Chemical composition, phytochemical profile and antimicrobial properties of the methanolic extracts of polluted and unpolluted leaves of Hyptis suaveolens (L)

Hyptis suaveolens, an aromatic plant commonly called Daddoya-ta-daji in Hausa language, is traditionally used as medicine and food. It is used as stimulant, antirheumatic, carminative, against parasitic diseases, headaches, infection of the uterus, stomach, and skin diseases. It is found growing in both oil polluted and non-oil polluted environment. Oil pollution of land is a challenge due to the presence of heavy metals and volatile organic compounds which are harmful to crops and plants. This study investigated the phytoconstituents of the methanol leaf extract as well as antimicrobial activities of Hyptis suaveolens collected from polluted and unpolluted sites. Methanol leaf extracts of H. suaveolens were screened for crucial phytochemicals using standard methods. The in vitro antimicrobial activity was carried out using agar disc-diffusion method by Yahaya et al. (2018), using Mueller Hinton agar medium and potatoes dextrose agar in petri plates seeded with clinical isolates of Escherichia coli, Salmonella typhi, Shigella sp, Staphylococcus aureus (bacteria), Candida albicans and Aspergillus niger (fungi) respectively, and the zone of inhibition determined. The phytochemical results showed that methanol extract of both the polluted and non-polluted H. suaveolens leaves exhibited the presence of some number of bioactive compounds. Gas Chromatography–Mass Spectrometry (GC-MS) of polluted and non-polluted leaves of H. suaveolens identified 13 and 21 compounds, respectively such as Octadec-9-enoic acid, 2-Ethylacridine, Methyl ester, Tetracyclo [4.4.1.1(7,10).0(2,5)] dodec-3-en-11-ol, 1,2-Diphenyl-1-isocyanoethane and 7-Isopropyl-1, 1, 4a-trimethy l-1,2,3,4,4a,9,10,10 aocta -hydrophenanthrene. These chemical compounds are considered biologically and pharmacologically important. The results from assessment of the antimicrobial potential of H. suaveolens (L.) on pathogenic microorganisms showed that the pathogenic microorganisms revealed inhibition zones ranging from 6 to 18 mm. This data indicates that the unpolluted methanol extract of H. Suaveolens exhibits a higher bioactive potential compared to the extract derived from polluted leaves. This disparity suggests that oil pollution may have a detrimental impact on the biochemical properties of the plant.