Antioxidant and antimicrobial activities of extracts obtained from the refining of autohydrolysis liquors of vine shoots

Vine shoots, considered a residue from winery operations, possess valuable antioxidant and antimicrobial activities that can be potentially obtained under the scheme of biorefinery. In this framework, we evaluated the autohydrolysis of vine shoots combined with a further stage of extraction with ethyl acetate as viable valorization process. The extraction yield ranged from 0.95 to 3.80 g extract/100 g vine shoots. Moderately high temperature (215 °C) was required for the maximum recovery of phenolics, flavonoids and antioxidant activities. The major phenolic compounds identified were derived from lignin: vanillin, acetovanillone, guaiacylacetone, syringaldehyde and acetosyringone. The ethyl acetate extract from the liquors obtained at 200 °C was assayed for antimicrobial activity against Gram positive and negative bacteria showing values of MIC and MBC in the range of 5-20 mg/mL. This work showed that the antioxidant extracts could be used as cheap source of natural compounds, with potential applications in the food and pharmaceutical industries.