Medicinal plants from Plectranthus genus are employed for skin ailments in traditional medicine [1], and have been validated for their antioxidant activity [2]. As far as we know, ROS can initiate complex molecular pathways for melanogenesis by enhancing tyrosinase activity and activating ECM enzymes, such as collagenase and elastase. Therefore, this study aims to perform a primary evaluation of Plectranthus spp. extracts and isolated compounds, for the synergistic treatment of skin disorders.
The compounds tested isolated from Plectranthus spp. using bioassay-guided fractionation of extracts (aqueous, acetone, methanol and ethyl acetate), were: 7α-acetoxy-6β-hydroxyroyleanone from P. grandidentatus; 6β,7α-dihydroxyroyleanone and 6,7-dehydroroyleanone from P. madagascariensis; Parvifloron D, β-sitosterol, stigmasterol, oleanolic and ursolic acids from P. ecklonii; (13S,15S)-6β,7α,12α,19-tetrahydroxy-13β,16-cyclo-8-abietene-11,14-dione from P. porcatus; (11R*,13E)-11-acetoxyhalima-5,13-dien-15-oic acid, Plectrornatin C, 1,6-di-O-acetylforskolin and 1,6-di-O-acetyl-9-deoxyforskolin from P. ornatus; α-amyrin and β-amyrin from P. neochilus; chlorogenic acid from P. saccatus and rosmarinic acid from the aqueous extracts of Plectranthus spp.
The ethyl acetate extracts of P. grandidentatus and P. ecklonii registered the highest antioxidant activity, most likely due to the presence of abietane diterpenes [3]. Concerning the skin-related enzymatic assays, all organic extracts of P. ecklonii, P. grandidentatus, P. madagascariensis and P. saccatus revealed highest tyrosinase and collagenase inhibition. Whereas abietane diterpenes and triterpenes highly inhibited tyrosinase and elastase.
Overall, the experimental results showed the powerful antioxidant and inhibitory action over tyrosinase, collagenase and elastase of Plectranthus spp. extracts and isolated compounds, supporting their further research as bioactives for cosmetic formulations.
[1] Lukhoba CW, Simmonds MS, Paton AJ. J Ethnopharmacol 2006; 103: 1–24;
[2] Rijo P, Batista M, Matos M, Rocha H, Jesus S, Simões MF. Biomed Biopharm Res 2012; 9: 225–235;
[3] Rosa S, Correia V, Ribeiro I, Rijo P, Simões MF, Saraiva N, Fernandes A. Biomed Biopharm Res 2015; 12: 59–67.