Glycyrrhiza acid-Licochalcone A complexes for enhanced bioavailability and anti-melanogenic effect of Licochalcone A: cellular uptake and in vitro experiments

Abstract

Licochalcone A (LicA) is a natural chalcones, well-known for its anti-melanogenic activity, however, its poor solubility leads to a limited topical bioavailability and clinical outcomes. Therefore, LicA-encapsulated glycyrrhiza acid (GA) (GA-LicA) micelles were formulated for higher cellular uptake and improved cutaneous applications. The physicochemical properties (morphology, size and charge), topical penetration, endocytic pathways, cellular uptake amount (CUA) and intracellular distribution of the GA-LicA micelles were studied. Moreover, the anti-melanogenic mechanisms including antioxidant properties, melanogenesis-mediated enzymes and melanin generation as well as cell apoptosis in A375 cells were demonstrated. We found that significant increase amount of LicA was obtained into the epidermis after encapsulated in GA micelles, and the hair follicles were the preferential route for LicA permeation. Moreover, HaCaT and melanocytes possessed a significantly higher effective uptake and CUA for GA-LicA micelles than that of the crude LicA. Caveolae-mediated and actin filaments-mediated endocytosis, caveolae-mediated endocytosis were respectively involved in cellular uptake of GA-LicA micelles for HaCaT cells and melanocytes. Furthermore, GA-LicA micelles possessed a synergistic anti-melanogenic effect by scavenging the free radicals, reducing the activity of α-glucosidase and tyrosinase, and inducing the cell apoptosis. Taken together, GA micelles can enhance the bioavailability and anti-melanogenic effect of LicA, and the article provided principles for rational design of formulations in whitening cosmetics.