Modulatory effects of Mentha longifolia and Mentha spicata essential oils on Candida albicans biofilm formation

Abstract

Mentha longifolia (horsemint) and Mentha spicata (spearmint) are economically valuable aromatic plants widely utilized in food, cosmetic, and pharmaceutical industries due to their rich reservoir of bioactive compounds. This study investigated the antifungal and antibiofilm properties of essential oils extracted from these species against various Candida strains, particularly Candida albicans, a major opportunistic pathogen responsible for oral and systemic infections. Essential oils were extracted via hydrodistillation using a Clevenger apparatus and chemically characterized through GC-MS, revealing that M. longifolia oil was predominantly composed of pulegone (29.7%), menthone (26%), and eucalyptol (17.8%), while M. spicata oil was mainly enriched in pulegone (68.5%), eucalyptol (5.2%), and thymol (3.5%). The antifungal activity, evaluated by agar-well diffusion and broth microdilution assays, showed inhibition zones ranging from 9-14 mm for M. longifolia and 9-12 mm for M. spicata, with corresponding minimal inhibitory concentrations (MICs) of 0.39-6.25 mg/mL and fungicidal concentrations (MFCs) of 12.5-100 mg/mL. Both oils markedly reduced biofilm biomass in a concentration-dependent manner, with up to 90% inhibition observed at 4× MIC. The potent biofilm disruption was attributed to the high terpenoid content, capable of altering fungal membrane integrity. Overall, these findings demonstrate that the essential oils of M. longifolia and M. spicata possess significant antifungal and antibiofilm potential, highlighting their possible application as natural, plant-derived therapeutic agents for controlling Candida-associated oral and biomedical infections.