Comparative GC–MS characterisation and in-vitro antioxidant evaluation of essential oils from leaf, stem and root combretum sordidum Exell.

Abstract

The increasing demand for natural antioxidants has stimulated research into plant-derived essential oils as potential alternatives to synthetic additives. This study examined the chemical composition and antioxidant activity of essential oils obtained from the leaves, stems, and roots of Combretum sordidum Exell. The oils were obtained by hydrodistillation using a Clevenger apparatus and analysed by Gas Chromatography–Mass Spectrometry (GC–MS). Their antioxidant activity was evaluated in vitro using the DPPH radical scavenging assay. Hydrodistillation produced colourless oils with yields of 0.56%, 0.43% and 0.40% from leaves, stems, and roots, respectively. GC–MS analysis revealed marked organ-specific variation in chemical composition. The stem oil exhibited the greatest chemical diversity, mainly composed of mono- and sesquiterpenes, such as cis,trans,cis-1,2,3-trimethylcyclohexane, germacrene D-4-ol, and linalool. The leaf oil was rich in oxygenated and chlorophyll-derived compounds, with phytol and α-ionone as major constituents. In contrast, the root oil contained mostly hexahydrofarnesyl acetone, neophytadiene, and benzofuran derivatives. All essential oils exhibited concentration-dependent DPPH radical scavenging activity, with the leaf oil showing the highest percentage inhibition of 50.40% at 150 μg/mL. The observed antioxidant activities are attributed to the presence and synergistic interactions of bioactive terpenoids and oxygenated compounds. These findings provide the first comprehensive report on the essential oil composition and antioxidant potential of C. sordidum, highlighting its promise as a natural source of antioxidant agents.