Antibacterial and antiparasitic effects of Bothropoides lutzi venom.

The therapeutic potential of toxins has aroused great interest in the scientific community. Microbial resistance is a serious current public health problem, in part because of the wide use of antimicrobial drugs. Furthermore, there are several problems in the treatment of parasitic diseases such as leishmaniosis and Chagas' disease, including the low efficacy in some clinical phases of the diseases and the loss of effectiveness of benzonidazole in the chronic phase of Chagas' disease. In this context, the aim of this work was to study the antimicrobial and antiparasitic effects of Bothropoides lutzi total venom (BltTV). The venom exerted an antibacterial effect on S. aureus, with MIC=MLC=200 microg/mL. The inhibitory effects of BltTV on promastigote forms of Leishmania amazonensis and L. chagasi were assessed by counting of viable cells after incubation with BltTV. IC50 values of 234.6 microg/mL and 61.2 microg/mL, were obtained, respectively. Furthermore, the venom repressed epimastigote forms of Trypanosoma cruzi growth. Finally, BltTV was verified to affect murine peritoneal macrophages, causing a cytotoxic effect at the highest concentrations (100 and 50 microg/mL). In conclusion, Bothropoides lutzi venom demonstrated antibacterial and antiparasite effects, suggesting that the venom contains some substance(s) of therapeutic value.

The antimicrobial activity of photodynamic therapy against Streptococcus mutans using different photosensitizers.

UNLABELLED: Several photosensitizers have been used against oral bacteria without standardization. Singlet oxygen ((1)O(2)) is an aggressive chemical species that can kill cells through apoptosis or necrosis. OBJECTIVE: to compare the antimicrobial activity of photodynamic therapy (PDT) with different photosensitizers at the same concentration against Streptococcus mutans. In addition, the (1)O(2) production of each photosensitizer was determined. The photosensitizers (163.5 µM) methylene blue (MB), toluidine blue ortho (TBO) and malachite green (MG) were activated with a light-emitting diode (LED; λ=636 nm), while eosin (EOS), erythrosine (ERI) and rose bengal (RB) were irradiated with a curing light (λ=570 nm). Light sources were operated at 24 J cm(-2). For each photosensitizer, 40 randomized assays (n=10 per condition) were performed under one of the following experimental conditions: no light irradiation or photosensitizer, irradiation only, photosensitizer only or irradiation in the presence of a photosensitizer. After treatment, serial dilutions of S. mutans were seeded onto brain heart infusion agar to determine viability in colony-forming units per milliliter (CFU mL(-1)). Generation of (1)O(2) was analyzed by tryptophan photooxidation, and the decay constant was estimated. Results were analyzed by one-way ANOVA and the Tukey-Kramer test (p<0.05). PDT with irradiation in the presence of the photosensitizers TBO and MG was effective in reducing S. mutans counts by 3 and 1.4 logs, respectively (p<0.01), compared to their respective untreated controls. MB generated 1.3 times more (1)O(2) than TBO, and both produced significantly higher concentrations of singlet oxygen than the other photosensitizers. Since in vitro bulk (1)O(2) production does not indicate that (1)O(2) was generated in the bacterial activity site, the bactericidal action against S. mutans cannot be related to in vitro singlet O(2) generation rate. In vitroS. mutans-experiments demonstrated TBO as the only photosensitizer that effectively reduced 99.9% of these microorganisms.

Latex proteins from the plant Calotropis procera are partially digested upon in vitro enzymatic action and are not immunologically detected in fecal material.

Soluble proteins from the latex of Calotropis procera (LP) were investigated in vitro and in vivo for digestibility as the latex has previously been shown to produce considerable toxic effects on animals. The latex is also an important biologically active compound that displays antiinflammatory and antidiarrhea properties. The proteins were digested by the action of trypsin, pepsin or chemotrypsin as revealed by gel filtration and SDS-PAGE analysis. Furthermore, the full LP digestion was easily achieved by protease treatment. Rabbit polyclonal antibodies raised against LP failed to detect cross-reactive molecules in fecal material of experimental rats following 35 consecutive days of LP consumption in water. Similar patterns of electrophoresis were observed for the negligible amounts of protein observed in the fecal extracts of control and test animals. No death or toxic effects were observed among animals. Taken together these results suggest that harmful and toxic effects on animals of the latex from C. procera are present in its rubber and low molecular weight fractions rather than its protein content.

Cytotoxic activity of chalcones isolated from lonchocarpus sericeus (pocr.) kunth.

In the present study, it was demonstrated that the hexanic extract obtained from the roots of Lonchocarpus sericeus and one of its major components, derricin, but not lonchocarpin, show cytotoxic activity to fertilized sea urchin eggs. Both inhibited the first cleavage of sea urchin eggs in a dose-dependent manner with an IC(50) of 30.4 (26.2-35.3) microgram/mL for the crude extract and 51.2 (42.1-62.3) microgram/mL for derricin (n = 6, in both cases). Furthermore, the hexanic extract of L. sericeus, and the isolated compounds, derricin and lonchocarpin showed cytotoxicity against CEM leukaemic cell line (IC(50) = 17.6 (13.7-22.6), 13.0 (12.0-14.0) and 10.4 (5.6-19.1) microgram/ml (n = 6), respectively). When these substances (6.25 to 125 microgram/25 microL) were examined for antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans, none of them were found to be active. Neither the hexanic extract, nor the isolated compounds derricin and lonchocarpin (0.5 to 250 microgram/mL) presented hemolytic activity. These results indicated a possible antimitotic activity of L. sericeus crude extract and their major constituents.