Chemical characterization, antimicrobial activity, and cytotoxic activity of Mikania micrantha Kunth flower essential oil from North East India

Mikania micrantha Kunth (mile-a-minute) is a major invasive weed with medicinal properties. It causes destruction of forests and threat to crop plantations, thus affecting the agriculture-based economy of a country. As an attempt to mitigate this problem, we have studied the applicability of M. micrantha flower essential oil against disease causing microorganisms and inhibition of cancerous cells. Sixty-six compounds were characterized from the flower essential oil by gas chromatography–mass spectrometry. The major constituents were: Isoledene (16%), δ-Cadinene (11.2%), Debromofiliformin (9.4%), Trans-Caryophyllene (9.1%), β-Bisabolene (7.4%), Germacrene-D (5.8%), and Zingiberene (5.3%). The oil is a complex mixture containing mainly sesquiterpene hydrocarbons (62.9%) and oxygenated sesquiterpenes (23.9%) with the other terpene compounds. Well-diffusion and resazurin assay were conducted to determine antimicrobial activity and minimum inhibitory concentration (MIC) of the essential oil. Flower oil showed best activity against Mycobacterium smegmatis and Candida albicans with MIC 8 µg/mL. Moreover, it is the first report of antimicrobial activity of the oil towards M. smegmatis, C. albicans, Staphylococcus aureus, and Pseudomonas aeruginosa. Minimum bactericidal and fungicidal concentration was determined and mechanism of antimicrobial activity was investigated by Field Emission-Scanning Electron Microscopy and Transmission Electron Microscopy analysis. It is the first cytotoxicity report of M. micrantha flower essential oil for cervical, ovarian, and pancreatic cancer cell lines. Through MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, we have found that oil has excellent cytotoxicity against HeLa cervical cancer cell lines (IC50 5.44 ± 1.33 µg/mL) and PA1 ovarian cancer cell lines (IC5010.57 ± 1.44 µg/mL). The essential oil extracted from the invasive weed M. micrantha flower is now found to have antimicrobial and anticancer properties from our study. Thus, this harmful weed can be utilized as antimicrobial and anticancer agents for the healthcare of human being.