NEW BIOACTIVE NATURAL PRODUCTS FROM FRESHWATER FUNGI

本申请要求对淡水丝状真菌的天然产物化学进行研究。这些很少被研究的真菌在生态学、形态学和分类学上都是独特的，它们通常对其他真菌表现出拮抗作用。就像我们之前对菌丝体和嗜粪菌的化学研究一样，这项研究将采用一种系统的、基于生态学的方法来进行生物选择，这代表了传统随机微生物筛选程序的背离。基于这些真菌对其他真菌表现出拮抗作用的倾向，以及对对抗人类机会性真菌感染的新治疗方法的日益迫切的需求，我们将努力寻找具有抗真菌作用的新代谢物。然而，纯化合物也将通过与一家大型制药公司的安排进行其他活性测试，并提交给NCI的抗肿瘤筛选。拟议的工作涉及PI小组与世界上最重要的水生真菌学专家之一卡罗尔·希勒教授的合作。对选定的水生分离物进行的初步研究已经提供了37种新的生物活性物质，其中包括一些结构不寻常的物质。这些初步结果提供了证据，证明这种独特的、几乎未被探索过的真菌群作为新型生物活性天然产物的来源显示出相当大的希望，并清楚地表明研究团队有能力进行拟议的研究。许多在直接竞争分析中表现出抗真菌作用的分离物可用于立即调查，并且没有文献报道先前对任何这些生物的化学研究。真菌分离物将在液体和固体基质生长条件下培养，从这些培养物中提取的提取物将进行抗真菌测定，以优先进行化学研究。活性成分将通过生物测定引导分离分离，其结构将使用光谱方法确定。随着化学研究的进展，更多的淡水物种将被分离、鉴定和筛选抗真菌活性，从而为研究提供源源不断的新分离物。

This application requests support for an investigation of the natural products chemistry of freshwater filamentous fungi. These rarely-studied fungi are ecologically, morphologically, and taxonomically distinctive, and they commonly display antagonistic effects against other fungi. Like our previous and productive chemical studies of sclerotial and coprophilous fungi, this investigation will employ a systematic, ecology-based approach to organism selection that represents a departure from traditional random microbial screening programs. Based on the propensity of these fungi to show antagonistic effects toward other fungi, together with the increasingly urgent need for new treatments to fight opportunistic fungal infections in humans, efforts will focus on a search for new metabolites with antifungal effects. However, pure compounds will also be tested for other activities through arrangements with a major pharmaceutical company, and by submission to the NCI's antitumor screens. The proposed work involves a collaboration between the PI's group and that of Prof. Carol Shearer, one of the world's foremost experts in aquatic mycology. Preliminary studies of selected aquatic isolates have already afforded 37 new bioactive agents, including some with unusual structures. These initial results provide evidence that this unique, virtually unexplored group of fungi shows considerable promise as a source of novel bioactive natural products, and clearly demonstrate the ability of the research team to perform the proposed studies. Many isolates that exhibit antifungal effects in direct competition assays are available for immediate investigation, and there are no literature reports of prior chemical studies of any of these organisms. Fungal isolates will be cultivated under both liquid and solid-substrate growth conditions, and extracts from these cultures will be subjected to antifungal assays to prioritize cultures for chemical study. Active components will be isolated through bioassay-guided fractionation, and their structures will be determined using spectroscopic methods. While chemical studies progress, further freshwater species will be isolated, identified, and screened for antifungal activity, thereby providing a continuing stream of new isolates for investigation.