Inhibition effects and spectrum of different solvent extracts from Mulgedium tataricum L. on α-amylase

The inhibition effects and types,ultraviolet spectrum and surface hydrophobicity of different solvent extractions from Mulgedium tataricum L.on α-amylase were investigated with 3,5-dinitrosaiicylic acid(DNS) and 8-anilino-1-naphthalene sulfonate(ANS). The results indicated that half maximal inhibitory concentration(IC₅₀) of water,butanol,petroleum ether,chloroform and ethyl acetate extracts on α-amylase were 2.002,4.086,1.248,4.299 and 6.904 mg/m L,respectively. Reversible noncompetitive inhibition was observed in water extract with inhibition constant(K_i) of 1.653 mg/m L,reversible mixed inhibition in n-butyl alcohol extract with K_i and enzyme-substrate complex(K_is) of 0.795 and 0.435 mg/m L,respectively,but petroleum ether extract exhibited irreversible inhibition on α-amylase with K_i of 2.893 mg/m L. Water,n-butyl alcohol and petroleum ether extracts all could enhance the ultraviolet absorption of α-amylase,but absorption peak remained unchanged.Water and n-butyl alcohol extract with low concentration could strengthen the fluorescence intensity of ANS,n-butyl alcohol extract with high concentration can reduce the fluorescence intensity of ANS,but petroleum ether extract was quite opposite to n-butyl alcohol extract.Moreover,ANS blue shifts were found to different degrees within all three extracts.The study can further provide a theoretical basis for the development of natural α-amylase inhibitors.