비파 부위별 추출물의 생리활성 연구

Abstract

ABSTRACT

A study on the Physiological Activities in Different Parts of the Loquat(Eriobotrya japonica Lindl) Ethanol Extract

by. Lee, Hwan Advisor : Prof. Lee, Myung-Yul, Ph.D. Department of Food and Nutrition, Graduate School of Chosun University

In Korea, the leaves of E. japonica have been widely used as a traditional medicine with beneficial effects for pain an chronic inflammatory diseases including headache, low back pain, dysmenorrhoea, asthma, phlegm and chronic bronchitis. In addition, the loquat seed has the inhibitory effect of oxidative-stress and hypoglycemic property. However, a little has been performed on the investigations of their physiological importance. Therefore, this study was carried out to discriminate the effects of the leaf, flesh, and seed of loquat (Eriobotrya japonica Lindle.) on antioxidative and anticancer capacity in vitro, proliferation and differentiation of pig preadipocytes and 3T3-L1 cells, liver function in hepatotoxicity-induced rat by alcohol administration, and serum, liver and adipose tissue lipid metabolism and body weight reduction in rats fed a high-fat/high-cholesterol diet.

The results obtained were as follows;

1. This study was investigated to compare the major chemical components of the leaf, flesh, and seed of the loquat as dry matter basis. Among the proximate compositions, the crude fat, crude ash and crude fiber of leaf contained higher than those of seed and flesh, while the content of carbohydrate was lower in seed and flesh. The main components of free sugars in the leaf, flesh, and seed were fructose, respectively. Total amino acids of leaf, flesh, and seed were 552.43 mg%, 63.00 mg% and 260.29 mg%, respectively. Although the amino acid composition of the leaf, flesh, and seed were different, glutamic acid and γ-aminobutyric acid were the major amino acids in the leaf, flesh, and seed. The major fatty acids of total lipids were oleic acid and stearic acid in leaf and seed, and linoleic acid in flesh. The major organic acids was in oxalic acid in leaf, maleic acid in flesh and citric acid in seed. The content of vitamin C was higher in seed than in leaf and flesh.

2. Total polyphenol contents of loquat flesh, leaf, and seed ethanol extract were found to be 17.77 mg/mL, 32.32 mg/mL, and 28.08 mg/mL in 500 ppm. Also, total flavonoid contents of loquat leaf, flesh and seed ethanol extracts were found to be 18.77 mg/mL, 28.73 mg/mL, and 21.35 mg/mL in 500 ppm, respectively. The DPPH radical scavenging activity and antioxidative activities of loquat leaf and seed ethanol extracts was highly and it was similar to the BHA and BHT. However, The antioxidative effects in leaf and seed was higher in flesh. The anticancer effect of seed and leaf ethanol extracts at 4 days on stomach cancer cell line (AGS), liver cancer cell line (H460) and lung cancer cell line (A549) showed higher values compared with the flesh ethanol extracts.

3. The current study was carried out to determine the effects of leaf, flesh, and seed of the loquat on proliferation and differentiation of pig preadipocytes and 3T3-L1 preadipocytes, aiming to seek the possibility of plant product being used as antilipogenic agent for the humans. To measure the cell proliferation the cells were treated with 25 ng/ml and 100 ng/ml ethanol extracts of leaf, flesh, and seed of the loquat, and Dimethyl sulphoxide (DMSO) was used as the control group. When pig preadipocytes and 3T3-L1 preadipocytes were exposed to the various concentrations of loquat flesh, no effect on proliferation and differentiation was found in preadipocytes. However, loquat leaf and seed ethanol extracts treated on cell proliferation stage and differentiation had a strong inhibitory effects. Twenty-five and 100 μg/mL of loquat seed and leaf ethanol extracts showed inhibitory action on proliferation and differentiation in dose-dependent manner. The degree of stimulation of cell differentiation by loquat leaf and seed ethanol extracts was greater than of cell proliferation. The most potent anti-lipogenic extract was obtained in ethanol extract of loquat seed. These actions indicate that the ethanol extracts of loquat leaf and seed may have potential to reduce the fat accumulation and obesity.

4. The hepatoprotective effects of an ethanol extracts of loquat flesh, seed, and leaf on alcohol-induced liver damage in rat were investigated. Sprague-Dawley rats weighing 100～150 g, were divided into 8 groups: normal diet group(N), alcohol (35%, 10 mL/kg/day) treated group(control, C), loquat flesh 400 mg/kg/day treated group (LF), loquat flesh 400 mg/kg/day and alcohol treated group (LFE), loquat seed 400 mg/kg/day treated group (LS), loquat seed 400 mg/kg/day and alcohol treated group (LSE), loquat leaf 400 mg/kg/day treated group (LL), loquat lesf 400 mg/kg/day and alcohol treated group (LLE). After the administration, rats were sacrificed to get serum and liver to analyze antioxidant enzyme activity, glutathione and lipid peroxide contents. The body weight gain and feed efficiency ratio were decreased by alcohol administration, however, was gradually increased to a little lower level than the normal diet group by the combined administration of alcohol and loquat extracts. The serum alanine aminotransferase (ALT), asparate aminotransferase (AST) and alkaline phosphatase (ALP) activities that were elevated by alcohol were significantly decreased by loquat extracts administration. It was also observed that thiobarbituric acid reactive substances (TBARS) content in liver that were increased by alcohol were markedly decreased in the combined alcohol and loquat extracts administered groups as compared with the alcohol only administrated group. The glutathione (GSH) content in liver was decreased by alcohol administration, however, increased after administering loquat extracts. Taken together, these results suggest that ethanol extracts of loquat leaf, seed and flesh may have a possible protective effect on liver function in hepatotoxicity-induced rat by alcohol administration.

5. This study was conducted to investigate the cholesterol lowering and anti-obesity effects of ethanol extracts of loquat leaf, seed and flesh in rats fed a high-fat/high-cholesterol diet. Male Sprague-Dawley rats weighing 150～155 g, were divided into 8 groups; a normal diet group (ND), a high-fat/high-cholesterol diet group (HCD), a high-fat/high-cholesterol diet and loquat flesh with 200 mg/kg treated group (HCD-FL), a high-fat/high-cholesterol diet and loquat flesh with 400 mg/kg treated group (HCD-LH), a high-fat/high-cholesterol diet and loquat seed with 200 mg/kg treated group (HCD-SL), a high-fat/high-cholesterol diet, loquat seed with 400 mg/kg treated group (HCD-SH), a high-fat/high-cholesterol diet and loquat leaf with 200 mg/kg treated group (HCD-LL), and a high-fat/high-cholesterol diet, loquat leaf with 400 mg/kg treated group (HCD-LH),. The body weight gain and mesenteric adipose tissue weight were increased by high-fat/high-cholesterol diet, but gradually decreased to the corresponding level of ND group after administered loquat extracts. The liver and epididymal adipose tissue weights of HCD group were the highest among eight groups although the difference was not significant. Food intake was lower in high-fat/high-cholesterol diet groups compared with normal diet group. The serum ALT and AST activities that were elevated by the high-fat/high-cholesterol diet were significantly decreased after loquat extracts administration. Levels of serum total cholesterol, LDL-cholesterol, triglyceride and the atherogenic index were tended to be decreased in loquat extracts administered groups compared with HCD group. However, HDL-cholesterol level in serum decreased in HCD group and markedly increased by loquat extracts administered groups. Levels of total cholesterol and triglyceride in liver and adipose tissue were also lower in loquat extracts administrated groups than in HCD group. The activities of heparin-releasable lipoprotein lipase (HR-LPL) and total-extractable LPL (TE-LPL) in adipose tissue were increased in HCD group compared with loquat extracts administered groups, but those of the HCD-L groups, HCD-S groups and HCD-F groups were similar to ND group. These results suggest that ethanol extracts of loquat leaf, seed and flesh may exert cholesterol-lowering effect and potentially reduce lipid storage.