Optimisation of ultrasound assisted extraction conditions for antioxidant and tyrosinase inhibitory activities of some vietnamese brown seaweed species

MINISTRY OF EDUCATION AND TRAINING NHA TRANG UNIVERSITY HASSAN IYUNADE HASSANAT OPTIMISATION OF ULTRASOUND-ASSISTED EXTRACTION CONDITIONS FOR ANTIOXIDANT AND TYROSINASE INHIBITORY ACTIVITIES OF SOME VIETNAMESE BROWN SEAWEED SPECIES MASTER THESIS KHANH HOA – 2020 MINISTRY OF EDUCATION AND TRAINING NHA TRANG UNIVERSITY HASSAN IYUNADE HASSANAT OPTIMISATION OF ULTRASOUND-ASSISTED EXTRACTION CONDITIONS FOR ANTIOXIDANT AND TYROSINASE INHIBITORY ACTIVITIES OF SOME VIETNAMESE BROWN SEAWEED SPECIES MASTER THESIS Major: Food Technology Topic allocation Decision: Decision on establishing the Committee: Defense date: Supervisors: DR NGUYEN THE HAN DR HONG NGOC THUY PHAM Chairman of Committee: Faculty of Graduate studies: KHANH HOA – 2020 UNDERTAKING I undertake that the thesis titled: Optimisation of ultrasound-assisted extraction conditions for antioxidant and tyrosinase inhibitory activities of some Vietnamese brown seaweed species is my work The work has not been presented elsewhere for assessment until the time this thesis is submitted Hassan Iyunade Hassanat 31/08/2020 iii ACKNOWLEDGEMENT All glory to my maker, the one that has made all this possible Special thanks to VLIR-NETWORK, Vietnam, for providing me with a fully-funded scholarship to study in Vietnam I will love to extend my sincere gratitude to my supervisors Dr Nguyen The Han and Dr Thuy Pham, for their timeless advice and for guiding me throughout the course of working on this thesis Your immerse support will always be remembered Special thanks to my colleagues who made this two-year master program fun despite its being tasking I appreciate the members and staff of Nha Trang University and my good friends, Funmilola, Sabine, Mule for their constant support and encouragement I wish to thank the Research Fund of Khanh Hoa province for financial support (Project number: ĐT-2017-20902-ĐL) Finally, many thanks to my parents, Mr and Mrs Hassan I could never ask for better parents To my siblings, Fade and Fola, thanks for the unconditional support To an exceptional man, Ayo Thanks for being the sweetest iv TABLE OF CONTENT UNDERTAKING iii ACKNOWLEDGEMENT iv TABLE OF CONTENT v LIST OF ABBREVIATIONS viii LIST OF TABLES ix LIST OF FIGURES .x APPENDICES xii ABSTRACT xiii CHAPTER INTRODUCTION AND LITERATURE REVIEW .1 1.1 Introduction 1.1.1 Problem statement 1.1.2 Research questions 1.1.3 Hypothesis .3 1.1.4 Prediction .3 1.1.5 Main objectives 1.1.6 Specific objectives 1.1.7 Conceptual framework 1.2 Literature review 1.2.1 Seaweed 1.2.2 Seaweed in Vietnam .6 1.2.3 Brown seaweed 1.2.4 Major antioxidant constituents of brown seaweed 1.3 Tyrosinase 15 1.3.1 Role of tyrosinase in melanogenesis 16 1.3.2 Physiological roles of melanin 18 v 1.3.3 Common tyrosinase inhibitors 19 1.3.4 Potential Applications of Tyrosinase Inhibitors from Brown Seaweed 21 1.4 Extraction of bioactive compounds from seaweed 22 1.4.1 Ultrasound-assisted extraction (UAE) 23 1.4.2 Factors that affect UAE 23 1.4.3 Optimisation of UAE process 24 CHAPTER MATERIALS AND METHODS 25 2.1 Materials 25 2.2 Experimental design 25 2.2.1 Screening brown seaweed samples 25 2.2.2 Single factor test 25 2.2.3 Response surface methodology (RSM) 26 2.2.4 Preparation of crude extract and fractions 27 2.3.1 Total Phenolic Content (TPC) 29 2.3.2 Antioxidant activities 30 2.3.3 Tyrosinase inhibitory activity 31 2.3.4 Recovery yield 32 2.4 Statistical analysis 32 3.1 TPC and antioxidant capacity of five brown seaweed species 33 3.2 The effect of single factors on the TPC and antioxidant power of Padina australis extract 35 3.2.1 Influence of ultrasonic temperature 35 3.2.2 Influence of extraction time 35 3.2.3 Influence of solvent concentration 36 3.2.4 Influence of solid-to-solvent ratio 37 3.3 Modeling of the UAE process 39 3.4 Effect of extraction variables on experimental responses of TPC, DPPH and FRAP ……………………………………………………………………………… 43 vi 3.5 Optimisation and validation 45 3.6 Recovery yield, TPC, antioxidant and tyrosinase inhibitory activities of Padina australis crude extract and fractions 48 CHAPTER CONCLUSION AND RECOMMENDATION 51 4.1 Conclusion 51 4.2 Recommendation 51 REFERENCES 52 APPENDICES I vii LIST OF ABBREVIATIONS UAE : Ultrasound-assisted Extraction TPC : Total Phenol Content RSM : Response Surface Methodology DPPH : 2,2-Diphenyl-1-picrillhydrazyl FRAP : Ferric Reducing Antioxidant Power GAE : Gallic Acid Equivalent TE : Trolox Equivalent AAE : Ascorbic Acid equivalent DM : Dry Matter DD : Dry Fraction viii LIST OF TABLES Table 1.1 Polysaccharide content of some major brown seaweed 12 Table 3.1 The TPC and antioxidant capacity of five different brown seaweed species 34 Table 3.2 Influence of ultrasound temperature on the TPC and antioxidant capacity of Padina australis extract 36 Table 3.3 Effect of extraction time on the TPC and antioxidant capacity of Padina australis extract 37 Table 3.4 Effect of solvent concentration on the TPC and antioxidant capacity of Padina australis extract 38 Table 3.5 Effect of solid-to-solvent ratio on the TPC and antioxidant capacity of Padina australis extract 38 Table 3.6 Box-Behnken design and experimental results 40 Table 3.7 Analysis of variance for the determination of model adequacy (TPC, DPPH and FRAP) 43 Table 3.8 Results of regression analysis of experimental values for TPC, DPPH and FRAP 44 Table 3.9 Comparisons between two various ratios of sample to solvent for the selection of optimum UAE conditions 46 Table 3.10 Recovery yield (% w/w on a dry weight basis), TPC, antioxidant capacity and tyrosinase inhibitory activity of crude extract and fractions of Padina australis 50 ix LIST OF FIGURES Figure 1.1 Research conceptual framework Figure 1.2 Structure of some marine algae Figure 1.3 Common applications of seaweed (Sanjeewa & Jeon, 2018) Figure 1.4 Macroscopic appearance of freshwater brown seaweed (Wehr, 2015) Figure 1.5 Chemical structure of fucoxanthin (Abu-Ghannam & Shannon, 2017) Figure 1.6 Chemical structure of alginic 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Curve 1.20000 y = 0.0012x + 0.0172 R² = 0.9988 Absorbance (515nm) 1.00000 0.80000 0.60000 0.40000 0.20000 0.00000 100 200 300 400 500 600 Concentration (µg/ml) Appendix Standard curve for DPPH radical scavenging activity I 700 800 900 Standard Curve 2.000 y = 0.0023x + 0.0204 R² = 0.9981 1.800 Absorbance (593nm) 1.600 1.400 1.200 1.000 0.800 0.600 0.400 0.200 0.000 100 200 300 400 500 Concentration (µg/ml) Appendix Standard curve for FRAP II 600 700 800 900 a b Appendix (a) n-hexane fraction (b) ethyl acetate fraction Appendix Condensation in a rotavapor III Appendix Confirmation letter from the editorial office for the submitted manuscript to the Journal of Food Processing and Preservation (Under review) Appendix Cover letter of editorial for the submitted manuscript to the Journal of Food Processing and Preservation (Under review) IV ... OF EDUCATION AND TRAINING NHA TRANG UNIVERSITY HASSAN IYUNADE HASSANAT OPTIMISATION OF ULTRASOUND- ASSISTED EXTRACTION CONDITIONS FOR ANTIOXIDANT AND TYROSINASE INHIBITORY ACTIVITIES OF SOME VIETNAMESE. .. Does Vietnamese brown seaweed contain phenolics and possess antioxidant and tyrosinase inhibitory activities? What UAE optimisation condition is best for maximum yield of phenolics and antioxidant. .. LIST OF TABLES Table 1.1 Polysaccharide content of some major brown seaweed 12 Table 3.1 The TPC and antioxidant capacity of five different brown seaweed species 34 Table 3.2 Influence of ultrasound