INHIBITORS FROM MELIA DUBIA AGAINST SDIA MEDIATED QUORUM SENSING OF UROPATHOGENIC E. COLI

Objective: To investigate the potentiality of Meliadubiastem extracts for quorum sensing (SdiA-selective) inhibitory activity against uropathogenic Escherichia coli (UPEC).Methods: The antimicrobial (cell-density) and anti-virulent (swarming motility, protein, protease, hemolysis, hemagglutination, hydrophobicity and biofilm inhibition) properties of the Meliadubia stem extracts were performed.Results: The biofilm, hemolysis, swarming motility were inhibited by 45.71%, 12.97 % and 33.33% respectively when the media were supplemented with 30 mg/ml of ethanolic extract. The GC-MS spectrum of ethanolic extract showed an array of 49 structurally unrelated compounds with the natural ligand, AHL. Their interaction with the quorum regulator, SdiA, was predicted by Glide module of Schrödinger suite and the ligands C 7, C 20, C 28 showed appreciable activity with the following G-Score 11.4, 10.7, 9.9 respectively. In vitro and in silico molecular docking analysis data showed fairly good correlation, suggesting that the ethanolic extract has the potential to attenuate the quorum sensing of UPEC. Further investigation is desired to study the antagonistic effect of the above ligand by in vitro and in vivo strategies.Conclusion: The quorum quenching activity of Meliadubia stem was proven from the overall analysis and its effect towards the inhibition of biofilm and virulence factors were analyzed.Â

Radiation-grafted anion-exchange membranes for CO2 electroreduction cells: an unexpected effect of using a lower excess of N-methylpiperidine in their fabrication

Giron Rodriguez et al. [ACS Sustainable Chem. Eng., 2023, 11, 1508] previously showed that radiation-grafted anion-exchange membranes containing N-benzyl-N-methylpiperidinium headgroups (MPIP-RG-AEM) are promising for use in CO2 electrolysis (cf. commercial and other RG-AEM types). For a more sustainable synthesis, MPIP-RG-AEMs have now been fabricated using a reduced 1.1 times excess of amine reagent (historically made using >5 times excess). A resulting RG-AEM promisingly had a bulk amination level that was comparable to those made with the traditional large excess. Unexpectedly, however, it had a significantly reduced water content, with two further batches showing that this observation was repeatable (and reproducible via measurements collected on a single batch using different techniques in different labs). The ionic conductivities of the RG-AEM made with a controlled 1.1 excess of amine were also lower, with higher activation energies. Terahertz time-domain spectroscopy measurements showed that the lower water uptake RG-AEMs, made with the 1.1 amine excess, contained smaller amounts of bulk water relative to bound water (a repeatable observation with different counter-anions). This lack of bulk water, yielding reduced water diffusion coefficients, led to a change in the water management when such RG-AEMs were tested in CO2 electrolysis cells, with significantly affected in situ performances. Small angle scattering data (X-ray and neutron) indicated that MPIP-RG-AEM fabrication with the 1.1 excess of amine reduced the size of the amorphous lamella domains on hydration, and this change is suspected to be the cause of the lower water uptakes and swelling. The finding that chemically similar AEMs can have significantly different hydration properties is potentially important to all ion-exchange membrane users and developers (beyond the CO2 electrolysis scope of this study)