The human skin is a dynamic ecosystem where a balanced microbial community maintains barrier integrity and prevents pathogen colonization. However, injuries and external factors can lead to dysbiosis, an imbalance that allows opportunistic “ESKAPE” pathogens—such as Staphylococcus aureus and Pseudomonas aeruginosa—to thrive. The global rise in antimicrobial resistance has created an urgent need for non-traditional strategies that suppress harmful bacteria without damaging beneficial commensals. Bioactive plant compounds from Centella asiatica, particularly triterpenes like asiaticoside and madecassoside, have emerged as a promising solution due to their broad antimicrobial, anti-inflammatory, and wound-healing properties. These molecules offer a sustainable, regulation-aligned alternative to traditional antibiotics by acting through multiple mechanisms and maintaining a favorable safety profile for topical application.
Methods
The study was conducted in three experimental phases: (1) in vitro suspension assays to determine the antibacterial efficacy of a 1% C. asiatica cream against ESKAPE and commensal strains; (2) ex vivo human skin explant models to evaluate the formulation’s preventive and therapeutic effects on pathogen-colonized skin; and (3) mixed-population ex vivo models to assess its ability to modulate the balance between pathogens and commensals. Bacterial viability was quantified through colony-forming unit (CFU) enumeration, while structural effects on the skin surface and bacterial biofilms were visualized using scanning electron microscopy (SEM).
Key Findings
- Broad-Spectrum Efficacy: In vitro assays showed the cream significantly reduced Gram-positive and Gram-negative pathogens by over 99.99%, including K. pneumoniae, P. aeruginosa, and A. baumannii.
- Preventive and Therapeutic Protection: Ex vivo models demonstrated that the cream acts as a filmogenic barrier, reducing S. aureus and P. aeruginosa colonization by up to 99.96% when used preventively and remaining highly effective even after pathogen establishment.
- Microbiome-Friendly Modulation: In dysbiotic models, the treatment selectively decreased pathogenic S. aureus (81.18%) while simultaneously promoting the growth of the beneficial commensal S. epidermidis (80.18%).
- Physical Barrier Function: Beyond its chemical properties, the galenic structure of the cream creates a physical protective system that limits the penetration of external contaminants and supports a localized concentration of bioactive compounds.
The novelty of this research lies in its characterization of Centella asiatica as a microbiome-modulating therapy rather than just a simple bactericidal agent; it is the first to demonstrate such selective action in a physiologically relevant human skin model. By preserving the “friendly” microbiota while aggressively targeting pathogens, the formulation offers a clinically relevant, sustainable approach to managing wound care and skin health. Future implications suggest this extract could serve as a vital non-antibiotic alternative to combat antimicrobial resistance, though further in vivo clinical studies and molecular analyses are required to fully elucidate its mechanisms and long-term effects on skin homeostasis.
Link to the study: https://doi.org/10.1099/acmi.0.001250.v1
