Antihypernociceptive effects of Petersianthus macrocarpus stem bark on neuropathic pain induced by chronic constriction injury in rats.

Petersianthus macrocarpus (Lecythidaceae) stem bark is traditionally used in West and Central Africa for the treatment of boils and pain. The present study examined the chemical composition of the aqueous and methanolic stem bark extracts of P. macrocarpus by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) . Their antinociceptive effect was evaluated using chronic constriction injury (CCI)-induced neuropathic pain in a rat model. On the ninth day post-surgery, the pain perception (allodynia and hyperalgesia) of the animals was assessed after the administration of aqueous and methanolic extracts at the doses of 100 and 200 mg/kg. In addition, the effect of the extracts was evaluated on nitric oxide activity and on the expression of pro-inflammatory cytokines (TNF-α, IL-1ß, and NF-κB). The LC-ESI-MS analysis revealed the presence of ellagic acid as the major constituent in the methanol extract. Both extracts at the employed doses (100 and 200 mg/kg), significantly (p < 0.01 and p < 0.001) reduced the spontaneous pain, tactile and cold allodynia, and mechanical hyperalgesia. The methanolic extract used at the dose of 200 mg/kg significantly reduced the nitric oxide level (p < 0.001) and the gene expression levels of NF-κB (p < 0.05) and TNF-α (p < 0.01) in the brain. These data may indicate that stem bark extracts of P. macrocarpus possess a potent anti-hypernociceptive effect on CCI neuropathic pain. The inhibition of the nitric oxide pathway as well as the reduction in NF-κB and TNF-α gene expression in the brain may at least partially contribute to this effect. The results further support the use of this plant by traditional healers in pain conditions.

Dibenzofuran, dibenzothiophene and N-methyl carbazole tethered 2-aminothiazoles and their cinnamamides as potent inhibitors of Mycobacterium tuberculosis.

Herein described the design, synthesis and antitubercular evaluation of novel series of dibenzofuran, dibenzothiophene and N-methyl carbazole tethered 2-aminothiazoles and their cinnamamide analogs. One pot condensation of N-methyl carbazole, dibenzofuran and dibenzothiophene methyl ketones with thiourea in the presence of Iodine and CuO gave respective 2-aminothiazoles 4-6 in very good yields. Aminothiazoles were further coupled with substituted cinnamic acids using acid-amine coupling conditions to give desired cinnamamide analogs 8a-e, 9a-e and 10a-e. All the newly synthesized compounds were fully characterized by their NMR and mass spectral analysis. In vitro screening of new derivatives against Mycobacterium tuberculosis H37Rv (Mtb) resulted 8c, 10d and 10e (MIC: 0.78 µg/mL) and 2-aminothiazoles 5 and 6 (MIC: 1.56 µg/mL) as potent compounds with lower cytotoxicity profile.

Inhibition of lipopolysaccharide (LPS)-induced neuroinflammatory response by polysaccharide fractions of Khaya grandifoliola (C.D.C.) stem bark, Cryptolepis sanguinolenta (Lindl.) Schltr and Cymbopogon citratus Stapf leaves in raw 264.7 macrophages and U87 glioblastoma cells.

BACKGROUND: Khaya grandifoliola (C.D.C.) stem bark, Cymbopogon citratus (Stapf) and Cryptolepis sanguinolenta (Lindl.) Schltr leaves are used in Cameroonian traditional medicine for the treatment of inflammatory diseases. Several studies have been performed on the biological activities of secondary metabolites extracted from these plants. However, to the best of our knowledge, the anti-neuro inflammatory and protective roles of the polysaccharides of these three plants have not yet been elucidated. This study aimed at investigating potential use of K. grandifoliola, C. sanguinolenta and C. citratus polysaccharides in the prevention of chronic inflammation. METHODS: Firstly, the composition of polysaccharide fractions isolated from K. grandifoliola stem bark (KGF), C. sanguinolenta (CSF) and C. citratus (CCF) leaves was assessed. Secondly, the cytotoxicity was evaluated on Raw 264.7 macrophages and U87-MG glioblastoma cell lines by the MTT assay. This was followed by the in vitro evaluation of the ability of KGF, CSF and CCF to inhibit lipopolysaccharides (LPS) induced overproduction of various pro-inflammatory mediators (NO, ROS and IL1ß, TNFα, IL6, NF-kB cytokines). This was done in Raw 264.7 and U87-MG cells. Finally, the in vitro protective effect of KGF, CSF and CCF against LPS-induced toxicity in the U87-MG cells was evaluated. RESULTS: CCF was shown to mostly contain sugar and no polyphenol while KGP and CSP contained very few amounts of these metabolites (≤ 2%). The three polysaccharide fractions were non-toxic up to 100 µg.mL- 1. All the polysaccharides at 10 µg/mL inhibited NO production, but only KGF and CCF at 12.5 µg/mL down-regulated LPS-induced ROS overproduction. Finally, 100 µg/mL LPS reduced 50% of U87 cell viability, and pre-treatment with the three polysaccharides significantly increased the proliferation. CONCLUSION: These results suggest that the polysaccharides of K. grandifoliola, C. citratus and C. sanguinolenta could be beneficial in preventing/treating neurodegenerative diseases in which neuroinflammation is part of the pathophysiology.

Depletion of M. tuberculosis GlmU from Infected Murine Lungs Effects the Clearance of the Pathogen.

M. tuberculosis N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmUMtb) is a bi-functional enzyme engaged in the synthesis of two metabolic intermediates N-acetylglucosamine-1-phosphate (GlcNAc-1-P) and UDP-GlcNAc, catalyzed by the C- and N-terminal domains respectively. UDP-GlcNAc is a key metabolite essential for the synthesis of peptidoglycan, disaccharide linker, arabinogalactan and mycothiols. While glmUMtb was predicted to be an essential gene, till date the role of GlmUMtb in modulating the in vitro growth of Mtb or its role in survival of pathogen ex vivo / in vivo have not been deciphered. Here we present the results of a comprehensive study dissecting the role of GlmUMtb in arbitrating the survival of the pathogen both in vitro and in vivo. We find that absence of GlmUMtb leads to extensive perturbation of bacterial morphology and substantial reduction in cell wall thickness under normoxic as well as hypoxic conditions. Complementation studies show that the acetyl- and uridyl- transferase activities of GlmUMtb are independently essential for bacterial survival in vitro, and GlmUMtb is also found to be essential for mycobacterial survival in THP-1 cells as well as in guinea pigs. Depletion of GlmUMtb from infected murine lungs, four weeks post infection, led to significant reduction in the bacillary load. The administration of Oxa33, a novel oxazolidine derivative that specifically inhibits GlmUMtb, to infected mice resulted in significant decrease in the bacillary load. Thus our study establishes GlmUMtb as a strong candidate for intervention measures against established tuberculosis infections.

Bis-spirochromanones as potent inhibitors of Mycobacterium tuberculosis: synthesis and biological evaluation.

On the basis of reported antimycobacterial property of chroman-4-one pharmacophore, a series of chemically modified bis-spirochromanones were synthesized starting from 2-hydroxyacetophenone and 1,4-dioxaspiro[4.5] decan-8-one using a Kabbe condensation approach. The synthesized bis-spirochromanones were established based on their spectral data and X-ray crystal structure of 6e. All synthesized compounds were evaluated against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain, finding that some products exhibited good antimycobacterial activity with minimum inhibitory concentration as low as [Formula: see text]. Docking studies were carried out to identify the binding interactions of compounds II, 6a and 6n with FtsZ. Compounds exhibiting good in vitro potency in the MTB MIC assay were further evaluated for toxicity using the HEK cell line.

Click-based synthesis and antitubercular evaluation of novel dibenzo[b,d]thiophene-1,2,3-triazoles with piperidine, piperazine, morpholine and thiomorpholine appendages.

A series of novel piperidine, piperazine, morpholine and thiomorpholine appended dibenzo[b,d]thiophene-1,2,3-triazoles were designed and synthesized utilizing azide-alkyne click chemistry in the penultimate step. The required azide building block 6a-e was synthesized from commercial dibenzo[b,d]thiophene in good yields following five step reaction sequence. All the new analogues 8a-f, 9a-f, 10a-f, 11a-f &12a-f were characterized by their NMR and mass spectral analysis. Screening all thirty new compounds for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, resulted 8a, 8f and 11e as potent analogues with MIC 0.78µg/mL, 0.78µg/mL & 1.56µg/mL, respectively, and has shown lower cytotoxicity. Interestingly, all six piperazine appended dibenzo[b,d]thiophene-1,2,3-triazoles 11a-f exhibited Mtb inhibition activity with MIC 1.56-12.5µg/mL. To some extent, the data observed here indicated Mycobacterium tuberculosis inhibition among the appendages is in the order, piperazine>thiomorpholine>morpholine.

Click-based synthesis and antitubercular evaluation of dibenzofuran tethered thiazolyl-1,2,3-triazolyl acetamides.

A series of novel dibenzofuran tethered thiazolyl-1,2,3-triazolyl acetamides, designed by assembling antitubercular pharmacophoric fragments, dibenzofuran, 2-aminothiazole and substituted triazoles in one molecular architecture, were evaluated against Mycobacterium tuberculosis. The new analogues 6a-p accomplished in four step synthetic sequence utilizing click chemistry in the penultimate step, was fully characterized by their NMR and mass spectral data. Among the compounds 6a-p screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, three compounds 6j (MIC: 1.56µg/mL); 6a and 6p (MIC: 3.13µg/mL) was found to be most active and exhibited lower cytotoxicity. Among these three, 6j could be a candidate to consider as a drug like hit analogue for further development.

Design, development of new synthetic methodology, and biological evaluation of substituted quinolines as new anti-tubercular leads.

Two series of quinoline-based compounds were designed, synthesised and evaluated for anti-tubercular activity against Mycobacterium tuberculosis H37Rv (ATCC 27294 strain). A new method for Friedländer quinoline synthesis has been developed in water under the catalytic influence of the Brønsted acid surfactant DBSA. Among the forty-two compounds tested for anti-TB activity, twenty-three compounds exhibited significant activity against the growth of M. tuberculosis (MIC 0.02-6.25µg/mL). In particular, the compounds 3b and 3c displayed excellent anti-TB activity with MIC values of 0.2 and 0.39µg/mL, respectively, and are more potent than the standard drugs E, Cfx and Z that are clinically used to treat TB. The cytotoxicity of the compounds with MIC ⩽6.25µg/mL was evaluated against Human Embryonic Kidney 293T cell lines and all of the active compounds were found to be nontoxic (<50% inhibition). The results suggest that the synthesised substituted quinolines are promising leads for development of new drug to treat TB.

Synthesis and antitubercular evaluation of novel dibenzo[b,d]thiophene tethered imidazo[1,2-a]pyridine-3-carboxamides.

A series of novel dibenzo[b,d]thiophene tethered imidazo[1,2-a]pyridine carboxamides 7a-s were designed and synthesized. The required building block, 2-dibenzo[b,d]thiophenyl imidazo[1,2-a]pyridine carboxylic acid (5) was synthesized from commercial dibenzo[b,d]thiophene in good yields following five-step reaction sequence. The desired carboxamides 7a-s was prepared through coupling of acid 5 with various benzyl amines. All the new analogues 7a-s was characterized by their NMR and mass spectral analysis. Among nineteen new compounds 7a-s screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, three compounds 7k (MIC: 0.78µg/mL); 7e and 7n (MIC: 1.56µg/mL) were identified as potent analogues with low cytotoxicity. The results reported here will help global efforts for identification of potential lead antimycobacterial agents.

Synthesis, biological evaluation and structure-activity relationship of 2-styrylquinazolones as anti-tubercular agents.

2-Styrylquinazolones are reported as a novel class of potent anti-mycobacterial agents. Forty-six target compounds have been synthesized using one pot reaction involving isatoic anhydride, amine, and triethyl orthoacetate followed by aldehyde to construct the 2-styrylquinazolone scaffold. The anti-mycobacterial potency of the compounds was determined against H37Rv strain. Twenty-six compounds exhibited anti-Mtb activity in the range of 0.40-6.25µg/mL. Three compounds 8c, 8d and 8ab showed MIC of 0.78µg/mL and were found to be non-toxic (<50% inhibition at 50µg/mL) to HEK 293T cell lines with the therapeutic index >64. The most potent compound 8ar showed MIC of 0.40µg/mL with the therapeutic index >125. An early structure activity relationship for this class of compounds has been established. The computational studies indicate the possibility of these compounds binding to the penicillin binding proteins (PBPs).

Energy-Based Pharmacophore and Three-Dimensional Quantitative Structure--Activity Relationship (3D-QSAR) Modeling Combined with Virtual Screening To Identify Novel Small-Molecule Inhibitors of Silent Mating-Type Information Regulation 2 Homologue 1 (SIRT1).

Silent mating-type information regulation 2 homologue 1 (SIRT1), being the homologous enzyme of silent information regulator-2 gene in yeast, has multifaceted functions. It deacetylates a wide range of histone and nonhistone proteins; hence, it has good therapeutic importance. SIRT1 was believed to be overexpressed in many cancers (prostate, colon) and inflammatory disorders (rheumatoid arthritis). Hence, designing inhibitors against SIRT1 could be considered valuable. Both structure-based and ligand-based drug design strategies were employed to design novel inhibitors utilizing high-throughput virtual screening of chemical databases. An energy-based pharmacophore was generated using the crystal structure of SIRT1 bound with a small molecule inhibitor and compared with a ligand-based pharmacophore model that showed four similar features. A three-dimensional quantitative structure-activity relationship (3D-QSAR) model was developed and validated to be employed in the virtual screening protocol. Among the designed compounds, Lead 17 emerged as a promising SIRT1 inhibitor with IC50 of 4.34 µM and, at nanomolar concentration (360 nM), attenuated the proliferation of prostate cancer cells (LnCAP). In addition, Lead 17 significantly reduced production of reactive oxygen species, thereby reducing pro inflammatory cytokines such as IL6 and TNF-α. Furthermore, the anti-inflammatory potential of the compound was ascertained using an animal paw inflammation model induced by carrageenan. Thus, the identified SIRT1 inhibitors could be considered as potent leads to treat both cancer and inflammation.

Development of acridine derivatives as selective Mycobacterium tuberculosis DNA gyrase inhibitors.

In this study we have designed p-phenylene diamine linked acridine derivative from our earlier reported quinoline-aminopiperidine hybrid MTB DNA gyrase inhibitors with aiming more potency and less cardiotoxicity. We synthesized thirty six compounds using four step synthesis from 2-chloro benzoic acid. Among them compound 4-chloro-N-(4-((2-methylacridin-9-yl)amino)phenyl)benzenesulphonamide (6) was found to be more potent with MTB DNA gyrase super coiling IC50 of 5.21±0.51µM; MTB MIC of 6.59µM and no zHERG cardiotoxicity at 30µM and 11.78% inhibition at 50µM against mouse macrophage cell line RAW 264.7.

Design, synthesis and biological evaluation of imidazo[2,1-b]thiazole and benzo[d]imidazo[2,1-b]thiazole derivatives as Mycobacterium tuberculosis pantothenate synthetase inhibitors.

In the present study, we have designed imidazo[2,1-b]thiazole and benzo[d]imidazo[2,1-b]thiazole derivatives from earlier reported imidazo[1,2-a]pyridine based Mycobacterium tuberculosis (MTB) pantothenate synthetase (PS) inhibitors. We synthesized thirty compounds and they were evaluated for MTB PS inhibition study, in vitro anti-TB activities against replicative and non-replicative MTB, in vivo activity using Mycobacterium marinum infected Zebra fish and cytotoxicity against RAW 264.7 cell line. Among them compound 2-methyl-N'-(4-phenoxybenzoyl)benzo[d]imidazo[2,1-b]thiazole-3-carbohydrazide (5bc) emerged as potent compound active against MTB PS with IC50 of 0.53±0.13 µM, MIC of 3.53 µM, 2.1 log reduction against nutrient starved MTB, with 33% cytotoxicity at 50 µM. It also showed 1.5 log reduction of M. marinum load in Zebra fish at 10mg/kg.

Anti-tubercular activities of 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4-amine analogues endowed with high activity toward non-replicative Mycobacterium tuberculosis.

Thirty three derivatives of 2-substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4-amine analogues were synthesized by molecular modification of a reported antimycobacterial molecule (GSK163574A). Compounds were evaluated in vitro against actively replicative and nutrient starved non-replicative Mycobacterium tuberculosis (MTB), enzymatic screening and cytotoxicity against RAW 264.7 cell line. Among the compounds, 2-ethyl-N-phenethyl-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4-amine (5c) was found to be the most active compound against non-replicative MTB with 2.7 log reduction of bacteria at 10µg/mL and was more potent than isoniazid (1.2 log reduction) and rifampicin (2.0 log reduction) at same dose level. Compound 5c also showed activity against MTB alanine dehydrogenase enzyme with IC50 of 1.82±0.42µM and showed 25% cytotoxicity against RAW 264.7 cell line at 50µg/mL.

Replacement of cardiotoxic aminopiperidine linker with piperazine moiety reduces cardiotoxicity? Mycobacterium tuberculosis novel bacterial topoisomerase inhibitors.

Recently numerous non-fluoroquinolone-based bacterial type II topoisomerase inhibitors from both the GyrA and GyrB classes have been reported as antibacterial agents. Inhibitors of the GyrA class include aminopiperidine-based novel bacterial type II topoisomerase inhibitors (NBTIs). However, inhibition of the cardiac ion channel remains a serious liability for the aminopiperidine based NBTIs. In this paper we replaced central aminopiperidine linker with piperazine moiety and tested for its biological activity. We developed a series of twenty four compounds with a piperazine linker 1-(2-(piperazin-1-yl)ethyl)-1,5-naphthyridin-2(1H)-one, by following a multistep protocol. Among them compound 4-(2-(7-methoxy-2-oxo-1,5-naphthyridin-1(2H)-yl)ethyl)-N-(4-nitrophenyl)piperazine-1-carboxamide (11) was the most promising inhibitor with Mycobacterium tuberculosis (MTB) DNA gyrase enzyme supercoiling IC50 of 0.29±0.22µM, with a good MTB MIC of 3.45µM. These kind of compounds retains good potency and showed reduced cardiotoxicity compared to aminopiperidines.

Design and development of new class of Mycobacterium tuberculosisl-alanine dehydrogenase inhibitors.

Mycobacterium tuberculosisl-alanine dehydrogenase (MTB l-AlaDH) is one of the important drug targets for treating latent/persistent tuberculosis. In this study we used crystal structure of the MTB l-AlaDH bound with cofactor NAD(+) as a structural framework for virtual screening of our in-house database to identified new classes of l-AlaDH inhibitor. We identified azetidine-2,4-dicarboxamide derivative as one of the potent inhibitor with IC50 of 9.22±0.72µM. Further lead optimization by synthesis leads to compound 1-(isonicotinamido)-N(2),N(4)-bis(benzo[d]thiazol-2-yl)azetidine-2,4-dicarboxamide (18) with l-AlaDH IC50 of 3.83±0.12µM, 2.0log reduction in nutrient starved dormant MTB model and MIC of 11.81µM in actively replicative MTB.

Cathepsin D inhibitors as potential therapeutics for breast cancer treatment: Molecular docking and bioevaluation against triple-negative and triple-positive breast cancers.

The main aim of this study was to discover small molecule inhibitors against Cathepsin D (CatD) (EC.3.4.23.5), a clinically proven prognostic marker for breast cancer, and to explore the mechanisms by which CatD could be a useful therapeutic target for triple-positive and triple-negative breast cancers (TPBC & TNBC). The crystal structure of CatD at 2.5 Å resolution (PDB: 1LYB), which was complexed with Pepstatin A, was selected for computer-aided molecular modeling. The methods used in our study were pharmacophore modeling and molecular docking. Virtual screening was performed to identify small molecules from an in-house database and a large commercial chemical library. Cytotoxicity studies were performed on human normal cell line HEK293T and growth inhibition studies on breast adenocarcinoma cell lines, namely MCF-7, MDA-MB-231, SK-BR-3, and MDA-MB-468. Furthermore, RT-PCR analysis, in vitro enzyme assay, and cell cycle analysis ascertained the validity of the selected molecules. A set of 28 molecules was subjected to an in vitro fluorescence-based inhibitory activity assay, and among them six molecules exhibited >50 % inhibition at 25µM. These molecules also exhibited good growth inhibition against TPBC and TNBC cancer types. Among them, molecules 1 and 17 showed single-digit micromolar GI50 values against MCF-7 and MDA-MB-231 cell lines.

Design, Synthesis, and Molecular Docking Studies of a Conjugated Thiadiazole-Thiourea Scaffold as Antituberculosis Agents.

In view of the emergence and frequency of multidrug-resistant and extensively drug-resistant tuberculosis and consequences of acquired resistance to clinically used drugs, we undertook the design and synthesis of novel prototypes that possess the advantage of the two pharmacophores of thiourea and 1,3,4-thiadiazole in a single molecular backbone. Three compounds from our series were distinguished from the others by their promising activity profiles against Mycobacterium tuberculosis strain H37Rv. Compounds 11 and 19 were the most active representatives with minimum inhibitory concentration (MIC) values of 10.96 and 11.48 µM, respectively. Compound 15 was shown to inhibit M. tuberculosis strain H37Rv with an MIC value of 17.81 µM. Cytotoxicity results in the Vero cell line showed that these three derivatives had selectivity indices between 1.8 and 8.7. In order to rationalize the biological results of our compounds, molecular docking studies with the enoyl acyl carrier protein reductase (InhA) of M. tuberculosis were performed and compounds 11, 15, and 19 were found to have good docking scores in the range of -7.12 to -7.83 kcal/mol.

A small molecule inhibitor of dengue virus type 2 protease inhibits the replication of all four dengue virus serotypes in cell culture.

BACKGROUND: Dengue has emerged as the most significant of arboviral diseases in the 21st century. It is endemic to >100 tropical and sub-tropical countries around the world placing an estimated 3.6 billion people at risk. It is caused by four genetically similar but antigenically distinct, serotypes of dengue viruses. There is neither a vaccine to prevent nor a drug to treat dengue infections, at the present time. The major objective of this work was to explore the possibility of identifying a small molecule inhibitor of the dengue virus protease and assessing its ability to suppress viral replication in cultured cells. METHODS: We cloned, expressed and purified recombinant dengue virus type 2 protease. Using an optimized and validated fluorogenic peptide substrate cleavage assay to monitor the activity of this cloned dengue protease we randomly screened ~1000 small molecules from an 'in-house' library to identify potential dengue protease inhibitors. RESULTS: A benzimidazole derivative, named MB21, was found to be the most potent in inhibiting the cloned protease (IC50 = 5.95 µM). In silico docking analysis indicated that MB21 binds to the protease in the vicinity of the active site. Analysis of kinetic parameters of the enzyme reaction suggested that MB21 presumably functions as a mixed type inhibitor. Significantly, this molecule identified as an inhibitor of dengue type 2 protease was also effective in inhibiting each one of the four serotypes of dengue viruses in infected cells in culture, based on analysis of viral antigen synthesis and infectious virus production. Interestingly, MB21 did not manifest any discernible cytotoxicity. CONCLUSIONS: This work strengthens the notion that a single drug molecule can be effective against all four dengue virus serotypes. The molecule MB21 could be a potential candidate for 'hit-to-lead' optimization, and may pave the way towards developing a pan-dengue virus antiviral drug.

Design and synthesis of novel carbazole tethered pyrrole derivatives as potent inhibitors of Mycobacterium tuberculosis.

A series of novel carbazole tethered pyrrole derivatives were designed by coupling core fragments of antitubercular agents, carbazole and substituted pyrrole in single molecular architecture. The synthesis of new analogues was achieved by FeCl3 mediated one pot three component condensation of 2-nitrovinylcarbazoles with aryl or alkyl amines and dimethylacetylene dicarboxylate (DMAD). All the new analogues 5a-l and 6a-l were fully characterized by their NMR and mass spectral data. Among the twenty four new compounds screened for in vitro anti-mycobacterial activity against Mycobacterium tuberculosis H37Rv, dimethyl 1-(4-fluorophenyl)-4-(9-methyl-9H-carbazol-3-yl)-1H-pyrrole-2,3-dicarboxylate (5b) was found to be most active with MIC 3.13µg/mL and has shown low cytotoxicity.