| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系所 === 97 === The purpose of this study is to evaluate the effects of guava fruit extracts on antioxidant activity in vitro and lipid metabolism in type 2 diabetic rats. The experiment is mainly divided into two parts, first, guava fruit pieces were extracted by hot water (60℃) or ethanol (95%) , after freeze drying, approximate compositions of the extracts were analyzed and anti-oxidant abilities were determined. Second, the animal test was executed, male Wistar rats received an intraperitoneal administration of nicotinamide (NA, 230 mg/kg BW) 15 min before an intravenous administration of streptozotocin (STZ, 65 mg/kg BW) to induce type 2 diabetes. The rats were feed with aqueous (WG) and ethanol ( EG) extracts from guava fruit at 400 mg/kg BW, the rats were sacrificed at sixth week and the plasma lipid and liver TBARS (2-thiobarbituric acid reactive substances) were analyzed.
The results showed moisture, ash, crude fat and crude protein in WG and EG were 15.62±0.77%, 16.19±0.65%, 0.92±0.19%, 6.06±0.37% and 16.17±0.71%, 7.51±0.12%, 7.55±0.46%, and 12.60±0.41%, respectively. DPPH (α,α-diphenyl-β-picrylhydrazyl) free radical scavenging ability of WG and EG at the concentration of 10.00 mg/ml were 96.80% and 96.10%, while the Fe2+-chilatimg ability at the same concentration were 63.30% and 60.30%, respectively. The reducing power activity of the WG was better than
the EG. The TEAC (trolox equivalent antioxidant capacity) of the WG (0.17 mM) obviously higher than that of EG (0.01 mM). Type 2 diabetic rats administered with WG and EG could not reduce their plasma CHOL (cholesterol) level (p> 0.05), there was no significant difference in HDL (high density lipoprotein) and LDL (low density lipoprotein) level (p>0.05) among the experimental groups. Normal rats fed with WG and EG significantly conducted the decreasing of liver TBARS (2-thiobarbituric acid reactive substances) (p<0.05). The results showed that WG and EG exhibited excellent on anti-oxidant ability, the anti-oxidant ability of WG was higher than EG. The animal test indicated that WG and EG can’t regulate the plasma lipid metabolism and liver TBARS (2-thiobarbituric acid reactive substances) of type 2 diabetic rats at 400 mg/kg BW.
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