Evaluation of antioxidant and antifungal activities of several plants against agents of postharvest citrus sour rot and green mould rot

Abstract

The antifungal activities of chloroform extracts of 10 plants species belonging to Lamiaceae family, which were collected from Kirklareli (Turkey), against Geotrichum candidum, theagent of postharvest citrus sour rot and Penicillium digitatum, the agent of postharvest citrus green mould rot, were researched. The lowest Minimum Inhibitory Concentration (MIC) values against G. candidum and P. digitatum were obtained in the extract of Marrubiumperegrinum L. (250 and 125 mu g/ml). In 1000 mu g/ml, the extracts of Melissa officinalis showed 100% inhibition on the spore germination of G. candidum and P. digitatum. In the Scanning Electron Microscope (SEM) observations of G. candidum and P. digitatum that was subjected to M peregrinum extract (4MIC) degenerative changes in the hyphal morphology were seen in the form of cell wall degradation, lysis and collapsing. The highest values of total phenolics were obtained from Mentha pulegium extracts (739.57 mg GAE/g). The lowest EC50 values (0.08 mg/ml) were found in the extracts of M peregrinum and Sideritis montana. The highest flavanol content was determined from M. officialis exctracts (12.71 mg CE/mg). This study demonstrates M. peregrinum extracts may possess high antifungal activity against G. candidum and P. digitatum.