Zeitschrift Fur Naturforschung Section C-A Journal of Biosciences最新文献

From the CHCl₃-soluble extract of Annona muricata L. (Annonaceae) leaves, one new 3-benzazepine-type alkaloid, anonazepine (1), and four known aporphine-type alkaloids, (+)-laurotetanine (2), (+)-norglaucine (3), (-)-xylopine (4), and lanuginosine (5), were isolated. Except for (-)-xylopine (4), these remaining known alkaloids were first reported in A. muricata. The structures of the isolated alkaloids were established by 1D and 2D NMR spectroscopy and MS, as well as comparison with literature data. The new 3-benzazepine-type alkaloid existed in an inseparable mixture of two equilibrium conformers. Its absolute configuration was determined based on comparing their experimental and calculated ECD data. The anti-inflammatory activity of the isolated alkaloids was investigated, but none of the alkaloids showed a significant result.

The current study describes the chemical identification, antimicrobial, and mosquito larvicidal activities of essential oils from Meistera caudata and Conamomum vietnamense, growing in Vietnam. Essential oils were extracted from the leaves and rhizomes, and characterized by the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. Monoterpenes (33.1-89.2 %) were the main chemical class found in these oils. β-Pinene (30.8 %) and α-pinene (23.8 %) were two major compounds in M. caudata leaf oil. C. vietnamense leaf and rhizome essential oils were dominated by 1,8-cineole (47.9-62.0 %) and limonene (10.3-16.2 %). With the same MIC (minimum inhibitory concentration) value of 25 μg/mL, C. vietnamense leaf and rhizome essential oils strongly inhibited the growth of Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus subtilis ATCC 6501, respectively. For 24 and 48-h treatments, C. vietnamense leaf essential oil strongly controlled the growth of mosquito Aedes aegypti with the respective LC₅₀ values of 7.67 and 6.73 μg/mL, and the respective LC₉₀ values of 13.37 and 10.83 μg/mL. In the same manner, C. vietnamense rhizome essential oil also showed strong mosquito larvicidal activity against Aedes albopictus with the LC₅₀ values of 12.37 and 12.00 μg/mL, and the LC₉₀ values of 20.56 and 18.58 μg/mL, respectively. C. vietnamense essential essential oils containing a high amount of 1,8-cineole are generally better than M. caudata essential essential oils in both two biological assays.

The preparation of a novel 4-methylbenzo[h] cinnolines entity via a three-step synthetic protocol is described. Cyclization of the naphthylamidrazones, in the presence of polyphosphoric acid (PPA), furnishes the respective target benzo[h]cinnolines directly. This one-pot synthesis involves intramolecular Friedel-Crafts acylation followed by instant elimination under heating conditions. It is noteworthy that the yield of the product from this step decreases dramatically if the heating is extended beyond 3 h. The target novel cinnolone derivatives were identified by mass spectrometry and their structures elucidated by spectroscopic techniques. Subsequently, molecular docking was performed to shed light on the putative binding mode of the newly synthesized cinnolines. The docking results indicate that these derivatives are potential inhibitors of tubulin polymerization and the best interaction was achieved with a computational ki = 0.5 nM and posed correctly over the lexibulin.

This study reports the synthesis of seven new 8-amino-7-(aryl/hetaryl)fluoroquinolones and their antibacterial activity against 10 bacteria associated with microbial infections and foodborne illnesses. These fluoroquinolones are prepared via the reactions of selected aryl(hetaryl)boronic acids with ethyl-7chloro-6-fluoro-8-nitroquinolone-3-carboxylate, under Suzuki-Miyaura cross-coupling conditions. Nitro group reduction of the latter resulted in the corresponding 8-aminoquinolone-3-esters which upon hydrolysis formed the respective 8-amino-7-(aryl/hetaryl)-quinolone-3-carboxylic acids. The latter compounds were tested against selected Gram-negative bacteria (Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumonia) and Gram-positive bacteria (Enterococcus feacalis, Listeria monocytogenes, Streptococcus agalactiae, Staphylococcus epidermidis, and Staphylococcus aureus). The tested fluoroquinolones showed a significant antimicrobial activity against most of the tested bacterial strains. The antimicrobial activity of some of the tested compounds were comparable to or higher than a wide range of standard antibiotics including ampicillin, ciprofloxacin, and imipenem. The results highlight the new synthesized 8-amino-7-(aryl/hetaryl)fluroquinolones as promising candidates for new antimicrobial drugs to treat bacterial infections. This study highlights that the newly synthetic 8-amino-7-(aryl/hetaryl)fluroquinolones are promising candidates for new antimicrobial drugs to treat human diseases including foodborne illnesses.

A series of novel 2-(quinolin-2-yl)-spiro[oxindole-3,3'-pyrrolines] were synthesized by one-pot three-component reaction involving dimethyl acetylenedicarboxylate, 1-phenylimidazo[1,5-a]quinoline and N-alkylisatins in chloroform at ∼60 °C for 24 h. Structures of these new spiro derivatives were deduced from HRMS and NMR spectral data. A plausible mechanism for the observed thermodynamic control pathway is presented herewith. Interestingly, the spiro adduct, derived from 5-chloro-1-methylisatin, exhibited excellent antiproliferative activity on MCF7, A549 and Hela human cell lines (IC₅₀ ≃ 7 μM).

A new series of aminoacetylenic nitroimidazole piperazine hybrid compounds were prepared via three-component reaction. Mannich-type reaction was utilized to couple the nitroimidazole containing propargylic moiety with secondary amines and formaldehyde in the presence of Cu (I) catalyst. The newly synthesized molecules 10a-10w, were characterized an ambiguously through NMR and mass spectrometry. The prepared compounds were assessed in vitro for their antibacterial activity against selected gram-positive and gram-negative bacteria. All of the compounds had shown insignificant activities toward gram-negative bacteria. While compounds 10m, 10q, 10s and 10t had shown moderate activities against the gram-positive bacteria Staphylococcus aureus, Bacillus subtilis and against fungi Escherichia coli and Proteus vulgaris.

Model α-chloro-β-nitrothieno[2,3-c]pyridazines incorporating N1-(aryl) entity appended with ortho-methoxycarbonyl or trifluoromethyl group were prepared via intramolecular cyclization of their respective N-arylhydrazone precursors. Interaction of these substrates with N'-(p-fluorophenyl)benzothiohydrazide, in the presence of NEt₃, furnished the respective 1,3,4-thiadiazoline-pyridazine thiolate hybrids that were S-methylated to produce the corresponding "sulfanyl" derivatives. Their structures were deduced from spectral data, and confirmed by single-crystal X-ray diffraction.

Piperazine-tagged imidazole derivatives 3a (symmetrical di-substituted piperazine) and 5-11 were synthesized through the combination of 4-nitroimidazole derivatives with piperazine moiety. The structural characterization was done by different physical and spectral techniques like NMR (¹H and ¹³C) and mass spectrometry. The constituency of compound 3a was confirmed by X-ray structural analyses. All compounds were assessed for their antiproliferative inhibition potency against five human cancer cell lines namely MCF-7, PC3, MDA-231, A549 and Fibro dental. Compound 5 was found to be the most potent anticancer agents against MCF-7 cell line with IC₅₀ values of (1.0 ± 0 µm) and against PC3 with IC₅₀ value of (9.00 ± 0.028 µm). The molecular docking of compound 5 had been studied, and the results revealed that the newly designed 4-nitroimidazole combined with piperazine moiety derivatives bond to the hydrophobic pocket and polar contacts with high affinity.

Four bioactive metabolites; ergosterol (1), peroxy ergosterol (2), α-cyclopiazonic acid (3) and kojic acid (4), were isolated from the fungal sp. Trichoderma viride MM21. Their structures were assigned by cumulative analysis of NMR and mass spectra, and comparison with literature. The antimicrobial activity of the fungus supernatant, mycelial cake, cumulative crude extract and compounds 1-4 was broadly studied against 11 diverse pathogens, revealing auspicious activity results. Based on the molecular docking, ergosterol (1) and peroxy ergosterol (2) were picked up to be computationally tested against topoisomerase IV of Staphylococcus aureus. The nominated enzyme is a possible target for the antibacterial activity of triterpenoidal/steroidal compounds. Compounds 1, 2 showed a deep inserting inside the enzyme groove recording a good binding affinity of -8.1 and -8.4 kcal/mol, respectively. Noteworthy that the antibacterial activity of ergosterol was higher (14-17 mm) than peroxy ergosterol (11-14 mm), although ergosterol formed only one hydrogen bond with the target, while peroxy ergosterol formed three hydrogen bonds. Such higher antibacterial activity of ergosterol may be attributed to its interference with other proteins included in this inhibition. The cytotoxic activity was tested against brine shrimp, revealing 100% mortality for the supernatant, crude extract and whole isolated compounds. Such strong cytotoxicity is attributed most likely to the abundant productivity/concentration of α-cyclopiazonic acid and kojic acid.