Determination of Chemical Composition and Evaluation of Antioxidant Activity of Essential Oil fromTinospora cordifolia(Willd.) Leaf

The work carried out on hitherto unknown chemical composition of essential oil isolated from leaf of Tinospora cordifolia (Willd.) and evaluation of its in vitro antioxidant activity is reported. Essential oil was obtained by hydrodistillation using Clevenger apparatus was found to contain 27 volatile compounds by GC-FID and GC-MS analyses. Identification of 25 constituents comprising 98.1 % of essential oil was done using NIST library and Wiley GC-MS library. This was further supported by the comparison of the reported retention indices with those determined. Confirmation of structural assignment of 13 compounds in leaf essential oil was done by co-injection with the authentic compounds. The compounds identified in essential oil include alcohols (32.1 %), phenols (16.6 %), aldehydes (16.2 %), fatty acids (15.7 %), alkanes (8.3 %), esters (3.2 %), terpenes (1.2 %), and other classes of compounds (4.8 %). Major components of the leaf essential oil were hydroquinone (16.6 %), 2-hexenal (14.2 %), palmitic acid (14.1 %), 2-hexen-1-ol (11.5 %) and phytol (11.4%). The essential oil demonstrated strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (IC50= 25±0.3 µg/mL). It also showed dose dependent reducing power activity. Total phenolic content of this essential oil was shown to be 28±0.4 mg GAE/g fresh leaves. This study demonstrates the strong potential of T. cordifolia leaf essential oil as a natural antioxidant.