Chemical diversification of essential oils, evaluation of complex mixtures and identification of a xanthine oxidase inhibitor†
A set of chemically engineered essential oils has been generated through chemical diversification by reaction with bromine. The impact of the reaction over the chemical composition of the mixtures was qualitatively demonstrated through GC-MS and utilizing multivariate analysis of 1H NMR and GC-MS. Most of the components of the essential oils are transformed by the reaction expanding the chemical diversity of the mixtures. Biological changes between essential oils and brominated essential oils were demonstrated through image analysis of xanthine oxidase autography profiles. The highest biological activity increase was obtained for the Foeniculum vulgare Mill essential oil. Coupling of xanthine oxidase autography with the BIOMSID strategy allowed the identification of the molecular formula of the active compound. Bioguided fractionation of the mixture led to the isolation of (RS)-2-bromo-1-(4-methoxyphenyl) propan-1-one for being responsible for the observed bioactivity. This xanthine oxidase inhibitor could have been formed from the inactive natural component anethole. The inhibitory potency of this semisynthetic compound was in the same order of magnitude as allopurinol, the most used inhibitor.