Introduction: Algae have garnered increasing interest in the fields of medicine and nutrition as a source of nutritious and non-toxic healthcare supplements. Spirulina platensis (SP), a microalga and a welldocumented nutritional supplement, is recognized for its high medicinal value and potential anticancer properties. The present study evaluated the apoptosis-inducing effect of methanolic extract of Spirulina platensis (SPM) on human breast cancer MDA-MB-231 cells. Methods: The extract was prepared using standard methanol extraction techniques. Cytotoxicity was assessed using the MTT assay over varying concentrations and time intervals. Morphological changes were observed under a phase-contrast microscope. Apoptosis was further confirmed through acridine orange/ ethidium bromide (AO/EB) dual staining and DNA fragmentation analysis. The effect of SPM on normal HEK-293 cells was also evaluated to determine its selectivity and safety profile. Results: HPLC analysis identified C-phycocyanin (C-PC) as the major bioactive phytoconstituent in the SPM extract. The extract showed antioxidant activity and dose- and time-dependent growth inhibition of MDA-MB-231 cells (IC50: 3433 μg/mL). Treated cells displayed apoptotic morphology under a phasecontrast microscope and late apoptosis at higher doses, confirmed by AO/EB staining. DNA fragmentation was observed in MDA-MB-231 cells but not in HEK-293 cells, which showed minimal cytotoxicity (IC₂⁽: 7250 μg/mL). Discussion: The presence of C-PC most likely contributes to the extract’s antioxidant and anticancer effects. SPM selectively induced apoptosis and inhibited proliferation in MDA-MB-231 cells, with a negligible impact on normal cells, highlighting its potential as a safe and natural anticancer candidate. Conclusion: As evident from the results, SPM extract has demonstrated potential for its clinical applications in cancer therapy as an adjunct to the main line of treatment, provided that further studies are carried out on other cancer cell lines and animal models in future.
Srivastava et al. (Fri,) studied this question.