Composition and antioxidant activity of <i>Senecio nudicaulis</i> Wall. ex DC. (Asteraceae): a medicinal plant growing wild in Himachal Pradesh, India

<div><p>The composition of essential oil isolated from <i>Senecio nudicaulis</i> Wall. ex DC. growing wild in Himachal Pradesh, India, was analysed, for the first time, by capillary gas chromatography (GC) and GC–mass spectrometry. A total of 30 components representing 95.3% of the total oil were identified. The essential oil was characterised by a high content of oxygenated sesquiterpenes (54.97%) with caryophyllene oxide (24.99%) as the major component. Other significant constituents were humulene epoxide-II (21.25%), α-humulene (18.75%), β-caryophyllene (9.67%), <i>epi</i>-α-cadinol (2.90%), <i>epi</i>-α-muurolol (2.03%), β-cedrene (1.76%), longiborneol (1.76%), 1-tridecene (1.16%) and citronellol (1.13%). The oil was screened for antioxidant activity using DPPH, ABTS and nitric oxide-scavenging assay. The oil was found to exhibit significant antioxidant activity by scavenging DPPH, ABTS and nitric oxide radicals with IC₅₀ values of 10.61 ± 0.14 μg mL^{− 1}, 11.85 ± 0.28 μg mL^{− 1} and 11.29 ± 0.42 μg mL^{− 1}, respectively.</p>