Homodinuclear copper(II) and zinc(II) complexes of a carboxylate-rich ligand as synthetic mimics of phosphoester hydrolase in aqueous solutions.

The synthesis, characterization and catalytic activities of two homodinuclear Cu(II) and Zn(II) complexes of a carboxylate-rich ligand, N,N'-Bis[2-carboxybenzomethyl]-N,N' -Bis[carboxymethyl]-1,3-diaminopropan-2-ol (H5ccdp) ligand towards the hydrolysis of (p-nitrophenyl phosphate) (PNPP) and bis(p-nitrophenyl) phosphate (BNPP) substrates in aqueous systems are described. Kinetic investigations were carried out using UV-Vis spectrophotometric techniques at 25 °C and 37 °C and different pH (7-10) conditions. The kinetic studies revealed that the turnover rate (kcat) values among the PNPP hydrolysis systems, the highest and the lowest kcat values were displayed by [Cu2(ccdp)(µ-OAc)]2- at 2.34 × 10-6 s-1 (pH 8 and 37 °C) and 2.13 × 10-8 s-1 (pH 8 and 25 °C), respectively. However, similar comparisons among the BNPP hydrolysis revealed that highest and the lowest kcat values were displayed by [Zn2(ccdp)(µ-OAc)]2- at 4.64 × 10-8 s-1 (pH 9 and 37 °C) and 2.38 × 10-9 (pH 9 and 25 °C). Significantly enough, the catalyst-substrate adduct species containing a metal bound PNPP and BNPP have been detected by ESI-MS techniques. Additionally, a PNPP-bound copper complex has been isolated and crystalized using single crystal X-ray diffraction technique. Based on the structural and activity information obtained in this study, reaction mechanisms for the hydrolysis of PNPP have been proposed.

Sustainable Pd(OAc)2 /Hydroquinone Cocatalyst System for Cis-Selective Dibenzoyloxylation of 1,3-Cyclohexadiene.

The 1,4-diacyloxylation of 1,3-cyclohexadiene (CHD) affords valuable stereochemically defined scaffolds for natural product and pharmaceutical synthesis. Existing cis-selective diacyloxylation protocols require superstoichiometric quantities of benzoquinone (BQ) or MnO2 , which limit process sustainability and large-scale application. In this report, reaction development and mechanistic studies are described that overcome these limitations by pairing catalytic BQ with tert-butyl hydroperoxide as the stoichiometric oxidant. Catalytic quantities of bromide enable a switch from trans to cis diastereoselectivity. A catalyst with a 1:2 Pd:Br ratio supports high cis selectivity while retaining good rate and product yield. Further studies enable replacement of BQ with hydroquinone (HQ) as a source of cocatalyst, avoiding the handling of volatile and toxic BQ in large-scale applications.

Oxoplatin-B, a cisplatin-based platinum(IV) complex with photoactive BODIPY for mitochondria specific "chemo-PDT" activity.

Oxoplatin-B, a platinum(IV) complex [Pt(NH3)2Cl2(L1)(OH)] (1) of 4-methylbenzoic acid (HL1) functionalized with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) was prepared, characterized and its antitumor activity studied. [Pt(NH3)2Cl2(L2)(OH)] (2) of 4-methylbenzoic acid (HL2) was studied as a control. Complex 1 showed an absorption band at 500 nm (ɛ = 4.34 × 104 M-1 cm-1) and an emission band at 515 nm (λex = 488 nm, ΦF = 0.64) in 1% dimethyl sulfoxide/Dulbecco's Modified Eagle's Medium (pH = 7.2). Visible light-induced (400-700 nm) generation of singlet oxygen was evidenced from 1,3-diphenylisobenzofuran titration study. Complex 1 showed photo-induced cytotoxicity in visible light (400-700 nm, 10 J cm-2) against human breast cancer (MCF-7), cervical cancer (HeLa) and lung cancer (A549) cells (IC50: 1.1-3.8 µM) while being less toxic in normal cells. Confocal imaging showed mitochondrial localization with additional evidence from platinum content from isolated mitochondria and 5,5,6,6'-tetrachloro-1,1',3,3' tetraethylbenzimi-dazoylcarbocyanine iodide (JC-1) assay. Cellular apoptosis was observed from Annexin-V-FITC (fluorescein isothiocyanate)/propidium iodide assay.

Synthesis and Biological Activity of New Brassinosteroid Analogs of Type 24-Nor-5ß-Cholane and 23-Benzoate Function in the Side Chain.

Brassinosteroids are polyhydroxysteroids that are involved in different plants' biological functions, such as growth, development and resistance to biotic and external stresses. Because of its low abundance in plants, much effort has been dedicated to the synthesis and characterization of brassinosteroids analogs. Herein, we report the synthesis of brassinosteroid 24-nor-5ß-cholane type analogs with 23-benzoate function and 22,23-benzoate groups. The synthesis was accomplished with high reaction yields in a four-step synthesis route and using hyodeoxycholic acid as starting material. All synthesized analogs were tested using the rice lamina inclination test to assess their growth-promoting activity and compare it with those obtained for brassinolide, which was used as a positive control. The results indicate that the diasteroisomeric mixture of monobenzoylated derivatives exhibit the highest activity at the lowest tested concentrations (1 × 10-8 and 1 × 10-7 M), being even more active than brassinolide. Therefore, a simple synthetic procedure with high reaction yields that use a very accessible starting material provides brassinosteroid synthetic analogs with promising effects on plant growth. This exploratory study suggests that brassinosteroid analogs with similar chemical structures could be a good alternative to natural brassinosteroids.

The synthetic synergistic cinnamon oil CIN-102 is active against Madurella mycetomatis, the most common causative agent of mycetoma.

Mycetoma is a devastating neglected tropical infection of the subcutaneous tissue and most commonly caused by the fungus Madurella mycetomatis. Treatment of mycetoma consists of a combination of a long term antifungal treatment with itraconazole and surgery. However, treatment is associated with low success rates. Therefore, there is a need to identify novel treatments for mycetoma. CIN-102 is a synthetic partial copy of cinnamon oils with activity against many pathogenic bacteria and fungi. In this study we determined the in vitro activity of CIN-102 against 21 M. mycetomatis isolates and its in vivo efficacy in a M. mycetomatis infected Galleria mellonella larval model. In vitro, CIN-102 was active against M. mycetomatis with MICs ranging from 32 µg/mL to 512 µg/mL. 128 µg/mL was needed to inhibit the growth in 50% of tested isolates. In vivo, concentrations below the MIC of 40 mg/kg and 80 mg/kg CIN-102 prolonged larval survival, but higher concentrations of CIN-102 did not.

Discovery of a novel series of guanidinebenzoates as gut-restricted enteropeptidase and trypsin dual inhibitors for the treatment of metabolic syndrome.

A novel series of guanidinebenzoate enteropeptidase and trypsin dual inhibitors has been discovered and SAR studies were conducted. Optimization was focused on improving properties for gut restriction, including increased aqueous solubility, lower cellular permeability, and reduced oral bioavailability. Lead compounds were identified with efficacy in a mouse fecal protein excretion study.

Synthesis of propyl benzoate by solvent-free immobilized lipase-catalyzed transesterification: Optimization and kinetic modeling.

The present study aimed to analyze reaction kinetics and mechanism for the synthesis of propyl benzoate in solvent-free conditions. Lipase was immobilized on Hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) polymer blend by entrapment method. Among different lipases immobilized on a support, Candida cylindracea (CCL) showed excellent activity. Systematic studies were done to optimize the reaction conditions. The activation energy was found to be 16.2 kcal/mol for immobilized CCL. Kinetic parameters were calculated, which depicted that propyl benzoate synthesized using immobilized CCL followed the ternary complex model in which propanol inhibits lipase activity at higher concentrations. Recyclability of the catalyst was checked up to four catalytic cycles and 40% retention of activity was observed up to the fourth cycle. Finally, the applicability of developed protocol to synthesize various alkyl benzoates was explored.

Design, synthesis, antimycobacterial activity and molecular docking studies of novel 3- (N-substituted glycinamido) benzoic acid analogues as anti tubercular agents.

We have recently identified mycolic acid methyl transferase (MmaA1) enzyme inhibitors as potential antitubercular agents using in silico modelling techniques. In continuation of that study, we synthesised a series of novel 3-(N-substituted glycinamido) benzoic acid derivatives with an aim to optimise the lead molecule. The newly synthesised compounds were evaluated for their in vitro antimycobacterial activity against M. tuberculosis H37Rv. Among these, 5 compounds A3, A4, A5, A6 and A10 exhibited most potent activity with an MIC value of 1.6 µg/ml. Further molecular docking studies were carried out to investigate the binding mode of the ligands with MmaA1 protein. The docking studies revealed that the ligands made strong interactions with the catalytic site residues TRP30, TYR 32, GLY 71, TRP 74, GLY 76, ALA 77 and GLU 136 of MmaA1 protein. Druglikeness and leadlikeness properties of the compounds were also studied using computational tools. The results of in silico and in vitro studies indicate that these novel compounds are propitious leads for tuberculosis therapy.

Benzyl and benzoyl benzoic acid inhibitors of bacterial RNA polymerase-sigma factor interaction.

Transcription is an essential biological process in bacteria requiring a core enzyme, RNA polymerase (RNAP). Bacterial RNAP is catalytically active but requires sigma (σ) factors for transcription of natural DNA templates. σ factor binds to RNAP to form a holoenzyme which specifically recognizes a promoter, melts the DNA duplex, and commences RNA synthesis. Inhibiting the binding of σ to RNAP is expected to inhibit bacterial transcription and growth. We previously identified a triaryl hit compound that mimics σ at its major binding site of RNAP, thereby inhibiting the RNAP holoenzyme formation. In this study, we modified this scaffold to provide a series of benzyl and benzoyl benzoic acid derivatives possessing improved antimicrobial activity. A representative compound demonstrated excellent activity against Staphylococcus epidermidis with minimum inhibitory concentrations reduced to 0.5 µg/mL, matching that of vancomycin. The molecular mechanism of inhibition was confirmed using biochemical and cellular assays. Low cytotoxicity and metabolic stability of compounds demonstrated the potential for further studies.

A promising drug delivery candidate (CS-g-PMDA-CYS-fused gold nanoparticles) for inhibition of multidrug-resistant uropathogenic Serratia marcescens.

Antibiotic resistance amongst microbial pathogens is a mounting serious issue in researchers and physicians. Various alternatives to overcome the multidrug-resistant bacterial infections are under search, and biofilm growth inhibition is one of them. In this investigation, a polymeric drug delivery system loaded with multi-serratial drugs to improve the delivery of drugs against urinary tract infection causative Serratia marcescens. The chitosan grafted pyromellitic dianhydride - cysteine (CS-g-PMDA-CYS) was conjugated with AuNPs by using the -SH group of CYS and RF (rifampicin) and INH (isoniazid) were loaded in AuNPs-fused CS-g-PMDA-CYS system. Several physicochemical techniques characterized this fabricated AuNPs/RF/INH/CS-g-PMDA-CYS system. The successful encapsulation of RF and INH in AuNPs-fused CS-g-PMDA-CYS polymer had confirmed, and it observed the loading capacity for RF and INH was 9.02% and 13.12%, respectively. The in vitro drug discharge pattern was perceived high in pH 5.5 compared with pH 7.4. The AuNPs/RF/INH/CS-g-PMDA-CYS escalates 74% of Caenorhabditis elegans survival during Serratia marcescens infection by aiming biofilm development and virulence in S. marcescens. Author postulate that the fabricated system is a promising drug carrier and delivery system for inhibition of multidrug-resistant bacterias like S. marcescens.

Design, synthesis and biological activity of novel substituted 3-benzoic acid derivatives as MtDHFR inhibitors.

The enzyme dihydrofolate reductase from M.tuberculosis (MtDHFR) has a high unexploited potential to be a target for new drugs against tuberculosis (TB), due to its importance for pathogen survival. Preliminary studies have obtained fragment-like molecules with low affinity to MtDHFR which can potentially become lead compounds. Taking this into account, the fragment MB872 was used as a prototype for analogue development by bioisosterism/retro-bioisosterism, which resulted in 20 new substituted 3-benzoic acid derivatives. Compounds were active against MtDHFR, with IC50 values ranging from 7 to 40 µM, where compound 4e not only had the best inhibitory activity (IC50 = 7 µM), but also was 71-fold more active than the original fragment MB872. The 4e inhibition kinetics indicated an uncompetitive mechanism, which was supported by molecular modeling which suggested that the compounds can access an independent backpocket from the substrate and competitive inhibitors. Thus, based on these results, substituted 3-benzoic acid derivatives have strong potential to be developed as novel MtDHFR inhibitors and also anti-TB agents.

Exploiting the 4-hydrazinobenzoic acid moiety for the development of anticancer agents: Synthesis and biological profile.

Thirteen 4-hydrazinobenzoic acid derivatives were elaborated and characterized by spectral analyses (NMR and MS). Evaluation of their in vitro cytotoxic activity showed that some of the targets demonstrated potent inhibitory effects against HCT-116 and MCF-7 cancer cells. The IC50 values ranged between 21.3 ± 4.1 and 28.3 ± 5.1 µM, respectively, whereas those of doxorubicin (reference drug) ranged between 22.6 ± 3.9 and 19.7 ± 3.1 µM, respectively. The active targets 6, 7 and 9 exhibited very weak cytotoxicity on normal cells (RPE-1) and showed higher IC50 values against HCT-116 and MCF-7 cells in comparison to doxorubicin. Furthermore, compounds 7, 9 and 10 inhibited the proliferation of MCF-7 by the induction of apoptosis. The bioassay results in the regression plots generated in 3D QSAR models were in agreement and correlated with the anticancer results of the target molecules. The 4-hydazinobenzoic acid derivatives can be used as cornerstones for further structural modifications as future anticancer agents.

Discovery of Novel Autophagy Inhibitors and Their Sensitization Abilities for Vincristine-Resistant Esophageal Cancer Cell Line Eca109/VCR.

Resistance phenomena, especially acquired drug resistance, have been severely hampering the application of chemotherapeutics during cancer chemotherapy. Autophagy plays a role in maintaining the survival of cancer cells and might mediate resistance to chemotherapy drugs. Herein, a new series of 5-amino-2-ether-benzamide derivatives were synthesized and evaluated as autophagy inhibitors. Selected from 14 synthesized compounds as lead autophagy inhibitor, N-(cyclohexylmethyl)-5-(((cyclohexylmethyl)amino)methyl)-2-((4-(trifluoromethyl)benzyl)oxy)benzamide (4 d) showed the most obvious effect of LC3B protein conversion. Further, its autophagy inhibition, evaluated by using transmission electron microscopy and confocal microscopy, showed that the fusion of autophagosomes and lysosomes in the final stage of autophagic flux was suppressed. We also found that 4 d could enhance the chemosensitivity of vincristine in vincristine-resistant esophageal cancer cell line Eca109/VCR in a synergistic, associative manner. Moreover, a computational study showed that 4 d might bind with p62-zz to inhibit autophagy. We also found 4 d to be relatively less cytotoxic to normal cells versus cancer cells than the reported p62-zz inhibitor.

Synthesis and leishmanicidal evaluation of sulfanyl- and sulfonyl-tethered functionalized benzoate derivatives featuring a nitroimidazole moiety.

A series of new nitroimidazole-containing derivatives was synthesized by coupling of 2-[2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethylthio]ethanol with diversely substituted benzoic acids. Upon treatment with m-CPBA, 12 of these sulfanyl compounds were further oxidized to their sulfonyl analogs. All the 26 synthetic compounds were examined for in vitro activity against Leishmania (V.) braziliensis and Leishmania (L.) mexicana, and some of them displayed an efficient antileishmanial activity. Among the compounds tested, the catecholic derivative 2-{[2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl]sulfanyl}ethyl 3,4-dihydroxybenzoate (9a, LC50 = 13 and 11 µM) and the pyrogallolic derivative 2-{[2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl]sulfanyl}ethyl 3,4,5-trihydroxybenzoate (9b, LC50 = 4 and 1 µM) were the most active ones against the two Leishmania strains.

Ethyl benzoate bearing pyrrolizine/indolizine moieties: Design, synthesis and biological evaluation of anti-inflammatory and cytotoxic activities.

Two new series of ethyl benzoate bearing pyrrolizine and indolizine moieties 8-11 were synthesized and evaluated for their anti-inflammatory and anticancer activities. Among these derivatives, compounds 9a, 10b and 11b displayed in vivo anti-inflammatory and analgesic activity comparable to ibuprofen. The acute ulcerogenicity and histopathological studies revealed better GIT safety profile than ibuprofen. Mechanistic study of these compounds revealed inhibitory activity against COX-1/2 with preferential inhibition of COX-2. Evaluation of cytotoxic activity of the new compounds using MTT assay revealed potent to moderate activity against three human (MCF-7, A2780 and HT29) cancer cell lines (IC50 = 0.02-23.35 µM). Compounds 9a, 10a,b and 11a,b exhibited high cytotoxic selectivity against MCF-7 cells (SI = 4-84). Although the indolizine bearing derivatives 8-11b exhibited higher selectivity to COX-2 than their corresponding pyrrolizine analogs 8-11a, but they were less active and selective against MCF-7 cells. Cell cycle analysis and annexin V-FITC/PI assay revealed G1 cell cycle arrest and induction of apoptosis in MCF-7 cells by compound 9a. The docking study revealed nice fitting of the new compounds into the active site of COX-1/2 with higher affinity to COX-2. Compounds 8-11 displayed drug-likeness score in the range of 0.67-1.56 compared to 1.06 for licofelone. These results suggested that compounds 9a, 10b and 11b could be promising agents in future research as anti-inflammatory and anticancer agents.

Parallel On-Target Derivatization for Mass Calibration and Rapid Profiling of N-Glycans by MALDI-TOF MS.

Glycosylation is an important post-translational modification of proteins, and abnormal glycosylation is involved in a variety of diseases. Accurate and rapid profiling of N-glycans by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is still technically challenging and hampered mainly by mass drift of instrument, manual identification of spectrum peaks, and poor cocrystallization with traditional matrices besides low ionization efficiency of analytes. In the present study, a parallel on-target derivatization strategy (POTDS), on the basis of two rationally combined matrices, i.e., 3-hydrazinobenzoic acid plus DHB (DHB/3HBA) and quinoline-3-carbohydrazide plus DHB (DHB/Q3CH), was proposed for mass calibration and rapid detection of reducing N-glycans. Both DHB/3HBA and DHB/Q3CH show high derivatization efficiency and can improve the ionization efficiency of reducing N-glycans significantly. For mass calibration, in combination with dextrans, DHB/3HBA and DHB/Q3CH prove to be highly sensitive matrices facilitating both MS and MS2 calibration for N-glycans in dual polarities. For rapid identification, the regular mass difference observed for each N-glycan labeled with Q3CH and 3HBA respectively can eliminate the occurrence of false positives and promote automated identification of N-glycans in complex samples. For relative quantitation, the acid-base pair of DHB/Q3CH generates a concentrated cocrystallization of glycan-matrix mixtures at the edge of the droplet uniformly, exhibiting good linearity (R2 > 0.998) and accuracy (RSD ≤ 10%). Furthermore, the established POTDS was successfully utilized to assess N-glycans of serum from HCC patients, revealing potential for biomarker discovery in clinical practice.

4H-Benzo[d][1,3]oxazin-4-ones and Dihydro Analogs from Substituted Anthranilic Acids and Orthoesters.

A one-pot route to 2-alkyl and 2-aryl-4H-benzo[d][1,3]oxazin-4-ones (also known as 4H-3,1-benzoxazin-4-ones) has been developed and studied. The method involves the reaction of aryl-substituted anthranilic acids with orthoesters in ethanol catalyzed by acetic acid. Additionally, we have also investigated the reaction under microwave conditions. Not all of the substrates were successful in yielding the target heterocycles as some of the reactions failed to undergo the final elimination. This process led to the isolation of (±)-2-alkyl/aryl-2-ethoxy-1,2-dihydro-4H-benzo[d][1,3]oxazin-4-ones. The formation of the dihydro analogs correlated with the electron density on the aromatic ring: Electron-donating groups favored the 4H- benzo[d][1,3]oxazin-4-ones, while electron-withdrawing groups tended to favor the dihydro product. Substituting a pyridine ring for the benzene ring in the substrate acid suppressed the reaction.

Discovery of New Selective Butyrylcholinesterase (BChE) Inhibitors with Anti-Aß Aggregation Activity: Structure-Based Virtual Screening, Hit Optimization and Biological Evaluation.

In this study, a series of selective butyrylcholinesterase (BChE) inhibitors was designed and synthesized from the structural optimization of hit 1, a 4-((3,4-dihydroisoquinolin-2(1H)-yl)methyl)benzoic acid derivative identified by virtual screening our compound library. The in vitro enzyme assay results showed that compounds 9 ((4-((3,4-dihydroisoquinolin-2(1H)-yl)methyl)phenyl)(pyrrolidin-1-yl)methanone) and 23 (N-(2-bromophenyl)-4-((3,4-dihydroisoquinolin-2(1H)-yl)methyl)benzamide) displayed improved BChE inhibitory activity and good selectivity towards BChE versus AChE. Their binding modes were probed by molecular docking and further validated by molecular dynamics simulation. Kinetic analysis together with molecular modeling studies suggested that these derivatives could target both the catalytic active site (CAS) and peripheral anionic site (PAS) of BChE. In addition, the selected compounds 9 and 23 displayed anti-Aß1-42 aggregation activity in a dose-dependent manner, and they did not show obvious cytotoxicity towards SH-SY5Y neuroblastoma cells. Also, both compounds showed significantly protective activity against Aß1-42-induced toxicity in a SH-SY5Y cell model. The present results provided a new valuable chemical template for the development of selective BChE inhibitors.

Enabling Synthesis of ABBV-2222, A CFTR Corrector for the Treatment of Cystic Fibrosis.

An enabling preclinical synthetic route to cystic fibrosis candidate ABBV-2222 is described. Two stereoselective steps provide access to an aminochroman intermediate with excellent control, and a late-stage demethylation/difluoromethylation sequence provides efficient access to the target molecule.

A Focused Library of NO-Donor Compounds with Potent Antiproliferative Activity Based on Green Multicomponent Reactions.

Cancer is the second leading cause of death worldwide. Herein, a strategy to quickly and efficiently identify novel lead compounds to develop anticancer agents, using green multicomponent reactions followed by antiproliferative activity and structure-activity relationship studies, is described. A second-generation focused library of nitric oxide-releasing compounds was prepared by microwave-assisted Passerini and Ugi reactions. Nearly all compounds displayed potent antiproliferative activities against a panel of human solid tumor cell lines, with 1-phenyl-1-[(tert-butylamino)carbonyl]methyl 3-[(3-phenylsulfonyl-[1,2,5]oxadiazol-4-yl N2 -oxide)oxy]benzoate (4 k) and N-[1-(tert-butylaminocarbonyl)-1-phenylmethyl]-N-(4-methylphenyl)-3-(3-phenylsulfonyl-[1,2,5]oxadiazol-4-yl N2 -oxide)oxyphenyl carboxamide (6 d) exhibiting the strongest activity on SW1573 lung cell line (GI50 =110 and 21 nm) with selectivity indices of 70 and 470, respectively. Preliminary mechanistic studies suggest a relationship between NO release and antiproliferative activity. Our strategy allowed the rapid identification of at least two molecules as future candidates for the development of potent antitumor drugs.