Polyphenol composition, antioxidant and bioplaguicide activities of the solid residue from hydrodistillation of Rosmarinus officinalis L.

Rosemary is one of the most important aromatic plants in terms of commercialization of essential oil. Nevertheless, a large amount of solid residue with a considerable content of bioactive compounds is generated during the hydrodistillation of the essential oil. In this work we have identified the major phenolic compounds present in such residue and evaluated its antioxidant and bioplaguicide activities. Antioxidant activity was determined by several in vitro methods, such as the β-carotene/linoleate model system, reducing power, DPPH radical scavenging, and iron and copper ion chelation. Bioplaguicide activity was investigated by means of the antifeedant effects against Leptinotarsa decemlineata Say, Spodoptera littoralis Boisd. and Myzus persicae Sulzer; and the phytotoxic activity against Lactuca sativa L., Lycopersicon esculentum L. and Lolium perenne L. Solid residue extract showed very high antioxidant activities, comparable to an extract from red grape pomace that was used as a natural antioxidant standard. It also showed strong antifeedant activity against L. decemlineata, S. littoralis and M. persicae with effective doses within the range of model antifeedants as well as limited phytotoxic effects on L. sativa, SL. esculentum and L. perenne. These results suggest a potential use of the solid residue from the hydrodistillation of rosemary as source of antioxidants and natural crop protectants.