Cobalt-Doped ZnO Nanocomposits for Efficient Dye Degradation: Charge Transfer.

Doping enhances the optical properties of high-band gap zinc oxide nanoparticles (ZnO NPs), essential for their photocatalytic activity. We used the combustion approach to synthesize cobalt-doped ZnO heterostructure (CDZO). By creating a mid-edge level, it was possible to tune the indirect band gap of the ZnO NPs from 3.1 eV to 1.8 eV. The red shift and reduction in the intensity of the photoluminescence (PL) spectra resulted from hindrances in electron-hole recombination and sp-d exchange interactions. These improved optical properties expanded the absorption of solar light and enhanced charge transfer. The field emission scanning electron microscopy (FESEM) image and elemental mapping analysis confirmed the CDZO's porous nature and the dopant's uniform distribution. The porosity, nanoscale size (25-55 nm), and crystallinity of the CDZO were further verified by high-resolution transmission electron microscopy (HRTEM) and selected area electron image analysis. The photocatalytic activity of the CDZO exhibited much greater efficiency (k=0.131 min-1) than that of ZnO NPs (k=0.017 min-1). Therefore, doped heterostructures show great promise for industrial-scale environmental remediation applications.

Antibacterial and Cytotoxicity of Extracts and Isolated Compounds from Artemisia abyssinica: A Combined Experimental and Computational Study.

Artemisia abyssinica is a widely cultivated hedge plant in Ethiopia. Traditionally, they have been used to treat a variety of health conditions, including intestinal problems, infectious diseases, tonsillitis, and leishmaniasis. Silica gel chromatographic separation of the methanol and ethyl acetate extracts of the leaves, roots, and stem barks of A. abyssinica led to the isolation of 12 compounds, labeled as 1-12. Among these, compounds 1, 3, 4, 5, and 7-11 are reported as new to the genus Artemisia. The extracts and isolated compounds from A. abyssinica were evaluated for their in vitro antibacterial activity against four bacterial strains: Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, using the disc diffusion assay. All of the extracts displayed weak antibacterial activity, with inhibition zone diameters (IZDs) ranging from 6.10 ± 0.3 to 9.30 ± 0.20 mm. The isolated compounds, on the other hand, exhibited weak to moderate antibacterial activity, with IZDs ranging from 6.00 ± 0.300 to 13.50 ± 0.50 mm. The most potent antibacterial activity was observed for compound 6, which showed an IZD of 13.30 ± 0.50 mm against E. coli and 13.50 ± 0.50 mm against P. aeruginosa. This activity was comparable to that of the positive control ceftriaxone, which had IZDs of 14.1 ± 0.3 and 13.8 ± 0.5 mm against E. coli and P. aeruginosa, respectively. The in silico molecular docking analysis against DNA gyrase B revealed that compound 5 showed a higher binding affinity (-6.9 kcal/mol), followed by compound 10 (-6.7 kcal/mol) and compound 12 (-6.3 kcal/mol), whereas ciprofloxacin showed -7.3 kcal/mol. The binding affinities of compounds 5, 11, 10, and 9 were found to be -5.0, -4.3, -4.2, and -4.0 kcal/mol against S. aureus Pyruvate kinase, respectively, whereas ciprofloxacin showed a binding affinity of -4.9 kcal/mol, suggesting that compound 5 had a better binding affinity compared with ciprofloxacin. The effect of extracts of A. abyssinica was evaluated for cytotoxic activity against the breast cancer cell line (MCF-7) by the MTT assay. The extracts induced a decrease in cell viability and exerted a cytotoxic effect at a concentration of 20 µg/mL. The highest percent cell viability was observed for the methanol extract of the stem (92.9%), whereas the least was observed for the methanol extract of the root (34.5%). The result of the latter was significant compared with the positive control. The binding affinities of the isolated compounds were also assessed against human topoisomerase inhibitors IIß. Results showed that compound 5 showed a binding affinity of -6.0 kcal/mol, followed by 11 (-5.4 kcal/mol), 10 (-5.0 kcal/mol), and 11 (-4.9 kcal/mol). Similar to ciprofloxacin, compounds 4, 5, 6, 9, 10, and 12 comply with Lipinski's rule of five. Overall, the comprehensive investigation of the chemical constituents and their biological activities reinforces the traditional medicinal applications of A. abyssinica and warrants further exploration of this plant as a source of novel therapeutic agents.

In Silico Molecular Docking Analysis, Cytotoxicity, and Antibacterial Activities of Constituents of Fruits of Cucumis dipsaceus.

Cucumis dipsaceus (Cucurbitaceae) is a plant traditionally used against diarrhea, teeth-ach, wounds, stomach ache, meningitis, and cancer. The extracts of C. dipsaceus after silica gel column chromatography gave nine compounds identified using spectroscopic methods such as hexacosane (1), octadecane (2), 17-(-5-ethyl-2,6-dihydroxy-6-methylhept-3-en-2-yl)-9-(hydroxymethyl)-13-methylcyclopenta[α]phenanthren-3-ol (3), erythrodiol (4), (9,12)-propyl icosa-9,12-dienoate (5), α-spinasterol (6), 16-dehydroxycucurbitacin (7), cucurbitacin D (8), and 23,24-dihydroisocucurbitacin D (9). Compounds 3 and 4 are new to the genus Cucumis. α-Spinasterol showed better inhibition zone diameter = 13.67 ± 0.57, 15.00 ± 0.10, and 13.33 ± 0.57 mm against Escherichia coli, Pseudomonas aeruginosa, and Streptococcus pyogenes compared with the other tested samples. α-Spinasterol (-8.0 kcal/mol) and 3 (-7.6 kcal/mol) displayed high binding affinity against DNA Gyrase compared to ciprofloxacin (-7.3 kcal/mol). α-Spinasterol and 16-dehydroxycucurbitacin showed better binding affinity against protein kinase. The cytotoxicity results revealed that the EtOAc extract showed the highest potency with IC50 = 16.05 µg/mL. 16-Dehydroxycucurbitacin showed a higher binding affinity (-7.7 kcal/mol) against human topoisomerase IIß than etoposide. The cytotoxicity and antibacterial activities and in silico molecular docking analysis displayed by the constituents corroborate the traditional use of the plant against bacteria and cancer.