Discovery of the anticancer drug vinblastine from the endophytic Alternaria alternata and yield improvement by gamma irradiation mutagenesis.

Abstract

Several fungal endophytes were isolated from some medicinal plants and screened for their ability to produce the anticancer drug vinblastine. An isolate was found to produce vinblastine (205·38 μg l-1 ), and the identity of the fungal vinblastine was confirmed by UV spectroscopic, high-performance liquid chromatography and electrospray ionization mass spectrometry analyses. Based on both morphological and molecular studies, the vinblastine-producing strain was identified as Alternaria alternata. Cytotoxic activities of the fungal vinblastine were evaluated against CHO-K1, MCF-7 and HepG-2 cell lines by the MTT assay. The proliferation of these cell lines was inhibited after treatment with fungal vinblastine and the recorded IC50 values of the respective cell lines were 12·15, 8·55 and 7·48 μg ml-1 . A strain improvement programme for improving vinblastine productivity by the fungal strain was also used. In addition, 10 broth media were evaluated for further increasing the production of vinblastine. The yield of vinblastine was intensified by 3·98-fold following gamma irradiation at 1000 Gy, and a stable mutant strain was isolated. Among the screened media, M1D broth (pH 6·0) stimulated the highest vinblastine production of 1553·62 μg l-1 by the isolated mutant strain. The present study is the first report on the production and yield improvement of the anticancer drug vinblastine by A. alternata. These findings suggest A. alternata as a viable and potent source with excellent biotechnological potential for the production of vinblastine.