This article was downloaded by: [JAMES COOK UNIVERSITY] On: 16 March 2015, At: 09:23 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Natural Product Research: Formerly Natural Product Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gnpl20 New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P V a b a a Tan Phat Nguyen , Thi Thao Vy Tran , Dinh Tri Mai , Tien Dung Le , a a Nhat Minh Phan & Trong Dat Bui a Institute of Chemical Technology, Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam b University of Technology, Vietnam National University, Ho Chi Minh City, Vietnam Published online: 04 Feb 2015 Click for updates To cite this article: Tan Phat Nguyen, Thi Thao Vy Tran, Dinh Tri Mai, Tien Dung Le, Nhat Minh Phan & Trong Dat Bui (2015): New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P V., Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2014.1003300 To link to this article: http://dx.doi.org/10.1080/14786419.2014.1003300 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content This article may be used for research, teaching, and private study purposes Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden Terms & Downloaded by [JAMES COOK UNIVERSITY] at 09:23 16 March 2015 Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions Natural Product Research, 2015 http://dx.doi.org/10.1080/14786419.2014.1003300 New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P V Tan Phat Nguyena*, Thi Thao Vy Tranb, Dinh Tri Maia, Tien Dung Lea, Nhat Minh Phana and Trong Dat Buia Downloaded by [JAMES COOK UNIVERSITY] at 09:23 16 March 2015 a Institute of Chemical Technology, Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam; bUniversity of Technology, Vietnam National University, Ho Chi Minh City, Vietnam (Received 20 November 2014; final version received 27 December 2014) OH 11 20 H HO 12 13 10 14 17 16 18 15 H COOH COOH 19 From the leaves of Schefflera sessiliflora De P V., one new C20-gibberellin diterpene 2b,12b-dihydroxygibberellin (12b-hydroxy-GA110 or 2b-hydroxy-GA112) (1), together with three known compounds, trans-tiliroside (2), kaempferol 3-O-b-D glucuronopyranoside (3), 5-p-trans-coumaroylquinic acid (4), was isolated for the first time from the genus Schefflera by various chromatography methods Their structures were elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and comparison with previous reported data The a-glucosidase inhibitory activity of all compounds was measured The isolates (2, 3) showed better a-glucosidase inhibitory activity (IC50 ¼ 134.60, 147.10 mM, respectively) than the standard drug acarbose (IC50 ¼ 214.50 mM) Keywords: Schefflera sessiliflora De P V.; Araliaceae; gibberellin; diterpene; a-glucosidase inhibition Introduction Schefflera is a large genus of the Araliaceae family with over 650 species (Hebbar & Nalini 2014), of which 56 species are found in Vietnam (La et al 2013) Phytochemical studies on plants in the Schefflera genus, such as Schefflera abyssinica (Tapondjou et al 2006), Schefflera actinophylla (Wanas et al 2010), Schefflera leucantha (Pancharoen et al 1994) and so on, showed that the principal components of the leaves were triterpene and triterpene-saponin Schefflera sessiliflora De P V (Araliaceae) is a new species in Vietnam, it was discovered and identified in 2004 (Nguyen et al 2004) Pharmacological extracts from this species possessed antistress activity, enhanced physical strength effects (Nguyen et al 2004; Huynh et al 2005); *Corresponding author Email: ntphat@ict.vast.vn or phat_nguyentan88@yahoo.com q 2015 Taylor & Francis T.P Nguyen et al Downloaded by [JAMES COOK UNIVERSITY] at 09:23 16 March 2015 antioxidant activity using DPPH assay and MDA test (Vo et al 2008) and androgenic effects (Tran et al 2012) Sapogenins oleanolic acid and hederagenin were isolated from the hydrolysis product of the total saponins (Vo et al 2003, 2004) In an earlier paper, two new triterpene saponins from the leaves of this species were reported (Nguyen et al 2015) This paper describes the isolation and structure elucidation of one new diterpene (1) and three known compounds (2 –4) which were isolated for the first time from the genus Schefflera; and a-glucosidase inhibitory activity of all isolates were evaluated from S sessiliflora De P V growing in Vietnam Results and discussion The EtOAc extract from the dried leaves of S sessiliflora De P V was subjected to column chromatography over silica gel normal-phase and reversed-phase RP-18 to give one new compound (1), and three known compounds (2 –4) Compound was obtained as pale yellow needles The molecular formula was established as C20H28O6 by high-resolution electrospray ionisation mass spectroscopy (HR-ESI-MS) data (m/z 363.1818 [M –H]2, calcd 363.1808) The 1H NMR data of revealed a pair of doublets of an AB system at dH 2.01 (d, J ¼ 12.0 Hz, H-5), 3.43 (d, J ¼ 11.5 Hz, H-6) characteristic of typical resonances of a trans relationship between H-5 and H-6 in a gibberellin framework (Fraga et al 2013); two olefinic protons at dH 5.04 (br s, H-17a) and 5.00 (br s, H-17b) characteristic of an exocyclic methylene group; and two tertiary methyl groups at dH 1.20 (s, H-18), 0.91 (s, H-20) The 13C NMR and DEPT spectrum showed has 20 carbons including carbonyl carbons, olefinic carbon, exocyclic methylene carbon, oxygenated methine carbons, quaternary carbons, methine carbons, methylene carbons and tertiary methyl carbons The presence of two tertiary methyl groups, one olefinic carbon at dC 149.4 (C-16), one exocyclic methylene carbon at dC 109.5 (C-17); and two carbonyl carbons at dC 179.8 (C-7) and 180.2 (C-19) indicated a C20-gibberellin diterpene as an aglycone The HMBC spectrum (Figure S1A) showed four protons at dH 2.45 (dd, J ¼ 4.0, 13.0 Hz, H-3a), 1.04 (t, J ¼ 12.0 Hz, H-3b), 1.99 (dd, J ¼ 4.0, 13.0 Hz, H-1a), 0.87 (t, J ¼ 11.5 Hz, H-1b) correlated with an oxygenated methine carbon at dC 66.0 (C-2); so, hydroxyl group was attached to C-2 In addition, two methine protons at dH 1.61 (d, J ¼ 10.5 Hz, H-9), 2.60 (br s, H-13) correlated with oxygenated methine carbon dC 73.4 (C-12) Beside, the ROESY spectral data of (Figure S1B) indicated that the methyl tertiary protons (H-20), a-type, were close in space to two oxygenated methine protons (H-2 and H-12) and the methine proton (H-6) Thus, protons H-2 and H-12 were a-type; and two hydroxyl groups of these carbons were b-type Based on data of IR, UV, HR-ESI-MS, 1D, 2D NMR and compared with previous published data (Mander et al 1996; Owen et al 1998), the structure of was identified as 2b,12b-dihydroxygibberellin (12b-hydroxy-GA110 or 2b-hydroxy-GA112) The structures of the three known compounds (2 –4) (Figure 1) were established, due to spectroscopic analysis (HR-ESI-MS and NMR) and compared with the reported values, as kaempferol 3-O-[600 -O-( p-trans-coumaroyl)]-b-D -glucopyranoside (trans-tiliroside) (2) (Timmers & Urban 2012), kaempferol 3-O-b-D -glucuronopyranoside (3) (Mostafa et al 2014) and 5-p-trans-coumaroylquinic acid (4) (Lu et al 2000) All compounds – were evaluated for their inhibitory activity against enzyme a-glucosidase (Table S1) Isolates and showed significantly better inhibitory (IC 50 ¼ 134.60, 147.10 mM, respectively) than the standard drug acarbose (IC50 ¼ 214.50 mM), while compounds and did not exhibit inhibitory activity One new C20-gibberellin diterpene (1), together with three known compounds (2 –4), was isolated from the ethyl acetate extract of the dried leaves of S sessiliflora De P V This work described for the first time the presence of these compounds (2 –4) from the genus Schefflera Their structures were elucidated by intensive spectroscopic and spectrometric analyses Natural Product Research 3' OH 11 20 H HO 10 1''' H 8''' H 9''' 4'' COOH Downloaded by [JAMES COOK UNIVERSITY] at 09:23 16 March 2015 O O 2'' 3'' O 5'' HO O HO 19 10 OH O 6'' 7''' 6''' 15 H COOH 18 6 5' 6' 5''' 17 16 1' 3''' 2''' 14 O 9 4''' 13 HO HO 12 OH 4' 2' 1'' OH 3' OH 4' 2' O HO O 1' 5' H 6' O 10 4'' HO HO 3'' O 1'' OH 2' 3' OH OH 1' 5' HOOC 2'' 6' 7' 5'' 8' H O O OH HOOC 6'' 9' 4' OH OH Figure Structure of compounds – Compounds and showed better inhibitory potential (IC50 ¼ 134.60, 147.10 mM, respectively) than the standard drug acarbose; and trans-tiliroside (2) was the most active Experimental 3.1 General experimental procedures The HR-ESI-MS was recorded on a Bruker MicrOTOF-QII spectrometer (Karlsruhe, Germany), University of Science (National University, Ho Chi Minh City, Vietnam) The 1H NMR (500 MHz), 13 C NMR (125 MHz), DEPT, COSY, HSQC and HMBC spectra were recorded on a Bruker AM500 FT-NMR spectrometer (Karlsruhe, Germany) using tetramethylsilane as internal standard, Institute of Chemistry (Vietnam Academy of Science and Technology, Hanoi, Vietnam) Column chromatography was carried out using Merck (Darmstadt, Germany) Silica gel normal-phase (230– 240 mesh) and reversed-phase C18 (Merck, Darmstadt, Germany) Analytical TLC was carried out in silica gel plates (Merck DC-Alufolien 60 F254) Compounds were visualised by spraying with aqueous 10% H2SO4 and heating for 3–5 3.2 Plant material The leaves of S sessiliflora De P V were provided by Center Cultivation and Processing of Medicinal Plants Da Lat, No 18 Hoang Van Thu Street, Da Lat city, Vietnam in July 2013 and identified by Dr Phan Van De – Department of Medicinal Resources, The Research Center of Ginseng and Medicinal Materials, Ho Chi Minh City, Vietnam A voucher specimen (No SS- T.P Nguyen et al Downloaded by [JAMES COOK UNIVERSITY] at 09:23 16 March 2015 126) was deposited in the Bioactive Compounds Laboratory, Institute of Chemical Technology, Vietnam Academy of Science and Technology, Vietnam The leaves were collected, washed, dried and powdered 3.3 Extraction and isolation The powder of the leaves of S sessiliflora De P V (5 kg) was extracted with 96% EtOH (v/v), residue was filtered, solvents were removed under low pressure and finally a crude extract was obtained (890 g) Then, the crude extract was suspended in distilled water and then extracted with n-hexane and ethyl acetate, and respective extracts were obtained The EtOAc extract (15 g) was applied to silica gel normal phase using gradient mixtures of n-hexane –EtOAc –MeOH (50:50:0, 25:75:0, 0:100:0, 0:90:10, 0:80:20, v/v) to yield five major fractions (I – V), respectively Fraction III (6 g) was eluted with CHCl3 – MeOH (95:5 ! 75:25, v/v), then purified by RP-18 to give (12 mg), (30 mg), (20 mg) and (42 mg) 3.3.1 2b,12b-dihydroxygibberellin (1) Pale yellow needles (MeOH); ẵa25 D ỵ 141 (c ẳ 0.35, MeOH); IR (KBr) y max: 3434, 2921, 1714, 1660, 1025 cm21; UV (MeOH) lmax: 204 nm; HR-ESI-MS m/z 363.1818 [M –H]2, Calcd for C20H27O6, 363.1808 1H NMR (CD3OD, 500 MHz, J in Hz): 1.99 (dd, J ¼ 4.0 and 13.0, H-1a), 0.87 (t, J ¼ 11.5, H-1b), 4.19 (m, H-2), 2.45 (dd, J ¼ 4.0 and 13.0, H-3a), 1.04 (t, J ¼ 12.0, H-3b), 2.01 (d, J ¼ 12.0, H-5), 3.43 (d, J ¼ 11.5, H-6), 1.61 (d, J ¼ 10.5, H-9), 1.80 (m, H-11a), 1.50 (m, H-11b), 3.80 (ddd, J ¼ 3.5, 7.5 and 10.5, H-12), 2.60 (br s, H-13), 1.80 (m, H-14), 2.24 (d, J ¼ 15.5, H-15a), 2.18 (d, J ¼ 15.5, H-15b), 5.04 (s, H-17a), 5.00 (br s, H-17b), 1.20 (br s, H-18), 0.91 (s, H-20) 13C NMR (CD3OD, 125 MHz): 49.0 (C-1), 66.0 (C-2), 48.0 (C-3), 45.0 (C-4), 59.8 (C-5), 50.5 (C-6), 179.8 (C-7), 52.0 (C-8), 58.8 (C-9), 45.9 (C-10), 27.9 (C-11), 73.4 (C-12), 49.0 (C-13), 43.7 (C-14), 47.0 (C-15), 149.4 (C-16), 109.5 (C-17), 28.5 (C-18), 180.2 (C-19), 16.3 (C-20) 3.4 a-Glucosidase inhibition assay The inhibitory activity of a-glucosidase was determined according to the modified method of Kim et al (2008) Acarbose was used as a positive control Supplementary material Supplementary material relating to this paper is available online, alongside Table S1 and Figures S1 –S9 References Fraga BM, Gonza´lez-Vallejo V, Bressa C, Guillermo R, Sua´rez S 2013 Gibberellin analogues by reaction of 7-oxoditerpenes with diacetoxyiodobenzene Tetrahedron 69:3002–3012 Hebbar DR, Nalini MS 2014 Evaluation of phytochemicals, total phenolics and antioxidant activities of Schefflera spp (Araliaceae) from southern India J Pharmacogn Phytochem 2:10–14 Huynh NT, Phan KL, Nguyen PD, Tran CL 2005 Studies on the effects of enhancing physical strength and antistress from the leaves of three Schefflera species as well as their combinative effects with red ginseng on mice J Med Hochiminh City 9:91–95 Kim KY, Nam KA, Kurihara H, Kim SM 2008 Potent a-glucosidase inhibitors purified from the red alga Grateloupia elliptica Phytochemistry 69:2820–2825 La DM, Chau VM, Tran VS, Pham QL, Phan VK, Tran HT, Tran MH, Ninh KB, Le MH 2013 Prospects of natural bioactive products from Araliaceae Juss Family in Vietnam Proceeding of the 5th National Conference on Ecology and Biological Resources Hanoi: Agriculture Publishing House p 1152–1158 Downloaded by [JAMES COOK UNIVERSITY] at 09:23 16 March 2015 Natural Product Research Lu Y, Sun YL, Foo Y, McNabb WC, Molan AL 2000 Phenolic glycosides of forage legume Onobrychis viciifolia Phytochemistry 55:67–75 Mander LN, Owen DJ, Croker SJ, Gaskin P, Hedden P, Lewis MJ, Talon M, Gage DA, Zeevaart JAD, Brener ML, Sheng C 1996 Identification of three C20-gibberellins: GA97 (2b-hydroxy-GA3), GA98 (2b-hydroxy-GA44) and GA99 (2b-hydroxy-GA19) Phytochemistry 43:23–28 Mostafa FA, Gamal MA, Sabrin IRM, Ehab ES 2014 Antioxidant and anti-inflamatory activities of phenolic constituents from Primula elatior L aerial part Int J Pharmacogn Phytochem Res 6:74–78 Nguyen TP, Le TVH, Mai DT, Le TD, Phan NM, Bui TD 2015 Two new oleanane-type triterpene saponins from the leaves of Schefflera sessiliflora De P.V Phytochem Lett 11:102– 105 Nguyen TTH, Nguyen TC, Do MA, Tran CL, Nguyen PD 2004 Studies on the combinative effects of the leaves of three Schefflera species (Araliaceae) with red ginseng on the effects of enhancing physical strength and antistress J Med Hochiminh City 8:151–155 Owen DJ, Mander LN, Storey JMD, Huntley RP, Gaskin P, Lenton JR, Gage DA, Zeevaart JAD 1998 Synthesis and confirmation of structure for a new gibberellin, 2b-hydroxy-GA12 (GA 110), from spinach and oil palm Phytochemistry 47:331–337 Pancharoen O, Tuniwachwuttikul P, Taylor WC, Picker K 1994 Triterpenoid glycosides from Schefflera leucantha Phytochemistry 35:987–992 Tapondjou LA, Mitaine-Offer AC, Miyamoto T, Lerche H, Mirjolet JF, Guilbaud N, Lacaille-Dubois MA 2006 Triterpene saponins from Schef?era abyssinica Biochem System Ecol 34:887–889 Timmers M, Urban S 2012 On-line (HPLC-NMR) and off-line phytochemical profiling of the Australian plant, Lasiopetalum macrophyllum Nat Prod Commun 7:551–560 Tran MT, Dang TTN, Tran CL, Nguyen TTH 2012 Study on androgenic effect of Schefflera sp3 J Med Mater – Hanoi 17:17–23 Vo DH, Nguyen TTH, Tran CL, Huynh TCH 2008 Study on the chemistry and in vitro antioxidant activity of saponin from Schefflera sp3 J Med Mater – Hanoi 13:17–21 Vo DH, Tran CL, Duong HTQ 2003 Survey characteristics and preliminary study of the chemical composition of leaves, stems and roots of Schefflera sp3 J Med Mater – Hanoi 6:17–21 Vo DH, Tran CL, Duong HTQ 2004 Studies on saponin composition of Schefflera sp3 J Med Mater – Hanoi 9:46–50 Wanas AS, Matsunami K, Otsuka H, Desoukey SY, Fouad MA, Kamel MS 2010 Triterpene glycosides and glucosyl esters, and a triterpene from the leaves of Schefflera actinophylla Chem Pharm Bull 58(12):1596– 1601 ... saponins from the leaves of Schefflera sessiliflora De P.V Phytochem Lett 11:102– 105 Nguyen TTH, Nguyen TC, Do MA, Tran CL, Nguyen PD 2004 Studies on the combinative effects of the leaves of three Schefflera. .. activity One new C20-gibberellin diterpene (1), together with three known compounds (2 –4), was isolated from the ethyl acetate extract of the dried leaves of S sessiliflora De P V This work described... New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P V Tan Phat Nguyena*, Thi Thao Vy Tranb, Dinh Tri Maia, Tien Dung Lea, Nhat Minh Phana and Trong Dat Buia Downloaded