Withania somnifera root extracts induce skin darkening in wall lizard melanophores via stimulation of cholinergic receptors

Melanogenic effect of purified mushroom tyrosinase on B16F10 Melanocytes: A Phase Contrast and Immunofluorescence Microscopic Study

Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social communication, and protection against harmful effects of solar radiation. It has been proven that tyrosinase plays a pivotal role in melanocytes dendrite formation; however, the molecular mechanism underlying this process has not been fully elucidated. The morphological changes were observed under a phase contrast microscope. These changes were evident, with globular cell bodies and increased numbers of tree branch-like dendrites. The present work aimed to study the morphoanatomic effects of purified tyrosinase to determine its skin-darkening potential using B16F10 melanocyte, which has not been done to date. Phase contrast and immunofluorescence microscopic analysis of B16F10 melanocytes has been done after treatment with various concentrations of purified tyrosinase along with standard tyrosinase (Sigma) in order to explore the mechanism of action of purified tyrosinase induced skin darkening. The phase contrast microscopic results showed that the number of melanocytes with melanin-loaded dendrites has increased significantly in purified tyrosinase treated cells in a dose dependent manner leading to skin darkening. In addition, immunofluorescence microscopic analysis revealed purified tyrosinase increase cellular tyrosinase expression in doze dependent manner due to tyrosinase absorption in B16F10 melanocyte. Present findings proved that purified tyrosinase possesses a skin darkening potential and could be used as a safe melanogenic agent for the treatment of hypopigmentation disorders or vitiligo.

Understanding the ultrastructural aspects of berberine-induced skin-darkening activity in the toad, Bufo melanostictus, melanophores

Berberine is an active compound of Berberis vulgaris (Daruhaldi) with known multiple pharmacological activities, including antimicrobial, antiviral, anti-inflammatory, cholesterol-lowering, and anticancer effects. The present work aimed to study the ultrastructural effects of berberine to determine its skin-darkening potential using Bufo melanostictus melanophores, which has not been done to date. Light and electron microscopic analysis of isolated dorsal skin melanophores of B. melanostictus has been done after treatment with various concentrations of berberine, along with specific antagonists and agonists of β-adrenoceptors in order to explore the mechanism of action of berberine-induced skin darkening. The results showed that the number of melanophores with melanin-loaded dendrites increased in the subepidermal layer significantly in berberine-treated skin pieces in a dose-dependent manner leading to skin darkening. Highly electron-dense melanosomes of Stage IV increased considerably due to the enhanced process of melanization. These effects were found to be antagonized by propranolol, and were also found to be highly potentiated by isoprenaline, which is a specific β-adrenoceptor agonist. The findings show that berberine possesses a skin-darkening potential and could be used as a safe melanogenic agent for the treatment of hypopigmentation disorders or vitiligo.