Clonostachys rosea, a marine algal endophyte, as an alternative source of chrysin and its anticancer effect

Abstract

Endophytic fungi were isolated from the marine green alga Chaetomorpha antennina and identified as Clonostachys rosea through molecular analysis. C. rosea was grown in a tryptophan medium for 21 days and after that, the metabolites were extracted by ethyl acetate. The ethyl acetate extract showed a high cytotoxic effect on MCF-7 cells. GC-MS analysis of the ethyl acetate extract revealed the presence of many compounds, and chrysin was one of the major compounds among them. Hence, further studies were concentrated on chrysin, as it was assumed to be the major attributor to the potent cytotoxicity, based on its high anticancer efficacies reported earlier. The fungal ethyl acetate extract had been analysed for chrysin using HPTLC and compared its R_f value with authentic chrysin and it was matched. Further, the purified fungal chrysin was structurally elucidated using techniques like LC-MS and NMR analyses. Quantification revealed that C. rosea produced 1050 mg/L of chrysin. This surplus production of chrysin was the major significance of the study. The purified fungal chrysin was found to be highly cytotoxic to MCF-7 cells with a low IC₅₀ value 35.5 ± 0.6 µM. Furthermore, DNA fragmentation and apoptosis analysis indicated the selective inhibition of MCF-7 by DNA damage. Thus, the present study implies that C. rosea is an alternative source and new method for surplus production of chrysin in the tryptophan medium. All results indicate that the marine algae endophytic C. rosa produces chrysin, and for the first time, an excess amount of production was revealed by the study.

Keywords: Chrysin; Clonostachys rosea; Cytotoxicity; DNA fragmentation; Marine algae.