GC/MS profiling of essential oils from Bontia daphnoides L., chemometric discrimination, isolation of dehydroepingaione and evaluation of antiviral activity

Bontia daphnoides L. has been utilized in traditional medicine for treatment of herpes, cough and colds. The aim of this study was to analyze the volatile constituents of this plant by GC/MS (Gas Chromatography coupled to Mass Spectrometry) and to assess their antiviral activity. A total of 64 compounds were identified where dehydroepingaione represented 83.60, 72.36, 58.78 and 34.18% in the leaves, stems, flowers and fruits, respectively. Principal component and hierarchical cluster analysis revealed the discrimination of the organs as the leaves and stems were distributed in the same cluster in contrast to the flowers and fruits. Furthermore, the antiviral activity was assessed where the oils of leaves and stems exhibited potent antiviral activity displaying IC(50) of 11.98, 12.62 µg/ml against HSV-1 and 13.34, 14.50 µg/ml against CoxB4, respectively. Dehydroepingaione was isolated from the n-hexane fraction of the leaves and showed activity against HSV-1 and CoxB with IC(50) of 24.46 and 25.32 µg/ml, respectively. Molecular modelling studies illustrated that the major compounds showed good affinity towards HSV type-1 thymidine kinase. Therefore, it can be concluded that the oils from B. daphnoides have promising antiviral activity that may be attributed to the major oxygenated sesquiterpenes.