The chemical constituents and biological activities of the essential oil and the extracts from leaves of Gynura divaricata (L.) DC. growing in Thailand

The chemical constituents of the essential oil from the leaves of Gynura divaricata (L.) DC. were investigated by GC-FID and GC-MS. Seventeen compounds, representing 97.1 % of the chromatographical fraction of the oil, were detected. The major constituents, cubenol (65.7 %) and spathulenol (6.4 %), were isolated using column chromatography and identified by NMR and MS analysis. The antioxidant, cytotoxicity and antimicrobial activities of the essential oil, the hexane, dichloromethane and methanol extracts of G. divaricata leaves were investigated. The essential oil and the crude extracts showed antioxidant activity using the ABTS and DPPH methods, respectively. The essential oil exhibited significant cytotoxicity against KB, MCF-7 and NCI-H187 cancer cell lines with the IC values of 5.79, 47.44 and 17.65 µg/mL, respectively and had a MIC of 50 μg/mL against Mycobacterium tuberculosis H37Ra. Cubenol had an IC50 value of 45.37 µg/mL against the NCI-H187 cancer cell line. All extracts were non-cytotoxic against Vero cells. The essential oil and the extracts showed antimicrobial activity using the disc diffusion assay. The methanol extract was the most potent of the three extracts.