Inhibitory Effect Of Extracts From Rhizoma Et Radix Poltgoni Cuspidati On A-glucosidase Activity In Vitro And In Vivo

OBJECTIVEAttempt to screening several high effective and low toxicitya-glucosidase inhibitors from the aqueous extracts of 20 traditional Chineseherbals. And examined the inhibitory type and inhibitory mechanism of apotent a-glucosidase inhibitors (the aqueous extracts of the Rhizoma etRadix Poltgoni Cuspidati (RRPC))on a-glucosidase activity.METHODS1. According to Chinese traditional medicine experience, we havechoosed 20 Chinese herbals medicines to evaluate their inhibition ona-glucosidase. The boiling water extracts was concentrated in a rotaryevaporators, and went on inhibitory test with the substrate (pNP-G) andpositive control (Acarbose).2. The total aqueous extract of RRPC was separated by chromatographyof macroporous adsorptive resins. The effects of the total extract and variousRRPC extracts on a-glucosidase activity were studied. The 30ï¼…ethanoleluent of RRPC (RRPCâ…¡) was examined the reversibility of inhibitory effectthrough the dialysis test. Also, the inhibitory type was detected by theLineweaver-Burk wave according to the data from a test there were a seriesconcentration of substrate while inhibitor concentration was certain.3. RRPCâ…¡intragastric administration was conducted to determine oralglucose tolerance test (OGTT), using sucrose as substrates. Sucrosetolerance examined the effect on the blood glucose level after a single oraladministrate of RRPCâ…¡to SD rats and STZ induced diabetic rats.RESULT The 20 Chinese traditional medicines showed different inhibition ona-glucosidase in vitro. The total extract of RRPC and 30% ethanol eluent ofRRPC (RRPCâ…¡) inhibiteda-glucosidase activity, in a concentrationdependent manner (IC₅₀ of 74 mg/ml and 15mg/ml), while the IC5o values ofdistilled water, 50ï¼…ethanol, 70ï¼…ethanol and 95ï¼…ethanol eluents of RRPCwere above 200 mg/ml. The inhibitory reaction is with the reversible andnoncompetitive mechanism.On the other hand, RRPCâ…¡showed significant hypoglycemic andanti-diabetic properties on normoglycemic and STZ induced rats. Theincrease in plasma glucose level was significantly suppressed (P＜0.05) bythe extract after substrates administration as same as Acarbose.CONCLUSIONRRPCâ…¡is a stronga-glucosidase inhibitor. This preliminary observationwill provide the basis for further examination of the suitability of Rhizoma etRadix Poltgoni Cuspidati as a medicinal supplement that contributes towardthe treatment and prevention of diabetes.