Abstract

The antibacterial, antifungal and insecticidal activities of the crude extract ofPolygonum persicaria, Rumex hastatus, Rumex dentatus, Rumex nepalensis,Polygonum plebejum and Rheum australe have been studied. Six bacterial species were used, of which Citrobacter frundii, Escherichia coli, Enterobacter aerogenesand Staphylococcus aureus were the most susceptible bacterial species to crude extract with MICs 16, 5.0, 25 and 0.156 mg/ml, respectively. Among the tested fungal species Fusarium solani, Aspergillus flavus and Aspergillus niger were more susceptible to crude extracts with MICs 0.75, 2.15, and 1.75 µg/ml, respectively. The crude extracts of R. dentatus and R. nepalensis show significant insecticidal activity against Sitophilus oryzae; P. persicaria and P. plebejum show significantinsecticidal activities against Tribolium castaneum, respectively. The above selected plants were shown by in vitro assays to be a potential source for natural antifungal, antibacterial and insecticidal agents.

Key words: Polygonum persicaria, Rumex hastatus, Rumex dentatus, Rumex nepalensis, Polygonum plebejum, Rheum australe, antibacterial, antifungal, insecticidal.