Promotion of Hair Growth by Rosmarinus Officinalis Leaf Extract

The study from 2012 investigated the effects of Rosmarinus officinalis leaf extract (RO-ext) on hair growth, particularly as a potential treatment for androgenic alopecia. The extract was topically applied to mice at a dosage of 2 mg/day/mouse, leading to improved hair regrowth in testosterone-treated C57BL/6NCrSlc mice and in shaved C3H/He mice. RO-ext showed significant inhibition of testosterone 5α-reductase, with up to 94.6% inhibition at 500 µg/mL, and the active component responsible was identified as 12-methoxycarnosic acid. Additionally, RO-ext and 12-methoxycarnosic acid inhibited androgen-dependent cell proliferation, suggesting they may block dihydrotestosterone from binding to androgen receptors. The study, which used groups of 10 mice for hair regrowth tests, concluded that RO-ext, especially due to 12-methoxycarnosic acid, could be a promising natural treatment for hair growth and androgenetic alopecia.