Synthesis of 13, 14 These compounds were synthesized according to the literature method Meyer, Taige, Strassner, Antimicrobial assays Antimicrobial activity was determined using the following microorganisms. Screenings for antimicrobial activities were carried out by the agar well diffusion method against test microorganisms Collins et al.
The inoculum suspensions of the tested bacteria and yeasts were prepared from the broth cultures h and the turbidity equivalent adjusted to 0. To test the antimicrobial activity of each unsymmetrically substituted imidazolium salts, Mueller Hinton Agar medium 25 mL was poured into each petri plate and was inoculated with 0. Plates inoculated with E. After incubation, the diameter of the inhibition zone was measured. The minimum inhibitory concentrations MIC were determined for antimicrobial activities by preparing a microdilution broth Jones et al.
All the bacteria were inoculated in the Nutrient Broth and incubated at 0C for 24 h while the yeasts were inoculated in Malt Extract Broth and incubated at 30 0C for 48 h. From the stock solution, two fold serial dilutions of the compounds were employed to determine the MIC ranging from to 0.
As positive controls, Streptomycin I. Ulagay for bacteria and Nystatine NS, Oxoid for yeast were used in the dilution method. The target salts shown in Figure 1 have been obtained by quaternization of 1-substituted imidazole by variously substituted benzyl halides. An adaptation of the Debus method, it is called the Debus-Radziszewski imidazole synthesis.
The starting materials are substituted glyoxal, aldehyde, amine, and ammonia or an ammonium salt. This reaction will give substantial yields only if the 1-vinyltetrazole is made efficiently from an organotin compound , such as 2-tributylstannyltetrazole. Imidazole can also be formed in a vapor-phase reaction. This forms a very pure imidazole product. The reaction has later been expanded to a two-step synthesis in which the aldimine is generated in situ: the Van Leusen Three-Component Reaction vL-3CR.
Biological significance and applications[ edit ] Imidazole is incorporated into many important biological molecules. The most pervasive is the amino acid histidine , which has an imidazole side-chain. Histidine is present in many proteins and enzymes and plays a vital part in the structure and binding functions of hemoglobin.
Imidazole-based histidine compounds play a very important role in intracellular buffering. Histamine can cause urticaria hives when it is produced during allergic reaction. The relationship between histidine and histamine is shown below: One of the applications of imidazole is in the purification of His-tagged proteins in immobilised metal affinity chromatography IMAC.
Imidazole is used to elute tagged proteins bound to nickel ions attached to the surface of beads in the chromatography column.
An excess of imidazole is passed through the column, which displaces the His-tag from nickel coordination, freeing the His-tagged proteins. Imidazole has become an important part of many pharmaceuticals.
Synthetic imidazoles are present in many fungicides and antifungal , antiprotozoal , and antihypertensive medications.
Unlike for the reference drugs Tamoxifen and Paclitaxel, the anticancer activity of acridine imidazolium ions is specific for only selected cancer types. Reasonable fluorescent behaviour of the products provide potential for visualization of the distribution of active drugs in tissue. Introduction Cancer has become a major cause of mortality, leading to an urgent need for more effective anticancer drugs.
Recently several reviews on acridine derivatives have been published, focusing on their therapeutic potential against cancer and bacteria. This is matched by reported bioactivities for imidazole and their derivatives, 13 covering antitumor activity as well.The reaction has later been expanded to a two-step synthesis in which the aldimine is generated in situ: the Van Leusen Three-Component Reaction vL-3CR. Unlike for the reference drugs Tamoxifen and Paclitaxel, the anticancer activity of acridine imidazolium ions is specific for only selected cancer types. Imidazole can also be found in various compounds that are used for photography and electronics. This forms a very pure imidazole product.
As an acid, the pKa of imidazole is
It also serves as a good ligand in various transition metal complexes Navarro, Lippert,
Inhibition zones mm of the compounds were listed in Table I. Imidazole derived NHC precursors are known in the field of organometallic chemistry for more than five decades and the imidazole ring presents a structural fragment that plays an important role in many biological systems such as enzymes, metallo-proteins as well as in natural products and anticancer drugs Jaouen, NMR multiplicities are abbreviated as follows: s, singlet; d, doublet; t, triplet; m, multiplet signal. Reasonable fluorescent behaviour of the products provide potential for visualization of the distribution of active drugs in tissue.
The difference between the imidazoles and the triazoles involves the mechanism of inhibition of the cytochrome P enzyme. Preventing copper corrosion is important, especially in aqueous systems, where the conductivity of the copper decreases due to corrosion. Preparation[ edit ] Imidazole was first reported in by the German-British chemist Heinrich Debus , although various imidazole derivatives had been discovered as early as the s. The basic site is the nitrogen with the lone pair and not bound to hydrogen. After incubation, the diameter of the inhibition zone was measured. In one microwave modification, the reactants are benzil , benzaldehyde and ammonia in glacial acetic acid , forming 2,4,5-triphenylimidazole "lophine".