| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系 === 91 === The objective of the present study was to investigate the effect of polysaccharide of Gracilaria tenuistipitata on antioxidative activity, prebiotic property and anti-hypercholesterolemia. The hydrolysates of polysaccharide, extracted from cultured Gracilaria tenuistipitata, were prepared by acidic, alkaline and enzymatic hydrolysis. Sixty five male alimentary-induced by hypercholesterol diet fed with different dosage of polysaccharide and algae of G. tenuistipitata for 8 weeks were employed.
The results indicated that no significant antioxidative activity was observed when lipid peroxidation coupling with (Fe+3/H2O2/ascorbate)and (Fe+2/H2O2)system were used under defined conditions. Forty percent of hydroxyl (OH•) free radical scavenging activity can be reached if G. tenuistipitata polysaccharide solution, up to 1 mg/ml, was employed. Better than BHA, using 0.5 mg/ml of G. tenuistipitata polysaccharide solution, 68% of superoxide scavenging effect was found. The content of total phenol was 11.48 mg/g G. tenuistipitata. The amount of hydrolysates was slightly increased by time no matter in chemical or enzymatic methodology. The better diversity of hydrolysates was obtained in enzymatic hydrolysis than those of acidic or alkaline treatments, and trimers and tetramers were the major products.
In vitro, the results of prebiotics test demonstrated that trimers and tetramers of G. tenuistipitata hydrolysates exhibited better stimulation of growth on Lactobacillus acidophilus, Bifidobacterium bifidum than that of monomer and dimmers. The prebiofic effect of cellulose hydrolysate in B. bifidum was slightly lower than those fructooligosaccharides （Taisugar Co.）and Oligos（King Car Co.）. Cellulase hydrolysate of G. tenuistipitata has little effect on growth of Clostridium perfringens. In anti-hypercholesterolemia study, the results illustrated that intake of high dosage of Gracilaria algae and polysaccharide can reduce the total cholesterol, but little significant difference was found in triglyceride after 8 weeks experimental diet period. No significant change was observed in HDL-C and LDL-C value among all test groups. The results of gross and microscopic finding indicated that Gracilaria polysaccharide was effective in preventing fatty liver. Evidence showed that the amount of TG and LDL-C excreted in feces were dependent upon the concentration of Gracilaria algae and polysaccharide and inferenced that the effect of anti-hypercholesterolemia can be improved by increase of lipid excretion.
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