Report on Vincristine-Producing Endophytic Fungus Nigrospora zimmermanii from Leaves of Catharanthus roseus

Vincristine is an anti-cancer compound and one of the most crucial vinca alkaloids produced by the medicinal plant Catharanthus roseus (L.) G. Don. (Apocynaceae). This plant is home to hundreds of endophytic microbes, which produce a variety of bioactive secondary metabolites that are known for their medicinal properties. In this study, we focused on isolating an endophytic fungus that could increase the yield of vincristine under laboratory conditions as an alternative to plant-mediated extraction of vincristine. The endophytic fungus Nigrospora zimmermanii (Apiosporaceae) was isolated from Catharanthus roseus and it was found to be producing the anticancer compound vincristine. It was identified using high-performance thin-layer chromatography by matching the Rf value and spectral data with the vincristine standard and mass spectrometry data and the reference molecule from the PubChem database. The generation study of this microbe showed that the production of vincristine in the parent fungus was at its maximum, i.e., 5.344 µg/mL, while it was slightly reduced in subsequent generations. A colonization study was also performed and it showed that the fungus N. zimmermanii was able to re-infect the plant Catharanthus roseus after 20 days of inoculation. The colonization study showed that N. zimmernanii could infect the plant after isolation. This method is an efficient and easy way to obtain a high yield of vincristine, as compared to plant-mediated production.