2-Chloroquinoline-3-carbaldehyde and 2-chloro-8-methylquinoline-3-carbaldehyde derivatives were synthesized through Vilsmeier formulation of acetanilide and N-(o-tolyl)acetamide. Aromatic nucleophilic substitution reaction was used to introduce various nucleophiles in place of chlorine under different reaction conditions. The carbaldehyde group was oxidized by permanganate method and reduced with metallic sodium in methanol and ethanol. The synthesized compounds were characterized by UV-Vis, IR, and NMR. The antibacterial activity of the synthesized compounds was screened against two Gram-positive bacteria (Bacillus subtilis ATCC6633 and Staphylococcus aureus ATCC25923) and two Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). Most of the compounds displayed potent activity against two or more bacterial strains. Among them, compounds 6 and 15 showed maximum activity against Pseudomonas aeruginosa with mean inhibition zones of 9.67 ± 1.11 and 10.00 ± 0.44 mm, respectively, while ciprofloxacin showed mean inhibition zone of 8.33 ± 0.44 mm at similar concentration. On the other hand, compound 8 exhibited maximum activity against Escherichia coli with inhibition zones of about 9.00 ± 0.55 mm at 300 μg/mL and 11.33 ± 1.11 mm at 500 μg/mL. The radical scavenging activity of these compounds was evaluated using 1,1-diphenyl-2-picryl hydrazyl (DPPH), and all of them displayed moderate antioxidant activity, with compound 7 exhibiting the strongest activity. The molecular docking study of the synthesized compounds was conducted to investigate their binding pattern with DNA gyrase, all of them were found to have minimum binding energy ranging from –6.0 to –7.33 kcal/mol, and the best result was achieved with compound 11. The findings of the in vitro antibacterial and molecular docking analysis demonstrated that the synthesized compounds have potential of antibacterial activity and can be further optimized to serve as lead compounds.

Root samples and rhizosphere soil of nine acacia species (Acacia abyssinica, Faidherbia albida, A. nilotica, A. senegal, A. seyal, A. sieberiana, A. saligna, A. tortilis and A. robusta) were collected from Bishoftu, Zeway and Addis Ababa sites with different land use types to assess their Arbuscular Mycorrhizal Fungal (AMF) diversity, spore density and root colonization. The percentage of root length colonized by AMF was estimated. Spores, spore clusters and sporocarps extracted from soil samples were counted and morphologically identified to species or specific morphotype. Roots of all acacia species were colonized from low to moderate or relatively high levels by AMF with the occurrence of arbuscules, vesicles and hyphae. Arbuscules were however not detected in roots of A. senegal. The highest AM fungal colonization was found in A. seyal (67.3%) from open grazing field (OGF) at Zeway followed by A. nilotica (44%), whereas the lowest AMF colonization of 12% was recorded in A. saligna at Bishoftu. Rhizosphere soils harbored AMF fungal spores ranging from 3.7 spores g -1 soil in A. nilotica to 15.0 spores g -1 in A. seyal from open grazing field (OGF) at Zeway. A total of 41 AMF species in 14 genera and 7 families of the Glomeromycota were identified. Nine species belonged to Acaulospora, 6 to Funneliformis, 4 each to Gigaspora, Glomus, and Rhizophagus, 3 each to Claroideoglomus, and Scutellospora, 2 each to Racocetra and Diversispora, and 1 each to Entrophospora, Sclerocystis, Paraglomus and Pacispora. Moreover, 2 unidentified morphotypes each of Glomus, and Acaulospora and 1 of Archaeospora were isolated. Based on relative abundance and isolation frequency of spores, C. claroideum, C. etunicatum, C. luteum, F. geosporus and G. aggregatum were the dominant species in the study. The study showed that the acacia species were characterized by relatively high AMF colonization and very high AMF diversity. AMF spore density and AM root colonization in acacia roots were influenced by soil factors such as available P and soil texture.

Emergence of antimicrobial resistance to standard commercial drugs has become a critical public health concern worldwide. Hence, novel antimicrobials with improved biological activities are urgently needed. In this regard, a series of quinoline-stilbene derivatives were synthesized from substituted quinoline and benzyltriphenylphosphonium chloride using Wittig reaction. Furthermore, a novel pinacol of quinoline was synthesized by pinacolinazation of 2-methoxyquinoline-3-carbaldehyde which was achieved by aluminum powder-potassium hydroxide reagent combination at ambient temperature in methanol. The structures of the synthesized compounds were established based on their spectral data. The antibacterial activities of the synthesized compounds were evaluated in vitro by the paper disc diffusion method against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Escherichia coli and Salmonella typhimurium). The best activity was displayed by compound 19 against E. coli with an inhibition zone of 16.0 ± 0.82 mm and 14.67 ± 0.94 mm at 500 and 250 μg/mL, respectively. This is close to ciprofloxacin which is used as a positive control. The results of in silico molecular docking evaluation of the compounds against E. coli DNA gyraseB were in good agreement with the in vitro antibacterial analysis. Compounds 19 (−6.9 kcal/mol) and 24 (−7.1 kcal/mol) showed the maximum binding affinity close to ciprofloxacin (−7.3 kcal/mol) used as positive control. Therefore, the antibacterial activity displayed by these compounds is encouraging for further investigation to improve the activities of quinoline-stilbenes by incorporating various bioisosteric groups in one or more positions of the phenyl nuclei for their potential pharmacological use. Findings of the DPPH radical scavenging assay indicated that some of the quinolone stilbenes and pinacol possess moderate antioxidant properties compared to ascorbic acid used as a natural antioxidant.

Currently, it has been common to see people being affected and dying from untreatable infections caused by multidrug-resistant (MDR) germs. To tackle this problem, developing new effective chemotropic agents is urgently needed. Hence, this project aims to design, synthesize, and evaluate their antibacterial and antioxidant activities of new series of [2,3′-biquinoline]-4-carboxylic acid and quinoline-3-carbaldehyde analogs. The molecular docking analysis of the compounds against E. coli DNA gyrase was computed to investigate the binding mode of the compounds within the active site of the enzyme. In this regard, a new series of [2,3′-biquinoline]-4-carboxylic acid and quinoline-3-carbaldehyde analogs were synthesized by utilization of Vilsmeier–Haack, Doebner, nucleophilic substitution, and hydrolysis reactions. The structures of the synthesized compounds were determined using UV-Vis, FT-IR, and NMR. The synthesized compounds were screened for their antibacterial activity against four bacterial strains using disc diffusion methods. The findings of the study revealed that seven of synthetic compounds possess good antibacterial activity compared to ciprofloxacin which was used as a positive control in the experiment. Among them, compounds 4, 9, and 10 displayed the highest mean inhibition zone of 13.7 ± 0.58, 16.0 ± 1.7, and 20.7 ± 1.5 mm, respectively, at 0.1 μg/μL. The radical scavenging property of these compounds was evaluated using DPPH radical assay where compounds 9 and 20 showed the strongest activity with IC50 values of 1.25 and 1.75 μg/mL, respectively. At the same concentration, the IC50 value of ascorbic acid was 4.5 μg/mL. The synthesized compounds were also assessed for their in silico molecular docking analysis. Compounds 4 (−6.9 kcal/mol), 9 (−6.9 kcal/mol), and 10 (−7.9 kcal/mol) showed the maximum binding affinity close to ciprofloxacin (−7.2 kcal/mol) used as a positive control. Thus, compounds 4, 9, and 10 showed the best antibacterial activities in both in vitro and molecular docking analyses among the synthetic compounds. The results of in silico molecular docking evaluation of the synthetic compounds against E. coli DNA gyrase B were in good agreement with the in vitro antibacterial analysis. Therefore, the antibacterial activity displayed by these compounds is encouraging for further investigation to improve the activities of [2,3′-biquinoline]-4-carboxylic acid by incorporating various bioisosteric groups in either of the quinoline rings.

The rapid conversion of native forests to farmland in Ethiopia, the cradle of biodiversity, threatens the diversity of the arbuscular mycorrhizal fungi (AMF) pivotal to plant nutrition and carbon sequestration. This study aimed to investigate the impact of this land-use change on the AMF species composition and diversity in southern Ethiopia. Soil samples were collected from nine plots in each of three land-use types: native forest, agroforestry, and khat monocropping. The plots of the three land-use types were located adjacent to each other for each of the nine replicates. Three 10 × 10m subplots per plot were sampled. AMF spores were extracted from the soil samples, spore densities were determined, and species composition and diversity were evaluated through morphological analysis. Both spore density and species richness were statistically significantly higher in the native forest than in the agroforestry plots with no clear difference to khat, whereas the true diversity (exponential of Shannon–Wiener diversity index) did not differ among the three land-use types due to high evenness among the species in agroforestry. In total, 37 AMF morphotypes belonging to 12 genera in Glomeromycota were found, dominated by members of the genera Acaulospora and Glomus. The highest isolation frequency index (78%) was recorded for Acaulospora koskei from native forest. Consequently, the agroforestry system did not appear to aid in preserving the AMF species richness of native forests relative to perennial monocropping, such as khat cultivation. In contrast, the native forest areas can serve as in situ genetic reserves of mycorrhizal symbionts adapted to the local vegetative, edaphic, and microbial conditions.