Enzyme-assisted extraction of bioactive compounds from bay leaves (Laurus nobilis L.)

Bay leaves (Laurus nobilis L.) are widely used as a condiment and their therapeutic benefits are well known. These biological properties were attributed to a plethora of highly bioactive secondary metabolites namely essential oils and phenolics. However, their recovery from plant matrix is generally limited by the presence of physical barrier (cell wall). Thus, the use of novel extraction procedures to enhance their release is particularly important. Therefore, the aim of this work is to assess the potential use of enzyme treatment (cellulase, hemicellulase, xylanase end the ternary mixture of them) as a tool to improve the extraction efficiency of bioactive compounds from bay leaves. Results showed that enzyme pre-treatment resulted in 243, 227, 240.54 and 0.48% increase in the essential oil yields in samples treated with cellulase, hemicellulase, xylanase and the ternary mixture, respectively. Compositional analysis by GC and GC MS revealed remarkable enrichment of the essential oils derived from enzyme-treated samples with oxygenated monoterpenes, leading hence to better antioxidant activity as revealed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and azino-bis-(3-ethylbenzothiolzoline 6-sulphonic acid) (ABTS) assays. The 1,8-cineole, alpha-terpinyl acetate, methyl eugenol, linalool, a-pinene, sabinene and beta-pinene were found as the most prominent components in all essential oils. Most importantly, enzyme treatment did not induce transformation of the volatile components, but it contributes to the liberation of some glycosidically bound volatiles. Moreover, it significantly enhances the release of phenolic compounds from the hydro distilled residual leaves and consequently their antioxidant activity. These results suggest that enzyme pre-treatment could be useful for extracting valuables components, and hold good potential for use in food, cosmetic and pharmaceutical industries. (C) 2015 Elsevier B.V. All rights reserved.