Background. The leaves of Leea rubra contain an abundance of phenolic constituents and have medicinal uses as antipyretic and diaphoretic agents and are also used in the treatment of stomach ache, rheumatism, arthritis etc. In spite of the traditional uses, data on the scientific evaluation of the plant are not sufficient. So, the present study was designed to evaluate the protective role of the extract against oxidative damage to DNA and human erythrocytes as well as antitumor and antibacterial activities against some resistant bacteria. Methods. The protective activity of the ethyl acetate fraction (EAF) of the extract was investigated by evaluating the inhibition of oxidative damage of pUC19 plasmid DNA as well as hemolysis and lipid peroxidation damage to human erythrocytes induced by 2,2′-azobis-2-amidinopropane (AAPH). Antitumor activity was assessed by evaluating the percentage inhibition of cell growth, morphological changes of Ehrlich’s ascites carcinoma (EAC) cells, and hematological parameters. Antimicrobial activity was determined by the disc diffusion method against different resistant microorganisms. Results. EAF effectively inhibited AAPH-induced oxidative damage to DNA because it can inhibit the transformation of the supercoiled form of plasmid DNA to open circular and further linear form. The oxidative hemolysis caused by AAPH in human erythrocytes was inhibited by EAF extract in a time-dependent manner, and the production of malondialdehyde (MDA) was significantly reduced, which indicates the prevention of lipid peroxidation. In antitumor assay, 76% growth of inhibition of EAC was observed compared with the control mice ( p < 0.05 ) at a dose of 100 mg/kg body weight. Antimicrobial activity was evaluated against two pathogenic resistant microorganisms (Escherichia coli and Pseudomonas aeruginosa), and the highest antimicrobial activity was observed against Pseudomonas spp. Conclusion. EAF may have great importance in preventing oxidative damage to DNA, erythrocytes, and other cellular components as well as can be a good candidate in cancer chemotherapy and treating infectious diseases caused by antibiotic-resistant bacteria.

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Objective: Diarrhea is a major global health issue that has become increasingly prevalent in developing countries. In Bangladesh, Mimosa pigra L. is used traditionally for the treatment of diarrhea and also to control infection. Our main objective was to evaluate whether the methanolic extract of Mimosa pigra (MEMP) leaves has the antidiarrheal effect as well as the antibacterial effect against diarrhea-causing bacteria. Methods: The antibacterial potentialities of MEMP leaves were investigated by the disc diffusion method against six Gram-positive and six Gram-negative bacteria at 500 μg/disc. Kanamycin (30 μg/disc) was used as the standard drug. Antidiarrheal activities of leaf extracts were determined at two doses (200 and 400 mg/kg) in a castor oil and magnesium sulfate-induced diarrheal model in mice. The results were evaluated by One-Way Analysis of Variance (ANOVA) followed by Dunnet’s test. **P<0.01 and ***P<0.001 were considered significant compared to control. Results: The MEMP leaves exhibited moderate to potent antimicrobial activity with the zone of inhibition range 11 to 17 mm against diarrhea causing bacteria such as Salmonella paratyphi (16.33 mm), Salmonella typhi (17 mm), Shigella boydii (12 mm), Shigella dysenteriae (12.67 mm) and Escherichia coli (11 mm). Furthermore the severity of diarrhea was significantly reduced (P<0.001) by MEMP leaves at a dose of 400 mg/kg (13±2.16) compared to control (30.25±2.87) by castor oil-induced method. The same dose of the extract also significantly inhibited (P<0.01) the severity of diarrhea (14.75±1.71) compared to control (24±2.16) by magnesium sulfate-induced diarrheal model. The percent inhibition of diarrhea in 3h by MEMP leaves at a dose of 400 mg/kg was 57.02% and 38.54% in castor oil and magnesium sulfate-induced diarrheal model, respectively. Conclusion: Confirmed findings in this study naturally suggested that MEMP leaves could be an effective antibacterial and antidiarrheal formulation.