Unraveling anticancer potential of a novel serine protease inhibitor from marine yeast Candida parapsilosis ABS1 against colorectal and breast cancer cells.

The study was planned to isolate a serine protease inhibitor compound with anticancer potential against colorectal and breast cancer cells from marine yeast. Protease enzymes play a crucial role in the mechanism of life-threatening diseases like cancer, malaria and AIDS. Hence, blocking these enzymes with potential inhibitors can be an efficient approach in drug therapy for these diseases. A total of 12 marine yeast isolates, recovered from mangrove swamps of Sundarbans, India, showed inhibition activity against trypsin. The yeast isolate ABS1 showed highest inhibition activity (89%). The optimum conditions for protease inhibitor production were found to be glucose, ammonium phosphate, pH 7.0, 30 °C and 2 M NaCl. The PI protein from yeast isolate ABS1 was purified using ethyl acetate extraction and anion exchange chromatography. The purified protein was characterized using denaturing SDS-PAGE, Liquid Chromatography Electrospray Ionization Mass Spectrometry (LC-ESI-MS), Reverse Phase High Pressure Liquid Chromatography (RP-HPLC) and Fourier Transform Infra-red Spectroscopy (FTIR) analysis. The intact molecular weight of the PI protein was determined to be 25.584 kDa. The PI protein was further studied for in vitro anticancer activities. The IC value for MTT cell proliferation assay was found to be 43 µg/ml against colorectal cancer HCT15 cells and 48 µg/ml against breast cancer MCF7 cells. Hoechst staining, DAPI staining and DNA fragmentation assay were performed to check the apoptotic cells. The marine yeast was identified as Candida parapsilosis ABS1 (Accession No. MH782231) using 18s rRNA sequencing.