Lactate hydroxy acid

Chemical Designations - Synonyms Ethyl Alpha-hydroxy-propionate Ethyl 2-hydroxypropanoate Ethyl DL-Lactate Lactic Acid Ethyl Ester Chemical Formula CH3CHOHCOOC2H3 Observable Characteristics - Physical State (as shipped) Liquid Color Colorless Odor Mild characteristic. 

In a related approach, Adam ef al. used glycolate oxidase with D-lactate dehydrogenase for the deracemization of a wide range of racemic a-hydroxy acids (20) (Figure 5.13) [23]. 

Adam, W., Lazarus, M., Saha-Moller, C.R. and Schreier, P. (1998) Quantitative transformation of racemic 2-hydroxy acids into (R)-2-hydroxy acids by enantioselective oxidation with glycolate oxidase and subsequent reduction of 2-keto acids with D-lactate dehydrogenase. Tetrahedron Asymmetry, 9 (2), 351-355. 

S)-(-)-Ethyl lactate Lactic acid, ethyl ester, L- (8) Propanoic acid, 2-hydroxy-, ethyl ester, (S)- (9) (687-47-8)... 

This enzyme [EC 1.1.99.6] catalyzes the reaction of (R)-lactate with an acceptor to produce pyruvate and a reduced acceptor. The enzyme, which requires FAD and a zinc ion, will utilize a number of (R)-2-hydroxy acids as substrates. 

This enzyme [EC 5.1.2.1], also referred to as lacticora-cemase and hydroxy acid racemase, catalyzes the interconversion of (5)-lactate and (i )-lactate. 

CYTOCHROME P-450 REDUCTASE DIHYDROOROTATE OXIDASE FMN ADENYLYLTRANSFERASE GLUTAMATE SYNTHASE GLYCOLATE OXIDASE (S)-2-HYDROXY-ACID OXIDASE l-LACTATE DEHYDROGENASE (CYTOCHROME)... 

ETHYL LACTATE Lactic Acid, ethyl ester, Ethyl 2-hydroxy-proploate, Ethyl 2-hydroxy-propanoate Combustible Liquid, III 2 2 0... 

Similarly to the case of amino acids, hydroxy acids can also be deracemized by combining an enantioselective oxidation with a non-enantioselective reduction with sodium borohydride. For example, the group of Soda has reported the transformation of DL-lactate into D-lactate in >99% (Scheme 5.38) [78]. 

Table I lists the refined values of the log formation constants for Ni(II) and L-serine and L-threonine. Under the conditions of the study where the ligands may be present either as the zwitterion or the anion, both forms could interact with the Ni(II). The zwitterions, HL, are similar to the aliphatic hydroxy acids, and the anions of such compounds possess a carboxylate group through which unindentate complexes may be formed—e.g., Ni(II)-lactate, log K 2.216 (18). The values for the protonated Ni(II)-threonine and Ni(II)-serine complexes in this study were comparable (Table I).

Hydroxy and Amino Acids. Reduction of 2-oxoacids with NADH. catalyzed by lactate dehydrogenase, is an established method for the preparation of hontochiral ur-hydroxy acids of both S and R configurations. The enzyme is found in all higher organisms and can be easily isolated from a variety of mammalian and bacterial sources. 

Enzyme-catalyzed syntheses of enantiomeric pure hydroxy acids use lactate dehydrogenases (LDH E.C. 1.1.1.27) or hydroxyisocaproate dehydrogenases (HicDH). Both kinds of enzymes are available as D- or L-specific catalysts. L-specific [5, 6] LDHs as well as D-specific [7-10] LDHs favorably catalyze the reduction of pyruvate, HicDHs (and mandelate dehydrogenase, too) convert keto acids with longer aliphatic or aromatic side chains. These enzymes can be isolated from Lactobacillus strains [11-14]. 

The use of aqueous chiral lanthanide complexes in the determination of the enantiomeric purity of chiral a-hydroxy acids has also been assessed by H NMR [21], Large lanthanide induced shifts, chemical shift non-equivalence and an apparent absence of kinetic resolution in complex formation is observed upon addition of racemic lactate to [Yb.3a]3+ (Figure 1). The lactate CH3 resonances are clearly resolved for the... 

X-Ray crystallographic analysis used alongside solution phase techniques such as NMR, is invaluable in the design of selective anion receptors as it can be used to define the solid-state structure of the anion-bound complex. Several X-ray structures of anion-bound complexes of [Ln.la]3+ have been defined recently (acetate, lactate, citrate, alanine, glycine, methionine, serine and threonine) [8,21,22], The complexes adopt a monocapped square antiprismatic structure with one base comprising of four N atoms of the macrocycle and the other base containing three O atoms of the pendent arms. The latter base is completed by a carboxylate O donor of the anion, which binds in a bidentate manner and simultaneously caps this base by O (acetate), OH (a-hydroxy acids) or NH2 (a-amino acids). The nature of the donor atom in the capping (or axial) position correlates well with the observed NMR shift in the solution phase. 

There are very many enantiomerically pure starting materials available cheaply from nature. The amino acids are varied in structure and the hydroxy acids such as malic acid 11 and lactic acid 13 provide another resource. We shall give just one example of this kind of synthesis. Ethyl lactate 14 can be converted into the mesylate (a leaving group like tosylate) 15 and then reduced to the... 

Enantiomerically enriched a-hydroxy acetals are interesting synthons and can be transformed to a variety of chiral building blocks such as 1,2-diols, a-hydroxy acids, or 1,2-amino alcohols (Scheme 18.4). Whereas the oxidation to (f )-ethyl lactate was rather difficult and required the protection of the OH group, the reduction could be easily accomplished after hydrolysis of the acetal. No significant racemization was observed. With a boronic acid derivative and a secondary amine as described by Petasis and Zavialov,24 it was also possible to synthesize an amino alcohol with high diastereoselectivity. 

There are two lactate dehydrogenases (LdHs) with different stereospecificities that have been very useful for the preparation of chiral 2-hydroxy acids.33 4 L-LdH (E.C. 1.1.1.27) and D-LdH (E.C. 1.1.1.28) are obtained from various microbial sources (Table 19.1). Along with hydroxyisocaproate... 

As described above, early in wound healing, there is an increase in HA. This transient increase correlates with hypoxia and the production of lactate that follows the compromised local blood supply. A cause and effect was documented in this laboratory between enhanced levels of HA and lactate production.251,252 Lactic acid is an alpha-hydroxy acid, the latter being a frequent additive to skin preparations. Enhanced HA deposition and the attendant water-of-hydration may be a common mechanism for the enhanced appearance of skin when such lotions are used. 

S)-Sulcatol cannot be made by this route, because the L-sugar is unavailable (even D-deoxyri-bose is quite expensive), so an alternative synthesis was needed that could be adapted to give either isomer. The solution is to go back to another hydroxy-acid, ethyl lactate, which is more widely available as its (5)-enantiomer, but which can be converted simply to either enantiomer of a key epoxide intermediate. From (S)-ethyl lactate, protection of the alcohol, reduction of the ester, and tosylation allows ring closure to one enantiomer of the epoxide tosylation of the secondary hydroxyl group followed by reduction and ring closure gives the other enantiomer. 

With inexpensive hydroxy acids as chiral tethers, only two stereochemic pure head-to-head 118 and head-to-tail 119 cycloadducts were isolated from lactate 117. With the corresponding dihydropyranone 120, the facial select decreased and head-to-head cycloadducts were obtained as a mixture of t diastereoisomers 121 and 122 (Scheme 27). I... 

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