Disease relevance of Pyridoxic acid

• The bacterial oxidation of vitamin B6. 4-Pyridoxic acid dehydrogenase: a membrane-bound enzyme from Pseudomonas MA-1 [1].
• Elevated plasma 4-pyridoxic acid in renal insufficiency [2].
• Urinary 4-pyridoxic acid excretion was normal in breast cancer [3].
• During 21 days of pair-feeding against the vitamin B6-deficient diet group, body weight gain, urinary excretion of xanthurenic acid and pyridoxic acid were measured [4].
• It was concluded from this investigation that most patients with urinary calculi had 4-pyridoxic acid excretion and oxalic acid excretion within normal limits [5].

High impact information on Pyridoxic acid

• The values of Vmax/Km and pKm were highest for PLP and 4-pyridoxic acid phosphate and lowest for pyridoxamine phosphate [6].
• At its optimal pH of 8.0-8.6, it catalyzes the oxidation of isopyridoxal (Km = 40 microM, turnover number = 10 s-1 molecule-1) by NAD+ (Km = 40 microM) to a mixture of 5-pyridoxic acid and 5-pyridoxolactone, which are produced in constant ratio throughout the course of the reaction [7].
• Reaction b also is enhanced when the poorly utilized analogues, 3-hydroxy-2-methylpyridine-5-carboxylic acid or NADH, replace 5-pyridoxic acid or NADPH, respectively, as substrates in Reaction a [8].
• This was reflected in the decreased production of 4-pyridoxic acid by the perfused liver from 3.8% to 1.2% of the dose by the addition of erythrocytes to the perfusate [9].
• However, in membrane fractions, oxygen supports 4-pyridoxic acid oxidation via a CN--sensitive electron transport chain, indicating that the dehydrogenase probably is coupled to ATP generation in such preparations [1].

Chemical compound and disease context of Pyridoxic acid

• Chlorite oxidizes PLP to the more fluorescent 4-pyridoxic acid 5'-phosphate, and avoids the toxicity and heating of the cyanide procedure [10].

Biological context of Pyridoxic acid

• The change in isotope abundance of urinary 4-pyridoxic acid following administration of [2H2]PN reflects the kinetics of labelling of the body pools of vitamin B6, and yields, non-invasively, the rate of degradation of glycogen phosphorylase [11].
• To evaluate PN-glucoside bioavailability, the subjects were administered a single oral dose of either deuterium-labeled ([2H2]) PN (Trial 1) or [2H2] PN-glucoside (Trial 2), and the urinary excretion rates of labeled 4-pyridoxic acid (4PA) were measured [12].
• The urinary 4-pyridoxic acid excretion of the DR groups responded to the reduced food intake and were lower at weeks 10 and 20 [13].

Anatomical context of Pyridoxic acid

• No increase was found in SCE frequency when lymphocytes were treated with pyridoxal-5-phosphate (P-5-P) or 4-pyridoxic acid (4-PA) to which vitamin B6 is finally converted [14].
• Detectable metabolites in blood plasma were pyridoxine, pyridoxal 5'-phosphate, pyridoxal and 4-pyridoxic acid [15].

Associations of Pyridoxic acid with other chemical compounds

• After supplementation with pyridoxine hydrochloride, and with PLP, the urinary excretion of 4-pyridoxic acid, which is derived from the degradation of PLP, was higher in patients who showed the least increase in plasma PLP levels [16].
• A comparison of linear regression models that either included or excluded dietary glycosylated vitamin B-6 content indicates that the intake of glycosylated vitamin B-6 had little, if any, effect upon maternal plasma pyridoxal 5'-phosphate concentration and maternal urinary excretion of total vitamin B-6 and 4-pyridoxic acid [17].
• From daily diet records the percentage of the intake of vitamin B6 excreted as urinary 4-pyridoxic acid (4PA) was calculated [18].
• Erythrocyte aspartate aminotransferase, urinary 4-pyridoxic acid excretion, blood (plasma and erythrocytes) and tissue B-6 vitamers were measured [19].
• Vitamin B-6 status was assessed by direct measures [plasma pyridoxal 5'-phosphate (PLP) and urinary 4-pyridoxic acid (4-PA)] and indirect measures [erythrocyte alanine (EALT-AC) and aspartate (EAST-AC) aminotransaminase activity coefficient] [20].

Gene context of Pyridoxic acid

• PLP, pyridoxal (PL) and 4-pyridoxic acid (4-PA) were the major B6 compounds in plasma and the only compounds which increased after supplementation [21].
• Depending on the indicator, between 20% and 70% of the subjects had inadequate values for 4-pyridoxic acid, total vitamin B-6, plasma pyridoxal 5'-phosphate, and erythrocyte alanine aminotransferase percentage stimulation at a vitamin B-6 intake of 1.33 mg/d (0.016 mg vitamin B-6/g protein) [22].
• RESULTS: Renal clearance of 4-pyridoxic acid was 232 +/- 94 mL/min in nonpregnant women, 337 +/- 140 mL/min in pregnant women, and 215 +/- 103 mL/min in lactating healthy women [2].
• The dietary vitamin B-6 to protein ratio of both diets was 0.017 mg/g. Urinary excretions of 4-pyridoxic acid and total vitamin B-6 were significantly lower (P < 0.05) during the high PNG diet period than when the low PNG diet was consumed [23].
• This compound, named tetrahydropentoxyline, is a new type of hydrophilic tetrahydro-beta-carboline, and its elution position was between those of 4-pyridoxic acid and kynurenic acid on C18 reversed-phase HPLC [24].

Analytical, diagnostic and therapeutic context of Pyridoxic acid

• Determination of urinary 4-pyridoxic acid using high performance liquid chromatography [25].
• There was no increase in pyridoxic acid excretion during a second 15-d bed rest study [26].
• The HPLC procedure correlated well (r = 0.94) with a modification of an enzymatic method involving apotryptophanase (Anal Biochem 1972;45:567-76) for measuring plasma pyridoxal phosphate, and also (r = 0.94) with a routine method for determining 4-pyridoxic acid in urine (Clin Chem 1964;10:479-89) [27].

References