Chemical composition and antimicrobial, anti-biofilm, and anti-quorum sensing activities of Mentha longifolia subsp. typhoides essential oil

Antibiotic resistance is a significant global health problem primarily caused by the inappropriate use of antibiotics. Therefore, the inadequacy of antibiotics in treating infections has led to exploring effective alternative treatment options, such as natural sources like essential oils. Mentha longifolia subsp. typhoides (Lamiaceae) is an economically important medicinal and aromatic plant used in traditional medicine as a spice and herbal tea. This study aimed to characterize the essential oil composition of this species (MLT-EO) and its biological activities. The chemical composition of the MLT-EO was analyzed using gas chromatography (GC) and GC-mass spectrometry (GC-MS). Piperitenone (25.7%), carvone (22.7%), piperitone (22.8%), pulegone (6.8%), and isomenthone (6.6%) were characterized as the main components. The MLT-EO exhibits antibacterial activity against Gram-negative bacteria. The MLT-EO exhibited the best MIC value against the test fungi, with <0.625 mg/mL values against Candida parapsilosis strains. The percentage of biofilm inhibition value of the MLT-EO (10 mg/mL) was 59.53%, and the percentage of violacein inhibition values calculated for sub-MICs concentrations of the MLT-EO (1 mg/mL and 0.5 mg/mL) were 63.68% and 38.08%, respectively. The results show that the high level of piperitenone, carvone, and piperitone detected in the MLT-EO may be responsible for these effects.