Comparative analyses and evaluation of the cosmeceutical potential of selected Chlorella strains

In the present study, aqueous extracts from eight Chlorella strains were evaluated towards selected cosmeceutical properties such as enzymatic and non-enzymatic antioxidant capacity, glutathione content, inhibition potency towards skin regulatory enzymes, and cytotoxic effect on human cell lines. The results showed that the Chlorella strains display wide catalytic diversity with different strains exhibiting quite varied antioxidant enzymatic activities. The enzymes glutathione reductase, peroxidase, and superoxide dismutase were found in all strains, whereas only Chlorella minutissima displays glutathione transferase activity. Total antioxidant capacity (TAC) measurements, using the FRAP, ABTS, and DPPH assays, indicated significant differences among strains suggesting a large chemical diversity of antioxidants in Chlorella species. Chlorella minutissima extract showed high inhibitory potency with IC₅₀ 23.3 ± 2.5 and 29.2±2.7 μg towards tyrosinase and elastase, respectively, suggesting a potential activity in controlling skin aging, inflammatory process, and pigmentation. Furthermore, the effect of C. minutissima extract on a human hepatoma cell line (Huh-7) was evaluated using cell proliferation assay and qRT-PCR to analyze the expression of marker genes (SOD1, GPx1, GPx2) involved in oxidative stress response. The results established the absence of cytotoxic effects of the aqueous extracts. SOD1, GPx1, and GPx4 expression levels showed a specific profile and appear to be slightly upregulated, downregulated, and remained unaffected, respectively. Taken together, these results demonstrate that Chlorella species can provide promising extracts rich in antioxidants, anti-aging, and skin-whitening ingredients with the potential for use as raw material in cosmetics industry.