Solubility-driven optimization of benzothiopyranone salts leading to a preclinical candidate with improved pharmacokinetic properties and activity against Mycobacterium tuberculosis

Solubility-driven optimization of the salts of nitro benzothiopyranone 1, which targets DprE1, led to an antimycobacterial preclinical candidate 2. Five pharmaceutically acceptable salts, including the maleate (2), fumarate (3), citrate (4, 5), and l-malate (6) of compound 1, were prepared via the salt formation reaction and evaluated for their physicochemical and pharmacokinetic properties. Compared with 1, all the target salts exhibited greatly increased aqueous solubility and improved oral bioavailability in mice. Maleate salt 2, which displayed higher chemical stability and lower log P, showed substantially improved bioavailability in rats and a much better in vivo effect compared with free base 1 at the same dose. The X-ray crystal structure of 2 revealed that the exposed hydrophilic piperazine-maleate moiety in the crystal structure cell may be critical in increasing the solubility of 2. Thus, this maleate salt 2 overcame the poor druggability of benzothiopyranone derivatives and was identified as a promising preclinical candidate for treating tuberculosis.

Reprogramming Escherichia coli pyruvate-forming reaction towards chorismate derivatives production

Microbial metabolic pathway engineering is a potent strategy used worldwide to produce aromatic compounds. We drastically rewired the primary metabolic pathway of Escherichia coli to produce aromatics and their derivatives. The metabolic pathway of E. coli was compartmentalized into the production and energy modules. We focused on the pyruvate-forming reaction in the biosynthesis pathway of some compounds as the reaction connecting those modules. E. coli strains were engineered to show no growth unless pyruvate was synthesized along with the compounds of interest production. Production of salicylate and maleate was demonstrated to confirm our strategy's versatility. In maleate production, the production, yield against the theoretical yield, and production rate reached 12.0 g L^-1, 67%, and up to fourfold compared to that in previous reports, respectively; these are the highest values of maleate production in microbes to our knowledge. The results reveal that our strategy strongly promotes the production of aromatics and their derivatives.

Design and synthesis of malonohydrazide based colorimetric receptors for discrimination of maleate over fumarate and detection of F-, AcO- and AsO2- ions

In this study, we have designed and synthesized two new organic receptors R1 and R2 based on malonohydrazide for the recognition of biologically important anions. The receptor R1 capable of colorimetric discrimination of maleate over fumarate ion, exhibit significant color change from pale yellow to wine red due to intermolecular hydrogen bond between the R1 and maleate ion, supported by ¹HNMR titration, where the peak at δ12.0 ppm attributed to the NH proton experiences a downfield shift upon binding with maleate ion. Receptor R1, equipped with two electron-withdrawing NO₂ moieties as the chromogenic signaling unit enhance the hydrogen bonding tendency and acidity, and thus when comparing with receptor R2, R1 displayed substantial higher redshift (∆λ_max) of 148 nm, 143 nm, and 140 nm towards F^-, AcO^-, and maleate anion in the DMSO. In addition, the synthesized receptors R1 and R2 are able to detect F^-, AcO^-, and AsO₂^- ions as their sodium salts in an aqueous solution with visual color change. Receptor R1 exhibit electrochemical response towards F^- and AcO^- ions. The receptors R1 and R2 are successfully applied for quantitative detection of F^- ion in the toothpaste solution in an aqueous medium. Additionally, R1 and R2 exhibit fluorescence enhancement towards F^- and AcO^- ions in the DMSO. As well, R1 and R2 demonstrate to be potentially useful colorimetric chemosensor for sensing maleate ion using the test strip. The theoretical calculation based on TD-DFT corroborates well with the experimental results of the receptors R1 and R2 with fluoride, acetate and maleate.

Sulforaphane prevents maleic acid-induced nephropathy by modulating renal hemodynamics, mitochondrial bioenergetics and oxidative stress

Maleic acid (MA)-induced nephropathy that is characterized by proteinuria, glycosuria, phosphaturia and a deficient urinary acidification and concentration. Sulforaphane (SF) is an indirect antioxidant that shows nephroprotective effects. The aim of the present work was to test the pre-treatment with SF against the MA-induced nephropathy. Wistar rats (230-260 g) were separated in the following groups: control, MA (which received 400 mg/kg of MA), SF + MA (which received MA and 1 mg/kg of SF each day for four days) and SF (which only received SF). MA induced proteinuria, an increase in urinary excretion of N-acetyl-β-d-glucosaminidase, and a decrease in plasma glutathione peroxidase activity, renal blood flow, and oxygenation and perfusion of renal cortex. All these impairments correlated with higher levels of oxidative damage markers and exacerbated superoxide anion production on renal cortex. Moreover, MA impaired mitochondrial bioenergetics associated to complex I, mitochondrial membrane potential and respiratory control index and increased the mitochondrial production of hydrogen peroxide. Further it disrupted mitochondrial morphology. SF prevented all the above-described alterations. In conclusion, the protective effect of SF against MA-induced nephropathy is associated with preservation of mitochondrial bioenergetics, amelioration of oxidative stress and improvement of renal hemodynamics and renal cortex oxygenation.

Designing greener plasticizers: Effects of alkyl chain length and branching on the biodegradation of maleate based plasticizers

The ubiquitous presence of the plasticizer di (2-ethylhexyl) phthalate (DEHP) in the environment is of concern due to negative biological effects associated with it and its metabolites. In particular, the metabolite mono (2-ethylhexyl) phthalate (MEHP) is a potential endocrine disruptor. Earlier work had identified the diester di (2-ethylhexyl) maleate (DEHM) as a potential greener candidate plasticizer to replace DEHP, yet its biodegradation rate was reported to be slow. In this study, we modified the side chains of maleate diesters to be linear (i.e., unbranched) alkyl chains that varied in length from ethyl to n-octyl. The plasticization efficiency of these compounds blended into PVC at 29 wt.% increased with the overall length of the molecule, but all compounds performed as well as or better than comparable samples with DEHP. Tests conducted with the equally long DEHM and dihexyl maleate (DHM) showed that branching has no effect on glass transition temperature (Tg) reduction efficiency. Biodegradation experiments with the common soil bacterium Rhodococcus rhodocrous in the presence of the plasticizer showed acceptable hydrolysis rates of maleates with unbranched side chains, while the branched DEHM showed almost no degradation. The addition of hexadecane as auxiliary carbon source improved hydrolysis rates. Temporary buildup of the respective monoester of the compounds were observed, but only in the case of the longest molecule, dioctyl maleate (DOM), did this buildup lead to growth inhibition of the bacteria. Maleates with linear side chains, if designed and tested properly, show promise as potential candidate plasticizers as replacements for DEHP.