Design, synthesis, molecular docking and biological evaluation of thiophen-2-iminothiazolidine derivatives for use against Trypanosoma cruzi.

In this study, we designed and synthesized a series of thiophen-2-iminothiazolidine derivatives from thiophen-2-thioureic with good anti-Trypanosoma cruzi activity. Several of the final compounds displayed remarkable trypanocidal activity. The ability of the new compounds to inhibit the activity of the enzyme cruzain, the major cysteine protease of T. cruzi, was also explored. The compounds 3b, 4b, 8b and 8c were the most active derivatives against amastigote form, with significant IC50 values between 9.7 and 6.03µM. The 8c derivative showed the highest potency against cruzain (IC50=2.4µM). Molecular docking study showed that this compound can interact with subsites S1 and S2 simultaneously, and the negative values for the theoretical energy binding (Eb=-7.39kcal·mol(-1)) indicates interaction (via dipole-dipole) between the hybridized sulfur sp(3) atom at the thiazolidine ring and Gly66. Finally, the results suggest that the thiophen-2-iminothiazolidines synthesized are important lead compounds for the continuing battle against Chagas disease.

Involvement of cerebral nervous system areas and cytokines on antihyperalgesic and anti-inflammatory activities of Kielmeyera rugosa Choisy (Calophyllaceae) in rodents.

Kielmeyera rugosa is a medicinal plant known in Northeastern Brazil as 'pau-santo', and it is used in the treatment of several tropical diseases such as malaria, schistosomiasis, and leishmaniasis. We evaluated antihyperalgesic and anti-inflammatory activities of methanol stem extract of K. rugosa (MEKR) in mice. The mechanical hyperalgesia induced by carrageenan and tumor necrosis factor-alpha (TNF-α), prostaglandin E2 , and dopamine were assessed. We also investigated the anti-inflammatory effect of MEKR on carrageenan-induced pleurisy and paw edema. Ninety minutes after the treatment, the animals were submitted to an imunofluorescence for Fos protein. MEKR (100, 200, and 400 mg/kg; p.o.) inhibited the development of mechanical hypernociception and edema. MEKR significantly decreased TNF-α and interleukin 1ß levels in pleural lavage and suppressed the recruitment of leukocytes. MEKR (1, 10, and 100 mg/mL) did not produce cytotoxicity, determined using the methyl-thiazolyl-tetrazolium assay in vitro. The locomotor activity was not affected. MEKR activated significantly the bulb olfactory, piriform cortex, and periaqueductal gray of the central nervous system. Our results provide first time evidence to propose that MEKR attenuates mechanical hyperalgesia and inflammation, in part, through an activation of central nervous system areas, mainly the periaqueductal gray and piriform cortex areas.

Thymus involution in alloxan diabetes: analysis of mast cells

We previously reported that alloxan-induced diabetes results in reduction in the number and reactivity of mast cells at different body sites. In this study, the influence of diabetes on thymic mast cells was investigated. Thymuses from diabetic rats showed marked alterations including shrinkage, thymocyte depletion, and increase in the extracellular matrix network, as compared to those profiles seen in normal animals. Nevertheless, we noted that the number and reactivity of mast cells remained unchanged. These findings indicate that although diabetes leads to critical alterations in the thymus, the local mast cell population is refractory to its effect. This suggests that thymic mast cells are under a different regulation as compared to those located in other tissues.

Kinetics of eosinophil and IgE-mast cell changes following infection with Angiostrongylus costaricensis in Wistar rats.

Human abdominal angiostrongyliasis is a severe eosinophilic disease caused by Angiostrongylus costaricensis. Previous studies have demonstrated that wild rodents are critically involved as definitive hosts to this nematode in nature. In this study, we have evaluated the susceptibility of Wistar rats (Rattus norvegicus) to A. costaricensis infection. Kinetics of parasitological and pathological changes, including the number of adult worms recovered from mesenteric arteries, and of IgE, mast cell and eosinophil levels in several compartments have been assessed. The oral inoculation of third-stage larvae (L3) into adult Wistar rats led to a marked accumulation of worms in the branches of the mesenteric arteries 25 and 50 days post-inoculation. Intense bone marrow eosinophilia ranging from 7 to 50 days was accompanied by marked accumulation of eosinophils in the blood, peritoneal and bronchoalveolar spaces. Eosinophilic periarteritis, oedema and granuloma in the intestinal and lung tissues were also histologically evident. Total serum IgE and specific anti-parasite IgE peaked at 25 days post-infection, as measured by ELISA and by the passive cutaneous anaphylaxis test, respectively. At that time point, there was a drastic reduction in the number of intact mast cells in the peritoneal effluent. These findings indicate that Wistar rats are permissive to A. costaricensis infection. IgE-mast cell activation and massive tissue eosinophil infiltration are marked features in the process and are likely to play a crucial role in the immune-response evoked by this parasite.