Chemical composition, antioxidant and antimicrobial activity of the essential oil from the rhizome of Curcuma longa L.

The benefits of essential oils are well known for ages due to the presence of the major and minor components in the oils and their synergistic effects. The essential oil of air-dried rhizome of Curcuma longa L. obtained through hydro distillation using Clevenger apparatus was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) while the antimicrobial assay was carried out using the agar diffusion method. In vitro antioxidant assay was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, ferric reducing antioxidant power and nitric oxide radical scavenging on the extracted essential oil. The major components of the essential oil of Curcuma longa L. were p-Menthane-1,8-diol (17.26%), 3-Ethylthiophene (9.47%), trans-Ascaridol glycol (7.98%), 3-Methyl-2-(3-methylpentyl)-3-buten-1-ol (7.93%), Carvone hydrate (6.78%), Bis(2ethylhexyl) phthalate (6.35%) 2-Ethylcyclohexanone (5.30%), Cyclohexanone, 4-hydroxy-4-methyl-(4.62%), -Phellandrene-8-ol (4.32%) and Sobrerol (5.94%). Results of the antioxidant activities of the essential oil of Curcuma longa L. showed promising antioxidant potentials when compared to the positive control (ascorbic acid), strong nitric oxide scavenging activity was observed in the essential oil (IC50 of 23.19 g/mL) than that of the standard drug used (IC50 of 34.24 g/mL). The antimicrobial activities of the essential oil against the most frequently encountered microorganisms which include Staphylococcus aureus (ATCC 29213), Streptococcus mutans, Escherichia coli (ATCC 25922) and Candida albicans (ATCC 10231) showed significant broad spectrum antibacterial and antifungal activities with zones of inhibition (mm) against Staphylococcus aureus (21.001.4), Streptococcus mutans (29.004.9), Escherichia coli (38.002.8) and Candida albicans (23.000.6).