| Citrus fruit is one of the biggest yield of fruit in the world, peel is their mainly byproduct and has 20%-40% output in the total citrus fruit. The research emphasis on two species of citrus, which are pummelo [C. grandis(L.), Osbeck] and orange [C.sinensis(L) Osbenck], respectively. Studying contents were components, antioxidation, hypolipidemic effect, effect on lead, NO~2, nitrosamine, safety of the extract from citrus peel which were or not treated with enzyme, then extracted by water, 70% ethanol, n-butanol and ethyl acetate, respectively. The results are reported as following :1. By single factor experiment and orthogonal experiment and reducing sugar as an assessing index, the main factors of effect the enzymatic reaction on pummelo peel were enzymic dose, action temperature >action time >pH. The optimum condition of the enzymatic reaction was 2% substrute, 100ml reaction volume, 3mg enzyme, keeping 50℃ of action temperature, 12h reaction time and pH 4.0. There were 21.56% reducing sugar under the condition.The main factors of effect the enzymatic action on orange peel were enzyme dose>reaction temperature>reaction time>pH, the optimum condition of enzymatic reaction was same with pummelo peel. Under the condition reducing sugar was 22.33%.2.There were rich reducing sugar, soluble fiber, pectin, vitamin C, flavonoid and some carotene, microelements in the citrus peel and their extracts. The contain of all composition were increased after enzymic action except fiber.3.There were good scavengers in water extract from the citrus peel on H2O2.The IC50 of water extract from pummelo peel and orange peel were 70.2mg/ml and 326.5mg/ml, respectively. After treatedby the enzyme , their IC50 were 46.7mg/ml and 233.4mg/ml, respectively. It could be concluded that scavenging effect on H2O2 were improved after enzymatic action.There were almost no scavenging effect on H2O2 of the extract of n-butanol from pummelo peel, of 70% ethanol, n-butanol and ethyl acetate from orange peel. There was scavenging effect of the extract of 70% ethanol from pummelo peel, its IC50 was 133.8 mg/ml.According to the value of IC50, the scavenging ability of the extracts were arranged as following: water extract from the enzymic treated pummelo peel> water extract from the unenzymic treated pummelo peel >70% ethanol extract from pummelo peel >water extract from the enzymatic treated orange peel >water extract from the unenzymic treated orange peel .Under the same experiment condition, there were not scavenging effect of pure vitamin C, glucose and carotene which had same concentration with water extract from citrus peel. But Rutin showed strongly scavenging effect on H2O2.4.The IC50 of scavenging on .OH of water extract from unenzymic treated pummelo peel and orange peel were 3.6 mg/ml and 9.24 mg/ml and the IC50 were 0.98 mg/ml and 2.0 mg/ml after enzymic treated, respectively. It could be concluded that the scavenging was increased after enzymatic action .The IC50 of 70% ethanol extract from pummelo peel was 16.2 mg/ ml, but the IC50 of 70% ethanol extract from orange peel almost was zero percent.The IC50 of n-butanol extract from orange peel and pummelo peel were 4.4 mg/ml and 9.2 mg/ml, respectively.The IC50 of ethyl acetate extract from orange peel and pummelo peel were 4.6 trig/ml and 30 mg/ml, respectively.According to the IC50 of the extracts, the scavenging ability could be arranged as following: water extract from enzymic treated pummelo peel>> water extraxct from enzymic treated orange peel > water extract from the unenzymic treated pummelo peel >n-butanol extract from orange peel > ethyl acetate extract from orange peel > water extract from the unenzymic treated orange peel≈n-butanol extract from pummelo peel > 70% ethanol extract from pummelo peel> ethyl acetate extract from pummelo peel.Under the same experiment condition, there was not scavenging on .OH of vitamin c, but strongly scavenging of glucose, carotene and Rutin. The scavenging rate was 70.42% when 15%, 100ul glucose was adde...
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