The Hypoglycemic Effect And The Fat-soluble Component Of Fruits Of Cucurbita Maxima

In order to study the effect of these extracts on α-glucosidase activity and antioxidant activity in vitro and screen out the cultivars with better activity, three kinds of solvent extracts totaling 75 samples were extracted with petroleum ether(PE), ethyl acetate(EA) and methanol(ME) in different cultivars successively with using 25 cultivars of Cucurbita maxima fruits as experimental materials. Selected 5 samples to reduce blood glucose in mice, and analyzed their chemical composition by using GC-MS and identified the main active ingredient, thus speculating that the mechanism of the hypoglycemic effect of Cucurbita maxima.1. The effect on α-glucosidase activity of the 25 cultivars of Cucurbita maximaDetermined the inhibitory activity of α-glucosidase in vitro, the results showed that: the extracts in different varieties and same varieties with different solvent showed different activity on α-glucosidase. Exracted with 3 solvent in the same variety, the effect of PE extract showed the best, the second was EA extract, the last was ME extract. The inhibitory activity of extracts on α-glucosidase was positively correlated with the extracts concentration. There were 12 varieties were selected through the experiment, they were PBHL, XHM, LXD, SL, LL, ZL3, LZM, DMH, LYLX, JHG, RB486 and YP. The activity of the PE extracts in these cultivars was better than Acarbose.2. The antioxidant activity of the 25 cultivars of Cucurbita maximaEvaluated the.extracts antioxidant activity of Cucurbita maxima in vitro by determining the scavenging activity of DPPH radical and ABTS radical and Fe3+ reducing ability. The results showed that: the DPPH free radical scavenging activity of Cucurbita maxima extracts was poor and ABTS radical activity was better, and 46 good scavenging activity samples and 9 good reducing ability samples were selected,. The results of the three methods showed that the antioxidant activity was quite different among different cultivars, and in the same cultivar, ethyl acetate extract antioxidant activity was best, petroleum ether extract was better, methanol extract against oxidation activity was worst. Above all, 6 cultivars with best antioxidant activity were selected,which were JCJL, LL, SL, LXD, XYHL an ZY., and their active sites were mainly ethyl acetate extracts.3.The effect of the petroleum ether extracts in Cucurbita maxima on diabetic miceSelected petroleum ether extracts from 5 cultivars in vivo to study the hypoglycemic effect in mice. The results showed that: the extracts from five varieties could reduce the fasting blood glucose(p<0.001, p<0.01), TC(p<0.001, p<0.01) and TG(p<0.001, p<0.01, p<0.05) in diabetic mice. Petroleum ether extracts from RBHL,LL,LXD and XHM could reduce postprandial blood glucose(p<0.001, p<0.01, p<0.05) and the serum MDA level(p<0.001, p<0.01) significantly. RBHL, XHMX, LL and ZL3 could increase glycogen content(p<0.001, p<0.01, p<0.05) and insulin level(p<0.001, p<0.05) in diabetic mice significantly. LXD, LL and ZL3 increased SOD significantly(p<0.01, p<0.05).4.Analysis of petroleum ether extracts by GC-MSFor the first time, the GC-MS method was used to analyze the volatile constituents from the petroleum ether extract of Cucurbita maxima The results showed that: the type and quantity of components in 5 extracts(LXD, LL, RBHL, XHM and ZL3) were different. 20, 21, 36, 12 and 22 components were isolated from the 5 ertracts, and 13, 12, 12, 7 and 11 chemical components were identified, in turn,the identification rates were 99.33%, 91.99%, 96.35%, 98.98% and 91.88%. Among them, palmitic acid, linoleic acid, petroselinic acid and antioxidant 2246 were common across the 5 extracts, and the relative percentages of palmitic acid, linoleic acid, linolenic acid, the petroselinic acid were higher.5.The hypoglycemic Mechanism of the petroleum ether extract in Cucurbita maximaAccording to the activity in vitro, the performance in diabetic mice and the volatile components in the ectracts, suggesting the hypoglycemic effect on 5 petroleum ether extracts of Cucurbita maxima might be achieved through the following means:(1) Inhibit the body’s α- glucosidase activity to decrease postprandial glucose;(2) Repair pancreatic β cells, promote nsulin secretion;(3) Improve insulin resistance;(4) Remove excess free radicals, anti-lipid peroxidation;(5) Improve lipid metabolism in diabetic mice.Hypoglycemic effect may be achieved by a particular mechanism or various mechanisms synergistic effect, the hypoglycemic mechanisms also have certain difference among different varieties.