Screening the dermatological potential of <i>Plectranthus</i> species components: antioxidant and inhibitory capacities over elastase, collagenase and tyrosinase

Abstract

A series of <i>Plectranthus</i> spp. plant extracts (aqueous, acetonic, methanolic and ethyl acetic) obtained from eight different species, and previously isolated compounds (ranging from polyphenols, diterpenes and triterpenes), were assayed for <i>in vitro</i> inhibition of the skin-related enzymes tyrosinase, collagenase and elastase, and for studying their antioxidant properties. The ethyl acetic extracts of <i>P. grandidentatus</i> and <i>P. ecklonii</i> registered the highest antioxidant activity, whereas acetonic, methanolic and ethyl acetic extracts of <i>P. ecklonii</i>, <i>P. grandidentatus</i>, <i>P. madagascariensis</i> and <i>P. saccatus</i> concerning the enzymatic inhibition assays revealed high anti-tyrosinase and anti-collagenase activities. From the isolated compounds tested, abietane diterpenes and triterpenes were highly active against tyrosinase and elastase activity. Overall, the experimental results showed the powerful antioxidant and inhibitory action on skin-related enzymes tyrosinase, collagenase and elastase of <i>Plectranthus</i> spp. extracts and/or isolated compounds, supporting their further research as bioactive metabolites against skin sagging and hyperpigmentation in cosmetic and pharmaceutical formulations.