Antioxidant and allelopathic activities of extract and fractions from Rosmarinus officinalis

Abstract

The species Rosmarinus officinalis L. is popularly known as rosemary, being widely used in traditional medicine. In the present study, the ethanol extract and fractions obtained from R. officinalis were evaluated for allelopathic and antioxidant activities and determined the content of phenolic compounds. The ethanol extract and fractions showed antioxidant activity in five concentrations tested. Regarding the EC50 values,the ethanol extract and fractions showed better results than the BHT, reference compound. The EC50 values obtained for the ethanol extract and fractions could not be correlated directly with the content of phenolic compounds present in the samples. For allelopathic activity, the samples were able to stimulate and also inhibited the growth of hypocotyl and radicle observed at different concentrations (50, 100 and 200 mg/mL). For the radicle onion (Allium cepa), the best results were obtained for the ethanol extract and fractions hexane and dichloromethane, which inhibited growth at all concentrations, and the dichloromethane fraction promoted an inhibition greater than 80.0%, at a concentration of 200 mg/mL. Regarding the onion hypocotyl, the effects were heterogeneous. The results for the growth of radicle and hypocotyl of lettuce seeds (Lactuca sativa) showed that the inhibitory effect was more significant than the stimulatory, when the seeds were treated with the ethanol extract and factions. Regarding the inhibitory effect, they emphasized the dichloromethane fraction with a 100.0% inhibition, at a concentration of 200 mg/mL. Inhibition of hypocotyl was more significant than the radicle for lettuce seeds. The ethanol extract and dichloromethane fraction had an inhibitory effect, at all concentrations tested. In the search for new antioxidants and allelochemicals of natural origin, the species Rosmarinus officinalis may be a good candidate.