Partial identification of a peptide from Lacticaseibacillus casei using MALDI TOF and it’s cytotoxic activity against MDA-MB-231 cell line

The current study focused to extract and purify the peptide of interest efficaciously from Lacticaseibacillus casei. The peptide of interest was partially identified and checked for anti-cancer activity using MDA-MB-231 triple negative breast cancer cell line. To begin with, it was purified via ammonium sulfate precipitation, ultrafiltration, and gel filtration chromatography. It was partially identified using mass matrix assisted laser desorption/ ionization-mass spectrometry (MS-MALDI) and checked for cytotoxic activity using (3-(4,5-Dimethylthiazol2-yl)-2,5-Diphenyltetrazolium Bromide) assay. As an outcome, the active part collected after ultra-filtration, 880 μg/ml of protein content with 15 mm zone diameter, was loaded on sephadexG50 column. The purified protein content was found to be 118 μg/ml with 15 mm of zone of inhibition against Listeria monocytogenes. A peak was obtained at a retention time of 9.371 minutes on subjected to high performance liquid chromatography. The result of MS-MALDI revealed it as an unnamed peptide with 75% query sequence similarity with the hypothetical protein of Lactobacillus reuteri. The cytotoxic study revealed its potential as an anti-cancer peptide, with the IC50 value of 108 μg/ml for MDA-MB-231 cancer cell line. In conclusion, this is the first report of this unknown peptide which showed both antibacterial and cytotoxic activity. It may act as a promising agent and can be further explored in future.