Browsing by Author "Ntungwe, Epole"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- In vitro assessment of antimicrobial, antioxidant, and cytotoxic properties of Saccharin-Tetrazolyl and-Thiadiazolyl derivatives: the simple dependence of the pH value on antimicrobial activityPublication . Frija, Luís M. T.; Ntungwe, Epole; Sitarek, Przemysław; Andrade, Joana M.; Toma, Monika; Śliwiński, Tomasz; Cabral, Lília; Cristiano, Maria de Lurdes; Rijo, Patrícia; Pombeiro, Armando J. L.The antimicrobial, antioxidant, and cytotoxic activities of a series of saccharin-tetrazolyl and -thiadiazolyl analogs were examined. The assessment of the antimicrobial properties of the referred-to molecules was completed through an evaluation of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against Gram-positive and Gram-negative bacteria and yeasts. Scrutiny of the MIC and MBC values of the compounds at pH 4.0, 7.0, and 9.0 against four Gram-positive strains revealed high values for both the MIC and MBC at pH 4.0 (ranging from 0.98 to 125 µg/mL) and moderate values at pH 7.0 and 9.0, exposing strong antimicrobial activities in an acidic medium. An antioxidant activity analysis of the molecules was performed by using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, which showed high activity for the TSMT (N-(1-methyl-2H-tetrazol-5-yl)-N-(1,1-dioxo-1,2-benzisothiazol-3-yl) amine, 7) derivative (90.29% compared to a butylated hydroxytoluene positive control of 61.96%). Besides, the general toxicity of the saccharin analogs was evaluated in an Artemia salina model, which displayed insignificant toxicity values. In turn, upon an assessment of cell viability, all of the compounds were found to be nontoxic in range concentrations of 0-100 µg/mL in H7PX glioma cells. The tested molecules have inspiring antimicrobial and antioxidant properties that represent potential core structures in the design of new drugs for the treatment of infectious diseases.
- Naphthoylhydrazones: coordination to metal ions and biological screeningPublication . Ribeiro, Nadia; Galvao, Adelino M.; Gomes, Clara S. B.; Ramos, Helena; Pinheiro, Rute; Saraiva, Lucilia; Ntungwe, Epole; Isca, Vera; Rijo, Patricia; Cavaco, Isabel; Ramilo-Gomes, Filipa; Guedes, Rita C.; Pessoa, Joao Costa; Correia, IsabelWe report the synthesis of 3-hydroxyl-2-naphthoylhydrazones containing pyrrole (HL1), furane (HL2) and thiophene (HL3) moieties and their V(IV)O-, Cu(II)- and Zn(II)-complexes. All compounds are characterized by the usual analytical techniques and coordination of the ligands to the metal ions is discussed based on spectroscopic data (FTIR, UV-vis, EPR and NMR) as well as CAMB3LYP DFT/TDDFT calculations, indicating the formation of neutral ML2 type complexes. The photophysical properties of ligands and complexes are disclosed. The binding to Bovine Serum Albumin (BSA) is evaluated in detail using several spectroscopic tools. Circular dichroism shows that the compounds, and particularly the ligand precursors, stabilize BSA, increasing its a-helical content. Fluorescence studies indicate the formation of 1 : 1 protein-compound adducts, which is corroborated by molecular docking studies that show the interaction between Trp 213 of BSA and the naphthalene rings. The general toxicity is evaluated using the Artemia salina lethality assay, with all compounds showing general toxicity towards the brine shrimp model. The cytotoxicity on human cancer cells (H1299, MCF7, and HCT116) is assessed for all compounds and the half-maximal inhibitory concentration (IC50) values are in the range from 0.57 to 27.35 mu M. Compounds containing L-1 (pyrrole derivative) are the most cytotoxic, with the vanadium and zinc complexes performing better than the copper ones, and some of them depicting IC50 values lower than 1.1 mM. However, selectivity needs improvement as the compounds show toxicity towards Artemia salina and normal fibroblasts.