Valorization of the residual bagasse of Mexican oregano (Lippia graveolens HBK) by obtaining fractions enriched in pinocembrin

Abstract

Mexican oregano (Lippia graveolens HBK) constitutes a spice of great commercial value mainly due to the presence of thymol and carvacrol, volatile fat-soluble compounds contained in its essential oil. However, little use has been made of its high content of water-soluble phenolic compounds, with proven antioxidant capacities. Among them, it stands out its high content of pinocembrin, flavanone with properties of great nutritional importance and for health due to its protective activity against cerebral ischemia. Mexico ranks second as a world producer of Mexican oregano. During the extractive process of the essential oil derived from its leaf, a large amount of solid waste rich in flavonoids is generated, which is minimally used and even becomes a source of contamination due to its poor disposal as waste. In order to value this agro-industrial waste, it was characterized by determining the content of total phenols, antioxidant activity (DHHP) and content of pinocembrin, observing a higher content of pinocembrin in the extract of oregano without essential oil (0.766 mg / ml) with respect to that corresponding to oregano without treatment (0.659 mg / ml). The results suggest that the residual bagasse from the extraction of the essential oil can be used with great potential due to its high content of polyphenols, antioxidant capacity and pinocembrin (27.93 mg / g BS). To achieve the concentration of pinocembrin, two separation methods were evaluated: chromatographic column with silica gel (hydrophilic) and separation with automated extraction in hydrophobic solid phase (Ultra C18) with pinocembrin recovery efficiencies of 56.6 and 90.1 %, respectively, being able to generate products enriched in pinocembrin with a 74.8 % purity. This work contributes to the potential development of new products and waste recovery processes in the growing natural essential oil extraction industry.