Effect of Harvesting Regions on Physico-chemical and Biological Attributes of Supercritical Fluid-Extracted Spearmint (Mentha spicata L.) Leaves Essential Oil

Abstract

The effects of different harvesting regions on the yield, volatiles composition and biological (antioxidant, antimicrobial and hemolytic) activities of supercritical fluid extracted spearmint (Mentha spicata L.) essential oil (SCFE-SEO) were explored. The SCFE-SEO content among populations from arid, irrigated, hilly and drought stressed regions varied from 0.46-0.64%. Using GC-FID/GC-MS, overall, 32 chemical constituents were identified representing 93.6 to 98.9% of the total oil composition. Variable levels of main components such as carvone (30.89-52.31%), cis-carveol (0.21-5.29%), menthone (1.09-22.58%), menthol (0.78-6.25%), limonene (1.31-9.39%), and 1,8-cineol (1.07-7.31%) were detected in the tested oils. The oils effectively scavenged DPPH free radicals as well as inhibited linoleic acid peroxidation depending upon variable contents of total phenolics and flavonoids. Moreover, the oils along with their major component (carvone), exhibited moderate to good antimicrobial activity against selected bacterial (E. coli, S. aureus, B. aereus,B. pumilis, B. subtilis P. aeruginosa, S. poona) and fungal (A. flavus, F. solani, A. solani, R. solani, A. alternate, A. niger and M. mucedo). Generally, the oil isolated from drought stressed spearmint plants exhibited superior antimicrobial and hemolytic activities while those from hilly regions depicted a higher extent of antioxidant activity and total phenolics and flavonoids that can be linked to the variable chemicals profiling of the selected plants.