Aminomethyl Benzimidazole Research Articles

Synthesis and characterization of a novel drug-loaded polymer, poly(lactic acid-co-aminomethyl benzimidazole)

Using aminomethyl benzimidazole (AMB) as a model of benzimidazole-type drugs, a potential biodegradable drug-loaded polymer poly(lactic acid-co-aminomethyl benzimidazole) (PLAAMB) is synthesized as designed via direct melt polycondensation starting from d,l-lactic acid (LA). When the molar feed ratio LA/AMB is 40/1, the optimal synthetic conditions, including catalyst type and dosage, polycondensation temperature, and copolymerization time are discussed. After the prepolymerization at 140 °C for 8 h, using 0.4 wt% stannous oxide (SnO) as the catalyst, the melt copolymerization at 160 °C for 6 h gives the copolymer with the biggest weight-average molecular weight (Mw) 5300 Da. The structure and properties of the copolymer are systematically characterized with Fourier transform infrared, 1H NMR, gel permeation chromatography, differential scanning calorimetry, and X-ray diffraction. And the investigations on the influences of different molar feed ratios on the properties of PLAAMB show that, the copolymer PLAAMB with the biggest Mw of 9400 Da can be obtained. After the drug model AMB as a monomer is introduced into polylactic acid during the condensation, the Tg of the obtained PLAAMB is lower than the Tg of homopolymer poly(d,l-lactic acid) (PDLLA). The Mw and crystallinity of PLAAMBs can meet the requirement of drug-loaded polymers in the drug delivery.

Equilibrium Studies of Binary and Mixed-Ligand Complexes of Zinc(II) Involving 2-(Aminomethyl)-Benzimidazole and Some Bio-Relevant Ligands

Binary and mixed-ligand complexes of zinc(II) involving 2-(aminomethyl)-benzimidazole (AMBI) and amino acids, peptides (HL) or DNA constituents have been investigated. Ternary complexes of amino acids or peptides are formed simultaneously. Amino acids form the complex Zn(AMBI)L, whereas amides form two complex species Zn(AMBI)L and Zn(AMBI)(LH−1). The ternary complexes of zinc(II) with AMBI and DNA are formed in a stepwise process, whereby binding of zinc(II) to AMBI is followed by ligation of the DNA constituents. The stability of ternary complexes is quantitatively compared with their corresponding binary complexes in terms of the parameters Δlog10 K, log10 βstat and log10 X. The effect of the side chains of amino acid ligands (ΔR) on complex formation is discussed. The values of Δlog10 K indicated that the ternary complexes containing aromatic amino acids are significantly more stable than the complexes containing alkyl- and hydroxyalkyl-substituted amino acids. This may be taken as evidence for a stacking interaction between the aromatic moiety of AMBI and the aromatic side chains of the bio-active ligands. The concentration distributions of various species formed in solution were also evaluated as a function of the pH.

Synthesis, Solution Equilibria and Antibacterial Activity of Co(II) with 2-(Aminomethyl)-Benzimidazole and Dicarboxylic Acids

Formation equilibria of cobalt(II) complexes of 2-(aminomethyl)-benzimidazole (AMBI) and the ternary complexes Co(AMBI)L (L = aliphatic or aromatic dicarboxylic acids) were investigated in aqueous solutions at 25 °C and 0.1 mol⋅dm−3 ionic strength. Stoichiometry and stability constants are reported for the complexes formed. The speciation of the complexes was resolved. Values of \(\log_{10}\ (K_{\mathrm{Co(AMBI)L}}^{\mathrm{Co(AMBI)}})\) and Δlog 10 K are calculated and discussed. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was examined. The effect of temperature on the dissociation constant of AMBI, CBDCA, and the formation constant of Co(AMBI) and Co(AMBI)-CBDCA complexes was studied and the thermodynamic parameters were calculated. Formation of the metal complexes has been found to be spontaneous, exothermic and entropically favorable. The solid complexes of [Co(AMBI)L] (L = oxalic acid, 1,1-cyclobutanedicarboxylic acid (CBDCAH2) and malonic acid) have been synthesized and characterized by elemental analysis, infrared, spectra, magnetic and conductance measurements. Electronic spectra and μ eff values suggest a tetrahedral geometry for Co(II)-complexes. The isolated metal chelates have been screened for their antibacterial activities and the complexes show a significant antibacterial activity against Pseudomonas fluorescence (Gram −ve) and Bacillus subtilis (Gram +ve). The activity increases at higher concentration of the compounds.

Ternary copper(II) complexes involving 2-(aminomethyl)-benzimidazole and some bio-relevant ligands. Equilibrium studies and kinetics of hydrolysis for glycine methyl ester under complex formation

Formation equilibria of copper(II) complexes of 2-(aminomethyl)-benzimidazole (AMBI) and the ternary complexes Cu(AMBI)L (L = amino acid, amide, dicarboxylic acid or DNA constituents) have been investigated. Ternary complexes of amino acids or amides are formed by a simultaneous mechanism. Amino acids form the complex Cu(AMBI)L, whereas amides form two complex species Cu(AMBI)L and Cu(AMBI)(LH −1). The ternary complexes of copper(II) with AMBI and dicarboxylic acids or DNA units are formed by a stepwise mechanism, whereby binding of copper(II) to AMBI is followed by ligation of the dicarboxylic acids or DNA components. The values of Δ log K indicate that the ternary complexes containing aromatic amino acids are significantly more stable than the complexes containing alkyl- and hydroxyalkyl-substituted amino acids. This may be taken as an evidence for a stacking interaction between the aromatic moiety of AMBI and the aromatic side chains of the bio-active ligands. The solid complexes Cu(AMBI)L where L = 1,1-cyclobutanedicarboxylic acid (CBDCA) and malonic acid were separated and identified by elemental analysis and infrared spectroscopy and magnetic moment. The decomposition course and steps for the isolated complexes were analyzed and the kinetic parameters of the non-isothermal decomposition were calculated. The hydrolysis of glycine methyl ester (MeGly) is catalyzed by the Cu(AMBI) 2+ complex. The kinetic data is fitted assuming that the hydrolysis reaction proceeds in two steps. The first step, involving coordination of the amino acid ester by the amino and carbonyl groups, is followed by rate-determining attack by OH − ion. The second step involves the equilibrium formation of the hydroxo-complex Cu(AMBI)(MeGly)(OH) followed by intramolecular OH − attack.