Pharmacological prospection in-vitro of Lamiaceae species against human pathogenic fungi associated to invasive infections

Abstract

The medical importance of invasive fungal diseases (IFD) contrasts with the limited therapeutic arsenal available and the increasing resistance rate of pathogenic fungi. Thus, the search for news antifungal drugs is imperative. Many studies highlight the antimicrobial activity of plants from Lamiaceae family such as Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus and Rosmarinus officinalis, but the antifungal potential these species remains still poorly known. The present study was to evaluate the effect of these Lamiaceae species against fungi involved in IFDs. Fresh plants were macerated with ethanol and the extract obtained was partitioned with different solvents. Phytochemical analyzes were conducted and the volatile compounds were investigated by gas chromatography/mass spectrometry (GC/MS). Subsequently, the standardized vegetal material was used to evaluate the antifungal activity through minimum inhibitory concentration (MIC) determination. Ethanol extract of M. officinalis, Mentha sp., O. basilicum, and R. officinalis showed good to moderate activity against Paracoccidioides spp. (MIC 62.5-500 μg/mL). The spectrum of antifungal activity of P. barbatus ethanol extract includes, besides P. brasiliensis (MIC 125–500 μg/mL), several species of Candida spp. (MIC 31.25-500 μg/mL) and the yeasts Cryptococcus gattii, Saccharomyces cerevisiae and Rhodotorula mucilaginosa (MIC 62.5 μg/mL). Flavonoids, steroids/triterpenes, and alkaloids were associated with antifungal activity of extracts and fractions, and the phytol was pointed as the main active compound of the extracts. Lamiaceae plants are a promising source of new antifungal prototypes and phytotherapeutic agents for the pharmaceutical industry, especially against Paracoccidioides spp.