Comparative GC-MS Analysis, In-vitro Antioxidant and Antimicrobial Activities of the Essential Oils Isolated from the Peel of Omani Lime

The aim of this study was, to analyze and compare the composition of volatile constituents in the essential oils from the peel of Citrus aurantifolia L. grown in three different regions of Oman and to investigate their antioxidant and antibacterial potential. The essential oil from the fresh peels was isolated by hydro-distillation method and chemical composition analysis of oils was carried out by Gas chromatography-Mass spectrometry (GC-MS). The antioxidant activity was investigated by a non enzymatic free radical scavenging method while antibacterial activity was tested against gram positive and gram negative bacteria by disc diffusion method. Molecular docking studies were also carried out to probe the mechanism of antioxidant activity. GC-MS analysis indicated variation in content and composition of chemical constituents in the peel oils. Limonene was found to be the major volatile constituent thus establishing lime peel oil as limonene chemotype. The peel essential oils of C. aurantifolia showed moderate antioxidant and antibacterial activitities. Molecular docking studies indicated alpha-farnesene to have better binding affinity for Xanthine oxidoreductase in comparison to limonene and pinene. Further studies are needed to develop the lime peel oil as an antimicrobial preservative and an alternative source of natural antioxidant(s).