Evaluation of tyrosinase inhibitory potential in flowers of Cassia auriculata L. for the development of natural skin whitening formulation

Abstract

IntroductionThe inhibition of tyrosinase has been a long-term target in the field of cosmetics for skin whitening purposes. Since the number of reports on issues related to toxicity of currently employed synthetic formulations is alarmingly increasing, there is an increased interest for plant based natural skin whitening agents. Therefore, this study focuses on the evaluation of skin whitening effect of the hydromethanolic extract prepared from the flowers of Cassia auriculata L., a plant widely employed in traditional medicine in Sri Lanka to improve complexion. MethodsThe skin whitening effect of the extract was determined by in vitro tyrosinase inhibitory assay while the antioxidant activity was evaluated by DPPH assay. Thereafter a topical formulation was developed using this extract and the tyrosinase inhibitory potential was further investigated. ResultsC. auriculata extract has displayed a strong tyrosinase inhibition with an IC50 of 42.49 μg/mL, while the IC50 value of the positive control (ascorbic acid) was determined as 33.70 μg/mL. The formulation developed from this extract has also displayed a potent inhibition of the enzyme with an IC50 of 70.70 μg/mL which was extremely remarkable than the commercial preparation of kojic acid. In addition, C. auriculata extract has exhibited a strong antioxidant activity with an EC50 value of 19.99 μg/mL, suggesting a possible correlation between tyrosinase inhibition and antioxidant activity. ConclusionThe preliminary findings reveal that C. auriculata has a high potential to be used as a natural skin whitening agent due to the inhibition of tyrosinase enzyme as well as the strong antioxidant activity.