Boosting hair growth through follicular delivery of Melatonin through lecithin-enhanced Pickering emulsion stabilized by chitosan-dextran nanoparticles in testosterone induced androgenic alopecia rat model

The strategy in this work was loading Melatonin (MEL), the powerful antioxidant photosensitive molecule, in novel Pickering emulsions (PEs) stabilized by chitosan-dextran sulphate nanoparticles (CS-DS NPs) and enhanced by lecithin, for treatment of androgenic alopecia (AGA). Biodegradable CS-DS NPs dispersion was prepared by polyelectrolyte complexation and optimized for PEs stabilization. PEs were characterized for droplet size, zeta potential, morphology, photostability and antioxidant activity. Ex-vivo permeation study through rat full thickness skin was conducted with optimized formula. Differential tape stripping trailed by cyanoacrylate skin surface biopsy was executed, for quantifying MEL in skin compartments and hair follicles. In-vivo evaluation of MEL PE hair growth activity was performed on testosterone induced AGA rat model. Visual inspection followed by anagen to telogen phase ratio (A/T) and histopathological examinations were conducted and compared with marketed 5% minoxidil spray "Rogaine ®". Data showed that PE improved MEL antioxidant activity and photostability. Ex-vivo results displayed MEL PE high follicular deposition. In-vivo study demonstrated that MEL PE treated testosterone induced AGA rat group, restored hair loss and produced maximum hair regeneration along with prolonged anagen phase amongst tested groups. The histopathological examination revealed that MEL PE prolonged anagen stage, increased follicular density and A/T ratio by 1.5-fold. The results suggested that lecithin-enhanced PE stabilized by CS-DS NPs was found to be an effective approach to enhance photostability, antioxidant activity and follicular delivery of MEL. Thus, MEL-loaded PE could be a promising competitor to commercially marketed Minoxidil for treatment of AGA.