Supplementary Material for: Plant Extracts in Acne Management: a narrative review

Background: Acne is a chronic inflammatory skin disease associated with impaired pilosebaceous unit function leading to the development of noninflammatory and inflammatory lesions and, in some cases, persistent post-inflammatory erythema, hyperpigmentation and scarring. Acne pathophysiology is complex, involving altered sebum production and composition, abnormal keratinization, microbiome dysbiosis, and skin inflammation. Conventional therapies, such as topical retinoids, antibiotics and benzoyl peroxide, are the first-line treatments for mild-to-moderate acne, but antibiotic resistance and local adverse effects can have a negative impact on therapeutic outcomes, leading to a growing interest in alternative strategies for disease management. The use of dermocosmetics is increasingly being recognized as a useful strategy to improve treatment outcomes and patient adherence. In particular, there has been a recent increase in research aiming to identify natural plant-based ingredients with properties that target the multiple pathogenic mechanisms involved in acne, but which have less impact on skin barrier function. Summary: This review provides a summary of the anti-acne properties of the most well-characterized plant extracts and phytocompounds used in dermocosmetic anti-acne products, based on insights gained from in vitro, ex vivo and in vivo studies. Evidence gained from clinical trials evaluating the effectiveness and safety of topical formulations containing these herbal ingredients is also presented. Finally, several less well-characterized herbal extracts and phytocompounds with promising anti-acne properties are described. Key Messages: Although research is ongoing for many of the anti-acne herbal ingredients identified so far, this review highlights the effectiveness of topical plant-based formulations for reducing lesion counts and disease severity in acne patients, as well as the rebalancing effects of herbal ingredients on sebum composition, microbial diversity, and pilosebaceous unit cell differentiation. Taken together with the antibiofilm, anti-inflammatory, antioxidant, and skin barrier repair properties demonstrated for many of these extracts, current evidence suggests that dermocosmetics with plant-based ingredients show great promise for acne management, either as monotherapies, maintenance treatments, or in combination with conventional drugs.