ABSTRACT
In a previous work, searching for new drugs with high efficiency and low toxicity, the in vitro antileishmanial activity of a series of seven amidine derivatives against Leishmania amazonensis promastigotes was reported. In order to compare the potential difference in the susceptibility between the two developmental stages of the parasite to these compounds, an analysis of the effects of these amidine derivatives on promastigotes and axenically grown amastigotes of L. amazonensis was carried out. Among the N,N'-diphenyl-4-R-benzamidine (where R = H, Cl, Br, CN, NO2, CH3 and OCH3) derivatives studied, the most active compounds in both developmental stages were those with -Br, -Cl, -NO2, and -OCH3 substituents, the nonsubstituted ones being the least active. However, the susceptibility to the drugs varied in these forms, being higher in promastigotes. The electronic theoretical parameters calculated by molecular modelling using the semi-empirical AM1 method showed good correlation with substituent constant (sigma para, sigma 1 and F). The chemical structure and biological activity relationships were investigated in all compounds, although a small but significant correlation was observed. The obtained results suggest that other factors than the electronic parameters have an influence on the biological response.
ABSTRACT
The Greater Metropolitan Area of Belo Horizonte currently contains 18 city parks (also known as "ecological parks") with various bodies of water (lakes, springs, streams, etc). Initial research in 17 of these parks showed the occurrence of intermediate mollusk hosts for Schistosoma mansoni in at least 4. Monthly captures done from August 1994 to February 1996 showed the following results for these planorbids: Julien Rien Park: 1,145 specimens of Biomphalaria glabrata (2 to 13 mm); Betânia Park: 149 specimens of B. glabrata (4 to 13 mm); Santa Lúcia Park: 2,431 specimens of B. straminea (3 to 9 mm); and Lagoa do Nado Park: 3 specimens of B. tenagophila (3 to 10 mm). Visits to the parks will continue, and after a diagnosis of each park's situation, control and/or eradication measures suitable for each one will be proposed to the municipal authorities.
ABSTRACT
In Belo Horizonte, Minas Gerais, Brazil, the snail Biomphalaria straminea was found in the Pampulha region. Recently the snail was found in ditches in the old Santa Lúcia Reservoir, a now-extinct focus of schistosomiasis transmission by B. glabrata. The snails were collected and examined to verify whether they were naturally infected with Schistosoma mansoni. Negative specimens were used for breeding or infection with the LE strain of S. mansoni from the laboratory and another strain obtained from eggs found in the feces of a schoolchild (VGS) from Belo Horizonte. Among the 1890 snails collected from 1994 to 1995, none were infected with S. mansoni. Among 87 snails collected and exposed to the LE strain, 9 (10.3%) shed cercariae; among 83 snails from F1, and exposed to LE, 10 (12.0%) shed cercariae. Among 88 snails exposed to VGS, 10 (11.3%) shed cercariae. In Belo Horizonte, schistosomiasis is transmitted by B. glabrata and B. tenagophila. However, currently there exists the risk of appearance of a focus in which B. straminea could be the host if prophylactic measures are not taken by the authorities responsible for the construction of a park and lake at that site.
