A novel enzymatic approach for a targeted fungal growth inhibition

Dandruff represents a complex, multifactorial disorder characterized by impaired barrier function, altered lipid composition, and microbial imbalance. The principal pathogenic mechanism, however, involves excessive colonization by Malassezia species, notably M. furfur, M. restricta and M. globosa, on the scalp. Standard antifungal options often lead to undesirable effects, including itching and irritation, and may negatively impact the scalp microbiome. This study evaluates combination of chitinase and chitosanase, targeting fungal cell wall chitin and chitosan, as a promising targeted approach for scalp Malassezia spp.

The in vitro antifungal activities of chitinase (100 U/g) and chitosanase (200 U/g) were evaluated against Malassezia furfur, Malassezia restricta, and Malassezia globosa at concentrations ranging from 0.125% to 5% w/w. Their efficacy was compared to that of conventional antifungal agents, including climbazole, piroctone olamine, selenium sulfide, zinc pyrithione, and propanediol caprylate. Cytotoxicity was assessed using fibroblast cell lines via MTT assay and fluorescence microscopy. A clinical study (n = 18) evaluated the impact of a solution containing 0.25% chitinase and 0.25% chitosanase on scalp M. furfur and M. restricta DNA and RNA levels using quantitative PCR (qPCR). A metagenomic analysis was conducted to assess the impact of enzymatic treatment on bacterial composition and diversity.

Individually, 0.25% chitinase and 0.25% chitosanase inhibited Malassezia spp. growth by 23.85% and 26.15%, respectively (p < 0.05). When combined at 0.25%, they achieved 98.38% inhibition (p < 0.05), with complete suppression observed at 0.5%. In a clinical study, a 3-hour scalp treatment with a solution containing 0.25% chitinase and 0.25% chitosanase followed by quantitative PCR of post-treatment samples demonstrated significant reductions in DNA and RNA levels of M. furfur and M. restricta. DNA content decreased 2.4- and 1.9-fold, and RNA levels declined 2.4- and 4.6-fold, respectively. Cytotoxicity was detected only at concentrations ≥ 7.6%, well above the effective antifungal doses. The metagenomic analysis demonstrated that a three-hour scalp treatment with chitinase - chitosanase solution increased alpha diversity (Chao1 index) and doubled the number of identifiable operational taxonomic units (OTUs).

The chitinase-chitosanase combination offers a promising targeted approach for scalp Malassezia spp. control without broad antimicrobial effects.