Isolation and identification of vinblastine from the fungus of Chaetomium globosum Cr95 isolated from Catharanthus roseus plant

Endophytic fungi are capable of synthesizing many plant secondary metabolites and as such make available new compounds for pharmaceutical investigation. Thus, the endophytic fungus Cr95 isolate was separated from the stem of Catharanthus roseus plant found in Iran and screened for the production of vinblastine. By considering its morphologic and genotypic properties, it became possible to identify this isolate, followed by grouping in the Chaetomium globosum species. Furthermore, the anti-proliferative activities of C. globosum Cr95 isolate against P. oryzae as a model fungus, was assessed. This endophytic fungus was screened for the production of vinca alkaloids using specific biochemical assays, tryptophan decarboxylase (TDC) encoding gene, and TLC and HPLC analyses. The endophytic isolate was found to have significant cytotoxic effects and showed the strongest anti-proliferative activity with an IC 50 value of 15.6 μg/ml. In the biochemical assays, C. globosum Cr 95 isolate showed a positive production of vinca alkaloids. TDC gene as the key enzyme in the terpenoid indole alkaloid biosynthetic pathway could be amplified from this isolate. The presence of vinblastine in fungal culture filtrate was confirmed through chromatographic and spectroscopic analyses, and the amount was estimated to be 78 μg/l. The cytotoxic activity of the partially purified fungal vinblastine against conidia of P. oryzae was evaluated using tetrazolium salt MTT assay, and maximum susceptibility was found to occur with the IC 50 value of 5 μg/ml. Fungal VBL in ethyl acetate extracts was characterized by TLC and HPLC, and its cytotoxic effects on P. oryzae were determined, which is indicative of its maximum susceptibility.To the best of the authors’ knowledge, this is the first report on vinblastine production from the endophytic fungus, C. globosum Cr 95 isolated from the C. roseus plant.