Imidazole-lactic acid

Interactions with Histidine. Imidazole lactic acid and imidazole acetic acid were identified as breakdown products when histidine was reacted with methyl linoleate, methyl linoleate hydroperoxide or hexanal for 3 weeks at 25°C and 51°C (33). It was postulated that these compounds were formed via free radical reactions. Two other products were also produced which yielded histidine upon acid hydrolysis. These were thought to be Schiff s base compounds arising... 

A significant increase in the measured COj concentration was observed after the addition of 10 mmol/1 of a-keto-isovaleric acid (148% increase from baseline), a-keto-isocaproic acid (120%), phenylacetic acid (100%), DL-a-keto-P-methyl-A-valeric acid (100%), homogentisinic acid (50%), P-phenylpyruvic acid (45%), hydroxyphenyl acetic acid (32%), propionic acid (25%), ace-toacetic acid (25%), hydroxyphenyl pyruvate acid (23%), and 20 mmol/1 of hydroxyphenyl lactid acid (65%) or salicylic acid (76%). A significant decrease was observed after the addition of 20 mmol/1 of ascorbic acid (33%), DL- -hydroxybutyric acid (25%) or imidazole lactic acid (25%). No effect after the addition of 10 mmol/1 of imidazole-4-acetic acid, methylmalonic acid, 5-hy-droxyindole acetic acid or 20 mmol/1 arginosuccinic acid, Z.-(+)-hydroxybu-tyric acid (E525). 

Histidine with peroxidizing lipid was altered both at the a-carbon and the imidazole side chain (23, 35). Histamine, imidazole acetic acid and imidazole lactic acid evidently... 

The general procedure used in these studies is to trace-label samples of the protein with H-FDNB at several pH-values in the presence of N-acetyl-histidine or imidazole lactic acid as internal standard. The reaction mixture is then made chemically homogeneous by fully reacting with unlabelled or " C-FDNB. In the case of proteins containing more than one histidine residue, peptides are isolated so than an unequivocal assignment of parameters can be made. For proteins containing a solitary histidine residue, imidazolyl-DNP-histidine is isolated after acid hydrolysis. The internal standard is purified separately and the data from scintillation counting is substituted into Equations (1) or (2) to derive rate constants. 

Fig. 5. Br0nsted plot for a series of imidazole compounds, and the histidine residue of lysozyme, a-lytic protease, and S.G. trypsin. The data for hydroxymethylimidazole (1), imidazole (2), a-N-acetylhistidine (3), L-jJ-imidazole lactic acid (4), and imidazole acetic acid (5) are taken from Reference 6, and the line is a linear regression on these data. The parameters for a-lytic protease ( ), S.G. trypsin ( ), and lysozyme (O) are those used to draw the solid lines of Figures 2, 3, and 4, respectively.

Fanfois et al. studied the optimization of lactic acid and 18-crown-6 as complexing agents. She found that 0.5 mM 18-crown-6 in a 10 mM imidazole buffer (pH 4.5) could resolve sodium from lead as well as ammonium from potassium cations. 

The glyoxalase system is able to convert a-oxoaldehydes into the corresponding a-hydroxyacids, a reaction that lowers oxidative stress. Glyoxalase I (EC 4.4.1.5) mimetic activity has been associated with imidazole derivatives, such as histidine and camosine, and their activity in liberating lactic acid from. S -lactoylglutathionc has been confirmed.613 However, mammalian tissue displays about 4000 times this activity. 

An acidic side-chain in imidazole derivatives produces a form in which the imidazole ting is protonated. This is exemplified in (A)-2-hydroxy-3-(lf/-imidazol-5-yl)propanoic acid hydrate 143, which has a fully extended lactic acid side-chain oriented nearly perpendicular to the imidazole plane. The imidazole ring is protonated, and the carbox-ylate group deprotonated, presenting a zwitterionic structure (Scheme 37) <1999AXC217>. 

The topical cream contains metronidazole USP at a concentration of 7.5 mg per gram (0.75%) in an emollient cream consisting of emulsifying wax, sorbitol solution, glycerin, isopropyl palmitate, benzyl alcohol, lactic acid or sodium hydroxide to adjust pH, and purified water. Metronidazole is a member of the imidazole class of antibacterial agents and is classified therapeutically as an antiprotozoal and antibacterial agent. Chemically, metronidazole... 

Histidine, histidinol, histamine, urocanic acid, and imidazole-pyruvic, -acetic, and -lactic acids were recovered from rumen fluid and separated on an aminopropyl column (Jl = 220 nm). Elution was complete in 25 min using a 21/79 water (67 mM K2HPO4 at pH 6.45)7(90/10 acetonitrile/water) mobile phase [1430]. Excellent resolution was achieved and peak shapes were excellent except for a very broad imidazolepyruvic acid peak. Decreasing pH increased retention for the analytes. The authors also noted that frequent rinsing of the system with phosphate buffer solution only was needed. A linear range of 1-500 pM along with detection limits of 0.8-5 pM (analyte dependent) were reported. 

Muramic acid has been determined quantitatively by a procedure that involves its degradation to acetaldehyde via lactic acid. Acetaldehyde was measured spectrophotometrically, and other components present in hydrolysates of bacterial cell walls did not interfere with the determination. The analysis of natural and synthetic N- and O-acylated sialic acids by g.l.c. of the TMS ethers has been described. The 0-acyl groups were not lost when iV-trimethylsilyl-imidazole was used as the silylating reagent. A quantitative determination of neuraminic acid by g.l.c.-m.s. (using multiple ion-detection) has been reported. A modified periodate-resorcinol procedure, which avoids extraction of the... 

Aminium lactates, such as piperazinium dUactate, imidazole lactate and hexamethylenediamine dilactate, are applied as intermediates for the production of polylactic acid (Kamm et al. 2000) and for the manufacture of high purity lactic acid (Kamm et al. 1999). Aminium lactates can be applied directly as constituents of pharmaceutical and cosmetic products as well. Piperazine lactate... 

CE has been widely used for the analysis of metal ions generally with indirect UV detection. A recent volume of J. Chromatography (201 has covered developments and applications. Typically a small amine such as imidazole or benzylamine is added to the buffer to provide the background UV absorbance signal. Low-pH buffers are normally employed to suppress EOF flow and enhance resolution. Selectivity of metal ion separations can be modified (21 ( by the addition of small oiganic acids such as lactic or formic acid. 

---