Decoding the Antimicrobial Components of Mentha piperita Plant Using Chemical Analysis and Fourier Transform Infrared Spectroscopy
Itohowo Okon Akpan *
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin LGA., PMB 1167, Akwa Ibom State, Nigeria.
Itoro Nyakno Willie
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin LGA., PMB 1167, Akwa Ibom State, Nigeria.
Ibanga Okon Isaac
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin LGA., PMB 1167, Akwa Ibom State, Nigeria.
Emaime Jimmy Uwanta
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin LGA., PMB 1167, Akwa Ibom State, Nigeria.
Usoro Monday Etesin
Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Mkpat Enin LGA., PMB 1167, Akwa Ibom State, Nigeria.
Ozioma Achugasim
Department of Pure and Industrial Chemistry, University of Port Harcourt, PMB 5323, Port Harcourt, Rivers State, Nigeria.
Regina Enyidiya Ogali
Department of Pure and Industrial Chemistry, University of Port Harcourt, PMB 5323, Port Harcourt, Rivers State, Nigeria and Department of Pharmaceutical and Medicinal Chemistry, College of Pharmacy, Gregory University, Uturu, Abia State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: This study investigated the antimicrobial phytochemicals present in Mentha piperita, characterised their functional groups using Fourier transform infrared (FTIR) spectroscopy, and evaluated their antibacterial and antifungal activities against selected human pathogens.
Study Design: Experimental laboratory-based phytochemical, spectroscopic, and antimicrobial study.
Place and Duration of the Study: The study was conducted in the Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Nigeria. Fresh Mentha piperita samples were collected from Mkpok Village, Eket Local Government Area, Akwa Ibom State, between March and July 2025.
Methodology: Ethanol extracts of fresh and dried leaves and stems were prepared by maceration. Qualitative and quantitative phytochemical analyses were performed using standard methods. Alkaloids, flavonoids, and cardiac glycosides were prepared and characterised using an Agilent Cary 630 FTIR Spectrometer in the range of 650 - 4000 cm⁻¹. The antimicrobial activities of the crude extract and isolated phytochemicals were evaluated against six bacterial (Staphylococcus aureus, Pseudomonas aeruginosa, Vibrio cholerae, Salmonella spp., Shigella spp., and Escherichia coli) and four fungal (Candida albicans, Saccharomyces cerevisiae, Aspergillus flavus, and Aspergillus niger) pathogens using the agar-well diffusion method, while minimum inhibitory concentrations (MICs) were determined by agar dilution.
Results: The extracts contained alkaloids, flavonoids, tannins, phlobatannins, cardiac glycosides, polyphenols, triterpenoids, steroids, and carbohydrates. Flavonoids (21.80 ± 2.40%) were the predominant phytochemicals, followed by cardiac glycosides (9.33 ± 1.71%) and alkaloids (4.47 ± 0.25%). FTIR spectra confirmed hydroxyl, carbonyl, amino, aromatic, and ether functional groups characteristic of bioactive compounds. The prepared crude phytochemicals exhibited broad-spectrum, concentration-dependent antimicrobial activity, with alkaloids showing the greatest antibacterial activity and cardiac glycosides exhibiting superior antifungal activity. MIC values ranged from 50 to 350 mg/mL.
Conclusion: Mentha piperita possesses abundant bioactive phytochemicals with significant antimicrobial potential. FTIR characterisation confirmed the structural features of the isolated compounds, while antimicrobial evaluation validated the plant's ethnomedicinal application. These findings highlight M. piperita as a promising, sustainable source of novel antimicrobial agents for combating antimicrobial resistance and advancing global health.
Keywords: Mentha piperita, phytochemical screening, antimicrobial activity, antimicrobial resistance, Fourier transform infrared spectroscopy, alkaloids, flavonoids, cardiac glycosides, minimum inhibitory concentration, ethanol extract, antibacterial activity, antifungal activity