Improvement of a Novel Purification Method of Phycocyanin Pigment from the Microalga Nostoc Minutum and Evaluation of Its Anticancer Activity

The efforts to discover anti-cancer drugs from natural sources to treat different types of cancer are of great importance and have received wide attention in recent years. Nowadays, microalgae are a unique source of bioactive compounds used in pharmaceuticals. In this study, the novel Iraqi blue-green alga, Nostoc minutum HA-YJ was identified using molecular and morphological diagnostics. DNA was recognized by the PCR technique and registered in the National Center for Biotechnology Information as a genus found in the aquatic environment north of Nineveh (Ain Safni). C-phycocyanin pigment from Nostoc minutum was purified using a novel method comprising freezing-thawing, ultrasonication, and ammonium sulfate precipitation, resulting in a purity index of 3.01. After that, dialysis, gel filtration chromatography, and SDS-PAGE electrophoresis were achieved. Two bands were observed corresponding to α (33 kDa) and β (36 kDa) subunits. The anticancer activity of purified PC was investigated using the human breast (MCF-7) and colon (HRT-18) cancer cell lines via MTT assay. The results exhibited a decrease in the percentage of cell viability of both cells in a concentration-dependent manner ranging from 31.25- 1000µg/ mL at 72h. The morphological changes in the cells associated with treatment by 1000µg/ mL were observed under light microscopy.