Identification of Mentha piperita L. and Ricinus communis L. polyphe-nols by HPLC-DAD-ESI-MS and evaluation of their insecticidal properties against Aphis spiraecola P

Aphids infest most crops, and are considered as one of the most destructive groups of insects in temperate regions. The purpose of this study was to identify the polyphenols of castor (Ricinus communis L.) and mint (Mentha piperita L.) with liquid chromatography coupled to diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS), and evaluate their insecticidal properties against Aphis spiraecola P. A total of 10 compounds were identified in castor mainly phenolic acids (gallic acid, protocatechuic acid, syringic acid, chlorogenic acid, gentisic acid and p-coumaric acid). On the other hands, flavonoids (catechin, naringin, diosmin, rutin, diosmetin, luteolin, neohesperidin, naringenin and apigenin) were the major polyphe-nols in mint representing 10 compounds out of 14. In the test of insecticidal activity, four concentrations were tested (5, 10, 20 and 40%). Both plants had a good inhibitory activity especially mint. The effect was dose dependent and the highest mortality was obtained with the maximum used concentration (40%). After the first day, a percentage of 44 and 76% of mortality was recorded in the presence of just 5% of castor and mint which increased to reach 100% after 7 days.