In vitro and in silico evaluation of the schistosomicidal activity of eugenol derivatives using biochemical, molecular, and morphological tools

Background Eugenol shows both antibacterial and antiparasitic activities, suggesting that it might be evaluated as an option for the treatment of praziquantel-resistant schistosome. Methods The in vitro activities of three eugenol derivatives (FB1, FB4 and FB9) on adult worms from Schistosoma mansoni were examined by fluorescence and scanning electron microscopy to analyze effects on the excretory system and integument damage, respectively. Biochemical tests with verapamil (a calcium channel antagonist) and ouabain (a Na+/K+-ATPase pump inhibitor) were used to characterize eugenol derivative interactions with calcium channels and the Na+/K+-ATPase, while in silico analysis identified potential Na+/K+-ATPase binding sites. Results The compounds showed effective doses (ED50) of 0.324 mM (FB1), 0.167 mM (FB4), and 0.340 mM (FB9). In addition, FB4 (0.322 mM), which showed the lowest ED50, ED90 and ED100 (p < 0.05), caused the most damage to the excretory system and integument, according to both fluorescence and scanning electron microscopy analysis. The death of adult worms was delayed by ouabain treatment plus FB1 (192 versus 72 hours) and FB9 (192 versus 168 hours), but the response to FB4 was the same in the presence or absence of ouabain. Besides, no changes were noted when all of the eugenol derivatives were combined with verapamil. Moreover, FB1 and FB9 inhibited Na+/K+-ATPase activity according to in silico analysis but FB4 did not show a time-dependent relationship and may act on targets other than the parasite Na+/K+-ATPase. Conclusion Eugenol derivatives, mainly FB4 when compared to FB1 and FB9, seem to act more effectively on the integument of adult S. mansoni worms.(AU)

Indirect potentiometric microdtermination of some antimony [III] antibilharzial compounds

Aqueous solution of the title compounds [0.3-5 mumol] is mixed with 3 ml KIO4 solution [1 g/300 ml water] at pH 3 [acetic acid-sodium acetate buffer], stirred for 2 minutes. The solution is adjusted to pH 5.2 and is percolated through a 2 cm x 1.5 cm2 column of a strong-base polystyrene anion-exchanger [Dowex] in the acetate form. Iodate is selectively removed from the column with 100 ml of 0.1 M NH4Cl at flow rates up to 5 ml/min. The eluted iodate is titrated potentiometrically with sodium arsenite solution in H2SO4 medium in presence of osmium tetroxide as a catalyst and the use of SCE and Pt electrodes couple. Tartar emetic, antimony sodium tartrate, piperazine diantimony tartrate and stibophon are easily determined with satisfactory accuracy