Ali Hasenah, Houghton P J, Soumyanath Amala
Pharmacognosy Research Laboratories, Pharmaceutical Sciences Research Division, King's College London, Franklin-Wilkins Building, 150, Stamford Street, London SE1 9NN, United Kingdom.
J Ethnopharmacol. 2006 Oct 11;107(3):449-55. doi: 10.1016/j.jep.2006.04.004. Epub 2006 Apr 18.
Extracts of six selected Malaysian plants with a reputation of usefulness in treating diabetes were examined for alpha-amylase inhibition using an in vitro model. Inhibitory activity studied by two different protocols (with and without pre-incubation) showed that Phyllanthus amarus hexane extract had alpha-amylase inhibitory properties. Hexane and dichloromethane extracts of Anacardium occidentale, Lagerstroemia speciosa, Averrhoa bilimbiPithecellobium jiringa and Parkia speciosa were not active when tested without pre-incubation. Extraction and fractionation of Phyllanthus amarus hexane extract led to the isolation of dotriacontanyl docosanoate, triacontanol and a mixture of oleanolic acid and ursolic acid. Dotriacontanyl docosanoate and the mixture of oleanolic acid and ursolic acid are reported from this plant species for the first time. All compounds were tested in the alpha-amylase inhibition assay and the results revealed that the oleanolic acid and ursolic acid (2:1) mixture was a potent alpha-amylase inhibitor with IC(50)=2.01 microg/ml (4.41 microM) and that it contributes significantly to the alpha-amylase inhibition activity of the extract. Three pure pentacyclic triterpenoids, oleanolic acid, ursolic acid and lupeol were shown to inhibit alpha-amylase.
采用体外模型，对六种在马来西亚久负治疗糖尿病盛名的植物提取物进行了α淀粉酶抑制作用检测。通过两种不同方案（预孵育和不预孵育）研究的抑制活性表明，苦味叶下珠己烷提取物具有α淀粉酶抑制特性。在不进行预孵育测试时，腰果、紫薇、阳桃、毛叶猴耳环和无忧花的己烷和二氯甲烷提取物没有活性。对苦味叶下珠己烷提取物进行提取和分馏，得到了二十二酸三十二烷酯、三十烷醇以及齐墩果酸和熊果酸的混合物。二十二酸三十二烷酯以及齐墩果酸和熊果酸的混合物首次从该植物物种中分离得到。所有化合物都进行了α淀粉酶抑制试验，结果显示，齐墩果酸和熊果酸（2:1）混合物是一种有效的α淀粉酶抑制剂，IC(50)=2.01微克/毫升（4.41微摩尔），且对提取物的α淀粉酶抑制活性有显著贡献。三种纯五环三萜类化合物，齐墩果酸、熊果酸和羽扇豆醇均显示出对α淀粉酶的抑制作用。
