Cosmeceutically relevant indigenous fast-growing green microalgae isolated from bloomed waters of Kerala, Peninsular India

Growing concerns regarding the safety and sustainability of synthetic cosmeceutical ingredients have increased interest in natural bioactive sources. However, the cosmeceutical potential of many freshwater microalgae remains insufficiently explored. Therefore, the present study focused on isolating and identifying ten indigenous cosmeceutically relevant freshwater green microalgae from the Western Ghats biodiversity hotspot (Kerala, Peninsular India) and ranked them based on a multiparametric assessment of biomass productivity, lipid content, fatty acid profile, total phenolics, antioxidants, glutathione, and ascorbic acid content. Nile red staining correlated positively with total lipid content, demonstrating its effectiveness for identifying lipid-rich algae (r = 0.701, p < 0.05). Tetradesmus obliquus and Parachlorella kessleri exhibited high biomass production and favourable biochemical content, highlighting the potential of unexplored microalgae as sustainable sources of cosmeceuticals. Chlamydopodium starrii displayed the highest lipid (25.34 ± 1.23 mg g− 1), carotenoid (0.376 ± 0.023 mg g− 1), and flavonoid (36.36 ± 0.34 mg QE g− 1) content, while Coelastrella rubescens exhibited the highest phenolic content (96.06 ± 1.13 mg GAE g− 1). Antioxidant activity assays identified Chlamydopodium starrii and Parachlorella kessleri as having the highest activity and Chlamydopodium starrii and Chlorolobion braunii as having high ascorbic acid and glutathione levels. The study suggests that all 10 species are cosmeceutically relevant, with 5 species (Chlamydopodium starrii (OQ626750), Parachlorella kessleri (PV125344), Chlorolobion braunii (OR131025), Tetradesmus obliquus (PV954894), and Coelastrella rubescens (PX686147)) showing greater promise as cosmeceutical bioresources. Overall, these findings demonstrate the applicability of integrated performance-based evaluation strategies for microalgal cosmeceutical screening. Future work should focus on validating the bioactive compounds isolated from the promising strains in skin cell lines to strengthen their translational potential.