Synthesis, antimicrobial, antiquorum-sensing, antitumor and cytotoxic activities of new series of cyclopenta(hepta)[ b ]thiophene and fused cyclohepta[ b ]thiophene analogs

Targeting the quorum sensing network in Acinetobacter baumannii: A dual target structure-based approach for the development of novel antimicrobials

Acinetobacter baumannii, a notorious opportunistic pathogen, has emerged as a significant threat to global healthcare due to its alarming rise in antibiotic resistance. This ability of this bacterium to develop and disseminate resistance mechanisms, facilitated by quorum-sensing (QS) systems, has rendered conventional antibiotic treatments ineffective. QS systems, particularly the AbaI and AbaR proteins, play a crucial role in its virulence and antibiotic resistance. AbaI, an autoinducer synthase, produces signalling molecules, while AbaR, a transcriptional regulator, controls gene expression in response to these signals. This study employed in-silico design and screening to identify potential dual-targeting inhibitors against proteins AbaI and AbaR, the key players in QS. Compounds from an open source library (Life Chemicals) was screened using Lipinski's filters, molecular docking (fast rank and exhaustive). The resulted six hit compounds were subsequently performed with molecular dynamics simulations (MDS). The MDS analysis reveals that among the six top hits, hit 2 demonstrated potent dual-targeting inhibition and favourable pharmacokinetic properties, displaying selectivity against the proteins. These findings offer a novel therapeutic agent to disrupt QS in A. baumannii, to develop effective treatments against antibiotic-resistant A. baumannii, addressing a critical health concern and improving patient outcomes.

Evaluation of antibacterial and anticancer properties of secondary metabolites isolated from soil Bacillus spp focusing on two strains of Bacillus licheniformis and Bacillus siamensis

BACKGROUND

Bacillus strains are well recognized for their inherent production of bioactive compounds that exhibit antibacterial and anticancer properties. This study aims to evaluate the antimicrobial and anticancer effects of the secondary metabolite isolated from Bacillus licheniformis and Bacillus siamensis strain.

MATERIAL AND METHOD

We developed and purified a new soil-derived Bacillus strain to study its metabolites on cancer cells and bacteria. After evaluating the antimicrobial effects of the selected strains' secondary metabolites by well diffusion, growth conditions and temperature optimised using liquid-liquid extraction, secondary metabolites isolated, and active compounds identified using GC-MS. Evaluation of PC-3 and HPrEpC cytotoxicity. AV/PI staining and comet assay assessed necrosis and apoptosis. Real-time PCR measured apoptotic gene expression. Finally, the scratch test measured cell movement.

RESULTS

Bacillus strain metabolites exhibit dual-purpose antimicrobial and anticancer properties. Bacillus licheniformis isolate 56 and S2-G12 isolate 60 demonstrated the greatest antibacterial activity. Among all Bacillus isolates, isolates 56 (Bacillus licheniformis) and 60 (Bacillus siamensis strain) had the highest antibacterial activity. Crude extracts obtained from strains 56 and 60 decreased PC-3 cell viability in a dose-dependent manner. At 200 µg/mL, the survival rate of cells treated with strain 56 and 60 crude extract was 23% and 25%, respectively (p < 0.001). The treatment of PC-3 cells with strains 56 and 60 crude extract led to considerable apoptosis (46.2% and 50.09%, respectively) compared to the control group. After treatment with the crude extract from strains 56 and 60 at an IC50 concentration, a significant number of PC-3 cells showed comet formation, indicating DNA fragmentation. Metabolites extracted from strain 56 and 60 enhanced caspase 3, caspase 8, and Bax genes expression and reduced Bcl-2 expression (p < 0.001). Cell migration was also prevented.

CONCLUSION

Our findings show that the secondary metabolites of B. licheniformis and B. siamensis have antibiotic and anticancer properties. However in vivo studies are necessary to confirm these findings.

Quorum sensing inhibitors as Therapeutics: Bacterial biofilm inhibition

The overuse and inappropriate use of antibiotics to treat bacterial infections has led to the development of multiple drug resistant strains. Biofilm is a complex microorganism aggregation defined by the presence of a dynamic, sticky, and protective extracellular matrix made of polysaccharides, proteins, and nucleic acids. The infectious diseases are caused by bacteria that flourish within quorum sensing (QS) mediated biofilms. Efforts to disrupt biofilms have enabled the identification of bioactive molecules produced by prokaryotes and eukaryotes. The QS system is quenched predominantly by these molecules. The phenomenon is also termed as quorum sensing (QS). Both synthetic and natural substances have been discovered to be useful in QS. This review describes natural and synthetic quorum sensing inhibitors (QSIs) with the potential to treat bacterial infections. It includes the discussion on quorum sensing, mechanism of quorum sensing, effect of substituents on the activity. These discoveries could result in effective therapies using far lower dosages of medications, particularly antibiotics, are currently needed.

A Brominated Furanone Inhibits Pseudomonas aeruginosa Quorum Sensing and Type III Secretion, Attenuating Its Virulence in a Murine Cutaneous Abscess Model

Quorum sensing (QS) and type III secretion systems (T3SSs) are among the most attractive anti-virulence targets for combating multidrug-resistant pathogenic bacteria. Some halogenated furanones reduce QS-associated virulence, but their role in T3SS inhibition remains unclear. This study aimed to assess the inhibition of these two systems on Pseudomonas aeruginosa virulence. The halogenated furanones (Z)-4-bromo-5-(bromomethylene)-2(5H) (C-30) and 5-(dibromomethylene)-2(5H) (named hereafter GBr) were synthesized, and their ability to inhibit the secretion of type III exoenzymes and QS-controlled virulence factors was analyzed in P. aeruginosa PA14 and two clinical isolates. Furthermore, their ability to prevent bacterial establishment was determined in a murine cutaneous abscess model. The GBr furanone reduced pyocyanin production, biofilm formation, and swarming motility in the same manner or more effectively than C-30. Moreover, both furanones inhibited the secretion of ExoS, ExoT, or ExoU effectors in all tested strains. The administration of GBr (25 and 50 µM) to CD1 mice infected with the PA14 strain significantly decreased necrosis formation in the inoculation zone and the systemic spread of bacteria more efficiently than C-30 (50 µM). Molecular docking analysis suggested that the gem position of bromine in GBr increases its affinity for the active site of the QS LasR regulator. Overall, our findings showed that the GBr furanone displayed efficient multi-target properties that may favor the development of more effective anti-virulence therapies.

Acetylcholinesterase inhibitors from Conocarpus lancifolius Engl. (Combretaceae)

Conocarpus lancifolius Engl. (Combretaceae) has several potential health-promoting effects, such as antidiabetic, antimicrobial, antioxidant, and cytotoxic effects. Phytochemical study of the ethyl acetate fraction of the leaf extract of this plant led to the isolation and identification of eight compounds viz., gallic acid (1), dihydromyricetin (2), myricetin (3), daucosterol (4), syringetin 3-O-β-D-glucopyranoside (5), quercetin 3-O-β-D-glucoside (6), gallocatechin (7), and (-)-epigallocatechin-3-O-gallate (8). Their acetylcholinesterase (AChE) in vitro and in silico inhibitory activities were evaluated. Daucosterol (4) showed the highest activity (IC₅₀ 0.316 μM) which was further validated by the superimposed docking orientation with the co-crystallized inhibitor, donepezil.

Pyrazolopyridine: An efficient pharmacophore in recent drug design and development

Among the various heterocyclic molecules employed for drug design and discovery, pyrazolopyridine is one of the promising pharmacophores. Pyrazolopyridine is a result of fusion of pyrazole and pyridine rings. The potent pharmacology of pyrazolopyridine may be the synergistic effect of pyrazole and pyridine moieties in a single framework. It has been used in drug design of a wide range of diseases such as anticancer, antimicrobial, anti-inflammatory, and neuroprotection. Cancer has become a common disease among elderly people now a days that might be because of genetic inheritance to some extent, carcinogens, pollution, and some infectious diseases. Whatever may be the reason, cancer is one of the major causes of deaths worldwide. In addition, over-usage and improper usage of antibiotics have led to drug resistance of microbes. Further, inflammation is a cause of various diseases such as arthritis, and other diseases. Thus, proinflammatory kinases are considered as primary target for inhibition of inflammation. In view of this, a work that compiles potent pharmacology of recently reported pyrazolopyridine analogs has been planned. The review is aimed to discuss pharmacology in brief along with structure-activity relationship (SAR). The review would emphasize importance of pyrazolopyridines in future drug design and discovery and may help in design of potent pharmacological agents.

Thiophene-containing compounds with antimicrobial activity

Thiophene, as a member of the group of five-membered heterocycles containing one heteroatom, is one of the simplest heterocyclic systems. Many synthetic strategies allow the accurate positioning of various functionalities onto the thiophene ring. This review provides a comprehensive, systematic and detailed account of the developments in the field of antimicrobial compounds featuring at least one thiophene ring in their structure, over the last decade.

Next generation quorum sensing inhibitors: Accounts on structure activity relationship studies and biological activities

Bacterial resistance is a growing threat which represents major scourge throughout the world. The suitable way to control the present critical situation of antimicrobial resistance would be to develop entirely novel strategies to fight antibiotic resistant pathogens such as quorum sensing (QS) inhibitors or its combination with antibiotics. Anti QS agents can eliminate the QS signals and put the barrier in bio-film formation, consequently, bacterial virulence will be reduced without causing drug-resistance to the pathogens. Among the various anti QS agents identified, especially those of natural origin, furanones or acylatedhomoserine lactones (AHLs) are most popular. Semi-synthetic and synthetic inhibitors have shown greatest potential and have inspired chemists to design synthetically modified QS inhibitors with lactone moiety. This review focuses on anti QS agents (bio-film inhibitors) of both natural and synthetic origins. Further, the synthesis, structure activity relationship and anti QS activity covering literature from 2015 till March 2020 has been discussed.

Discovery of New Apoptosis-Inducing Agents for Breast Cancer Based on Ethyl 2-Amino-4,5,6,7-Tetra Hydrobenzo[b]Thiophene-3-Carboxylate: Synthesis, In Vitro, and In Vivo Activity Evaluation

A multicomponent synthesis was empolyed for the synthesis of ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate 1. An interesting cyclization was obtained when the amino-ester 1 reacted with ethyl isothiocyanate to give the benzo[4,5]thieno[2,3-d][1,3]thiazin-4-one 3. Acylation of the amino-ester 1 with chloroacetyl chloride in DCM and Et₃N afforded the acylated ester 4. The amino-ester 1 was cyclized to benzo[4,5]thieno[2,3-d]pyrimidin-4(3H)-one 8, which was reacted with some alkylating agents leading to alkylation at nitrogen 9–13. Hydrazide 14 was utilized as a synthon for the synthesis of the derivatives 15–19. Chloro-thieno[2,3-d]pyrimidine 20 was synthesized and reacted with the hydrazine hydrate to afford the hydrazino derivative 21, which was used as a scaffold for getting the derivatives 22–28. Nucleophilic substitution reactions were used for getting the compounds 29–35 from chloro-thieno[2,3-d]pyrimidine 20. In the way of anticancer therapeutics development, the requisite compounds were assessed for their cytotoxicity in vitro against MCF-7 and HepG-2 cancer cell lines. Twelve compounds showed an interesting antiproliferative potential with IC₅₀ from 23.2 to 95.9 µM. The flow cytometric analysis results showed that hit 4 induces the apoptosis in MCF-7 cells with a significant 26.86% reduction in cell viability. The in vivo study revealed a significant decrease in the solid tumor mass (26.6%) upon treatment with compound 4. Moreover, in silico study as an agonist for inhibitors of JAK2 and prediction study determined their binding energies and predicted their physicochemical properties and drug-likeness scores.

5-Nitro-Thiophene-Thiosemicarbazone Derivatives Present Antitumor Activity Mediated by Apoptosis and DNA Intercalation

BACKGROUND

Considering the need for the development of new antitumor drugs, associated with the great antitumor potential of thiophene and thiosemicarbazonic derivatives, in this work we promote molecular hybridization approach to synthesize new compounds with increased anticancer activity.

OBJECTIVE

Investigate the antitumor activity and their likely mechanisms of action of a series of N-substituted 2-(5-nitro-thiophene)-thiosemicarbazone derivatives.

METHODS

Methods were performed in vitro (cytotoxicity, cell cycle progression, morphological analysis, mitochondrial membrane potential evaluation and topoisomerase assay), spectroscopic (DNA interaction studies), and in silico studies (docking and molecular modelling).

RESULTS

Most of the compounds presented significant inhibitory activity; the NCIH-292 cell line was the most resistant, and the HL-60 cell line was the most sensitive. The most promising compound was LNN-05 with IC50 values ranging from 0.5 to 1.9 µg.mL-1. The in vitro studies revealed that LNN-05 was able to depolarize (dose-dependently) the mitochondrial membrane, induceG1 phase cell cycle arrest noticeably, promote morphological cell changes associated with apoptosis in chronic human myelocytic leukaemia (K-562) cells, and presented no topoisomerase II inhibition. Spectroscopic UV-vis and molecular fluorescence studies showed that LNN compounds interact with ctDNA forming supramolecular complexes. Intercalation between nitrogenous bases was revealed through KI quenching and competitive ethidium bromide assays. Docking and Molecular Dynamics suggested that 5-nitro-thiophene-thiosemicarbazone compounds interact against the larger DNA groove, and corroborating the spectroscopic results, may assume an intercalating interaction mode.

CONCLUSION

Our findings highlight 5-nitro-thiophene-thiosemicarbazone derivatives, especially LNN-05, as a promising new class of compounds for further studies to provide new anticancer therapies.

Synthesis and antifungal activities of novel thiophene-based stilbene derivatives bearing an 1,3,4-oxadiazole unit

BACKGROUND

Natural stilbenes (especially resveratrol and its derivatives) are well-known phytoalexins that are active against many plant diseases. However, oxidative degradation and low bioavailability limit their exogenous application as fungicides on crops. In this study, a new class of resveratrol-inspired thiophene-based stilbene derivatives bearing an 1,3,4-oxadiazole unit was synthesized and the derivatives' antifungal activities against phytopathogenic fungi were investigated.

RESULTS

The results revealed that compounds 5h and 5j exhibited improved antifungal activity against Botrytis cinerea with median effective concentrations (EC₅₀ ) of 168.5 and 155.4 µg mL^-1 , respectively, which were superior to the EC₅₀ of resveratrol (263.1 µg mL^-1 ). Compound 5j was shown to effectively control disease development in B. cinerea-infected tomatoes in vivo. Notably, considerably abnormal mycelial morphology and increased cell membrane conductivity were observed in the presence of compound 5j.

CONCLUSION

A new class of thiophene-containing stilbene derivatives was designed and synthesized. Bioassay results showed that compound 5j exhibited promising antifungal activity, suggesting practical potential for fungal disease control. © 2018 Society of Chemical Industry.

Synthesis and in vitro antitumor evaluation of some new thiophenes and thieno[2,3-d]pyrimidine derivatives

New thiophene (2-13) and thienopyrimidine (15-27) derivatives have been synthesized. Twenty three compounds were screened against five cell lines namely; hepatocellular carcinoma (liver) HepG-2, epidermoid carcinoma (larynx) Hep-2, mammary gland (breast) MCF-7, human prostate cancer PC-3 and epithelioid cervix carcinoma HeLa. The results revealed that compounds 15,16,17,24 and 25 showed the highest antitumor activity against all tested cell lines compared to Doxorubicin. In order to explain the expected mode of action of the observed anticancer activity, compounds 15,16,17,24 and 25 were selected to screen their DNA binding affinity and enzyme inhibitory activity against DNA polymerase, thymidylate synthase and tyrosine kinase. The results revealed that the tested compounds showed good DNA binding affinity as well as good inhibitory activity against the three enzymes which might explain the observed anticancer activity of the target compounds.

Synthesis and Biological Evaluation of Azamacrolide Comprising the Triazole Moiety as Quorum Sensing Inhibitors

Novel azamacrolides comprising the triazole moiety were synthesized and evaluated for their quorum sensing inhibitor activities on the Agrobacterium tumefaciens. It was found that the inhibition rate of compound Z12-3 at 200 mg/L (0.45 mM) can reach 67%. The potential binding modes between these molecules and the TraR QS receptor was performed by molecular docking. The results showed that the two nitrogen atoms in the triazole ring of Z12-3 formed hydrogen bonds with GLN-2, and the carbonyl group (C=O) in the amide formed hydrogen bonds with water. It was worth noting that the carbonyl group on the macrolides formed hydrogen bonds with the G-106 base in the DNA. These azamacrolides may block quorum sensing expression through key amino acid residues or DNA bases in the TraR QS receptor by hydrogen-bonded.