In silico and biological activity evaluation of quercetin-boron hybrid compounds, anti-quorum sensing effect as alternative potential against microbial resistance.

Boronic acid compounds and the natural flavonoid compound quercetin were handled to synthesize two novel ligands encoded as B1(2,2'-(1,4-phenylenebis (benzo [1,3,2] dioxaborole-2,5-diyl)) bis (3,5,7-trihydroxy-4H- chromen-4-one) and B2(3.3.6. 3,5,7-trihydroxy-2-(2-(6-methoxypyridin-3-yl)benzo[d][1,3,2]dioxaborol-5-yl)- 4 H-chromene-4). Antioxidant activities of ligands were investigated by DPPH, ABTS and CUPRAC methods. Cholinesterase inhibition effects of ligands were determined by acetylcholinesterase and butyrylcholinesterase enzyme inhibition methods, cytotoxic effects of ligands were applied to healthy breast and colon cancer cell lines by MTT method, and urease and tyrosinase enzyme activities were determined. Antimicrobial properties of the compounds were analyzed by detecting their anti-QS potentials on Chromobacterium violaceum biosensor strain. Both compounds were found to have significant antioxidant effects compared to controls. It was determined that the compound B1 at 1-10 µg/mL was more active than the reference compounds (α-TOC and BHT). Moreover, the enzyme activity studies on ligands demonstrated that acetylchoinesterase and butyrylcholinesterase enzyme inhibitions were higher than the reference compounds. As expected, boron derivatives exhibited respectable activity against the biofilms of Escherichia coli (E. coli) and P. aeruginosa (P. aeruginosa). These results demonstrate the potential applicability of boron derivatives in the treatment of biofilm-associated infections and provide a practical strategy for the design of new boron-based antimicrobial materials. In silico molecular docking studies were performed on ligands to identify newly synthesized compounds. The binding parameter values and binding sites of the compounds were also determined. In conclusion, our studies showed that newly synthesized hybrid compounds could be solutions for antimicrobial resistance and enzyme-related disorders.

Cream production and biological in vivo/in vitro activity assessment of a novel boron-based compound derived from quercetin and phenyl boronic acid.

Boronic acids constitute an important class of synthetic intermediates due to their high chemical stability, ease of use, moderate organic Lewis acid properties, reduced reactivity profiles and numerous biological activities such as antibacterial and antioxidant. The present study documents the synthesis and characterization of a novel boronic ester compound (3,5,7-trihydroxy-2- (2-phenyl benzo [d] [1,3,2] dioxaborol-5-yl) -4H-chromen-4-a) which was derived from phenyl boronic acid and quercetin. The new boron-based compound was used in the cream formulation after evaluating its antioxidant, antibacterial, anti-enzyme, anticancer activities and electrochemical oxidation behaviour. Furthermore, the cream has been dermatologically and microbiologically tested. Also, histological evaluation of the agent was estimated on multiple rat organs by hematoxylin-eosin staining method. Antioxidant potential of the new compound was tested by ABTS cation radical (IC50: 0.11 ± 0.01 µg/mL), DPPH free radical scavenging (IC50: 0.14 ± 0.01 µg/mL), and CUPRAC (A0.5: 1.73 ± 0.16 µg/mL) methods, respectively. The compound determined to have a dominant antioxidant activity. In addition, the synthesized compound had no toxic effect on the healthy cell line (PDF), while having a very high (IC50: 18.76 ± 0.62 µg/mL) cytotoxic effect on the cancerous cell line (MCF-7). In general, the compound showed moderate acetylcholinesterase enzyme activity (IC50: 115.63 ± 1.16 µg/mL), high butyrylcholinesterase (IC50: 3.12 ± 0.04 µg/mL), antiurease (IC50: 1.10 ± 0.06 µg/mL), and antithyrosinase (IC50: 11.52 ± 0.46 µg/mL) enzyme activities. In addition, the compound was found to be effective against Escherichia coli (ATCC 25922) bacteria studied at concentrations of 6.50 mg/mL. Moreover, the test results of the boronic ester compound used in the cream formulation demonstrated that it was microbiologically and dermatologically appropriate. Histologic analysis showed that the control group and experimental group were at similar properties without significant change. The phenyl boronic acid derivative compound synthesized from quercetin may have higher biological activity potential than quercetin. Due to the high biological activity potential of the synthesized compound, it has the potential to be used in food, feed, pharmaceutical and cosmetic industries.

The synthesis of boronic-imine structured compounds and identification of their anticancer, antimicrobial and antioxidant activities.

Boronic acid compounds with different substituted groups were handled to synthesize various ligands encoded as B1, B2, B3, B4, B5, B6, B7 and B8. B5 and B7 were tested for the cytotoxic activity against the prostate cancer cells and it was found that the cell viability of cancer cells was decreased while most of the healthy cells could still be viable. 5 µM solutions of B5 and B7 decreased the cell viability to 33% and 44% whereas healthy cells were 71% and 95%, respectively, after treatment. Antimicrobial properties were explored against the bacterial and fungal microorganisms with B1, B5 and B7. The inhibition zones were evaluated for all boronic structures, and the growth inhibition zones were determined in a range of 7-13 mm diameter for different microorganism species. Staphylococcus aureus was the common microorganism that three boronic compounds with imine ligands showed the activity. Antioxidant features of B2, B3, B4, B5, B6, B7 and B8 were investigated by different processes such as Beta-carotene bleaching (BCB), 2,2-diphenyl picryl hydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and CUPric reducing antioxidant capacity (CUPRAC) methods. Significant antioxidant activity was achieved by the phenyl boronic based ligands and these compounds demonstrated as much activity as standards (α-Toc and BHT). In addition, all structures were applied properly without any decomposition during the experiments. They were rather stable both in aqueous media and solid state.