59份野生桑桑叶中的DNJ含量及粗提物对α-糖苷酶的抑制活性

DNJ Contents in Leaves of 59 Wild Mulberry Species and Inhibitive Activities of the Leaf Crude Extract to α-Glycosidase

对来自云南省不同地区的59份野生桑桑叶中的1-脱氧野尻霉素(DNJ)含量,以及桑叶粗提物对淀粉酶、蔗糖酶和麦芽糖酶的体外抑制活性进行了测定,同时采用液-质联用(LC-MS)仪分离纯化桑叶粗提物中的DNJ,并对其抑制蔗糖酶的机制进行了初步研究,期望筛选出适用于治疗糖尿病药物开发的药用桑资源,以及为解析桑叶粗提物和纯化的桑叶DNJ抑制α-糖苷酶活性的机制提供线索。研究结果表明:不同来源的野生桑桑叶中的DNJ含量存在明显差异,其中来自开远地区的岩桑桑叶中DNJ的质量分数高达0.791 1%,是具有药用开发价值的野生桑资源;不同来源的野生桑桑叶粗提物对淀粉酶、蔗糖酶和麦芽糖酶活力的体外抑制率差异显著,但抑制活性的大小与样品中的DNJ含量不成正比,推测桑叶中除含有DNJ外还含有具有明显的α-糖苷酶抑制活性的多种DNJ类似物;从野生桑桑叶粗提物中分离纯化的DNJ对淀粉酶无明显抑制活性,但对蔗糖酶和麦芽糖酶有显著的抑制活性,对蔗糖酶表现为非竞争性抑制作用。

In order to select wild mulberry varieties suitable to exploit medicine for treating diabetes mellitus and provide clues for understanding mechanisms on inhibitive activities of mulberry leaf crude extracts and purified 1-deoxynojirimycin （DNJ） to α-glycosidase,DNJ contents in leaves of 59 different wild mulberry species in Yunnan Province were measured,and inhibitive effects of the leaf crude extracts on sugar-metabolizing key enzymes such as amylase,sucrase and maltase were determined in vitro.Meanwhile,DNJ was separated and purified by liquid chromatography-mass spectrometry （LCMS） ,and the potential mechanism （s） of its inhibitive activity to sucrase was studied.The results indicated that the content of DNJ was significantly different between different wild mulberry leaves.The highest content of DNJ was 0.791 1% in M.mongolica Koidz.from Kaiyuan Area,being a promising wild mulberry resource for further development.Mulberry leaf extracts from different areas had significantly different in vitro inhibitive activities on amylase,sucrase and maltase,but the inhibitive effect was not directly proportional to its DNJ content,suggesting that there be other DNJ analogs in mulberry leaves with potential inhibitive activity to α-glycosidase.The purified DNJ from wild mulberry leaf had evident inhibitive effect on sucrase and maltase,but had no significant inhibitive activity on amylase.And its inhibitive activity to sucrase was presented in a non-competitive pattern.