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Dandruff, a common scalp disorder characterized by flaking dead skin, is often treated with conventional topical products. However, limitations exist due to potential side effects and high costs. Therefore, searching for natural, cost-effective solutions for dandruff and hair loss is crucial. Rosemary herb and neem tree, both cultivated in Egypt, possess well-documented anti-inflammatory properties derived from their rich phenolic phytoconstituents. This study formulated a standardized combined extract of rosemary and neem (RN-E 2:1) into hair gel and leave-in tonic formats. This extract demonstrated superior efficacy against Malassezia furfur (a causative agent of dandruff) and Trichophyton rubrum (associated with scalp disorders) compared to the conventional antifungal agent, ketoconazole. The combined extract (RN-E 2:1) also exhibited potent anti-inflammatory activity. Additionally, the suppression of iNOS expression is considered concentration-dependent. Quality control verified formulation stability, and ex-vivo studies confirmed effective ingredient penetration into the epidermis, the primary site of fungal presence. Remarkably, both formulations outperformed the standard treatment, minoxidil in hair growth trials. These findings highlight the potential of natural extracts for scalp and hair health., (© 2024. The Author(s).)

Dandruff is a recurrent chronic scalp disorder, affecting majority of the population worldwide. Recently a metagenomic study of the Indian scalp microbiome described an imperative role of bacterial commensals in providing essential vitamins and amino acids to the scalp. Coconut oil and its formulations are commonly applied on the scalp in several parts of the world to maintain scalp health. Thus, in this study we examined the effect of topical application of coconut oil on the scalp microbiome (bacterial and fungal) at the taxonomic and functional levels and their correlation with scalp physiological parameters. A 16-weeks-long time-course study was performed including 12-weeks of treatment and 4-weeks of relapse phase on a cohort of 140 (70 healthy and 70 dandruff) Indian women, resulting in ~ 900 metagenomic samples. After the treatment phase, an increase in the abundance of Cutibacterium acnes and Malassezia globosa in dandruff scalp was observed, which were negatively correlated to dandruff parameters. At the functional level, an enrichment of healthy scalp-related bacterial pathways, such as biotin metabolism and decrease in the fungal pathogenesis pathways was observed. The study provides novel insights on the effect of coconut oil in maintaining a healthy scalp and in modulating the scalp microbiome.

Dandruff is known to be associated with Malassezia restricta. Zinc pyrithione (ZPT) has been used as an ingredient in anti-dandruff treatments. The mechanism of ZPT has been investigated in several studies; however, a non-pathogenic model yeast, such as Saccharomyces cerevisiae was most often used. The aim of the present study was to understand how ZPT inhibits the growth of M. restricta. We analyzed the cellular metal content and transcriptome profile of ZPT-treated M. restricta cells and found that ZPT treatment dramatically increased cellular zinc levels, along with a small increase in cellular copper levels. Moreover, our transcriptome analysis showed that ZPT inhibits Fe-S cluster synthesis in M. restricta. We also observed that ZPT treatment significantly reduced the expression of lipases, whose activities contribute to the survival and virulence of M. restricta on human skin. Therefore, the results of our study suggest that at least three inhibitory mechanisms are associated with the action of ZPT against M. restricta: (i) an increase in cellular zinc levels, (ii) inhibition of mitochondrial function, and (iii) a decrease in lipase expression.