가자 열매로부터 추출된 항산화 활성 다당체의 구조 분석
Structure analysis of antioxidant polysaccharide isolated from dried fruits of Terminalia chebula
- 주제(키워드) Terminalia chebula , Amylopectin , Polysaccharide , Antioxidant activity
- 발행기관 아주대학교
- 지도교수 백승훈
- 발행년도 2019
- 학위수여년월 2019. 8
- 학위명 박사
- 학과 및 전공 일반대학원 약학과
- 실제URI http://www.dcollection.net/handler/ajou/000000028967
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Dried fruits of Terminalia chebula (TF) have been used as herbal medicine for diverse symptoms, and antioxidant activity was known to be involved in its bioactivities. The aim of this study is to elucidate structure and evaluate antioxidant effects of active TF polysaccharide (TFP). TFP was prepared using hot water extraction and HP-20 resin treatment remarkably reduced levels of phenolics, and proteins in extracts. Neutral polysaccharide (TFP-a) isolated by IEC was homogenous α-Glc(p)-rich polysaccharide (over 70% of α-Glc, 534.9 kDa, PDI 1.36) with smooth, porous, and flake-like morphology assessed using HPGPC, HPLC monosaccharide composition, FT-IR, and SEM analysis. GC-MS linkage and 1D/2D NMR data comprehensively supported that backbone of TFP-a was (1→4)-α-Glc(p) with branch at C6/C2 in and terminal α-Glc(p). Side chains were composed of (1→4)-β-Gal(p) substituted, or terminated with α-Ara(f), β-GalUA(p), β-GalUA(p)-Me, and α-Rhm(p). These results suggested that TFP-a consisted of amylopectin backbone with complex side chains of (1→4)-β-galactan linked at C4 in α-Glc(p). Antioxidant activity assays revealed that TFP-a exhibited potent, and concentration-dependent antioxidant effects including DPPH, superoxide radical scavenging and reducing power activities. Taken together, TFP-a is amylopectin type polysaccharide, and has potential to be developed as a natural antioxidant. In the future, we will study about the structure-activity relationships, and the antioxidant mechanism of TFP-a in vivo.
more목차
ABSTRACT..........I
LIST OF CONTENTS..........III
LIST OF FIGURES..........VI
LIST OF TABLES..........IX
LIST OF ABBREVIATION..........X
I. INTRODUCTION..........1
1. Natural polysaccharide..........1
2. Oxidative stress, and antioxidant natural polysaccharides..........6
3. Terminalia Fructus..........8
4. Purpose of this study ..........9
II. MATERIALS AND METHODS..........11
1. Plant material and chemical reagents..........11
2. Extraction and purification..........13
3. Determination of total carbohydrate, uronic acid, protein, and phenolic contents..........14
4. Antioxidant activity assays..........15
4.1. DPPH radical scavenging assay..........15
4.2. Superoxide radical scavenging assay..........16
4.3. Ferric reducing antioxidant power (FRAP) assay..........18
5. Scanning electron microscopy (SEM) analysis..........19
6. Gel permeation chromatography (GPC) analysis..........19
7. FT-IR analysis..........20
8. Monosaccharide composition analysis..........20
9. Glycosidic linkage analysis.......... 27
9.1. Reduction of carboxylic acids in TFP-a..........27
9.2. Synthesis of PMAAs from carboxyl reduced TFP-a..........29
9.3. GC-MS analysis conditions for PMAAs..........32
10. NMR analysis..........34
III. RESULTS AND DISCUSSION..........35
1. Extraction and isolation of TFP..........35
1.1. IEC fractionation of TFP..........35
1.2. HP-20 resin treatment effect..........41
2. Antioxidant activities of TFP-a..........44
2.1. DPPH radical scavenging activities of TFP-a.......... 44
2.2. Superoxide radical scavenging activities of TFP-a..........45
2.3. FRAP assay results of TFP-a..........46
3. SEM analysis..........51
4. Homogeneity and molecular weight determination..........53
5. FT-IR analysis..........54
6. Determination of monosaccharide composition of TFP-a..........56
7. Glycosidic linkage and NMR analysis of TFP-a..........58
7.1. Glycosidic linkage analysis using GC-MS..........58
7.2. Anomeric configuration analysis using NMR..........74
8. Proposed structure of TFP-a..........84
9. Discussion..........86
IV. CONCLUSION.......... 88
V. ACKNOWLEDGMENT..........90
VI. REFERENCE..........91
