| Tea(Camellia sinensis(L.)O.Kuntze)is perennial woody plant.Tea Flower is one of the reproductive organs of tea,however,compared with the leaf of tea,the utilization rate of tea flower is very low.The nutritional components of tea flower are similar to the leaf of tea.Tea flower contains a variety of beneficial ingredients and active substances such as tea polysaccharide,protein,amino acids,polyphenols,flavonoids,tea saponins,superoxide dismutase(SOD)and catalase(CAT),etc,which have many functions such as detoxification,antibacterial,antidiabetic,anti-cancer agent,anti-oxidant and strengthening the immune system of human body.But there are few reports on the components of tea flower,especially tea flower saponins(Floratheasaponins).In recent years,with the change of the lifestyle and eating habits,the prevelence of diabetes is increasing dramatically.Diabetes becomes one of the most harmful human diseases with highest morbidity in the world,and the prevention and treatment of diabetes have gradually been paid more and more attention.Research in this area is becoming more and more important.As for the hypoglycemic strategies of antidiabetic drugs,inhibiting enzyme activity,especially a-glucosidase,has been paid attention slowly for its highly hypoglycemic effect and lower physical hazards.Therefore,from the development of the tea saponins and the inhibition of a-glucosidase,this article optimized the extraction process of the Floratheasaponins and its inhibition of a-glucosidase.Main results are listed as follows:1.Using tea flowers as material,the Floratheasaponins was extracted using ethanol extraction method,ethyl acetate and N-butanol for forward extraction,and detected by vanillin-sulfuric acid method.Response surface analysis was used to determine the optimum extraction process:extraction time 100 min,extraction temperature 80?,the solid-liquid ratio 22:1.From the analysis of variance(ANOVA),the extraction time,extraction temperature and ratio of liquid to solid had strong impact on the Floratheasaponins yield.Among different factors,the extraction time and temperature had a good interaction,and so was the extraction temperature and the solid-liquid ratio,but not obvious between extraction time and the solid-liquid ratio.This phenomenon also proved that the extraction temperature was the most significant factor affecting the Floratheasaponins yield,followed by the solid-liquid ratio,and extraction time was relatively the least important influencing factor.2.PNPG was used as substrate to determine a-glucosidase inhibitory effect of the Floratheasaponins.The results showed that when the a-glucosidase concentration was 0.16 U/mL,the maximum reaction rate(Vmax)of the enzyme reaction was 0.0776 ?mol/(mLˇmin)and the Michaelis constant(Km)was 8.28 mmol/L..The regression equation between Floratheasaponins concentration and enzyme inhibitory rate showed that half inhibitory concentration(IC50)of the Floratheasaponins was 2.48 mg/mL.Compared to the Acarbose medicine sold from the pharmacy(IC50= 5.06 mg/mL),Floratheasaponins exhibited better inhibitory effect.Therefore,it is reasonable to further study the inhibitory effect of Floratheasaponins.Experiment by studying the inhibition kinetics of the Floratheasaponins proved that tea Floratheasaponins had reversible inhibition to a-glucosidase.And the Lineweaver-Burk figure proved that Floratheasaponins was noncompetitive inhibitor,and the inhibitor constant is Ki= 2.27 mg/mL.Acarbose medicine also had reversible inhibition to a-glucosidase,but the Lineweaver-Burk figure proved that the acarbose was competitive inhibitor,and the inhibitor constant was Ki= 4.97 mg/mL. |
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