Mesalazine, often referred to as mesalamine or 5-aminosalicylic acid (5-ASA), and its derivatives are some of the first medications to be approved for treating digestive tract inflammations, including ulcerative colitis and mild to moderate Crohn’s disease. Sulfasalazine, discovered in 1938 for therapeutic use, was the first mesalazine derivative. High yields of four different mesalazine derivatives were synthesized, including two Schiff bases and two azo compounds. The present study involved the synthesis of Schiff bases through the reaction of mesalazine with pyrrole-2-carbaldehyde or indole-2-carbaldehyde, resulting in the formation of 5-(((1H-pyrrol-2-yl)methylene)amino)-2-hydroxybenzoic acid (1) or 5-(((1H-indol-2-yl)methylene)amino)-2hydroxybenzoic acid (2), respectively. The synthesis of azo compounds involved the coupling of mesalazine with sulfamethoxazole or pyridoxine, resulting in the formation of 5-amino-2-hydroxy-3-((4-(N-(5-methylisoxazol-3-yl)sulfamoyl)phenyl)diazenyl)benzoic acid (3) or 2-hydroxy-5-((5-hydroxy-3,4-bis(hydroxymethyl)-6-methylpyridin-2-yl)diazenyl)benzoic acid (4), respectively. The identification of the synthesized compounds was carried out using IR and 1H-NMR spectroscopy. Antibacterial assessment of the synthetic compounds was performed in vitro against gram-negative bacteria (such as Escherichia coli and Pseudomonas aeruginosa) and gram-positive bacteria (Staphylococcus aureus). The antibacterial activity studies demonstrated that against Escherichia coli and Staphylococcus aureus, the Schiff base compounds are more active than azo compounds. Compound 1 showed the highest activity, resulting in a 23 mm inhibition zone against E. coli at 1000 ug/ml. In contrast, the antibacterial activity of compound 2 was observed to be 25 mm against S. aureus at the same highest concentration.
Schiff bases (SB) are an important type of organic compounds and have a wide range of biological activities due to commercial and pharmaceutical trading uses. The different activities of these compounds induced the researchers to synthesized and studied new types of these compounds. Two series of Schiff base derivatives were synthesized by the condensation reactions of substituted aldehydes salicylaldehyde, 4-(N,Ndimethylamino) benzaldehyde or 2,4-dimethoxybenzaldehyde with 2-amino-5-iodobenzoic acid (1:1) or with 3,5- diamenobenzoic acid (1:2) in ethanol absolute as a solvent. Different analytical techniques characterized the structure of the synthesized Schiff bases; for instance, Fourier transform infrared FT-IR and proton nuclear magnetic resonance 1H-NMR. The purity of the synthesized compounds was tested by elemental microanalysis CHN and thin layer chromatography TLC. The structural properties of the studied molecules were investigated theoretically by performing density functional theory (DFT) using the HyperChem software. The lipophilicity of the tested compounds showed that the compounds 2c, 2b, 2a, and 1c have logP values less than (5), 2.90, 3.78, 3.82 and 4.57, respectively, whereas, 1b and 1a have logP values higher than (5), 5.01 and 5.03, respectively. The Mulliken charge distribution showed that the carbonyl oxygen atom of the carboxylic group is more negative (~ - 0.4) as compared to other oxygen atoms (~ -0.3) in all selected compounds. Frontier molecular orbitals energy diagram and their bandgap provided indications about chemical reactivity and kinetic stability of the molecules. The synthesized compounds were tested for antifungal effects against Aspergillus niger and Candida albicans, which indicated that the compounds had good antifungal activity.
Simple and sensitive spectrophotometric method is described for the determination of phenolic compounds in both in pure form and in pharmaceutical preparations. The method is based on the formation of a new ligand from the reaction between 4-aminoantipyrine with phenolic compounds and then reacts with copper (II) to give a colored complex at room temperature. The maximum absorbance of the prepared complexes were measured at 450,500 and 480 nm for pyridoxine, resorcinol and phloroglucinol complexes respectively. Beer’s law was obeyed in the concentration range of 1.5-20, 2.530 and 2.0-25 μg/ml-1, the molar absorptivity values are 2.4778 x 104,1.6740x104 and 1.7001 x 104 L mol−1cm−1, the Sandal sensitivity values are 0.0501x10−3,0.1740x10−3and 0.1228x10−3μg cm−2 for Pyridoxine, resorcinol and phloroglucinol complexes respectively. The correlation coefficients were 0.9999, 0.9998 and 0.9999, the limits of detection(LOD) were 0.47793, 0.15125 and 0.01434μg ml−1, the limits of quantification were (LOQ) 1.4482, 0.45833 and 0.04347 for pyridoxine, resorcinol and phloroglucinol complexes respectively. The stoichiometry of the complexes formed (1:2) was determined by Job’s continuous variations method and molar ratio method. Furthermore the stability constant (K) and Gibbs free energy ΔG) for the complexes were also calculated. The proposed methods were applied successfully for the determination of phenolic compounds in commercial tablets.
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