Essential oil from the leaves of Croton thorelii Gagnep.: chemical composition and biological activities

Aim: Croton thorelii Gagnep. is a lesser-known plant with ethnobotanical relevance. This study investigates the essential oil extracted from its leaves for potential use in natural preservatives and functional foods. Although traditionally used in folk medicine, information on its chemical composition and biological properties remains limited. Methods: Essential oil was obtained by hydrodistillation using a Clevenger-type apparatus from fresh leaves collected in Central Vietnam. Chemical composition was determined by gas chromatography-mass spectrometry. Biological activities were assessed through cytotoxicity (SRB assay on SK-LU-1 and HepG2 cells), antioxidant assays (DPPH and ABTS), and anti-inflammatory testing (nitric oxide inhibition in LPS-stimulated RAW 264.7 macrophages). All tests were performed in triplicate. Results: A total of 59 compounds were identified, accounting for 99.5% of the oil. Major groups included sesquiterpene hydrocarbons (44.5%), oxygenated monoterpenes (41.1%), and oxygenated sesquiterpenes (9.4%). The principal components were β-selinene (22.0%), 1,8-cineole (20.7%), linalool (11.2%), and (E)-caryophyllene (9.5%). The essential oil showed strong cytotoxicity with IC50 values of 54.52 ± 1.40 µg/mL (SK-LU-1) and 48.29 ± 2.09 µg/mL (HepG2), and over 90% inhibition at 100 µg/mL. Antioxidant activity was weak, with IC50 values above 500 µg/mL in the DPPH assay and 453.85 ± 15.87 µg/mL in the ABTS assay. In macrophages, nitric oxide inhibition exceeded 61% at 100 µg/mL, though cell viability was reduced to 57.91 ± 2.98%. Conclusions: Essential oil from C. thorelii displays promising cytotoxic and anti-inflammatory activities for potential use in functional foods, but further studies are needed to address safety and optimize application.