Synthesis of new N-isobutyryl-L-cysteine/MEA conjugates: evaluation of their free radical-scavenging activities and anti-HIV properties in human macrophages

Structure Revision of a Widespread Marine Sulfonolipid Class Based on Isolation and Total Synthesis

The cosmopolitan marine Roseobacter clade is of global biogeochemical importance. Members of this clade produce sulfur-containing amino lipids (SALs) involved in biofilm formation and marine surface colonization processes. Despite their physiological relevance and abundance, SALs have only been explored through genomic mining approaches and lipidomic studies based on mass spectrometry, which left the relative and absolute structures of SALs unresolved, hindering progress in biochemical and functional investigations. Herein, we report the structural revision of a new group of SALs, which we named cysteinolides, using a combination of analytical techniques, isolation and degradation experiments and total synthetic efforts. Contrary to the previously proposed homotaurine-based structures, cysteinolides are composed of an N,O-acylated cysteinolic acid-containing head group carrying various different (α-hydroxy)carboxylic acids. We also performed the first validated targeted-network based analysis, which allowed us to map the distribution and structural diversity of cysteinolides across bacterial lineages. Beyond offering structural insight, our research provides SAL standards and validated analytical data. This information holds significance for forthcoming investigations into bacterial sulfonolipid metabolism and biogeochemical nutrient cycling within marine environments.

Design, synthesis, and biological studies of the new cysteine-N-arylacetamide derivatives as a potent urease inhibitor

Inhibition of Helicobacter pylori urease is an effective method in the treatment of several gastrointestinal diseases in humans. This bacterium plays an important role in the pathogenesis of gastritis and peptic ulceration. Considering the presence of cysteine and N-arylacetamide derivatives in potent urease inhibitors, here, we designed hybrid derivatives of these pharmacophores. Therefore, cysteine-N-arylacetamide derivatives 5a-l were synthesized through simple nucleophilic reactions with good yield. In vitro urease inhibitory activity assay of these compounds demonstrated that all newly synthesized compounds exhibited high inhibitory activity (IC50 values = 0.35-5.83 μM) when compared with standard drugs (thiourea: IC50 = 21.1 ± 0.11 μM and hydroxyurea: IC50 = 100.0 ± 0.01 μM). Representatively, compound 5e with IC50 = 0.35 μM was 60 times more potent than strong urease inhibitor thiourea. Enzyme kinetic study of this compound revealed that compound 5e is a competitive urease inhibitor. Moreover, a docking study of compound 5e was performed to explore crucial interactions at the urease active site. This study revealed that compound 5e is capable to inhibit urease by interactions with two crucial residues at the active site: Ni and CME592. Furthermore, a molecular dynamics study confirmed the stability of the 5e-urease complex and Ni chelating properties of this compound. It should be considered that, in the following study, the focus was placed on jack bean urease instead of H. pylori urease, and this was acknowledged as a limitation.

Nickel-Catalyzed Acid Chlorides with Tetrasulfides for the Synthesis of Thioesters and Acyl Disulfides

Herein, we report a novel method for the synthesis of thioesters and acyl disulfides via nickel-catalyzed reductive cross-electrophile coupling of acid chlorides with tetrasulfides. This approach for the synthesis of thioesters and acyl disulfides is convenient and practical under mild reaction conditions, relying on easy availability. In addition, a wide range of thioesters and acyl disulfides were obtained in medium to good yields with good functional group tolerance. Moreover, thioesters and acyl disulfides can also be prepared at the gram scale, indicating that they have certain potential for industrial application.

Novel Morpholine-Bearing Quinoline Derivatives as Potential Cholinesterase Inhibitors: The Influence of Amine, Carbon Linkers and Phenylamino Groups

A series of novel 4-N-phenylaminoquinoline derivatives containing a morpholine group were designed and synthesized, and their anti-cholinesterase activities and ABTS radical-scavenging activities were tested. Among them, compounds 11a, 11g, 11h, 11j, 11l, and 12a had comparable inhibition activities to reference galantamine in AChE. Especially, compound 11g revealed the most potent inhibition on AChE and BChE with IC₅₀ values of 1.94 ± 0.13 μM and 28.37 ± 1.85 μM, respectively. The kinetic analysis demonstrated that both the compounds 11a and 11g acted as mixed-type AChE inhibitors. A further docking comparison between the 11a- and 12a-AChE complexes agreed with the different inhibitory potency observed in experiments. Besides, compounds 11f and 11l showed excellent ABTS radical-scavenging activities, with IC₅₀ values of 9.07 ± 1.34 μM and 6.05 ± 1.17 μM, respectively, which were superior to the control, Trolox (IC₅₀ = 11.03 ± 0.76 μM). It is worth noting that 3-aminoquinoline derivatives 12a–12d exhibited better drug-like properties.

Palladium-Catalyzed Desulfonative Carbonylation of Thiosulfonates: Elimination of SO2 and Insertion of CO

A palladium-catalyzed desulfonative carbonylation of thiosulfonates has been explored. Without any additive, a series of S-aryl/alkyl benzenesulfonothioates were successfully transformed to thioesters in moderate to excellent yields by SO₂ extrusion and CO insertion under the pressure of 1 bar of CO. The solvent dimethylacetamide (DMAc) facilitated this desulfonative carbonylation due to its high absorbing ability of SO₂.

Copper-catalyzed thiocarbonylation and thiolation of alkyl iodides

In the present study, an efficient Cu-catalyzed transthiolation of alkyl iodides is developed. Notably, in the presence of CO, thioesters could also be obtained with copper and cobalt as the co-catalyst. This transformation displayed good functional group tolerance and afforded thioesters or sulfides from the corresponding alkyl iodides.

Visible-Light-Mediated Cross Dehydrogenative Coupling of Thiols with Aldehydes: Metal-Free Synthesis of Thioesters at Room Temperature

Thioesters play a crucial role in biological systems and serve as important building blocks for organic synthesis. Herein, Eosin Y and TBHP mediated photochemical cross dehydrogenative coupling (PCDC) between feedstock aldehydes and thiols has been described at room temperature to synthesize thioesters. This thioesterification protocol proceeds smoothly to give the desired products in good to excellent yields by the suitable PCDC of both alkyl/aryl- aldehydes with a variety of alkyl/aryl-thiols and generates water and ^tBuOH as green byproducts. This method is also found to be scalable with good efficiency. Mechanistic investigations reveal that under this photochemical condition, the formation of acyl radical can be achieved from aldehyde. This acyl radical was further intercepted with an intermediate disulfide, generated in situ via the dehydrogenation of thiol to give the desired thioester. Moreover, disulfides, which are relatively easier to handle, also provided good to excellent yields in the optimized reaction condition. This protocol was further extended toward the more challenging direct transformation of alcohols to thioesters.

Palladium-Catalyzed Linear Hydrothiocarbonylation of Unactivated Terminal Alkenes: Synthesis of Aliphatic Thioesters

A Pd-catalyzed hydrothiocarbonylation of unactivated terminal alkenes is presented. According to this protocol, aliphatic thioesters were synthesized with exclusive linear selectivity under mild reaction conditions. Good to excellent yields (up to 91% yield), broad substrate scope, broad functional group tolerance, and utility of the method demonstrated the advantages of this protocol.

Deaminative carbonylative thioesterification of activated alkylamines with thiophenols under transition-metal-free conditions

A transition-metal-free radical carbonylation of activated alkylamines with thiophenols has been successfully developed. Various thioesters were selectively produced with moderate to good yields.

Synthesis, characterization, in-vitro antimicrobial properties, molecular docking and DFT studies of 3-{(E)-[(4,6-dimethylpyrimidin-2-yl)imino]methyl} naphthalen-2-ol and Heteroleptic Mn(II), Co(II), Ni(II) and Zn(II) complexes

Heteroleptic divalent metal complexes [M(L) (bipy)(Y)]•nH2O (where M = Mn, Co, Ni, and Zn; L = Schiff base; bipy = 2,2’-bipyridine; Y = OAc and n = 0, 1) have been synthesized from pyrimidine Schiff base ligand 3-{(E)-[(4,6-dimethylpyrimidin-2-yl)imino]methyl} naphthalen-2-ol, 2,2’-bipyridine and metal(II) acetate salts. The Schiff base and its complexes were characterized by analytical (CHN elemental analyses, solubility, melting point, conductivity) measurements, spectral (IR, UV-vis, 1H and 13C-NMR and MS) and magnetometry. The elemental analyses, Uv-vis spectra and room temperature magnetic moment data provide evidence of six coordinated octahedral geometry for the complexes. The metal complexes’ low molar conductivity values in dimethylsulphoxide suggested that they were non-ionic in nature. The compounds displayed moderate to good antimicrobial and antifungal activities against S. aureus, P. aeruginosa, E. coli, B. cereus, P. mirabilis, K. oxytoca, A. niger, A. flevus and R. Stolonifer. The compounds also exhibited good antioxidant potentials with ferrous ion chelation and, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging assays. Molecular docking studies showed a good interaction with drug targets used. The structural and electronic properties of complexes were further confirmed by density functional theory calculations.

Hydroxytyrosol nicotinate, a new multifunctional hypolipidemic and hypoglycemic agent

Hydroxytyrosol (HT) is a natural polyphenol antioxidant that exists in olive oil. In the study of multifunctional hypolipidemic of nicotinic derivatives, we found that hydroxytyrosol nicotinate (HT-N) incorporation of niacin with HT displayed ?-glucosidase inhibitory activities in vitro, such as yeast ?-glucosidase (IC₅₀?=?117.72??M) and rat intestinal ?-glucosidases maltase (IC₅₀?=?31.86??M) and sucrase (IC₅₀?=?22.99??M), and had a good control of postprandial blood glucose (PBG). HT-N shown significantly hypoglycemic action by 16.9% and protection of pancreatic tissue in type 2 diabetic mellitus (T2DM) mouse model. HT-N also shown a potent antioxidant activity and property of anti-glycation in vitro, which were benefit for ameliorating diabetic complications. Moreover, HT-N exhibited much significant hypolipidemia, lowering plasma triglyceride (TG), total cholesterol (TC), and malonaldehyde (MDA) by 34.6%, 45.8% and 32.1% respectively, in hyperlipidemic mice induced by Triton WR 1339. The results indicated that HT-N has hypolipidemic, hypoglycemic and antioxidant actions. All these properties could be conducive to amelioration of oxidative stress, hyperlipidemia, and diabetes that HT-N may serve as a multifunctional potential therapeutic strategy in diabetic patients with hyperlipidemia.

Intracellular redox state as target for anti-influenza therapy: are antioxidants always effective?

Influenza virus infections represent a big issue for public health since effective treatments are still lacking. In particular, the emergence of strains resistant to drugs limits the effectiveness of anti-influenza agents. For this reason, many efforts have been dedicated to the identification of new therapeutic strategies aimed at targeting the virus-host cell interactions. Oxidative stress is a characteristic of some viral infections including influenza. Because antioxidants defend cells from damage caused by reactive oxygen species induced by different stimuli including pathogens, they represent interesting molecules to fight infectious diseases. However, most of the available studies have found that these would-be panaceas could actually exacerbate the diseases they claim to prevent, and have thus revealed "the dark side" of these molecules. This review article discusses the latest opportunities and drawbacks of the antioxidants used in anti-influenza therapy and new perspectives.