Antimicrobial Activities of New Macrocyclic Esters Containing Furan and Thiophene Rings

Abstract

Extended AbstractCyclic polyethers, commonly known as crown ethers, were first synthesized by Pederson in 1967 [1,2]. Crown ethers were the first synthetic molecules which could, by virtue of their ability to assume a conformation resulting in an electronrich cavity, function as macrocyclic hosts, [3] Prior to 1967 host/guest chemistry was restricted to biologically active hosts, with cyclodextrins being the most common. The oxygen atoms have been replaced by sulfur, [4] nitrogen, [5] and the ethyleneoxy units have been interchanged with heterocycle such as pyridine, furan, thiophene.We have recently reported the synthesis of [2+2] condensed cyclic amides and investigated antimicrobial activities of these cycloheterophane amides [6]. As a continuation of this work new heterocyclic macrothioesters which contain furan and thiophene rings were synthesized with 2-mercaptoethyl ether and MICs were determined by the microbroth dilution method using the National Committee for Clinical Laboratory Standards (NCCLS) recommendations [7]. For this purposes Gram -Escherichia coli ATCC 25922, Gram -Escherichia coli 0157H7, Gram + Staphylococcus aureus ATCC 25923, Gram -Listeria monocytogenes ATCC 19115, Gram -Salmonella thphimurium ATCC 14028, Gram + Bacillus cereus ATCC 11778 and also Candida albicansATCC 10231 as yeast were used for the investigation of the antimicrobial activity. For comparing antimicrobial activity, Ampicillin, Gentamycin and Amphotericin were used.Serial dilutions were made that furnished a concentration range from 16 to 256 μg/ml. Minimum inhibitory values (MIC) were determined at 600nm. As a result macro thioesters showed strong activity againstS. Aureus, Bacillus cereus, Candida albicans and Listeria. After having these results we havesynthesized new heterocyclic macroesters with 2,2′-thiodiethanol and we are studying the antimicrobial activities of the compounds.

Synthesis of 2-Ethylhexyl 5-Bromothiophene-2-Carboxylates; Antibacterial Activities against Salmonella Typhi, Validation via Docking Studies, Pharmacokinetics, and Structural Features Determination through DFT

“…XDR S. Typhi is resistant to medically important antibiotics including chloramphenicol, ampicillin, co-trimoxazole, ceftriaxone, and ciprofloxacin, and is sensitive to azithromycin, imipenem, and meropenem. The agar well diffusion method was used to test the thiophene derivatives 4A-4G for in vitro antibacterial activity compared to Salmonella Typhi at five dissimilar concentrations (10,20,30,40, and 50 mg/well) based on the results of molecular docking and DFT. By associating the regular diameter of the bacterial growth inhibition zones surrounding the well (measured in mm) with ciprofloxacin (an antibiotic control), it is possible to assess how susceptible certain microbial isolates are to the test chemicals.…”

“…In brief, Mueller-Hinton agar plates were streaked with 0.5 McFarland bacterial suspension, and a sterile 6 mm cork borer was used to create wells in separate plates. Using sterile pipettes, dif-ferent concentrations of the compounds 4A-4G in each 100 DMSO solvent (10,20,30,40, and 50 mg/mL) were independently put in the wells. The plates were then retained overnight for aerobic incubation at 37 °C.…”

“…Thiophenes are a class of sulfur-based heterocyclic compounds that may have therapeutic effects on a variety of infections. Thiophene-based compounds can be made quickly and have biological functions, which has provoked a lot of interest in their synthesis [4][5][6][7][8][9][10][11][12][13]. Their biological outcomes comprise antifungal, antiviral, antibacterial, anti-inflammatory, and cytotoxic characteristics [14,15].…”