Endophytes as a potential source of new anticancer agents

C31

A recent decline in obtaining natural products has created a need for alternative sources. Endophytes, which are still poorly explored, have been found to be an outstanding source of bioactive metabolites following the discovery of paclitaxel producing fungus. Of the 350 endophytic extracts screened against P388, a murine leukemic cell line, 61% were categorized as non-active and 39% were otherwise (IC₅₀<20μg/ml). In fact, three of the endophytic extracts had an IC₅₀ of < 0.1 μg/ml. These extracts were further tested against tumor type (HCT116 and MCF7) and non-tumor type (Chang) cell lines. Generally, the endophytic extracts were found to be five times more potent than oxaliplatin and about 15 times to that of the 5-FU. On the contrary, only one out of three active endophytic extracts was found to be more potent than paclitaxel but not that of tamoxifen. When compared the cell line selectivity of the three endophytic extracts, they were generally more selective towards tumor type cell lines. The extracts were 210 times more selective towards HCT116 and 26 times more selective towards MCF7, with Chang as the reference for comparison. The selectivity of the endophytic extracts towards tumour type cell lines may contribute to the effective use of these extracts as effective anticancer agents. Further subjection of these extracts to bioactivity guided fractionation and dereplication techniques found two out of three extracts to possess unknown compounds. More extensive investigations should be carried out to uncover the anticancer potential of these extracts.