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Journal of Chemistry publishes original research articles as well as review articles on all aspects of fundamental and applied chemistry, including biological, environmental, forensic, inorganic, organic, physical and theoretical.
Journal of Chemistry maintains an Editorial Board of practicing researchers from around the world, to ensure manuscripts are handled by editors who are experts in the field of study.
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Mechanistics of pH-Dependent Sulfmyoglobin Formation: Spin Control and His64 Proton Relay
The chemistry of hydrogen sulfide (H2S) has been directed towards physiologically relevant hemeproteins, including myoglobin, hemoglobin, and other similar proteins. Despite substantial efforts, there remains a need to elucidate the mechanism and identify the species involved in the reaction between oxy-hemeproteins and H2S. Here, we summarize both our experimental data and computational modeling results revealing the mechanisms by which sulfmyoglobin (sulfMb) and sulfhemoglobin (sulfHb) are formed. Our experimental data at pH 7.4 reveal differences in intensity between sulfMb and sulfHb chromophores in the 620 nm charge transfer region. This behavior could be attributed to the incomplete reaction of tetrameric oxy-Hb with H2S, where not all heme groups form sulfheme. The data also show that, for the reaction of oxy-myoglobin (oxy-Mb) and H2S, the 622 nm charge transfer band increases in intensity from a pH of 6.6 to 5.0. This increase is attributed to the presence of the heme pocket distal His64εδ, which is positively charged, resulting in an elevated yield of sulfMb formation compared to the mono-protonated tautomer, His64ε. Computational hybrid QM/MM methods support the conclusion, indicating that oxy-Mb His64εδ (pH 5.0) reacts with H2S in the triplet state, favored by −31.0 kcal/mol over the singlet His64ε (pH 6.6) species. The phenomenon is facilitated by a hydrogen bonding network within the heme pocket, between His64εδ, heme Fe(II)O2, and H2S. The results establish an energetically favored quantitative mechanism to produce sulfMb (−69.1 kcal/mol) from the reactions of oxy-Mb and H2S. Curiously, the mechanism between met-aquo Mb, H2O2, and H2S shows similar reaction pathways and leads to sulfheme formation (−135.3 kcal/mol). The energetic barrier towards intermediate Cpd-0 is the limiting step in sulfheme formation for both systems. Both mechanisms show that the thiyl radical, HS•, is the species attacking the β-β double bond of heme pyrrole B, leading to the sulfheme structure.
Selective mPGES-1 Inhibitor Ameliorated Adjuvant-Induced Arthritis in the Rat Model
Endogenous prostaglandin E2 (PGE2) plays an important role in maintaining the homeostasis conditions. However, the overexpression of PGE2 in response to various inflammatory stimulations is an important target of anti-inflammatory drugs. Both inducible COX-2 (cyclooxygenase-2) and mPGES-1 (microsomal prostaglandin E2 synthase-1) enzymes are responsible for the inflammatory overexpressed PGE2 production. Among them, mPGES-1 is regarded as a more promising ideal target for anti-inflammatory drugs without the gastrointestinal and cardiovascular side effects. As our continuous research for the discovery of novel mPGES-1 inhibitors, we have characterized MPO-0144 as a selective mPGES-1 inhibitor with a selectivity index of >270 over COX-1 and >25 over COX-2, respectively. Herein, we evaluated the anti-inflammatory effect of MPO-0144 in an adjuvant-induced arthritis rat model. MPO-0144 attenuated the inflammatory responses without severe gastrointestinal side effects and organ toxicities. These overall data suggest a possibility that MPO-0144 downregulates PGE2 production by potent mPGES-1 and weak COX-2 inhibitory activities, thus attenuating the paw swelling in AIA (adjuvant-induced arthritis) rat models. MPO-0144 also exhibited favorable ADMET profiles. However, MPO-0144 did not show any inhibitory effects on human mPGES-1 enzyme at a high concentration. Therefore, MPO-0144 represents a valuable pharmacological tool for the study of regulation of inducible mPGES-1 in an inflammatory arthritis rat model.
Antibacterial and Antioxidant Activities of Triterpenoids and Cyclic 1,7-Diarylheptanoids from the Stem Bark of Myrica salicifolia: A Combined Experimental and Computational Study
Myricasalicifolia A Rich (Myricaceae) is a tree growing in Central and East Africa. Traditionally, the plant is used to treat malaria, respiratory disorders, inflammations, and infections. A new compound, 3β-O-trans-caffeoylisomyricadiol (7), was isolated from MeOH : CHCl3 (2 : 1) extract of the stem bark of Myrica salicifolia along with seven known compounds, namely, myricanone (1), myricanol (2), myricanol-11-O-β-D-xylopyranoside (3), taraxerone (4), taraxerol (5), myricadiol (6), and methyl-β-D-glucopyranoside (8). This is the first report of the isolation of taraxerene-type triterpenes from this plant. The structures were determined by a comprehensive analysis of 1D/2D NMR spectroscopy, HR-MS, and by comparison with literature data. The compounds showed a wide range of DPPH scavenging activities from very weak (IC50 value = 282.61 μM) to very strong (IC50 = 13.48 μM). Antibacterial activities of the compounds were evaluated using the disk diffusion agar method, where some of the compounds showed modest antibacterial activities against S. pyogenes and S. aureus at 250 μg/mL. Compounds 2, 3, and 7 were assessed for their in silico molecular docking analysis. The lowest binding affinity for compound 7 was found to be −7.26 to −10.35 kcal/mol against PqsA protein of P. aeruginosa, pyruvate kinase (PK) enzyme of S. aureus, LuxS protein of S. pyogenes, and DNA gyrase B of E. coli, which showed better binding affinity compared to the standard drug ampicillin (−7.36 to −8.03 kcal/mol) and ciprofloxacin (−6.19 to −6.83 kcal/mol). In silico ADMET predictions revealed that compounds 3 and 8 met all the requirements for pharmacokinetic properties.
Characterization of Gold Nanoparticles Synthesized with Zingiber zerumbet Extracts
Gold nanoparticles have been used as drug carriers and imaging reagents. The plant extract-capped gold nanoparticles provide better properties than chemically synthesized gold nanoparticles. In this study, Zingiber zerumbet extract-mediated green production of gold nanoparticles (Z. zerumbet@Au NPs) was established. Based on the UV-visible spectroscopy and transmission electron microscope (TEM) results, most Z. zerumbet@Au NPs were spherical. When more Z. zerumbet extracts were added, more spherical nanoparticles were formed. The hydrodynamic size changed slightly along with time, and the average size was approximately 170 nm. Capping of Z. zerumbet extract on the surface of gold nanoparticles was confirmed by Fourier transform infrared spectroscopy (FTIR). In general, phenolic compounds or flavonoid compounds were considered to be the reducing agent. However, zerumbone was identified as the reducing agent in this study. The resulting oxidized products were characterized by high-performance liquid chromatography-mass spectrometry (HPLC-MS). As a result, the solvent was proven to be involved in nanoparticle synthesis. Overall, Z zerumbet@Au NPs showed great potential to be used in cosmetic- or biomedicine-related fields.
Oil Palm Biomass Sap-Rotten Rice as a Source to Remove Metal Ions and Generate Electricity as By-Products through Microbial Fuel Cell Technology
Microbial fuel cell (MFC) is a new and interesting technology that can be used to treat wastewater without using electricity. The current research focuses on electron generation, which is one of the technique’s major challenges. According to the latest literature, the study was planned to successfully remove the metals from artificial wastewater at high concentrations and generate electricity. On average, after 18 days of operation, it offered 610 mV with 1000 ῼ constant external resistance. The internal resistance was found to be 520 ῼ. The achieved power density was 3.164 mW/m2 at an external resistance of 1000 ῼ. The achieved removal efficiencies of Pb2+, Cd2+, Cr3+, and Ni2+ were 83.67%, 84.10%, 84.55%, and 95.99%, respectively. The operation lasted for 25 days. The cyclic voltameter studies show that there is a gradual oxidation rate of organic substances, while on day 25, the removal efficiency reached its maximum. The specific capacitance was found to be high between days 15 and 20, i.e., 0.0000540 F/g. It also indicated that biofilm was stable around day 18. Furthermore, the biological characterization also demonstrated that MFC operation was very smooth throughout the process, even at high concentrations (100 mg/L) of metal ions. Finally, there is the MFC method, as well as some new challenges and future recommendations.
Synthesis and Antitubercular Evaluation of Diverse Glycosylated Ureas from D-Glucose
Dedicated to Dr. Rama P. Tripathi, Former Chief Scientist at CSIR-Central Drug Research Institute, Lucknow, India, for his extraordinary contribution to “Drug development against Tuberculosis”