Response surface methodology-based approach for enhanced C-Phycocyanin production from Oscillatoria sp. for its...

The present study focuses mainly on the extraction of C-Phycocyanin (CPC) pigment from cyanobacteria, its optimization and evaluation of its radical scavenging and antiproliferative abilities. Optimization of the pigment production was conducted both experimentally and statistically by response surface methodology (RSM). Quadratic models were fitted to the responses obtained from the box-Behnken design (BBD), to examine the interactions among Carbon, Nitrogen, Phosphate, pH and Temperature, and their impact on pigment production. Analysis of variance (ANOVA) validated the model,revealing that higher levels of carbon, nitrogen and phosphate significantly influenced (p < 0.05) CPC production. The optimum conditions were determined as Carbon-30 mM, Nitrogen-10 mM, phosphate-5.5 mM, Temperature-27.5 °C and pH-7.5 resulting in phycocyanin yield of 47.6 mg in 0.483g of cell mass. Under the RSM-optimized conditions, it was found that Oscillatoria sp. was able to produce a twofold increase in CPC production compared to the BG 11 medium over a period of 34 days. A blue-colored pigment was extracted, with a total protein concentration of 278 µg/ml. Concentration of the pigment led to a tenfold increase in protein purity. Fourier transform infrared spectroscopy (FTIR) analysis of the lyophilized pigment and control phycocyanin revealed similar functional groups, including Hydroxyl group, C - H stretch, C = O stretch and C - N stretch. The molar mass of the CPC dimer was recognized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as 19 kDa for α subunit and 21 kDa for β subunit. The free radical scavenging potential of the CPC was determined by IC₅₀ values obtained from the DPPH = 56.45 μg/ml & ABTS = 85.8 μg/ml assays. Its cytotoxic potential was evaluated against HepG2 (liver), A549 (lung) & MCF7 (breast) cancer cell lines with an IC₅₀ value recorded at 47.6, 47.7 and 63.2 µg/ml, respectively. Fluorescent imaging revealed apoptotic and necrotic stages in treated cancer cells, accompanied by cytochrome damage. DNA smearing was observed in HepG2 cells, indicating effective damage of genetic material. These findings suggests that CPC possesses promising antioxidant and anticancer potentials, making it a potential drug for pharmaceutical and food industries.

The online version contains supplementary material available at 10.1007/s13205-025-04357-8.