乳苣不同溶剂提取物对α-淀粉酶的抑制作用及光谱研究

摘要

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 (IC5o) of water,butanol,petroleum ether,chloroform and ethvl acetate extracts on α-amylase were 2.002,4.086,1.248,4.299 and 6.904 mg/mL,respectively.Reversible noncompetitive inhibition was observed in water extract with inhibition constant (Ki) of 1.653 mg/mL,reversible mixed inhibition in n-butyl alcohol extract with Ki and enzyme-substrate complex (Kis) of 0.795 and 0.435 mg/mL,respectively,but petroleum ether extract exhibited irreversible inhibition on α-amylase with Ki of 2.893 mg/mL.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.%利用3,5-二硝基水杨酸(DNS)和8-苯胺-1-萘磺酸(ANS)荧光探针法,研究乳苣不同溶剂提取物对α--淀粉酶的抑制作用和类型、紫外光谱和表面疏水性的影响.结果表明:水、正丁醇、石油醚、氯仿和乙酸乙酯提取物对α--淀粉酶的半抑制浓度(IC5o)分别为2.002、4.086、1.248、4.299和6.904 mg/mL.水提取物对α-淀粉酶为可逆非竞争性抑制,抑制常数(K)为1.653 mg/mL.正丁醇提取物对α-淀粉酶为可逆混合性抑制,Ki和酶-底物络合物抑制常数(Kis)分别为0.795和0.435 mg/mL.石油醚提取物对α--淀粉酶为不可逆竞争性抑制,K,为2.893 mg/mL.水、正丁醇和石油醚提取物可增强α-淀粉酶紫外吸收,但均不改变吸收峰.水提取物增强ANS荧光强度,低浓度正丁醇提取物增强了荧光强度,高浓度则降低了荧光强度,石油醚提取物则与此相反.另外,各提取物均使ANS发生蓝移.该研究可为进一步开发天然淀粉酶抑制剂提供理论依据.