Evidence of benzilic rearrangement during the electrochemical oxidation of D-glucose to D-glucaric acid

Crystal structure, spectral investigations, DFT and antimicrobial activity of brucinium benzilate (BBA)

The unreported brucinium benzilate (BBA) crystal and Hirshfeld surface analysis indicated the influence of intramolecular hydrogen bonding network on the crystal structure. Protonation occurs at the tertiary nitrogen as it is the most basic site. The protonated N-H⁺ proton was observed at 7.08 ppm and the benzilate carbon COO^- at 178.41 ppm. Molecular electrostatic potential (MEP) studies showed the electron-rich and electron-deficient sites in the molecule for understanding BBA interaction with an enzyme. Frontier molecular orbital (FMO) studies indicated that BBA molecule is thermodynamically stable and the HOMO-LUMO energy gap was found to be 4.454 eV. The highest interaction has the energy (322.86 kcal/mol) between tertiary ammonium N(LP) and H⁺. Inhibition tests showed that brucinium benzilate inhibits Bacillus cereus and Salmonella typhimurium bacteria. ADMET properties indicated that BBA has drug characteristics in binding plasma protein.

Electrosynthesis of Biobased Chemicals Using Carbohydrates as a Feedstock

The current climate awareness coupled with increased focus on renewable energy and biobased chemicals have led to an increased demand for such biomass derived products. Electrosynthesis is a relatively new approach that allows a shift from conventional fossil-based chemistry towards a new model of a real sustainable chemistry that allows to use the excess renewable electricity to convert biobased feedstock into base and commodity chemicals. The electrosynthesis approach is expected to increase the production efficiency and minimize negative health for the workers and environmental impact all along the value chain. In this review, we discuss the various electrosynthesis approaches that have been applied on carbohydrate biomass specifically to produce valuable chemicals. The studies on the electro-oxidation of saccharides have mostly targeted the oxidation of the primary alcohol groups to form the corresponding uronic acids, with Au or TEMPO as the active electrocatalysts. The investigations on electroreduction of saccharides focused on the reduction of the aldehyde groups to the corresponding alcohols, using a variety of metal electrodes. Both oxidation and reduction pathways are elaborated here with most recent examples. Further recommendations have been made about the research needs, choice of electrocatalyst and electrolyte as well as upscaling the technology.

Substrate-imprinted docking of Agrobacterium tumefaciens uronate dehydrogenase for increased substrate selectivity

Agrobacterium tumefaciens uronate dehydrogenase (AtuUdh) belongs to the short-chain dehydrogenase superfamily, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. It is apparently required for the production of D-glucaric acid. AtuUdh-catalyzed reaction is reversible with dual substrate-specific activity (D-galacturonic acid and D-glucuronic acid) in nature. In our study, 34 mutants were pre-screened from 155 mutants generated from AtuUdh (wild-type) and selected 10 structurally stable mutants with increased substrate selectivity. The specificity, efficiency, and selectivity of these mutants for different substrates and cofactors were predicted from 121 docked models using a substrate-imprinted docking approach. Q14F, S36L, and S75T mutants have shown a high binding affinity to D-glucuronic acid and its substrate intermediates such as D-glucaro-1,4-lactone and D-glucaro-1,5-lactone. These mutants exhibited a low binding affinity to the substrate and cofactor required for D-galactaric acid. D34S, N112E and S165E mutants found to show a high selectivity of D-galacturonic acid and its substrate intermediates for D-galactaric acid production. Ser75, Ser165, and Arg174 are active residues playing an imperative role in the substrate selectivity and also contributed in the conjecture the mechanism of transition state stabilization catalyzed by AtuUdh mutants. The present approach was used to reveal the substrate binding mechanism of AtuUdh mutants for a better understanding of the structural basis for selectivity and function.

Catalytic oxidation of carbohydrates into organic acids and furan chemicals

A review on the development of new routes for the production of organic acids and furan compoundsviacatalytic oxidation reactions.