Phytochemical studies on medicinally important plants

基于民族医学知识的植物生物勘探为发现新药提供了可能。例如，combretastatins是从南非树Combretum caffrum的树皮中分离出来的一组抗有丝分裂剂。紫杉醇（Taxol®）是一种抗癌药物，从太平洋紫杉（Taxus brevifolia）中分离得到。酶在包括代谢、分解代谢、细胞信号转导、细胞循环和发育在内的各种生化过程中发挥着重要作用。这些生化过程中的任何故障都会导致疾病和不适。生物化学过程的故障是由于酶的功能障碍以及酶的过度表达或过度激活。这些故障可以通过使用适当的酶抑制剂来纠正。基于酶抑制剂在人类生活中的重要性，我们对从药用植物中发现乙酰胆碱酯酶、α -葡萄糖苷酶和谷胱甘肽s -转移酶抑制剂感兴趣。具有这些生物活性的天然产物可能在治疗阿尔茨海默病、糖尿病或改善抗癌/抗寄生虫化疗方面具有应用价值。我们从马尼托巴省和南非收集了苦艾、硬索、Sorbus scopulina、Ribes americanum、Lilium tomentosa、Drypetes natalensis、Combretum brteosum、Vepris lanceolata、Anastrabe integerima等植物。所有这些植物提取物在我们的台式生物测定中显示出酶抑制和抗菌活性。拟议研究的主要目标是：(i)生物测定指导下从药用重要植物中分离生物活性天然产物；（ii）借助核磁共振和质谱方法确定生物活性化合物的结构；（iii）利用化学和微生物反应对生物活性天然产物进行结构修饰，研究其结构-活性关系；（iv）对强效生物活性化合物的生物活性进行详细的体外和体内研究。

Bioprospecting of plants, based on ethnomedical knowledge, holds out the possibility for discovering new pharmaceuticals. For instance, combretastatins are a group of anti-mitotic agents isolated from the bark of the South African tree, Combretum caffrum. Paclitaxel (Taxol®), an anti-cancer drug, was isolated from the Pacific yew tree, Taxus brevifolia. Enzymes play a significant role in performing various biochemical processes including metabolism, catabolism, cellular signal transduction, cell cycling and development. Any malfunction in these biochemical processes leads to diseases and discomforts. Malfunctioning of biochemical processes is due to the dysfunction of enzymes as well as overexpression or hyperactivation of enzymes. These malfunctions may be corrected by using appropriate enzyme inhibitors. Based on the importance of enzyme inhibitors in human's life, we are interested in discovering acetylcholinesterase, alpha-glucosidase and glutathione S-transferase inhibitors from medicinally important plants. Natural products with these biological activities might have applications in curing Alzhemier's disease, diabetic or improvements of anti-cancer/anti-parasitic chemotherapy. We have collected a number of plants including Artemisia absinthium, Solidogo rigida, Sorbus scopulina, Ribes americanum, Lilium tomentosa, Drypetes natalensis, Combretum bracteosum, Vepris lanceolata, and Anastrabe integerima etc. from Manitoba and South Africa. All of these plant extracts exhibited enzyme inhibitory and antimicrobial activities in our bench top bioassays. The major objectives of the proposed research are: (i) bioassay-guided isolation of bioactive natural products from medicinally important plants (ii) structure determination of bioactive compounds with the aid NMR and mass spectroscopic methods (iii) structural modifications of bioactive natural products using chemical and microbial reactions to study their structure-activity relationships (iv) detailed in-vitro and in-vivo study of bioactivity of potent bioactive compounds.