Ocimum sanctum as a Source of Quorum Sensing Inhibitors to Combat Antibiotic Resistance of Human and Aquaculture Pathogens.

Biofilms play a decisive role in the infectious process and the development of antibiotic resistance. The establishment of bacterial biofilms is regulated by a signal-mediated cell-cell communication process called "quorum sensing" (QS). The identification of quorum sensing inhibitors (QSI) to mitigate the QS process may facilitate the development of novel treatment strategies for biofilm-based infections. In this study, the traditional medicinal plant Ocimum sanctum was screened for QS inhibitory potential. Sub-MICs of the extract significantly affected the secretion of EPS in Gram-negative human pathogens such as Escherichia coli, Pseudomonas aeruginosa PAO1, Proteus mirabilis, and Serratia marcescens, as well as aquaculture pathogens Vibrio harveyi, V. parahaemolyticus, and V. vulnificus, which render the bacteria more sensitive, leading to a loss of bacterial biomass from the substratum. The observed inhibitory activity of the O. sanctum extract might be attributed to the presence of eugenol, as evidenced through ultraviolet (UV)-visible, gas chromatography-mass spectroscopy (GC-MS), Fourier transformer infrared (FTIR) spectroscopy analyses, and computational studies. Additionally, the QSI potential of eugenol was corroborated through in vitro studies using the marker strain Chromobacterium violaceum.

Synthesis, crystal structure, DFT and molecular docking studies of N-acetyl-2,4-[diaryl-3-azabicyclo[3.3.1]nonan-9-yl]-9-spiro-4'-acetyl-2'-(acetylamino)-4',9-dihydro-[1',3',4']-thiadiazoles: A potential SARS-nCoV-2 Mpro (COVID-19) inhibitor.

In this paper, we describe the synthesis and crystal structure analysis of N-acetyl-2,4-[diphenyl-3-azabicyclo[3.3.1]nonan-9-yl]-9-spiro-4'-acetyl-2'-(acetylamino)-4',9-dihydro-[1',3',4']-thiadiazole (3a) and N-acetyl- 2,4-[bis(p-methoxyphenyl)-3-azabicyclo[3.3.1]nonan-9-yl]-9-spiro-4'-acetyl-2'-(acetylamino)-4',9-dihydro-[1',3',4']-thiadiazole (3b). The title compounds 3a and 3b are characterized by 1D NMR and single crystal x-ray diffraction analysis. Non-covalent interactions in a molecule were identified by Hirshfeld surface (dnorm contacts and 2D fingerprint plot) analysis. In addition, the existence of chalcogen bond (S•••O bond) in the molecular structures (3a and 3b) are described by NCI-RDG and QTAIM analysis. NBO analysis is employed to describe the orbital interactions and electron transfer between sulfur and oxygen atoms. Molecular docking is carried out for compounds 3a and 3b with COVID-19 viral protein SARS-nCoV-2 Mpro (PDB ID: 6LU7).

Localization of α 2u-globulin in the acinar cells of preputial gland, and confirmation of its binding with farnesol, a putative pheromone, in field rat (Millardia meltada).

Pheromones, low molecular weight chemical entities that bind to pheromone carrier proteins, are chemical signals that play an important role in the communication system in animals. This has been rather fairly well-studied in the rodents. The preputial gland, a rich source of pheromones in many rodents, contains a low molecular mass protein (18-20 kDa) that acts as one such pheromone carrier. However, the presence of this protein in the notorious rodent pest Millardia meltada has not yet been proven. Therefore, we aimed at identifying this protein, and the pheromones that are bound to it, in this rodent so as to utilize the information in the control of this pest. Twenty volatile compounds were identified in the preputial gland using GC-MS. Total protein of the gland was fractioned by both one and two-dimensional electrophoresis when we identified a low molecular mass protein (19 kDa, pI-4.7). Adopting MALDI-TOF MS and LC-MS analyses, the protein was confirmed as α 2u-globulin. To identify the volatiles bound to this protein, we used column chromatography and GC-MS. We found that farnesol and 6-methyl-1-heptanol are the volatiles that would bind to the protein, which we propose to be putative pheromones. Immunohistochemical analysis confirmed localization of α 2u-globulin in the acinar cells of the preputial gland. Thus, we show that α 2u-globulin, a pheromone-carrier protein, is present in the preputial gland acinar cells of M. meltada and suggest farnesol and 6-methyl-1-heptanol to be the volatiles which would bind to it. The α 2u-globulin together with farnesol and 6-methyl-1-heptanol contribute to pheromonal communication of M. meltada.

Tuning organic carbon dioxide absorbents for carbonation and decarbonation.

The reaction of carbon dioxide with a mixture of a superbase and alcohol affords a superbase alkylcarbonate salt via a process that can be reversed at elevated temperatures. To utilize the unique chemistry of superbases for carbon capture technology, it is essential to facilitate carbonation and decarbonation at desired temperatures in an easily controllable manner. Here, we demonstrate that the thermal stabilities of the alkylcarbonate salts of superbases in organic solutions can be tuned by adjusting the compositions of hydroxylic solvent and polar aprotic solvent mixtures, thereby enabling the best possible performances to be obtained from the various carbon dioxide capture agents based on these materials. The findings provides valuable insights into the design and optimization of organic carbon dioxide absorbents.