Abstract 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.

We describe the synthesis and evaluation of N-acylhydrazone compounds bearing different electron-donating groups in one of its aromatic rings, obtained using a four-step synthetic route. IC50 values against pathogenic fungi and bacteria were determined by serial microdilution. Compounds showed low activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. By contrast, a derivative with a meta-oriented electron-donating group showed significant activity (IC50) against Candida albicans (17 µM), C. krusei (34 µM) and C. tropicalis (17 µM). Results suggest this is a promising lead-compound for synthesis of potent antifungal agents.

We report herein the synthesis of some beta-D-galactopyranosylamine and beta-lactosylamine amides and sulfonamides. The interactions of these compounds with lectins from the seeds of Erythrina cristagalli (LEC) and Ricinus communis (RCA120) were evaluated in a hemagglutination inhibitory activity assay. D-Galactose and lactose were used as reference compounds. The beta-lactosylamine amides and sulfonamides were nearly as active as lactose in inhibiting LEC mediated hemagglutination and were less active against RCA120 agglutinin. The beta-D-galactopyranosylamine amides and sulfonamides were, with one exception, considerably less active than D-galactose in the assay with both lectins.