Phenyllactate

Phenyl-jodidchlorid, n. phenyl iodochloride, -milchsaure, /. phenyllactic acid, -saure, /. phenylic acid (phenol, CeHaOH). -schwefel-saure, /. phenylsulfuric acid, -senfol, n. phenyl mustard oil. -siliciumchlorid, n. trichlorophenylsilane, CaHiSiCla. -verbindung, /. phenyl compound, -wasserstoff, m. phenyl hydride, benzene. 

Two reactions for the production of L-phenylalanine that can be performed particularly well in an enzyme membrane reactor (EMR) are shown in reaction 5 and 6. The recently discovered enzyme phenylalanine dehydrogenase plays an important role. As can be seen, the reactions are coenzyme dependent and the production of L-phenylalanine is by reductive animation of phenylpyruvic add. Electrons can be transported from formic add to phenylpyruvic add so that two substrates have to be used formic add and an a-keto add phenylpyruvic add (reaction 5). Also electrons can be transported from an a-hydroxy add to form phenylpyruvic add which can be aminated so that only one substrate has to be used a-hydroxy acid phenyllactic acid (reaction 6). 

The following chemicals were obtained commercially (Sigma Chemical Co.) and bioassayed with C. album and Amaranthus retroflexus L. (seeds collected in North Carolina in 1980) following identification DL-3-hydroxybutyric acid (DL-3-hydroxy-butyric acid as a Na salt) and L-3-phenyllactic acid (L-2-hydroxy-3-phenyl-propanoic acid). 

Figure 3. The effect of DL-B-hydroxybutyric acid ( HBA) and L-g-phenyllactic acid (BPLA) on C. album hypocotyl length (HL).

Some of the pancreatic enzymes in the lumen include pancreatic amylase, pancreatic lipase, elastase, trypsin, a-chymotrypsin, and carboxypeptidase A. For example, the aspirin derivatives aspirin phenylalanine ethyl ester, aspirin phenyllactic ethyl ester, and aspirin phenylalanine amide have been studied as substrates for carboxypeptidase A [67,68], with the phenylalanine ethyl ester derivative proving to be the best substrate. This study indicated that the carboxypeptidase A may serve as a reconversion site for many drug derivatives. 

In eq. [20] the chemical correlation between (S)-( — )-phenyllactic acid (known absolute configuration) and (- )-epoxychalcone is shown. 

Phenyllactic acid is converted to the (S)-( - )-hydroxyketone via its ester and amide. Reduction of the (- )-epoxychalcone yields the ( + )-rotating a-hydroxyketone. Therefore the configuration of the a-carbon of the epoxy-chalcone must be R. Since epoxychalcones are derived from /rans-chalcones, the configuration of the (3-carbon in the epoxychalcone must be 5, as shown in Figure 12. 

Strom et al have isolated a Lactobacillusplantarum strain (MiLAB 393) with antifungal properties from grass silage. Three antifungal substances produced by the strain have been isolated, that is, cyclo(Phe-Pro), cyclo(Phe- w j-4-OH-Pro), and 3-phenyllactic acid. 

In the tricyclic inhibitor series amidation of benzhydryl ester 81b with phenyllactic acid or mono-ferf-butyl /i-benzylsuccinate gives 395 (92EPP481522) and 396 (95USP5455242), respectively. A similar amidation... 

Table II. Correlation coefficients between growth parameters affected by a-phenyllactic acid and, p-ethoxybenzoic acid in the light...

In individuals with PKU, a secondary, normally little-used pathway of phenylalanine metabolism comes into play. In this pathway phenylalanine undergoes transamination with pyruvate to yield phenylpyruvate (Fig. 18-25). Phenylalanine and phenylpyruvate accumulate in the blood and tissues and are excreted in the urine—hence the name phenylketonuria. Much of the phenylpyruvate, rather than being excreted as such, is either decarboxylated to phenylacetate or reduced to phenyllactate. Phenylacetate imparts a characteristic odor to the urine, which nurses have traditionally used to detect PKU in infants. The accumulation of phenylalanine or its metabolites in early life impairs normal development of the brain, causing severe mental retardation. This may be caused by excess phenylalanine competing with other amino acids for transport across the blood-brain barrier, resulting in a deficit of required metabolites. 

FIGURE 18-25 Alternative pathways for catabolism of phenylalanine in phenylketonuria. In PKU, phenylpyruvate accumulates in the tissues, blood, and urine. The urine may also contain phenylacetate and phenyllactate. 

Correct answer = B. Phenyllactate, phenyl-acetate, and phenylpyruvate, which are not normally produced in significant amounts in the presence of functional phenylalanine hydroxylase, are elevated in PKU, and appear in the urine. In patients with PKU, tyrosine cannot be synthesized from phenylalanine and, hence, becomes essential and must be supplied in the diet Treatment must begin during the first seven to ten days of life to prevent mental retardation. Discontinuance of the phenylalanine-restricted diet before eight years of age is associated with poor performance on IQ tests. Adult PKU patients show deterioration of attention and speed of mental processing after discontinuation of the diet. Life-long restriction of dietary phenylalanine is, therefore, recommended. 

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