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Secondary Metabolites and their Biological Activity from Marine Bio-resource

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Abstract
Natural products have long been used as foods, fragrances, pigment, insecticides, medicines, and so on. From 1970s, marine natural products have attracted the attention of biologists and chemists in the world. Marine organisms produce secondary metabolites that are structurally distinct from those produced by terrestrial organisms, possibly due to factors unique to marine environments such as high salinity, pressure and a relatively constant temperature. Unusual functional groups, such as isocyanate, isonitrile, dichloroimine, and halogenated functionalities, occur predominantly in marine metabolites. So far, approximately 16,000 have been isolated from marine organisms. Among the marine organisms, marine macro-algae, known as seaweeds are normally used as foods and crude drug in the Asian countries. In the recent years, many secondary metabolites have been isolated from marine macro-algae with interesting biological activities and potential beneficial effects. Furthermore, marine-derived fungi have proved to be a rich and promising source of novel bioactive natural products. Most of these microorganisms grow in a unique and extreme habitat and therefore have the capability to produce unique and unusual secondary metabolites.
Therefore, in this study, the chemical composition of the brown alga, Padina arborescens Holmes has been investigated. Three new glyceroglycolipid compounds (SQMG, OGG and NGG) and one known compound (POGG) were isolated from the CHCl3 and EtOAc fractions. The new compounds, SQMG, OGG and NGG showed higher cell growth inhibitory effects than POGG in HL-60 cancer cells. The treatments with SQMG, OGG and NGG could induce the apoptosis in HL-60 cells through up-regulation of BAX and caspase-3, down-regulation of Bcl-xL.
In order to develop the new marine bio-resource, we tried to isolate marine-derived fungi. Thirty six fungal strains were isolated from four types of marine samples. Most broth and mycelium extracts of marine fungi showed strong anti-oxidant activities against DPPH radical, especially the strains from Penicillium sp. and Eurotium sp. Several extracts exhibited inhibitory effects on NO production in LPS-stimulated RAW 264.7 cells without cytotoxicity. The extracts of an unidentified strain 013-1 exhibited highest cell growth inhibitory activity in HL-60 cells among all the isolated marine fungi.
The isolated marine-fungus, Eurotium amstelodami was selected as the target strain for research of natural products and their biological activities. Four compounds were isolated from broth extracts. Among them, asperflavin and questinol showed inhibitory effects of NO and PGE2 production in LPS-stimulated RAW 264.7 cells without cytotoxicity. They were also found to decrease the production of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). The mechanism of the potential anti-inflammatory effects of asperflavin and questinol may attribute to the suppression of iNOS. Therefore, our study suggests a potential use of these compounds might be selected as a promising agent for the prevention and therapy of inflammatory disease.
Author(s)
양수동
Issued Date
2012
Awarded Date
2012. 8
Type
Dissertation
URI
http://dcoll.jejunu.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000006006
Alternative Author(s)
Yang, Xiudong
Affiliation
제주대학교
Department
대학원 해양생물공학과
Advisor
전유진
Table Of Contents
SUMMARY VI
LIST OF FIGURES VIII
LIST OF TABLES XIV
INTRODUCTION 1

PART І - Isolation and Biological Activities of Secondary Metabolites from the Marine Brown Alga, Padina arborescens Holmes

ABSTRACT 13
1. MATERIALS AND METHODS 14
1.1. General materials 14
1.2. Plant materials 14
1.3. Extraction and isolation 16
1.4. Cell culture 20
1.5. Cell growth inhibitory assay 20
1.6. Nuclear staining with Hoechst 33342 21
1.7. Cell cycle analysis 21
1.8. Western blot analysis 22

2. RESULTS 23
2.1. Isolation of the active compound from marine brown alga, Padina arborescens Holmes 23
2.2. Anticancer effects of the glyceroglycolipids from P. arborescens Holmes 41
2.3. Induction effects of apoptosis in HL-60 cells by the isolated compounds 43
2.4. Sub-G1 DNA contents 45
2.5. Regulation of caspase-3, Bax and Bcl-xL by the isolated compounds 47
3. DISCUSSION 49
4. CONCLUSION 51

PART ІІ - Isolation, Culture of Marine-Derived Fungi and Screening the Biological Activities of their Extracts

ABSTRACT 53
1. MATERIALS AND METHODS 54
1.1. General reagents 54
1.2. Samples and fungal strain isolation from collected samples 54
1.3. Isolation and Identification of fungal strains in pure culture 55
1.4. Liquid Culture and Extraction 56
1.5. DPPH radical scavenging assay 56
1.6. Screening nitric oxide (NO) production inhibitory the effects of extracts from marine-derived fungi 57
1.6.1. Cell culture 57
1.6.2. MTT assay 57
1.6.3. Determination of nitric oxide (NO) production 58
1.7. Screening anti-cancer effects of the extracts from marine-derived fungi...59
1.7.1. Cell culture 59
1.7.2. Cell growth inhibitory assay 59

2. RESULTS and Discussion 60
2.1. Culture and Isolation of Marine-Derived Fungi 60
2.2. DPPH scavenging activities 62
2.3. Assessment of Cell Viability 64
2.4. Effects of the extracts from marine-derived fungi on LPS-induced NO production 66
2.5. Cell growth inhibitory the effects of extracts from marine-derived fungi in HL-60 cells 68
3. CONCLUSION 70

PART ІІІ – Natural Products from the Marine-Derived Fungus Eurotium amstelodami and their Biological Activities

ABSTRACT 72
1. MATERIALS AND METHODS 73
1.1. General reagents 73
1.2. Fungal Material 73
1.3. Extraction and Isolation of Natural Products 75
1.4. Anti-inflammatory effects of the compounds isolated from E. amstelodami 79
1.4.1. Cell culture 79
1.4.2. MTT assay 79
1.4.3. Determination of Nitric Oxide (NO) Production 79
1.4.4. Determination of PGE2 Production 80
1.4.5. Measurement of Pro-inflammatory Cytokines (TNF-α, IL-1β and IL-6) Production 80
1.4.6. Western Blot Analysis 81
1.5. Statistical analysis 82

2. RESULTS and DISCUSSION 83
2.1. Isolation and identification of bioactive natural products from E. amstelodami 83
2.2. Anti-inflammatory effects of asperflavin and questinol in LPS-stimulated Raw 264.7 cells 94
2.2.1. Cell viability in Raw 264.7 cells 94
2.2.2. Effects of asperflavin and questinol on NO production in LPS-treated RAW 264.7 cells 96
2.2.3. Effects of asperflavin and questinol on PGE2 production in LPS-treated RAW 264.7 cells 98
2.2.4. Effects of asperflavin and questinol on production of pro-inflammatory cytokines in LPS-stimulated RAW 264.7 cells 100
2.2.5. Effects of asperflavin and questinol on expression of iNOS and COX-2 protein in LPS-stimulated RAW 264.7 cells 104
3. DISCUSSION 107
4. CONCLUSION 108
Degree
Doctor
Publisher
제주대학교 대학원
Citation
양수동. (2012). Secondary Metabolites and their Biological Activity from Marine Bio-resource
Appears in Collections:
General Graduate School > Marine Life Sciences
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