Antioxidant and tyrosinase inhibitory activities of A. sicula L. aqueous extract

Overexpression of tyrosinase in humans causes an increase in melanin production in the skin, which can result in hyperpigmentation consequences such as freckles, melasma, age spots, and melanoma. Free radicals also play a significant role in the increase of the biosynthesis of melanin. Tyrosinase inhibitors capable of inhibiting the biosynthesis of melanin are used currently in various hyperpigmentation and cosmetic agents to control the formation of freckles. Several synthetic tyrosinase inhibitors have been associated with several serious side effects. Also, synthetic antioxidants had many toxicological side effects including carcinogenicity. There is an increasing interest in the search for natural tyrosinase inhibitors and antioxidant agents. The objective of this study is to evaluate total polyphenol and flavonoid contents as well as examine the antioxidative and tyrosinase inhibitory effects of A. sicula L. aqueous extract. Antioxidant activities evaluated using superoxide radical scavenging and reducing power methods. tyrosinase inhibitory assay was used to determine anti-hyperpigmentation. The results showed that this extract was rich in total polyphenols (58.01±1.18 micrograms of gallic acid equivalents per milligrams of extract) and flavonoids (17.91±1.81 micrograms quercetin equivalents per milligram of extract). A. sicula L. aqueous extract was capable of scavenging free radicals (IC50 =11.87±0.13 μg/mL) and acts as a strong reducing agent (A 0.5= 6.37±0.42µg/mL). A. sicula L. had a potent tyrosinase inhibitory potential (IC50= 12.63±1.15 μg/mL), which was higher compared to kojic acid as standard (IC50= 25,23±0,78 μg/mL, P <0.001). These results support that A. sicula L. could be a new source of antioxidant and cosmetic use. Further studies focusing on the isolation and characterization of active principles of antioxidant and tyrosinase inhibitory activities are needed.