Exploring Antimicrobial Features for New Imidazo[4,5-b]pyridine Derivatives Based on Experimental and Theoretical Study.

5-bromopyridine-2,3-diamine reacted with benzaldehyde to afford the corresponding 6-Bromo-2-phenyl-3H-imidazo[4,5-b]pyridine (1). The reaction of the latter compound (1) with a series of halogenated derivatives under conditions of phase transfer catalysis solid-liquid (CTP) allows the isolation of the expected regioisomers compounds (2-8). The alkylation reaction of (1) gives, each time, two regioisomers, N3 and N4; in the case of ethyl bromoactate, the reaction gives, at the same time, the three N1, N3 and N4 regioisomers. The structures of synthesized compounds were elucidated on the basis of different spectral data (1H NMR, 13C NMR), X-Ray diffraction and theoretical study using the DFT method, and confirmed for each compound. Hirshfeld surface analysis was used to determine the intermolecular interactions responsible for the stabilization of the molecule. Density functional theory was used to optimize the compounds, and the HOMO-LUMO energy gap was calculated, which was used to examine the inter/intra molecular charge transfer. The molecular electrostatic potential map was calculated to investigate the reactive sites that were present in the molecule. In order to determine the potential mode of interactions with DHFR active sites, the three N1, N3 and N4 regioisomers were further subjected to molecular docking study. The results confirmed that these analogs adopted numerous important interactions, with the amino acid of the enzyme being targeted. Thus, the most docking efficient molecules, 2 and 4, were tested in vitro for their antibacterial activity against Gram-positive bacteria (Bacillus cereus) and Gram-negative bacteria (Escherichia coli). Gram-positive bacteria were more sensitive to the action of these compounds compared to the Gram-negative, which were much more resistant.

Antibacterial, antifungal and antioxidant activity of total polyphenols of Withania frutescens.L.

Our objective in this work is evaluated the antibacterial, antifungal and antioxidant activity of the phytochymic compounds of the roots and leaves of a species Withania frutescens. In the first part, the phenolic compound is determinate by the Folin-Ciocalteau reaction, the richness of the roots in polyphenols (53.33 ±â€¯1.20 mg EGA/g Extract) is six times higher than that of the leaves. The antioxidant test is evaluated by four methods: DPPH test, reducing power test (FRAP), total antioxidant capacity (CAT) and the ß-carotene discoloration test. The IC-50 values of the DPPH test of the studied parts are of the order of 0.36 µg/ml and 6.63 µg/ml, which showed a lower anti-free radical activity than that of BHT (0.12 µg/ml). The results obtained by the FRAP method revealed a low reducing power of iron for two extracts (EC-50 of 0.45%) compared to Quercetine (EC-50 of 0.03%). The compounds of root and leaf extracts have a significant total antioxidant capacity, respectively 477.65 ±â€¯37.60 and 317.03 ±â€¯46.64 mg EAA/g Extract. In the ß-carotene discoloration test, extracts from the aerial and underground parts showed antioxidant activity of 57% followed by (36%), respectively. The evaluation of the antibacterial activity of in vitro extracts against microorganisms is carried out by two methods: disc diffusion and microdilution. The results show that the extracts exert an intermediate inhibitory effect (inhibition diameter between 8 and 15 mm, the smallest MIC obtained is 2.80 mg/ml) on all strains tested. The antifungal activity was estimated by determining the growth inhibition rate of the fungus tested. Indeed, the compounds studied exhibit a good antifungal effect since the minimum inhibitory concentration (MIC) of 4.5 mg/ml for root extract and 9 mg/ml for leaf extract.

Crystal structure, Hirshfeld surface analysis and corrosion inhibition study of 3,6-bis-(pyridin-2-yl)-4-{[(3aS,5S,5aR,8aR,8bS)-2,2,7,7-tetra-methyl-tetra-hydro-5H-bis-[1,3]dioxolo[4,5-b:4',5'-d]pyran-5-yl)meth-oxy]meth-yl}pyridazine monohydrate.

In the title compound, C27H30N4O6·H2O, the two dioxolo rings are in envelope conformations, while the pyran ring is in a twisted-boat conformation. The pyradizine ring is oriented at dihedral angles of 9.23 (6) and 12.98 (9)° with respect to the pyridine rings, while the dihedral angle between the two pyridine rings is 13.45 (10)°. In the crystal, O-Hwater⋯Opyran, O-Hwater⋯Ometh-oxy-meth-yl and O-Hwater⋯Npyridazine hydrogen bonds link the mol-ecules into chains along [010]. In addition, weak C-Hdioxolo⋯Odioxolo hydrogen bonds and a weak C-Hmeth-oxy-meth-yl⋯π inter-action complete the three-dimensional structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (55.7%), H⋯C/C⋯H (14.6%), H⋯O/O⋯H (14.5%) and H⋯N/N⋯H (9.6%) inter-actions. Hydrogen-bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing. Electrochemical measurements are also reported.

Comparative Evaluation of Polyphenol Contents and Antioxidant Activities between Ethanol Extracts of Vitex negundo and Vitex trifolia L. Leaves by Different Methods.

The in vitro antioxidant potential assay between ethanolic extracts of two species from the genus Vitex (Vitex negundo L. and Vitex trifolia L.) belonging to the Lamiaceae family were evaluated. The antioxidant properties of different extracts prepared from both plant species were evaluated by different methods. DPPH scavenging, nitric oxide scavenging, and ß-carotene-linoleic acid and ferrous ion chelation methods were applied. The antioxidant activities of these two species were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and Ethylene diamine tetra acetic acid (EDTA). Both species of Vitex showed significant antioxidant activity in all of the tested methods. As compared to V. trifolia L. (60.87-89.99%; 40.0-226.7 µg/mL), V. negundo has been found to hold higher antioxidant activity (62.6-94.22%; IC50 = 23.5-208.3 µg/mL) in all assays. In accordance with antioxidant activity, total polyphenol contents in V. negundo possessed greater phenolic (89.71 mg GAE/g dry weight of extract) and flavonoid content (63.11 mg QE/g dry weight of extract) as compared to that of V. trifolia (77.20 mg GAE/g and 57.41 mg QE/g dry weight of extract respectively). Our study revealed the significant correlation between the antioxidant activity and total phenolic and flavonoid contents of both plant species.