Antimicrobial Activity of Volatile and Non-Volatile Extracts of <em>Hyptis suaveolens</em> Leaves

Medicinal plants serve as valuable reservoirs of bioactive compounds with therapeutic potential, offering alternatives in the fight against drug-resistant infections. Hyptis suaveolens (L.) Poit., though widely used in traditional medicine, remains underexplored despite reports of antimicrobial, anti-inflammatory, and other pharmacological activities. Given the global need for novel antimicrobials, this study investigated the volatile (essential oils) and non-volatile (methanolic) extracts of H. suaveolens leaves, aiming to assess their antimicrobial activity against selected bacterial and fungal pathogens. Fresh Hyptis suaveolens leaves were collected and authenticated at Adekunle Ajasin University, Nigeria. Essential oils were obtained via hydro-distillation, while methanolic extracts were prepared by maceration. Antimicrobial activity against clinical isolates (E. coli, P. aeruginosa, B. cereus, K. pneumoniae, and C. albicans) was assessed using agar well diffusion, with MIC and MBC determined through macro-broth dilution techniques. Hydro-distillation of fresh leaves yielded 2.7% essential oil, while methanol extraction of dried leaves produced 1.5% crude extract. Both extracts inhibited all six clinical isolates, with the methanolic extract showing greater efficacy. The highest inhibition zone was recorded against Candida albicans (32 mm), and the lowest against Staphylococcus aureus (27 mm). Minimum inhibitory concentration (MIC) testing revealed consistent activity of the methanolic extract across all concentrations, whereas the essential oil displayed variable inhibition. Minimum bactericidal concentration (MBC) assays confirmed bactericidal activity of both extracts, with E. coli and Pseudomonas aeruginosa eradicated at 25–50 mg/mL, while Klebsiella pneumoniae required the highest concentration (12.5 mg/mL). Hyptis suaveolens extracts exhibited broad-spectrum antimicrobial and bactericidal activity, with methanolic extract showing superior potency, highlighting its potential as a natural alternative antimicrobial source.