Vietnam Journal of Chemistry

This work describes an effective electrodeposition method for generating gold plasmonic electrodes which are further used for detecting glucose in solution without the presence of any enzymes (i.e Gox). Under light irradiation, the electro‐catalytic oxidation of glucose on the electrodeposited gold nanoparticle (AuNP) surfaces has been investigated. The wavelength‐dependent electrochemical oxidative current intensity implies that the hot carriers transferred from the excited plasmonic AuNPs to the absorbed molecules are responsible for enhancing electro‐catalysis performance. Hot holes can particularly contribute to the oxidation reaction of glucose on the plasmonic surfaces without the presence of any enzymes in solution. Furthermore, the presence of nano‐sized gold particles exhibits a larger active surface area, which leads to a significant improvement in recorded oxidative current for the oxidation of glucose. These results reveal a promising manner for generating non‐enzymatic glucose electrochemical sensor upon plasmonic excitation.

Two series of novel hybrid compounds, in which a variety of 2‐mercapto‐3‐arylquinazolin‐4(3H)‐ones (3a‐d)/6‐bromo‐2‐mercapto‐3‐phenylquinazolin‐4(3H)‐one (9) act as fundamental moieties are incorporated in particular 3‐(2‐bromoacetyl)‐2H‐chromen‐2‐one (4) or 2‐chloro‐N‐(2‐oxo‐2H‐chromen‐3‐yl)acetamide (5) via alkylation of the thiol group in quinazolin‐4(3H)‐one ring, were synthesized. The key intermediates (3a‐d) and (9) were prepared by the reaction of anthranilic acid (1)/2‐amino‐5‐bromobenzoic acid (8) with carbon disulfide and appropriate aromatic amines in an alkaline medium. These compounds’ structures were confirmed by comparing their physical characteristics and spectral data to the earlier ones. Ten novel products (6a‐d, 7a‐d, 10, 11) were synthesized and the structures were determined by their IR, ¹H‐NMR, ¹³C‐NMR and HR‐MS spectral data. Subsequently, their antimicrobial activities were estimated in vitro test against four bacterial strains including P. aeruginosa NRRL B‐14781 and E. coli NRRL B‐409 (Gram‐negative), B. cereus ATCC 10876 and L. monocytogenes ATCC 13932 (Gram‐positive), by agar well diffusion assay. The outcome showed that all hybrid compounds have potential inhibition of tested Gram‐negative bacteria. Compound (6d) revealed remarkable antibacterial effects on P. aeruginosa and E. coli growth. Besides, compounds (6a), (7a), (7d) and (10) have also inhibitory effects on B. cereus strain at tested concentrations. The compounds mentioned above contain the 3‐chlorophenyl/phenyl substituent at position 3 in the quinazoline ring.

Dammarenolic‐acid derivatives experimentally demonstrated possessing inhibition activity towards α‐glucosidase might be used as the evidence to retrieve an inhibitory mechanism and subjected for computational screening on other diabetes‐related proteins, e.g. tyrosine phosphatase 1B. Seven structures reported in our preceding work (denoted as 1‐7) were subjected for an in silico investigation in this study on inhibitability towards protein structure PDB‐3W37 by molecular docking simulation. The computer‐based results see a good agreement with those from laboratory‐based reports, with the order of static stability: 3‐3W37 > 1‐3W37 > 7‐3W37 > 2‐3W37 > 6‐3W37 ~ 5‐3W37 ~ 4‐3W37 (negligible activity). Together, experiment‐theory reveals the most promising candidates are 1‐3 and 7. The in‐theory order for most promising inhibitors regarding protein structure UniProt‐PTP1B is: 1‐PTP1B > 6‐PTP1B > 4‐PTP1B. Quantity‐structure relationship analyses (i.e. QSARIS and ADMET) expect 1‐3 as compounds with sufficient bio‐ and pharma‐compatibility. Altogether, the results specify 1 as the most promising candidate for multi‐purpose inhibition towards diabetes‐based proteins, thus encouraging elevated efforts for validation and further development for application.