaris plants have dried and broken branches for a long time, currently there are only main branches and branches with a few shoots A corniculata in plot 04 have a very high density, the first phase recorded the density of plants is 61.325 trees/ha and gradually reduced to the third stage to 59.400 trees/ha K candel density recorded in the first and second stages was 3.875 trees/ha and reduced to 3.775 trees/ha in the third stage because trees damaged by the storm S caseolaris trees in OTC 05 have a stable density during the phase with a density of 500 trees/ha Wood density in plot 05 at the end of the study was 63.675 trees/ha K candel and S caseolaris are not similar stem diameter, but the growth of stem diameter is clearly A corniculata in plot 05 had similar stem diameters and also increased through the phase report In plot 05, S caseolaris is non-regenerated species, only K candel and A corniculata can regenerated with low speed  Biomass A corniculata have the high number of plants so the average biomass is highest The average biomass of A corniculata in the second phase (157.975 tons/ha) was lower than the first one (158.175 tons/ha) due to the decreasing of density In Phase 3, the stem diameter increase, the average biomass of this species (164.925 tons/ha) increased compared to the first 11 phase The average biomass of S caseolaris in plot 05 increased slightly (from 56.25 tons/ha to 56 tons/ha) K candel had the lowest average biomass in the plot 05 and also slightly increased through the phase report (from 3.650 tons/ha to 4.075 tons/ha) At the end of the study (April 2016), the average biomass of wood mangroves in plot 05 was 225 tons/ha 3.2.2.6 The community of A corniculata, S caseolaris, K candel participate in low density (Plot 06)  Describe the structure: This type of community is located in the core zone of National Park, Con Ngan (Bong Trang) To study this type of community, we established a plot at the coordinates N: 20015’28.5”, E: 106034’33.1”, plot size 20 x 20 m (400 m2) This is a mangrove community with the participation of A corniculata, S caseolaris, K candel Different from community type in plot 05, in this type, the K candel only participates in very low density with a few plants The bush stage is O ro plants Stratification: The cross of canopy stage consists of S caseolaris, K candel with a height up to 4-8 m The canopy stage consists of A corniculata and K candel A corniculata has height of 1.5 - m K candel has height of - m The bushes, regenerated trees recorded the appearance of O ro plants with the height from 0.6 to 0.9 m There are also two regenerated species of A corniculata and K candel with a height of 10 - 30 cm A corniculata in this community are well growth, with no decay or dryness The A corniculata density decreased from 63.725 trees/ha to 62.325 trees/ha S caseolaris has been dried and broken for a long time, with only the main stem and branches with a few shoots Only 16 S caseolaris were recorded in the plot with good density throughout the three phase K candel dítributed random, good growth, no dry tops Plot 06 have only 30 mature K candel recorded in the 1st, 2nd, and 3rd phase At the end of the study, wood mangrove density in this plot was 63.450 trees/ha, lower than plot 05 K candel plants in plot 06 have similar stem diameters, the stem diameter growth is not clear The A corniculata, S caseolaris plants in this plot have not similar stem diameters and increased through phase report In plot 06, only K candel and A corniculata can regenerated with low density  Biomass In the plot 06, the A corniculata community had the highest biomass and increased through the phase report (3.051 tons/ha – 3.358 tons/ha) S caseolaris has the average biomass of 78.7 tons/ha in phase and 79.3 tons/ha in phase K candel community were only involved in small numbers in this plan so the lowest biomass was recorded and there were also signs of increasing through each phase (2.35 tons/ha - 2.5 tons/ha) At the end of the study, the average biomass of wood mangrove in plot was 165.75 tons/ha 3.3 Sampling, bioactivity screening of some mangrove plants 3.3.1 Sampling results Table 3.34 A list of 22 mangrove species was collected in Xuan Thuy National Park Sample No Scientific name Familia Familiar name sign 12 Annona glabra L XT_CBB1 Annonaceae Ipomoea pes-caprae L XT_CBB2 Convolvulaceae Clerodendrum (L.) Gaertn XT_CBB3 Verbenaceae Vitex trifolia L XT_CBB4 Verbenaceae Acanthus ilicifolius L XT_CBB5 Acanthaceae Acrostichum aureum L XT_CBB6 inerme 11 Myoporum bontioides (Siebold & Zucc.) A Gray Suaeda maritima (L.) Dum Premna corymbosa Rottb et Willd Phyta nodiflora (L.) Greene Hibiscus tiliaceus L 12 Derris trifoliata Lour 10 13 14 15 16 17 18 19 20 Sauropus bacciformis (L) AiryShaw Sonneratia apetala Buch.-Ham Vitex rotundifolia L f Kandelia candel (L.) Druce Excoecaria agallocha L Sonneratia caseolaris (L.) Engl Lumnitzera racemosa Willd Pluchea pteropoda Hemsl ex Forbes & Hemsl Pteridaceae XT_CBB7 Myoporaceae XT_CBB8 Chenopodiaceae XT_CBB9 Verbenaceae Binh bat nuoc, Na bien Rau muong bien, Muong bien , Bim chan de, Ma de thao, Ma mong hoa Vang hoi, Ngoc nu bien, Trum gong Tu bi bien, Man kinh tu O ro bien Rang bien thuong, Quan chung Bach sao, Cho Muoi bien, Phi diep bien Vong cach, Cach bien XT_CBB10 Verbenaceae Day luc XT_CBB11 Malvaceae Tra lam chieu Day coc ken, Coc ken nuoc, Day coc XT_CBB12 Leguminosae XT_CBB13 Euphorbiaceae Bo ngot qua phi XT_CBB14 Sonnetariaceae Ban khong canh XT_CBB15 Verbenaceae XT_CB02C Euphorbiaceae Tu bi bien Trang, Vet dia, Vet thang Gia, Gia mu XT_CB03C Sonneratiaceae Ban chua XT_CB04C Combretaceae Coc trang XT_CB01C Rhizophoraceae XT_CB05C Asteraceae 13 Cuc tan bien Rhizophora stylosa XT_CB07C Rhizophoraceae Duoc voi Griff Aegiceras corniculatum 22 XT_CB08C Myrsinaceae Su (L.) Blanco 3.3.2 Bioactivity screening results of some mangrove plants 3.3.2.1 Antimicrobial activity screening results Selected samples were tested for antimicrobial activity against four bacterial strains: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtillis, Staphylococcus aureus subsp aureus and four fungal strains: Aspergillus niger, Fusarium oxysporum, Candida albicans, Saccharomyces cerevisiae The results show that: I pescaprae have activity against fungal strain Fusarium oxysporum with an MIC value of 200 μg/ml S maritime have activity against bacterial strain Gr (+) Staphylococcus aureussubsp Aureus with MIC value of 200 μg/ml H tiliaceus have activity against fungal strain Aspergillus niger with MIC value of 200 μg/ml E agallocha have activity against bacterial strain Gr (+) Bacillus subtillis with MIC value of 200 μg/ml S caseolaris have activity against fungal strain Aspergillus niger with MIC value of 200 μg/ml R stylosa have activity against bacteria strain Gr (+) Bacillus subtillis and fungal strain Aspergillus niger with the same MIC value of 200 μg/ml 3.3.2.2 Cytotoxic activity screening results The methanol fraction of 22 plant samples screened for cytotoxic activity at 100 μg/ml on KB and LU cell lines The results show that: There are 11 samples including: A glabra, V trifolia, D trifoliata, S bacciformis, K candel, E agallocha, S caseolaris, L racemosa, P pteropoda, R stylosa, A corniculatum exhibits inhibition activity more than 50% KB cell growth, continue to be determined IC50 value There are samples including: D trifoliata, S bacciformis, K candel, E agalocha, S caseolaris, racemosa, P pteropoda, R stylosa, A corniculatum exhibits inhibition activity more than 50% LU cell growth, continue to be determined IC50 value Cytotoxic activity results against KB cancer cell Test result show that: A corniculatum have good cytotoxic activity with IC50 values of 4.77 g/ml, following that is the samples E agallocha, D trifoliata, S bacciformis, S caseolaris, R stylosa with corresponding IC50 values of 19.77g/ml, 24.04 µg/ml, 30.83 µg/ml, 41.09 µg/ml, 41.03 µg/ml The others samples show weak cytotoxic activity Cytotoxic activity results against LU cancer cell Test result show that: A corniculatum have good cytotoxic activity with IC50 values of 1.28 µg/ml, following that is the samples E agallocha, R stylosa, S caseolaris with corresponding IC50 values of 15.23 µg/ml, 23.17µg/ml, 25.44 µg/ml The others samples show weak cytotoxic activity 3.4 Results of isolation and determination of compounds structure from two species of mangrove plants 21 14 3.4.1 Results of compounds isolation from S albaolaris The air-dried and powdered leaves of Sonneratia caseolaris (3.5 kg) was extracted three times with MeOH After concentration, the MeOH extract (570 g) was suspended in water and then partitioned successively with n-hexane, chloroform, ethyl acetate to give corresponding extracts and water layer The Ethyl acetate extract (18 g) was subjected to silica gel cc using stepwise elution of CH2Cl2/MeOH (from 20:1 to 0:1) to afford fractions E1-E5, respectively Fraction E2 (2g) was isolated and purified by silica gel CC using CH2Cl2/MeOH 40:1 to obtain BCA17 (5mg) Fraction E3 (4.5 g) was divided into four smaller fraction: E3.1, E3.2, E3.3, E3.4 by silica gel CC using CH2Cl2/MeOH 15:1 Fraction E3.1 was isolated by YMC RP-18 CC using MeOH/H2O 1:1 to give compounds BCA16 (5mg) and BCA7 (20 mg) Fraction E3.2 was isolated by silica gel CC using CH2Cl2/MeOH/H2O 3:1:0,1 to obtain BCA (15 mg) Fraction E3.3 was isolated by silica gel CC using CH2Cl2/MeOH 10:1 to give BCA24 (30 mg) Fraction E3.4 was isolated by silica gel CC using EtOAc/MeOH/H2O 2:1:0,1 to obtain BCA21 (10 mg) (Figure 3.2, appendix 3) The Water extract was chromatographed on a column of Sephadex LH-20 and eluted with MeOH/H2O 1:1 to give 10 fractions W1-W5 Fraction W2 was further separated by silica gel CC eluted with CH2Cl2/Acetone/MeOH 2:1:0.1, followed by YMC RP-18 CC using MeOH/H2O 1:1 as eluent to obtain compound BCW1 (30 mg) and followed by Sephadex LH-20 CC using MeOH/H2O 1:1 as eluent to give compound BCW7 (5 mg) Fraction W3 was isolated by silica gel CC eluted with a solvent system of EtOAc/MeOH/H2O 12:1:0,1 to give smaller fractions: W3.1-W3.3 Fraction W3.1 was separated by Sephadex LH-20 CC using MeOH/ H2O 1:1 and purified by preparative TLC to give compound BCW5 (7mg) and BCW (5 mg) Fraction W3.2 was isolated by silica gel CC using EtOAc/MeOH/H2O 20:1:0,2 to obtain BCW (5 mg) and BCW (7 mg) Fraction W3.3 was isolated by YMC RP-18 CC using MeOH/H2O 1:4 to give BCW3 (15 mg) (Figure 3.3, appendix 3) From Sonneratia caseolaris, 13 compounds was isolated, and determined the structure of compounds: Table 3.40 Chemical structure of compounds isolated from Sonneratia caseolaris BCA7: Methyl gallate BCA8: Gallic acid BCA 24: benzyl-O-β-Dglucopyranoside BCW1: (6R, 9R)-3-Oxo-αionol β-D-glucopyranoside 15 BCA16: Eriodictyol BCA21: Eriodictyol-7-Orutinoside BCW3: (+)-Isolariciresinol 3a-O-β-glucopyranoside BCW2: Annphenone BCW7: Chrysoeriol 7glucopyranoside BCA17: Jacoumaric acid BCW4: Pinoresinol-4-O--D-glucoside BCW5: Luteolin 7-rutinoside (Scolymoside) BCW6: Apigenin 7-O-rutinoside 3.4.2 Results of compounds isolation from R stylosa Dried leaves of R stylosa (3.5 kg) were powdered and extracted with hot MeOH (3 times at 50oC for h each) to give a MeOH residue (450g) after removal of the solvent under vacuum This extract was suspended in water and partitioned in turn with n-hexane and CH2Cl2 to provide the corresponding extracts: n-hexane (H, 80 g), CH2Cl2 (C, 20 g) and a water layer Extracts H and C were combined and crudely separated by silica gel CC using a gradient concentration of MeOH in CH2Cl2 (0100%) to obtain fractions (H1H7) Fraction H4 (4.1 g) was further separated by YMC RP-18 CC and eluted with MeOH:water (2.5:1, v/v), followed by silica gel CC with n-hexaneacetone (3:1, v/v) to give DV16 (20.0 mg) and DV17 (5.0 mg) Fraction H5 (5.2 g) was further divided into sub-fractions (H5AH5E) by silica gel CC and eluted with CH2Cl2:MeOH (15:1, v/v) DV8A (3.0 mg), DV8B (3.5 mg), (5.0 mg), DV12 and DV10 (3.5 mg) were purified from sub-fraction H5B (180.0 mg) by YMC RP-18 CC and eluted with MeOH:water (1.5:1, v/v), followed by silica gel CC and elution with CH2Cl2:MeOH:water (20:1:0.01, v/v) Similarly, sub-fraction H5D was purified by YMC RP-18 CC and eluted with MeOH-water (1:1, v/v), followed by silica gel CC and elution with CH2Cl2:MeOH (10:1, v/v) to provide compound DV1 (14.0 mg) Fraction H6 was further separated by silica gel CC eluted with CH2Cl2:MeOH 10:1, followed by YMC RP-18 CC using Acetone/H2O 1:1.5 as eluent to obtain compound DV18 (350 mg) The water layer was passed through a Diaion HP-20 column using stepwise elution with waterMeOH (10:0, 2.5:7.5, 5:5, 7.5:2.5, and 0:10, v/v) to obtain fractions (W1W3) after removal of the fraction eluted with only water Fraction W2 (1.5 g) was purified by silica 16 gel CC and eluted with EtOAC:MeOH:water (4:1:0.1, v/v), followed by YMC RP-18 CC and elution with MeOH:water (2:1, v/v) to provide DV19 (7.0 mg) From R stylosa, compounds was isolated, including new compound The chemical structure of compounds was determined and show in the following table Table 3.41 Chemical structure of compounds isolated from R stylosa DV16: Blumenol A DV1: Rhizostyloside (Chất mới) DV10: Polystachyol DV19: (6S, 7E, 9R)-6,9dihydroxy-4,7megastiymadien-3-one 9O-[α-L-arabinopyranosyl(l→6)-β-Dglucopyranoside] DV17: (+)-Pinoresinol DV12: (+)-Isolariciresinol DV8A: 7S,8R)-3,3,5trimethoxy-4,7-epoxy-8,5neolignan-4,9,9-triol DV8B: Lawsonicin DV18: Kaempferol 3rutinoside 3.5 Results of biological activity of compounds isolated from mangrove species R stylosa and S caseolaris 3.5.1 Evaluation results of antimicrobial activity compounds DV10, DV18, DV19, BCW4 have activity against one bacterial strain, which is fungal strain MeO HO 7' OMe 6' 5' 1' 8' OH 9' OH 2' 4' 3' MeO OMe OH DV10: Polystachyol Antimicrobial activity against A niger (MIC = 50 g/ml) 17 DV18: Kaempferol 3-rutinoside Antimicrobial activity against Fusarium oxysporum (MIC = 50 g/ml) DV19: (6S, 7E, 9R)-6,9-Dihydroxy-4,7megastiymadien- 3-one 9-O-[α-Larabinopyranosyl-(l→6)-β-Dglucopyranoside] Antimicrobial activity against Fusarium oxysporum (MIC = 50 g/ml) BCW4: Pinoresinol-4-O--D-glucoside Antimicrobial activity against Fusarium oxysporum (MIC = 50 g/ml) 3.5.2 Evaluation results of cytotoxic activity In the initial experiments, cytotoxic activity of compounds: BCW1, BCW3, BCW4, BCW5, BCW6, DV12, DV19, DV10, DV8A against two LU, KB cell lines was assessed Results showed that all of these compounds exhibited no cytotoxic activity on the selected cancer cell lines DV1 showed strong activity on all three cancer cell lines: KB (IC50 = 4.63 ± 0.08 μM), SK-Mel-2 (IC50 = 4.12 ± 0.1 μM) and LU (IC50 = 3.20 ± 0.07 μM) 3.6 Conservative solution scenarios for mangrove ecosystems in Xuan Thuy National Park and use of promising species 3.6.1 Conservative solution scenarios for mangrove ecosystems in Xuan Thuy National Park 3.6.1.1 Impacts of climate change and human on mangrove ecosystem - Storm, tides have been losing the area of mudflats, mangroves, casuarina forests - Cold and bad weather caused some mangroves to degrade and die - Stellate barnacle makes the mangrove grow and develop poorly - Pressure from increasing population in 05 communes of the buffer zone - Change the use of water surface, tidal flat - Intrusion of induced species - Management and conservation activities are inadequate 3.6.1.2 Conservative solution scenarios for mangrove ecosystems - Strengthening law enforcement - Training for locals and related parties - Promoting the work of scientific research and international cooperation - Implementing mangrove forest co-management in the buffer zone - Building sustainable alternative livelihood models - Selected mangrove species researching suitable for the area 3.6.2 Proposed use for promising biological activity species 3.6.2.1 Promising biological activity species The initial results of the antimicrobial activity assay and cytotoxic activity of plant samples collected in Xuan Thuy National Park showed that there were 14 active plant samples 18 including plant samples are resistant to antimicrobial activity assay is Ipomoea pes-caprae, Suaeda maritima, Hibiscus tiliaceus There are seven plant samples showed cytotoxic activity which is Annona glabra, Vitex rotundifolia, Derris trifoliate Lour., Sauropus bacciformis, Kandelia candel, Lumnitzera racemosa, Pluchea pteropoda, and four plant samples were both the antimicrobial activity assay and cytotoxic activity, which can be considered as a basis for the proposed use, conservation, development as well as orientation for subsequent mangrove studies in Xuan Thuy National Park, are Excoecaria agallocha, Sonneratia caseolaris, Rhizophora stylosa Griff., Aegiceras corniculatum (L.) Blanco 3.6.2.2 Proposed use for promising biological activity species a Rhizophora stylosa Griff Rhizophora stylosa Griff belongs to Rhizophoraceae, which been studied extensively in terms of its chemical composition, biological activity, natural abundance, growth and distribution, suitable with the new compound DV1, having good cytotoxic activity on both test cancer lines, is a promising prospect of medicine Therefore, the species has been selected for use  Morphological, biological and ecological characteristics Morphological characteristics: Mangrove trees, 2.5 - m high, stem diameter up to cm Single leaf, opposite; thick blade, oval 10-12 x 6-8 cm, pointed tip, leafy edges, faint veins, petioles 1,5-2 cm; 2-3 cm in length Cyme inflorescence has 3-4 cm in length peduncle including 5-8 flowers The receptacle has four short lobes; petals; stamens; fruit sepal with 40 cm long fruit peduncle The level of exploitation for research and medicine (mainly branches, leaves and fruits exploitation) neither affect the conservation status of the species nor the environment and ecological balance Biological, ecological characteristics and appropriate harvesting time: This is the main mangrove species in Xuan Thuy National Park Plants flowering in May 3-5, fruiting in May 5-8 The best time to harvest is after the flower-fruit season, from September to February of the following year in order not to affect the reproducibility of the species  Distribution and conservation status: In the world: The species is widely distributed from Myanmar, Thailand, Malaysia, Indonesia, the Philippines, China to Papua New Guinea and Australia According to the IUCN Red List (2010), this species is classified as Least Concern (LC) Species not listed in the Annex to forbidden species, restricted to international trade and exploitation for commercial purposes under the Convention on Endangered Species of Wild Fauna and Flora (CITES) Due to its fast growing characteristics and adaptation to a variety of different mangrove conditions, this species is well-known for its mangroves in many countries and territories This species is either threatened or extinction in the world In Vietnam: Species distributed along the coast of Quang Ninh (Mong Cai, Tien Yen) to Khanh Hoa and Ba Ria - Vung Tau (Con Dao) Species not listed in Vietnam Red Book (2007); Not listed in the Annex of Decree 32/2006-CP of the Government on management of endangered and rare forest fauna and flora; Not listed in Circular 40/2013 / TT-BNNPTNT on the promulgation of the list of wild fauna and flora species specified in the annexes of the 19 Convention on International Trade in Wild Fauna and Flora emergency This species was selected as the most popular mangrove forest in Vietnam This species is either threatened or extinction in Vietnam  Species value in use: In Vietnam, previously, the species was exploited for timber (large trees) to build the boat; harvest tannins for tanning Currently, due to the conservation, there are no longer encounters for timber and cork based products for these purposes There is no record of drug exploitation of this species in Vietnam  Chemical composition and biological activity: Nine compounds are isolated from Rhizophora stylosa Griff In Xuan Thuy National Park including a new compound Rhizophora stylosa Griff collected in Xuan Thuy National Park has antimicrobial activity assay on Gr (+) Bacillus subtillis and Aspergillus niger with MIC= 200 g/ml This species also exhibited cytotoxic activity on both KB and LU test cell lines For cleanly isolated coumpounds, DV10, DV18, DV19 compounds have antimicrobial activity assay DV1 showed strong activity on all three test cell lines KB, SK-Mel-2 and LU From the results of this study, Rhizophora stylosa Griff in Xuan Thuy National Park has medicinal prospects  Distribution and reserve in Xuan Thuy National Park : Rhizophora stylosa Griff is only distributed in the mangrove at Con Lu area (Nut beach) and planted at the Mangrove Research Center Although growing well in the study area, the density of this species is low (400 trees / ha) According to the results, the average biomass of the species recorded in the survey in April 2016 was 8.55 tons/ha in Xuan Thuy National Park Therefore, solutions should be taken to plant Rhizophora stylosa Griff in the mudflats to increase the density and stock of species in Xuan Thuy National Park, thereby ensuring the ability to exploit and use sustainably  Appropriate havesting methods: - Parts can be exploited: in order to exploit for the purpose of research and medicine not affect the conservation status as well as the environment and ecological balance, should focus on exploiting branches, fruit - The appropriate harvesting time: In order not to affect the reproductive ability of the species, the best time to harvest is after the flower-fruit season, from September to February of the following year b Aegiceras corniculatum (L.) Blanco Scientific name: Aegiceras corniculatum (L.) Blanco, belongs to Myrsinaceae  Morphological, biological and ecological characteristics: Morphological characteristics: shrub or small wood, - m high, single or branched, grows into shrub with 30-50 branches, dark gray cork Single leaf, alternate; - 10 x - cm oval leaf blade, rounded or slightly conical, spherical and slightly curved, lower leaflets with small points Umbel inflorescence in leaf axillary or shoot top Flowers are white, fragrant; The petals form the tube at the bottom; five lobes, up to 1.5 cm long Cylindrical capsules, pointed, straight or slightly crescent shaped, - cm long Seed - cm long 20 Biological and ecological characteristics: In Xuan Thuy National Park, plants flowering in November to March next year, fruiting in May - Plants are real mangrove vegetation  Distribution and conservation status: In the world: This species is distributed in many countries such as India, China, Cambodia, Malaysia, Singapore, Australia and Vietnam According to the IUCN Red List (2010), this species is classified as Least Concern (LC) Species not listed in the Annex to Species forbidden, restricted to international trade and exploitation for commercial purposes under the Convention on Endangered Species of Wild Fauna and Flora (CITES) Due to its fast growing characteristics and adaptation to a variety of different mangrove conditions, this species is well-known for its mangroves in many countries and territories This species is not threatened with extinction In Vietnam: Aegiceras corniculatum (L.) Blanco trees grow into low forest, in salty beaches in coastal mud from Quang Ninh, Hai Phong, Nghe An, Quang Binh to Khanh Hoa, Ninh Thuan, Ho Chi Minh City, Tien Giang Besides, this species encountered in the mainland in Lao Cai, Hoa Binh This species is not listed in Vietnam Red Book (2007), Annex of Decree 32/2006 / CP of the Government on management of endangered and rare forest fauna and flora and Circular 40/2013/ TT-BNNPTNT on the promulgation of the list of wild fauna and flora species specified in the annexes of the Convention on International Trade in Wild Fauna and Flora emergency This species was selected as the most popular mangrove forest in Vietnam This species is not threatened with extinction in Vietnam  Species value in use: Plants have the effect of protecting coastal dykes The cork or leaves use to cook mouthwash to treat goiter in some areas  Chemical composition and biological activity: Within the framework of the dissertation, the chemical composition of Aegiceras corniculatum (L.) Blanco has not been researched According to author Vo Van Chi in the Vietnamese Medicinal Herbs Dictionary, the cork contains 7-8% saponins, a few resins, a rubber-like substance and a crystalline compound; it has been isolated from the genin coat A and isorhamnitin Fruits and leaves contain saponins, in fruit is 1.5%, in leaves is 0.5% According to the results of the thesis, the extract of MeOH of Aegiceras corniculatum (L.) Blanco collected in Xuan Thuy National Park exhibiting cytotoxic activity on two KB cell lines, LU with IC50 values of 4.77 mg/ml and 1.28 mg/ml  Distribution and reserve in Xuan Thuy National Park : Aegiceras corniculatum (L.) Blanco is distributed in the mangrove of Con Lu and Con Ngan in Xuan Thuy National Park Despite the negative effects of extreme weather phenomena, the population of S Aegiceras corniculatum (L.) Blanco grows and develops well in the research area Among six typical mangrove vegetation communities of Xuan Thuy National Park have been studied, species appear in five communities Along with K candel, Aegiceras corniculatum (L.) Blanco is one of the two most important mangrove species with density, biomass and largest acreage in Xuan Thuy National Park This has ensured the ability to exploit for the purpose of research and medicine 21  Appropriate havesting methods: - Parts can be exploited: in order to exploit for the purpose of research and medicine not affect the conservation status as well as the environment and ecological balance, should focus on exploiting branches, fruit - The appropriate harvesting time: In order not to affect the reproductive ability of the species, the best time to harvest is after the flower-fruit season, from September to October every year  Recommendations: Aegiceras corniculatum (L.) Blanco in Xuan Thuy National Park have high density and acreage is quite large so it can fully meet the exploitation for research and use purposes Therefore, at this time, only focus on the care and protection solutions for the current Aegiceras corniculatum (L.) Blanc population CONCLUSIONS AND RECOMMENDATIONS CONCLUSIONS - The number of medicinal plant species in Xuan Thuy National Park is quite plentiful Initially 116 species, 101 genera, 42 families of Magnoliophyta and Tracheophyta were recorded Magnoliophyta dominates with 93.97% of all species in the research area - The vascular plants of Xuan Thuy National Park characterized by tropical factors (32.76%); followed by tropical and inter-tropical factors accounting for 16.38%; Indochina factor 7.76%; endemicity of Vietnam accounts for 1.76% with species; Hainan - Taiwan - The Philippines with the lowest rate of species (0.86%) - There are 11 groups of vegetative resources have been identified with 108 species of plant species, of which the group of medicinal plants account for the largest proportion (46.76%), followed by the group of edible plants (13.42 %); the lowest was the group of handicraft (0.92%) There is only one rare species for conservation value which is Scirpus kimsonnensis N.K.Khoi This species is not only endemic to Vietnam but also listed in the Vietnam’s Red Data Book and classified as endangered species - There are typical mangrove communities were identified in Xuan Thuy National Park and described the structure and biomass - Data were recorded at the last survey in April 2016 - Antimicrobial activity assay expurgation was proceeded on eight strains of antimicrobial activity assay, and cytotoxic activities was conducted on two LU and KB cell lines for 22 samples collected The results show that there are 14 biologically active plants including samples Excoecaria agallocha, Sonneratia caseolaris, Rhizophora stylosa Griff have both antimicrobial activity assay and cytotoxic Sonneratia caseolaris strongly cytotoxic on both LU and KB cell lines - Chemical compounds from Sonneratia caseolaris, Rhizophora stylosa Griff were analyzed There are nine chemical compounds were isolated including a new compound is named Rhizostyloside from Rhizophora stylosa Griff., and 13 chemical compounds were isolated from Sonneratia caseolaris 22 Among compounds isolated from Sonneratia caseolaris, there is only one compound has antimicrobial activity assay was BCW4 resist to the Fusarium oxysporum with MIC = 50 g/ml Three compounds from Rhizophora stylosa Griff have antimicrobial activity assay are DV10 resist to A niger with MIC = 50 g/ml Both DV18 and DV19 resist to Fusarium oxysporum with MIC = 50 μg / ml The new DV1 is isolated from the Rhizophora stylosa Griff showed good cytotoxic activity on all three cancer cell lines tested: KB (IC50 = 4.63 ± 0.08 μM), SK-Mel-2 IC50 = 4.12 ± 0.1 μM) and LU (IC50 = 3.20 ± 0.07 μM) - A number of factors have been identified for mangrove ecosystems in Xuan Thuy National Park and six specific solutions have been proposed to conserve mangrove ecosystems - Two promising species of biological activity have been identified are Rhizophora stylosa Griff and Aegiceras corniculatum (L.) Blanco, suggesting the usage in order to contribute to the preservation and development of valuable mangrove vegetation in Xuan Thuy National Park RECOMMENDATIONS - A number of plant communities in Xuan Thuy National Park, particularly K candel community in Con Ngan, are showing signs of diminished density; therefore, it is necessary to take solutions to rehibilitate and protect such as lopping densely populated areas to facilitating the regeneration of trees, planting new species of mangrove plants that are well adapted to swamp - The mangrove vegetation in Xuan Thuy National Park has many promising biological activities, especially A corniculatum with very impressive cytotoxic activity results that need to be further studied on chemical composition and biological activity - The DV1 compound, Rhizostyloside isolated from R stylosa showed highly active on three cancer strains KB, LU, SK-Mel-2 needs to be tested deeply on biological activity for ability of killing cancer cells in vivo contributing to the medical value of R stylosa NEW CONTRIBUTIONS OF THE DISSERTATION - Thai Van Trung method was used to classify typical mangrove plant communities in Xuan Thuy National Park This carpet type have communities: The K candel community; The K candel, S caseolaris, A corniculata, R stylosa community; The mangrove community of K candel, A corniculata participate but have not advantage; The mangrove community of A corniculata, K candel participate but have not advantage; The A corniculata, S caseolaris, K candel community; The community of A corniculata, S caseolaris, K candel participate in low density Provided data on the chemical composition and biological activities of Sonneratia caseolaris, Rhizophora stylosa There are nine chemical compounds were isolated including a new compound is named Rhizostyloside from Rhizophora stylosa Griff., and 13 chemical compounds were isolated from Sonneratia caseolaris There is only one compound has antimicrobial activity assay was BCW4 and three compounds from Rhizophora stylosa Griff have antimicrobial activity assay are DV10, DV18, DV19 23 The new compound DV1 is isolated from the Rhizophora stylosa Griff showed good cytotoxic activity on all three cancer cell lines tested: KB, SK-Mel-2 and LU Two promising species of biological activity have been identified are Rhizophora stylosa Griff and Aegiceras corniculatum (L.) Blanco, suggesting the usage in order to contribute to the preservation and development of valuable mangrove vegetation in Xuan Thuy National Park 24 LIST OF PUBLICATION RELATED TO THE THESIS Phan Thi Thanh Huong, Chau Ngoc Diep, Nguyen Van Thanh, Vu Anh Tu, Tran Hong Hanh, Nguyen The Cuong, Nguyen Phuong Thao, Nguyen Xuan Cuong, Do Thi Thao, Tran Huy Thai, Nguyen Hoai Nam, Ninh Khac Ban, Phan Van Kiem and Chau Van Minh, A New Cycloartane Glucoside from Rhizophora stylosa, Natural Product Communications, 2014, 9(9), 1255-1257 Phan Thi Thanh Huong, Tran Huy Thai, Nguyen The Cuong, Tran Thi Phuong Anh, Nguyen Hoai Nam, Contribute to study the current structure of mangrove plant communities in Xuan Thuy National Park, Nam Dinh, Vietnam Jounal of Biology, 2014, 36(3), 330-335 Phan Thi Thanh Huong, Nguyen Van Thanh, Chau Ngoc Diep, Nguyen The Cuong, Nguyen Xuan Cuong, Nguyen Hoai Nam, Tran Huy Thai, Phan Van Kiem, Chau Van Minh, Five lignans from the mangrove Rhizophora stylosa Griff., Vietnam Jounal of Chemistry, 2015, 53(2e), 42-47 Phan Thi Thanh Huong, Nguyen Van Thanh, Chau Ngoc Diep, Nguyen Phuong Thao, Nguyen The Cuong, Nguyen Xuan Cuong, Nguyen Hoai Nam, Chau Van Minh, Antimicrobial compounds from Rhizophora Stylosa, Vietnam Jounal of Science and Technology, 2015, 53(2), 205-210 Pham Thi Mai Huong, Nguyen Van Thanh, Phan Thi Thanh Huong, Nguyen The Cuong, Chau Ngoc Diep, Vu Anh Tu, Tran Thi Hong Hanh, Nguyen Phuong Thao, Nguyen Xuan Cuong, Nguyen Hoai Nam, Phan Van Kiem, Chau Van Minh, Flavonoids from Sonneratia caseolaris L.), Vietnam Jounal of Science and Technology, 2014, 52 (5B), 403 – 409 Pham Thi Mai Huong, Nguyen Van Thanh, Phan Thi Thanh Huong, Ninh Thi Ngoc, Chau Ngoc Diep, Vu Anh Tu, Tran Thi Hong Hanh, Le Thi Vien, Nguyen Xuan Cuong, Nguyen Hoai Nam, Chau Van Minh, Initial research on the chemical composition of Sonneratia caseolaris L., Proceedings of national conference on marine biology and sustainable development in Vietnam II, 2014, 659 – 665 ... (L.) Engl and Rhizophora stylosa Griff from Xuan Thuy National Park - Propose sustainable usage on mangrove vegetation which have biological activities in Xuan Thuy National Park 2.3 Research. .. Xuan Thuy National Park 3.2.1 Classification of carpet mangroves in Xuan Thuy National Park According to T.V Trung (1978) and N.N Thin (2004), typical carpet mangroves in Xuan Thuy National Park. .. mangrove vegetation which have biological activities in Xuan Thuy National Park and propose sustainable usage The meaning of dissertation topic  Scientific significance This dissertation contributed