Phytochemical Composition, Antioxidant and Insecticidal Activities of Essential Oil from Senecio dalzellii C. B. Clerke

Abstract

Senecio dalzelii, a member of this genus, holds significant value in traditional medicine and ethnobotanical practices. However, the phytochemical composition and bioactivities of its essential oil (EO) remain underexplored. The EO was extracted from fresh aerial parts of S. dalzelii using hydro-distillation in a Clevenger-type apparatus. Subsequent GC-MS profiling and phytochemical screening were performed to identify bioactive compounds. A total of 35 chemical compounds were identified, accounting for 91.68% of the total EO yield. The major constituents were Thymyl Methyl Ether (18.78%), 4-(2', 4', 4'-trimethyl-yciclo 4.1.0], hept-2'-en-3'-yl)-3-buten-2-one (9.9%), Estragole (7.64%), α-Curcumene (6.2%), (-)-δ-Cadinol (4.64%), Caryophyllene (4.24%). TLC profiles showed 8 bands with iodine vapor and 9 bands at 254 and 366 nm, respectively, indicating the diverse bioactive components. EOs found to be rich in phytochemicals with potential attributed to the inclusion of flavonoids (9.16 μg quercetin equivalents mg⁻¹ EO), and total phenols (3.41 μg gallic acid equivalents (GAE) mg⁻¹ EO). EO exhibited significant antioxidant activity, as measured by DPPH, showing an IC50 value of 1.06 mg/mL, and the Ferric reducing antioxidant power assay (FRAP) showed 59.41±2.38 μg ascorbic acid equivalent at 2 mg¹ EO, respectively. The EO also exhibited significant adulticidal efficacy against Callosobrochus maculatus; the LC50 and LC95 values of the EO were 8.89 and 17.58 μL/mL, respectively. This Study shows that S. dalzelii EO contains various phytochemicals, particularly thymyl methyl ether and phenolics, which contribute to its significant antioxidant and insecticidal properties. Therefore, these findings suggest potential use of S. dalzellii EO as a natural antioxidant and biopesticide for agro-pharmaceutical or biocontrol applications.