Biological activities and phytochemicals profiling of different cyanobacterial and microalgal biomass

Potential uses of methanolic extracts derived from cyanobacterial and microalgal biomass were evaluated as promising sustainable sources of bioactive phytochemicals for nutraceutical, cosmetic, and pharmaceutical applications. Among the cyanobacteria and microalgae tested, cyanobacterium Nostoc sp. AARL C008 biomass exhibited the highest phytochemicals, correlating with high occurrence of antioxidant activities. The antioxidant potential of Nostoc sp. AARL C008 was assessed using 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and potassium ferricyanide reducing antioxidant power (PFRAP) assays, giving ABTS activity of 38.99 mg TE/g extract, DPPH activity of 9.16 mg GAE/g extract and PFRAP activity of 11.48 mg GAE/g extract. Nostoc sp. AARL C008 yielded high levels of total phenolic contents (54.10 mg GAE/g extract) and pigments including chlorophyll (6.42 mg/g DW) and carotenoids (1.56 mg/g DW). Interestingly, Nostoc sp. AARL C008 showed high potent cytotoxic activity against malignant melanoma skin cancer cells (A375 cells), providing IC50 of 0.42 mg/mL. LC-ESI-QTOF-MS/MS tentatively identified 83 phenolic compounds with favorable bioactivities from the methanolic extract of Nostoc sp. AARL C008. Among phytochemical profiles, the most abundant phenolic compound was p-coumaric acid (40.70%), indicating valuable biological activities. Results demonstrated that phytochemicals extracted from cyanobacterial biomass can be used as bioactive ingredients, with potential applications in the nutraceutical, cosmetic, and pharmaceutical industries.