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Abstract
Current paradigmatic approaches towards the identification of bioactive principles are built on a cyclic process known as bioassay‐guided fractionation (BAGF). In our efforts to evaluate antimycobacterial leads from the ethnobotanical fundus of Alaska (Oplopanax horridus) and the Central‐South Asian International Conservation and Biodiversity Group (ICBG) project (Litsea mollifolia, Dubanga grandiflora), a strategy involving countercurrent chromatography (CCC) of crude extracts improves the significance and prioritization power of early BAGF steps. One major factor is the high individual resolution of CCC having a small polarity window of separation, and leading to sharp individual resolution between constituents. The proposed strategy involves the CCC‐based primary fractionation of extracts for two principal cases. Firstly, when working with unknown active constituents, the crude extract is divided into three main groups A (K<0.5), B (0.5<K<2), and C (K>2). As a result, the bioactivity pattern is restricted to 8 possibilities due to the nature of the separation, with a bioactive mass reduction of ca. 50–70%, depending on the extract and choice of solvent system. Secondly, when working with bioactivity targets, the polarity window can be specifically chosen around the lead constituent, resulting in significant enrichment of activity of 90% (w/w) or better.
Acknowledgments
We thank Mr. Shixin Deng, UIC, Chicago, for providing reference material and partition data of falcarindiol. Furthermore, we are grateful for partial support of this work by NIH/NCCAM through grant 1R43AT001758‐01.
