Green synthesis of silver and gold nanoparticles in Callistemon viminalis extracts and their antimicrobial activities.

In the current study, the bottlebrush [Callistemon viminalis (Sol. ex Gaertn.) G. Don] plant was selected for the green synthesis of silver (Ag) and gold (Au) nanoparticles and to evaluate its antibacterial and antifungal activities. Phytochemical screening of C. viminalis confirmed the presence of alkaloids, anthraquinones, saponins, tannins, betacyanins, phlobatanins, coumarins, terpenoids, steroids, glycosides, and proteins. To characterize the synthesized Ag and Au NPs, UV-Visible spectroscopy, FTIR spectroscopy for functional group identification, field emission scanning electron microscopy (FE-SEM) for particle size, and elemental analysis were performed using EDX. The UV-Visible absorption spectra of the green-synthesized Ag and Au nanoparticles were found to have a maximum absorption band at 420 nm for Ag NPs and 525 nm for Au NPs. FE-SEM analysis of the synthesized NPs revealed a circular shape with a size of 100 nm. Elemental analysis was performed for the synthesis of Ag and Au NPs, which confirmed the purity of the nanoparticles. The greenly synthesized Ag and Au NPs were also evaluated for their anti-bacterial and anti-fungal activities, which exhibited prominent inhibition activities against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans, C. krusei, Aspergillus sp., and Trichoderma species. The highest zone of inhibition 15.5 ± 0.75 and 15 ± 0.85 mm was observed for Ag NPs against E. coli and P. aeruginosa. Similarly, Trichoderma sp. and Aspergillus sp. were inhibited by Ag NPs up to 13.5 ± 0.95 and 13 ± 0.70 mm. This work will open doors for the development of new antimicrobial agents using green chemistry.

Novel 5-(Arylideneamino)-1H-Benzo[d]imidazole-2-thiols as Potent Anti-Diabetic Agents: Synthesis, In Vitro α-Glucosidase Inhibition, and Molecular Docking Studies.

A novel series of multifunctional benzimidazoles has been reported as potent inhibitors of α-glucosidase. The procedure relies on the synthesis of 5-amino-1H-benzo[d]imidazole-2-thiol 5 via the multistep reaction through 2-nitroaniline 1, benzene-1,2-diamine 2, 1H-benzo[d]imidazole-2-thiol 3, and 5-nitro-1H-benzo[d]imidazole-2-thiol 4. Further treatment of 5 with aromatic aldehydes 6a-m provided access to the target 5-(arylideneamino)-1H-benzo[d]imidazole-2-thiols 7a-m. The results of the bioactivity assessment revealed all the compounds as excellent inhibitors of the enzyme (IC50 range: 0.64 ± 0.05 µM to 343.10 ± 1.62 µM) than acarbose (873.34 ± 1.21). Among them, 7i was the most active inhibitor (IC50: 0.64 ± 0.05 µM) followed by 7d (IC50: 5.34 ± 0.16 µM), 7f (IC50: 6.46 ± 0.30 µM), 7g (IC50: 8.62 ± 0.19 µM), 7c (IC50: 9.84 ± 0.08 µM), 7m (IC50: 11.09 ± 0.79 µM), 7a (IC50: 11.84 ± 0.26 µM), 7e (IC50: 16.38 ± 0.53 µM), 7j (IC50: 18.65 ± 0.74 µM), 7h (IC50: 20.73 ± 0.59 µM), 7b (IC50: 27.26 ± 0.30 µM), 7k (70.28 ± 1.52 µM) and finally 7l (IC50: 343.10 ± 1.62 µM). Molecular docking revealed important interactions with the enzyme, thereby supporting the experimental findings.

Probing the chemical constituents of Cassia javanica and its in vitro analyses as a potent drug.

The phytochemical screening of the crude methanolic stem extracts of Cassia javanica plant showed the presence of different classes of organic compounds like alkaloids, tannins, flavonoids, saponins, phlobatanins, steroids, anthraquinone and cardiac glycoside. The starching frequencies of these functional groups were determined from FT-IR spectroscopic data. The crude and their fractions were examined for antibacterial potential against Klebsiella pneumoniae and Proteus mirabilis. The antibacterial assay showed maximum zone of inhibition for ethyl acetate fraction, i.e. 20 mm against Proteus mirabilis and 18 mm against Klebsiella pneumoniae in the comparison with Levofloxacin used as standard (40 mm). Meanwhile for methanolic crude extract, the inhibition zone was recorded 14 mm against Klebsiella pneumoniae and 22 mm against Proteus mirabilis. The minimum inhibitory concentrations and minimum bactericidal concentrations were recorded as 187.5 µg ml-1 against Proteus mirabilis and 93.75 µg ml-1 against Klebsiella pneumoniae. The scavenging free radical assay was noted as 69.61% at the concentration of 100 ppm.

Synthesis, Bioactivity Assessment, and Molecular Docking of Non-sulfonamide Benzimidazole-Derived N-Acylhydrazone Scaffolds as Carbonic Anhydrase-II Inhibitors.

This research reports the synthesis of new benzimidazole-derived N-acylhydrazones (NAH), their characterization using various spectroscopic methods, and in vitro evaluation as potent carbonic anhydrase-II inhibitors. Among the target compounds (9-29), few showed higher inhibition than the standard acetazolamide (IC50: 18.6 ± 0.43 µM), for example, compound 9 (IC50: 13.3 ± 1.25 µM), 10 (IC50: 17.2 ± 1.24 µM), 12 (IC50: 14.6 ± 0.62 µM), and 15 (IC50: 14.5 ± 1.05 µM). Molecular docking was performed on the most active compounds, which revealed their binding interactions with the active site of the enzyme, thus supporting the experimental findings.

New Bioactive Heteroleptic Copper(II) Carboxylates: Structure, Enzymatic and DNA-Binding Studies.

Two new binuclear O-bridged copper(II) carboxylates with chemical formulas [Cu2(3-ClC6H4CH2COO)4(phen)2] (1) and [Cu2(3-ClC6H4CH2COO)4(bipy)2] (2) where phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine have been synthesized and characterized by FT-IR, UV-Visible spectroscopy, CHN analysis and single crystal XRD. The results revealed distorted square pyramidal geometry around each copper atom of 1 and 2. The DNA interaction studies showed strong binding with Kb = 5.07 × 103 and 4.62 × 103 M-1 for 1 and 2, respectively. Both complexes showed strong enzyme inhibition, i.e., 70% and 90% for α-glucosidase with IC50 = 34.6 and 30.1 µM for 1 and 2, respectively, where acarbose was employed as control. However, both the complexes were found inactive against α-amylase. Using galantamine hydrobromide as control, 1 showed moderate inhibition activity (47%) with IC50 = 179.4 µM for acetylcholine esterase whereas 2 showed strong inhibition activity (76%) with IC50 = 95.8 µM for butyrylcholine esterase. The data reflects active anti-diabetic and anti-Alzheimer's nature of the synthesized complexes.