Promising plant-derived secondary metabolites for treatment of acne vulgaris: a mechanistic review

Acne vulgaris is the most common skin condition associated with inflammation of pilosebaceous unit. Since conventional therapies have not demonstrated desirable effectiveness and possess remarkable side effects, there is a growing interest in the use of herbal medicines for the management of acne vulgaris. In this study, plant-derived molecules investigated in acne vulgaris have been reviewed and their possible underlying mechanisms of action were discussed. For this purpose, different electronic databases including PubMed, Scopus, Cochrane library and Google Scholar were searched to obtain any in vitro, in vivo, or human studies evaluating the phytochemicals in the management of acne vulgaris. Data were collected from 1980 to 2018 (up to October). Most of the phytochemicals investigated in acne were from the category of polyphenols including resveratrol, myricitrin, schisandrin, terchebulin, alpha-mangotin, curcumin, ellagic acid and epigallocatechin 3-gallate. Moreover, alkaloids and terpenoids such as berberine, ursolic acid, lupeol were evaluated in acne vulgaris with less abundance. Various molecular mechanisms were involved in effects of phytochemicals including antioxidant (through down-regulation of H₂O₂, MDA, ROS and upregulation of SOD), anti-inflammatory (through reduction of proinflammatory cytokines, i.e., IL-1ß, IL-6, IL-8, TGF-β, TNF-α, NF-κB), immunomodulatory, antibacterial (against Propionibacterium acnes and Propionibacterium granulosum), antiandrogenic, reducing sebum production, and lipogenesis inhibitory activities. Therefore, phytochemicals seem to be a precious source for identifying new medicines for treatment of acne vulgaris; however, since most of studies are preclinical, further clinical studies are needed to achieve more conclusive and reliable results.