Antimicrobial activity of Anonna mucosa (Jacq.) grown in vivo and obtained by in vitroculture

Brazilian flora includes numerous species of medicinal importance that can be used to develop new drugs. Plant tissue culture offers strategies for conservation and use of these species allowing continuous production of plants and bioactive substances. Annona mucosa has produced substances such as acetogenins and alkaloids that exhibit antimicrobial activities. The widespread use of antibiotics has led to an increase in multidrug-resistant bacteria, which represents a serious risk of infection. In view of this problem, the aim of this work was to evaluate the antibacterial potential of extracts of A. mucosa obtained by in vitro techniques and also cultured under in vivo conditions. Segments from seedlings were inoculated onto different culture media containing the auxin picloram and the cytokinin kinetin at different concentrations. The calluses obtained were used to produce cell suspension cultures. The materials were subjected to methanol extraction and subsequent fractionation in hexane and dichloromethane. The antimicrobial activity against 20 strains of clinical relevance was evaluated by the macrodilution method at minimum inhibitory and minimum bactericidal concentrations. The extracts showed selective antimicrobial activity, inhibiting the growth of Streptococcus pyogenes and Bacillus thuringiensis at different concentrations. The plant tissue culture methods produced plant materials with antibacterial properties, as well as in vivo grown plants. The antibacterial activity of material obtained through biotechnological procedures of A. mucosa is reported here for the first time.

Efficacy of Bacillus thuringiensis israelensis, VectoBac WG and DT, formulations against dengue mosquito vectors in cement potable water jars in Cambodia.

This study reports the evaluation of Bacillus thuringiensis israelensis (Bti), a biological larvicide, in cement jars holding river, well and rain water. Two Bti formulations, VectoBac WG and VectoBac DT, were evaluated in a village in Phnom Penh. Thirty-one households with cement jars supporting the colonization of Ae.aegypti immatures were chosen. In each house 3 jars were aligned next to each another and filled with the same type of water. One of the 3 jars was treated with VectoBac WG at 0.4 g per 50 liters, a second jar was treated with VectoBac DT at 1 tablet per 50 liters, and a third jar was an untreated control (UTC). The jars were not covered, kept outdoors and not subjected to water exchange activity. The efficacy of VectoBac to control natural Ae.aegypti infestation was measured by Ae.aegypti pupae surveillance, conducted 3 days per week for 3 months post-treatment (June-September 2004). All pupae were removed, allowed to emerge in the Cambodia National Malaria Center insectarium and the emerged adults were identified and counted. The VectoBac treatments were more effective in river water, followed by well and rain water. The VectoBac treatments significantly reduced the pupae numbers for a minimum of 3 months in the river water and 2.5 months in the well water (p < 0.05). In the rain water, the pupae densities in the VectoBac WG and DT treated jars were not significantly different from the untreated jars, although the treated jars yielded 2.0 to 5.2 fold less pupae, respectively, than in the untreated jars during the 3 months post-treatment. The efficacy of VectoBac WG to control Ae.aegypti was similar to the efficacy of VectoBac DT in the 3 water types (p > 0.05). It was also observed that VectoBac WG and DT were target specific, without any adverse effects on aquatic predatory insects common in well and rain water. VectoBac WG and DT were found to be easy-to-use formulations, with no need to repackage them prior to use in the containers. The amounts of VectoBac WG and DT used were 12.5 fold less by weight than temephos (Abate 1.0% SG).

Sensitivity of mosquito-pathogenic bacterial strains to various antibodies.

Four strains of Bacillus sphaericus, 1593, 2362, 9001 and 9002, B. thuringiensis H-14 and B. thuringiensis neoleonensis were tested for sensitivity against 18 antibiotics. The results revealed that all the four strains of B. sphaericus are resistant to colistin, nalidixic acid, polymyxin B and streptomycin. However, B. thuringiensis H-14 was resistant to 9 antibiotics, viz. ampicillin, cephalexin, carbenicillin, co-trimoxazole, colistin, cloxacillin, penicillin, nitrofurantoin and polymyxin B whereas B. thuringiensis neoleonensis was found to be resistant to 8 antibiotics. These results may help in isolation of potential and resistant mosquito pathogenic bacteria.