Antioxidant, Anti-Collagenase, Anti-Elastase and Anti-Tyrosinase Activities of an Aqueous Cosmos caudatus Kunth (Asteraceae) Leaf Extract.

Cosmos caudatus Kunth (Asteraceae) or wild cosmos is traditionally used as a culinary and medicinal herb. The leaves and shoots of the plant are reputed to promote a younger skin complexion if consumed regularly. However, research to support its potential use as a cosmeceutical is lacking. This study investigated the antioxidant, anti-collagenase, anti-elastase and anti-tyrosinase activities of C. caudatus leaf water extract (CCW) in vitro to scientifically evaluate its potential as a cosmeceutical. The antioxidant activity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, anti-collagenase and anti-elastase activity were measured using fluorescence assays and anti-tyrosinase assay was measured by colorimetric assay. The DPPH and ABTS assays showed CCW to have IC50 values of 163.6 and 57.2 µg/mL, respectively. Significant collagenase, elastase and tyrosinase inhibitions were observed with 51.3, 63.7 and 72.7% inhibition, respectively at 1000 µg/mL CCW treatment, compared with controls. Flavonol glycosides derived from quercetin and kaempferol, and flavone C-glycosides derived from apigenin were the main compounds identified in CCW using high resolution LC-UV-MS/MS. These results suggest the potential application of CCW as a cosmeceutical with antioxidant, anti-collagenase, anti-elastase, anti-tyrosinase activities.