In Vitro Assessment of N-Phenyl Imides in the Management of Meloidogyne Incognita

The infestation with root knot nematode Meloidogyne spp. is a key issue in agriculture. Conventional control methods are based on the use of synthetic nematicides, which comes with severe environmental problems. In this study, n-phenyl imide and n-phenyl phthalamic acid were synthesized and reacted independently with Enantia chlorantha crude extract–manganese chloride complex. The effects of the resulting organic compounds were appraised against the root knot nematode Meloidogyne incognita (Kofoid and White 1919) juveniles and eggs in two laboratory experiments. The most active compound was n-phenyl phthalamic acid (PN/TLMA) with 4% egg hatch over a 9-day observation after treatment as against distilled water which recorded 100% egg hatch at 9 days after treatment. n-Phenyl phthalamic acid showed 100% juvenile mortality at 10 days of observation compared to carbofuran dissolved in water (CBFN/water) and carbofuran dissolved in hydroxypropyl-β-cyclodextrin (CBFN/HPCD) while no outstanding (P < 0.05) difference was recorded between the effects of other organic compounds and carbofuran in both solvents. The different rates of treatment applications were not appreciably (P<0.05) dissimilar on percentage juvenile mortality and egg hatch. The nematicidal test results indicated that the synthesized imide compounds with manganese complex moiety are a promising basis for developing new nematicidal compounds with less environmental hazard.

Enhancement of Antibacterial Activity of Paludifilum halophilum and Identification of N-(1-Carboxy-ethyl)-phthalamic Acid as the Main Bioactive Compound

The aim of this study was to determine the combined effect of fermentation parameters and enhance the production of cellular biomass and antibacterial compounds from Paludifilum halophilum SMBg3 using the response surface methodology (RSM). Eight variables were screened to assess the effects of fermentation parameters on growth and metabolite production by Taguchi experimental design. Among these, the initial pH, temperature, and the percentage of MgSO4·7H2O in the medium were found to be most influential. The Box–Behnken design was applied to derive a statistical model for the optimization of these three fermentation parameters. The optimal parameters were initial pH: 8.3, temperature growth: 44°C, and MgSO4·7H2O: 1.6%, respectively. The maximum yield of biomass and metabolite production were, respectively, 11 mg/mL dry weight and 15.5 mm inhibition zone diameter against Salmonella enterica, which were in agreement with predicted values. The bioactive compounds were separated by the thick-layer chromatography technique and analyzed by GC/MS, NMR (1D and 2D), and Fourier-transform infrared spectroscopy (FT-IR). In addition to several fatty acids, N-(1-carboxy-ethyl)-phthalamic acid was identified as the main antibacterial compound. This element exhibited a potent activity against the ciprofloxacin-resistant Salmonella enterica CIP 8039 and Pseudomonas aeruginosa ATCC 9027 with a minimum inhibitory concentration (MIC) value range of 12.5–25 μg/mL. Results demonstrated that P. halophilum strain SMBg3 is a promising resource for novel antibacterial production due to its high-level yield potential and the capacity for large-scale fermentation.

Synthesis, Characterization and Antimicrobial Screening of New Schiff Bases Linked to Phthalimidyl Phenyl Sulfonate Moiety

A series of Schiff bases linked to phthalimidyl phenyl sulfonate moiety have been synthesized via multistep synthesis. The first step involved reaction of phthalic anhydride with aniline producing N-phenyl phthalamic acid which was subsequently dehydrated to the corresponding N-phenyl phthalimide via treatment with acetic anhydride and anhydrous sodium acetate. The synthesized imide was treated with chlorosulfonic acid in the third step producing 4-(N-phthalimidyl) phenyl sulfonyl chloride which was introduced in reaction with 4-hydroxy acetophenone in the fourth step producing 4-[4-(N-phthalimidyl) phenyl sulfonate] acetophenone and this in turn was introduced successfully in condensation reaction with various aromatic primary amines affording the desired new Schiff bases. The newly synthesized compounds were characterized through spectral data including FTIR, 1HNMR and 13CNMR. Antimicrobial activity of the prepared Schiff bases was evaluated against two types of bacteria and one type of fungi and the new Schiff bases were found to exhibit good antimicrobial activity against the tested organisms.

Pseudonodule Formation by Wild-Type and Symbiotic Mutant Medicago truncatula in Response to Auxin Transport Inhibitors

Rhizobium and allied bacteria form symbiotic nitrogen-fixing nodules on legume roots. Plant hormones play key roles in nodule formation. We treated Medicago truncatula roots with auxin transport inhibitors (ATI) N-(1-naphthyl)phthalamic acid (NPA) and 2,3,5-triiodobenzoic acid (TIBA) to induce the formation of pseudonodules. M. truncatula mutants defective for rhizobial Nod factor signal transduction still formed pseudonodules in response to ATI. However, a M. truncatula ethylene-insensitive supernodulator, sickle 1-1, did not form pseudonodules in response to TIBA, suggesting that the ethylene response pathway is involved in ATI-induced pseudonodule formation. We compared the transcriptional responses of M. truncatula roots treated with ATI to roots inoculated with Sinorhizobium meliloti. Some genes showed consistently parallel expression in ATI-induced and Rhizobium-induced nodules. For other genes, the transcriptional response of M. truncatula roots 1 and 7 days after ATI treatment was in the opposite direction to roots treated with S. meliloti; then, by 21 days, the transcriptional patterns for the two conditions became similar. We silenced 17 genes that were upregulated in both ATI and S. meliloti treatments to determine their effect on nodule formation. Some gene-silenced roots showed a decrease in nodulation efficiency, suggesting a role in nodule formation but not in later nodule functions.