Microwave-assisted extraction of Lawsonia inermis L. leaves: Method validation, optimization, and tyrosinase-stimulating activity

Abstract

Vitiligo is a long-term skin condition characterized by the development of pale white patches due to a lack of melanin. Lawsonia inermis L. leaves, which contain lawsone, have been explored as a potential alternative treatment for vitiligo. This study aimed to optimize the microwave-assisted extraction of L. inermis leaves and evaluate its ability to stimulate tyrosinase activity, which is relevant to vitiligo treatment. The Box-Behnken design was employed, with three factors being varied: microwave power, time, and cycle. Two responses were monitored: extraction yield and lawsone content. To determine the lawsone content, validated high-performance liquid chromatography was utilized, which demonstrated good linearity, specificity, precision, and accuracy. The optimal conditions that provided the highest extraction yield and lawsone content were then used to evaluate the extract’s ability to stimulate tyrosinase activity. The results revealed that a microwave power of 300 W and a microwave time of 20 s for one cycle yielded an extraction yield of 12.99% ± 0.10% and a lawsone content of 94.85 ± 3.12 mg/g extract. The accuracy of the prediction, with a percent error of less than 10%, confirmed the reliability of the computer program used for data prediction. Furthermore, the extract exhibited significant stimulation of tyrosinase activity, indicating its potential usefulness in vitiligo treatment. The optimal microwave-assisted extraction method identified in this study holds promise for maximizing extraction yield and lawsone content in L. inermis leaves extract. This extract could serve as a basis for developing topical products for the treatment of vitiligo.