Nematicidal, larvicidal and antimicrobial activities of some new mannich base imidazole derivatives

Purpose: To synthesize Mannich base imidazole derivatives, and evaluate their antimicrobial, nematicidal and larvicidal properties .Methods: Compounds 1a-g and 2a-g were prepared using a Mannich condensation method. The chemical structures of compounds 2a-g were confirmed by Fourier transform infrared spectroscopy (IR), proton nuclear magnetic resonance (1H-NMR), carbon nuclear magnetic resonance (13C-NMR), and mass spectrometry (MS) and elemental analyses. Compounds 1a-f and 2a-f were screened for antimicrobial properties using an agar diffusion method. The nematicidal activity of the compounds was evaluated against juvenile Meloidogyne javanica as test organism while larvicidal activity was assessed against the urban mosquito, Culex. Quinquefasciatus, using a standard bioassay protocol.Results: Compounds 1b, 1g, 2e and 2g were highly active against a few bacterial organisms compared with the reference antibacterial, ciprofloxacin while the antifungal activity of compound 2d was high compared with the reference, clotrimazole. Compounds 1c, 1e, 1g, and 2e showed high toxicity levels of larvicidal activity based their half maximal lethal dose (LD50) values. Compounds 1d, 1e, 1f, 1g, 2d and 2e were highly toxic to nematodes.Conclusion: Compounds 1b, 1g, 2e and 2g may be useful as lead molecules for the development of new classes of larvicidal, nematicidal and antimicrobial agents

Synthesis and antimicrobial activity of some new pyrrole derivatives

New pyrrole derivatives were synthesized and structures were confirmed by IR, 1H NMR, 13C NMR, mass spectra, and elemental analyses data. The reaction was performed by using ordinary condensation type, which enabled to easy work-up and good yield. Synthesized compounds were screened for antimicrobial activity.KEY WORDS: Pyrrole, 1,3,4-oxadiazol-2-amine, 4H-1,2,4-triazol-3-ol, Cyclization, Antimicrobial activity, Structure activity relationship Bull. Chem. Soc. Ethiop. 2012, 26(3), 429-435.DOI: http://dx.doi.org/10.4314/bcse.v26i3.1

Larvicidal, nematicidal, antifeedant and antifungal, antioxidant activities of Mentha spicata (Lamiaceae) root extracts

Purpose: To evaluate the larvicidal, nematicidal, antifeedant, and antifungal effects of 10 solvent extracts of Mentha spicata root.Methods: Ten solvent extracts were investigated for their total flavonoid and phenolic content and screened for larvicidal, nematicidal, antifeedant, and antifungal activities. The total phenolic content of the extracts was determined using the Folin–Ciocalteu method, while total flavonoid content was determined by aluminium chloride (AlCl3) colorimetric assay. Four solvents extracts were screened for antifungal activity against Aspergillus niger, Candida albicans, recultured Cryptococcus neoformans, and Microsporum audouinii using the agar diffusion method. The nematicidal activity of the compounds was evaluated against the juvenile Meloidogyne javanica organism, while larvicidal properties were evaluated against the urban mosquito Culex quinquefasciatus using a standard bioassay protocol. The antifeedant activity of marine acclimated Oreochromis mossambicus was used for evaluating ichthyotoxic potential.Results: The total flavonoid content in the extracts ranged from 18.5 to 83.4 mg/g, and the amount of free phenolic compounds ranged from 14.7 to 91.9 mg/g of extract powder. The water extract of these plants exhibited significant antioxidant activity and significant levels of phenolics and flavonoids. The water extract exhibited higher larvicidal (LD50 = 11.77 μg/mL), nematicidal (LD50 = 11.78 μg/mL), antifeedant (LD50 > 40 μg/mL), and antifungal activities (minimum inhibitory concentration: 16 μg/mL) against M. audouinii compared with the other extracts.Conclusion: These results show that the water extract of Mentha spicata may be used as a potential natural alternative source of nutritional and pharmaceutical ingredients.Keywords: Mentha spicata, Larvicidal, Nematicidal, Antifeedant and Antifungal activities, Nutritional supplement, Pharmaceutical ingredient

Identification and characterization of antibacterial compound(s) of cockroaches (Periplaneta americana)

Infectious diseases remain a significant threat to human health, contributing to more than 17 million deaths, annually. With the worsening trends of drug resistance, there is a need for newer and more powerful antimicrobial agents. We hypothesized that animals living in polluted environments are potential source of antimicrobials. Under polluted milieus, organisms such as cockroaches encounter different types of microbes, including superbugs. Such creatures survive the onslaught of superbugs and are able to ward off disease by producing antimicrobial substances. Here, we characterized antibacterial properties in extracts of various body organs of cockroaches (Periplaneta americana) and showed potent antibacterial activity in crude brain extract against methicillin-resistant Staphylococcus aureus and neuropathogenic E. coli K1. The size-exclusion spin columns revealed that the active compound(s) are less than 10 kDa in molecular mass. Using cytotoxicity assays, it was observed that pre-treatment of bacteria with lysates inhibited bacteria-mediated host cell cytotoxicity. Using spectra obtained with LC-MS on Agilent 1290 infinity liquid chromatograph, coupled with an Agilent 6460 triple quadruple mass spectrometer, tissues lysates were analyzed. Among hundreds of compounds, only a few homologous compounds were identified that contained isoquinoline group, chromene derivatives, thiazine groups, imidazoles, pyrrole containing analogs, sulfonamides, furanones, flavanones, and known to possess broad-spectrum antimicrobial properties, and possess anti-inflammatory, anti-tumour, and analgesic properties. Further identification, characterization and functional studies using individual compounds can act as a breakthrough in developing novel therapeutics against various pathogens including superbugs

Synthesis and anticancer activity of some new series of 1, 4-dihydropyridine derivatives

1140-1144A series of 1,4-dihydropyridine derivatives 1a-c have been prepared from 4-substituted aromatic aldehyde, ethyl acetoacetate and ammonium hydroxide following Hantzsch method. The compounds 1a-c have been reacted with semicarbazide to give the compounds 2a-c. The compounds 1a-c have been reacted with thiosemicarbazide to give the compounds 3a-c. The structures of synthesized compounds are confirmed by IR, ¹H and ¹³C NMR, mass spectrometry and elemental analyses. The newly synthesized compounds have been screened for preliminary anti-cancer activity against HepG2 (Liver), Hela (Cervical) and MCF-7 (Breast) cancer cells. The compound 2a is highly active against HepG2, MCF-7 and 3a is highly active against Hela (Cervical) and these have been selected for advanced preclinical development

Anti-inflammatory and antimicrobial activities of novel pyrazole analogues

A new sequence of pyrazole derivatives (1–6) was synthesized from condensation technique under utilizing ultrasound irradiation. Synthesized compounds were characterized from IR, 1H NMR, 13C NMR, Mass and elemental analysis. Synthesized compounds (1–6) were screened for antimicrobial activity. Among the compounds 3 (MIC: 0.25 μg/mL) was exceedingly antibacterially active against gram negative bacteria of Escherichia coli and compound 4 (MIC: 0.25 μg/mL) was highly active against gram positive bacteria of Streptococcus epidermidis compared with standard Ciprofloxacin. Compound 2 (MIC: 1 μg/mL) was highly antifungal active against Aspergillus niger proportionate to Clotrimazole. Synthesized compounds (1–6) were screened for anti-inflammatory activity and the compound 2-((5-hydroxy-3-methyl-1H-pyrazol-4-yl)(4-nitrophenyl)methyl)hydrazinecarboxamide (4) was better activity against anti-inflammatory when compared with standard drugs (Diclofenac sodium). Compounds (2, 3 and 4) are the most important molecules and hence the need to develop new drugs of antibacterial, antifungal and anti-inflammatory agents

Antimicrobial and cytotoxic activities of novel pyrimidine-2,4-dione connected with 2H-thiopyran derivatives

Objectives: The purpose of this study is to develop a new pyrimidine-2,4-dione hybrid with 2H-thiopyran molecules as a potential antibacterial and antifungal agents against clinical pathogens that cause infectious diseases, in addition to conducting the cytotoxic screening. Methods: The synthesis of 2H-thiopyran connecting pyrimidine-2,4-dionederivatives was carried out in a medium consisting of water with an Mg(II) acetate catalyst. The antimicrobial activity of all synthesized compounds was tested against Gram-positive (Staphylococcus aureus (ATCC-25923), Enterococcus faecalis (clinical isolate), and Gram-negative (Klebsiella pneumoniae (clinical isolate), Escherichia coli (ATCC-2522), and Pseudomonas aeruginosa) bacteria. Antifungal activity was examined in vitro using Aspergillus niger, Candida albicans, Microsporum audouinii, and Cryptococcus neoformans as test organisms (clinical isolates). Cytotoxic assay was also performed in vitro at various concentrations. Results: The highly active compound in this study was 3-((2,6-di(furan-2-yl)dihydro-2H-thiopyran-4(3H)-ylidene)amino)dihydropyrimidine-2,4(1H,3H)-dione which exhibited the lowest MIC value (8 µg/mL) with broad activity against one Gram-positive and three Gram-negative. The compound, 3-((2,6-di(furan-2-yl)dihydro-2H-thiopyran-4(3H)-ylidene)amino)dihydropyrimidine-2,4(1H,3H)-dione showed least MIC value (MIC: 0.25 µg/mL) against C. albicans. The compound 3-((2,6-bis(4-hydroxyphenyl)dihydro-2H-thiopyran-4(3H)-ylidene)amino)dihydro pyrimidine-2,4(1H,3H)-dione was highly active (GI50 0.03 µm) against HeLa cancer cell lines. Conclusions: The overall results indicated that a successful preparation of a few of the promising molecules, which are antimicrobials well as cytotoxicity has been achieved

Synthesis and Anticonvulsant Activity of a New Series of 1,4-Dihydropyridine Derivatives

A series of 1,4-dihydropyridine derivatives (1a–g) were prepared from three compounds condensation of Hantzsch synthesis. A new series of 2,2’-{[4-(aryl)-2,6-dimethyl-1,4-dihydropyridine-3,5-diyl]dicarbonyl}dihydrazinecarbothioamide (2a-g) were prepared from compounds diethyl 4-(aryl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate (1a-g) reacted with thiosemicarbazide to give the corresponding compounds (2a-g) by hydrazinolysis method. The synthesized compounds were confirmed by IR, 1HNMR, 13CNMR, mass spectral and elemental analyses. The newly synthesized compounds (2a-g) were screened for anticonvulsant activity against in swiss albino rat. The test was evaluated by maximal electrode induced convulsion method. Synthesized compounds were used two (50 and 100 mg/kg) concentrations. Compounds (1a-g) were inactive while compounds (2a-g) have moderate anti-convulsant activity compared with standard phenytoin drug. The compound 2,2’-{[4-(furan-2-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-diyl]dicarbonyl} dihydrazinecarbothioamide (2a) has highly active compared with other compound (2b-2g)

Cytotoxic, larvicidal, nematicidal, and antifeedant activities of piperidin-connected 2-thioxoimidazolidin-4-one derivatives

The objective of this study was to investigate brine shrimp cytotoxicity, larvicidal, nematicidal, and antifeedant activities of novel piperidin-connected 2-thioxo-imidazolidin-4-one derivatives. The activities of target compounds were compared with some naturally occurring (−)-pinidinol, hydantocidin, and positive controls. Target compounds were synthesized via cyclocondensation method. The compounds were synthesized and then characterized by infrared spectroscopy, 1H NMR, 13C NMR, mass spectral, and elemental analyses. Brine shrimp cytotoxicity assay was investigated using freshly hatched, free-swimming nauplii of Artemiasalina. Larvicidal screening was performed against urban mosquito larvae (Culex quinquefasciatus). Nematicidal activity was evaluated using juvenile nematodes of Meloidogyne javanica. Regarding antifeedant activity, marine-acclimated Oreochromis mossambicus fingerlings were used. Compounds 3a-c (piperidin-connected 2-thioxoimidazolidin-4-one) were found to be lethal to the second instar larvae of mosquito, which produced LD50 values of 1.37, 6.66, 6.51 μg/mL, compared to compounds (−) pinidinol and hyantocidin LD50 values of 18.28 and 22.11 μg/mL respectively. Compound 3a-c was found to kill 100% of fish fingerlings within 6 h at 20 µg/mL, with LD50 values of 1.54, 1.79, 1.52 µg/mL, compared to compounds (−) pinidinol and hyantocidin with LD50 values of 10.21 and 21.05 μg/mL respectively. Compound 3c with LD50 value of 1.57 μg/mL demonstrated high nematicidal activity compared to compound 3a, 3b, (−) Pinidinol and Hyantocidin LD50 values of 6.45, 2.42, 14.25, 26.30 μg/mL respectively. Therefore, the 2-thioxoimidazolidin-4-one with piperidin ring showed high potential cytotoxic, larvicidal, nematicidal, and antifeedent activities. Keywords: 2-thioxoimidazolidin-4-one, Brine shrimp cytotoxicity, Larvicidal activity, Nematicidal activity, Antifeedant activit