Chemical Characterization, Antimicrobial, Antiproliferative and Antioxidant Activities of the Essential Oil of Monarda citriodora Growing in Kashmir

Objectives: The main aim of this research was to evaluate phytochemicals, antimicrobial, antiproliferative and antioxidant Activities of the essential Oil of Monarda citriodora growing in Kashmir (India). Materials and Methods: Essential oil obtained by hydrodistillation from the flowers of Monarda citriodora was analysed by a combination of capillary gas chromatographymass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) techniques. The essential oil was evaluated for its antimicrobial and antioxidant potential. Antimicrobial activity was evaluated against two fungal and seven bacterial strains. The antiproliferative efficacy was evaluated by Sulphorhodamine-B assay. Results: A total of 13 components were identified constituting 99.4% of the total oil composition. Thymol (79.7%), P-cymene (7.7%), Tricyclene (4.5%) and carvacrol (3.0%) were found to be the major components. The oil composition was totally dominated by oxygenated monoterpenes constituting 83.2%. Additionally, potent and broad-spectrum of antimicrobial activities were shown by the essential oil. In vitro cytotoxic studies revealed concentration dependent growth inhibition of all target cancer cell lines in the 10-100 μg/ml dilution range, with IC₅₀ values of 24.2μg/ml (THP-1), 55.5μg/ml (A-549), 31μg/ml (HEP-2) and 37.5μg/ml (Caco-2). Antioxidant studies of the essential oil evaluated by two complementary assays viz DPPH and hydroxyl radical assays confirmed that the oil exhibited potent and dose-dependent inhibition of the DPPH and hydroxyl radicals with IC₅₀ values of 19.3μg/ml and 39.2μg/ml respectively. Conclusion: We concluded that the essential of Monarda citriodora growing in Kashmir is rich in chemical composition and possess significant antimicrobial, antioxidant and antiproliferative activities.