Inhibitory Effect of Endophytic Fungus HP-12 from Moringa on the Proliferation of Colon Cancer Cells

Purpose To isolate and purify endophytic fungi from moringa seeds, and to explore the inhibitory effects of fermentation broth on proliferation of colon cancer cells.

Methods Moringa seeds were collected from Jinghong, Yuanjiang, and Yuanmou, Yunnan Province, and the endophytic fungi were isolated, purified, and cultured for fermentation. The MTT method was used to detect the effects of different endophytic fungi fermentation broth on the proliferation of human colon cancer HCT116 cells.

Results A total of 122 endophytic fungi strains were obtained from moringa seeds. After the treatment of HCT116 cells with the dichloromethane extract from fermentation broth (DEFB) of endophytic fungi, 11 strains of endophytic fungi were screened out to significantly inhibit the proliferation of HCT116 cells. The DEFB from these obtained strains was further used to treat NCM460 cells, human colorectal epithelial cells, and the HP-12 isolate showing weak inhibition of NCM460 cell proliferation was identified. Morphological and phylogenetic analyses preliminarily identified HP-12 as belonging to genus Lachnellula sp.. HP-12 DEFB significantly inhibited the proliferation of HCT116 cells, with a half maximal inhibitory concentration (IC₅₀) of 29.40 μg/mL, whereas there was no significant effect on NCM460 cells proliferation. After treatment with HP-12 DEFB, HCT116 cells became wrinkled and round, and their ability to adhere to the substrate was dramatically decreased. Compared with the control group, in the treatment groups with HP-12 DEFB (30, 45, and 60 μg/mL), the activity of Na/K-ATPase was significantly decreased, and the free fatty acid content was significantly increased. HP-12 DEFB had good thermal stability at 90 ℃ and below, and long-term ultraviolet radiation (UV) did not affect its inhibitory activity against colon cancer cells.

Conclusion A strain of Lachnellula sp., HP-12, was obtained from moringa seeds. The fermentation broth of HP-12 significantly inhibits HCT116 colon cancer cell proliferation, and it is also stable under high temperature and long-term UV radiation conditions.