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PubMed2006

Color properties of four cyanidin-pyruvic acid adducts.

Four anthocyanin-pyruvic adducts were synthesized through the reaction of cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, cyanidin 3-O-sophoroside, and cyanidin 3-O-sambubioside with pyruvic acid, structurally characterized by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR), and their chromatic properties were studied (pH and SO2 stability assays). Overall, these pigments were shown to have a higher resistance to discoloration toward pH variations and also in the presence of SO2, being that this resistance to discoloration was explained by a higher protection of the chromophore group against the water or bisulfite nucleophilic attack that gives rise to the colorless hemiacetal form. Only slight differences in the protection against the nucleophilic attack of water and bisulfite were found to occur between all of the cyanidin-pyruvic acid adducts studied. Indeed, anthocyanin-pyruvic acid adducts with glucose or sambubiose attached to the 3-O position of the flavylium moiety were shown to have smaller bleaching constants compared with similar pigments that possess a rutinosyl or sophorosyl moiety. The study of the pigments (A-D and cyanidin-3-O-glucoside) color parameters, namely, chroma (C), lightness (L), and the hue angle (h(a,b)), obtained from the CIELAB system, revealed that different patterns of sugars in the anthocyanin-pyruvic acid adduct moiety affected the referred three parameters of color. The loss of saturation (DeltaC < 0) and the increase of lightness (DeltaL > 0) presented by the cyanidin-pyruvic acid adduct solutions at acidic pH values (1.0 and 2.0) showed that they are much less colored than the cyanidin-3-O-glucoside. For higher pH values (5.0 and 7.0), the reverse trend was observed. This means that the cyanidin-pyruvic acid adducts A-D are much more colored than the anthocyanin at these pH values. The higher coloring capacity of these pigments at higher pH values may be an important feature, indicating a putative application of these compounds in food products.

Anthocyanins↗
PubMed1987

Formation of a beta-carboline (1,2,3,4-tetrahydro-1-methyl-beta-carboline-1-carboxylic acid) following intracerebroventricular injection of tryptamine and pyruvic acid.

Tritium labelled 1-carboxy-tetrahydroharman was identified in rat brain following i.c.v.-injection of [3H]tryptamine and pyruvic acid. The animals had been treated with the MAO inhibitor pargyline (40 mg/kg) 30 min before i.c.v. injection. Under these conditions, only trace amounts of [3H]indole acetic acid could be detected in the brain. The formation of 1-CTHH was time-dependent. Five minutes following the i.c.v. injection, approximately 0.45% of the administered tryptamine was converted into 1-CTHH and 23% were still unchanged. The amount of the radioactive 1-CTHH increased slightly within 1 h (0.8%; [3H] tryptamine: 6%). Pretreatment of the rats with high doses of pargyline (75 mg/kg; 90 min before i.c.v. injection) prevented the formation of both [3H]1-CTHH and [3H]indole acetic acid (IAA) suggesting that high doses of pargyline inhibit the formation of 1-CTHH. As control for a possible non-enzymatic formation of 1-CTHH, [3H]tryptamine and various concentrations of pyruvic acid were incubated in phosphate buffer at pH 7.4. 1-CTHH was not detected under these conditions. However, the formation of 1-CTHH was observed at high pyruvic acid concentrations (final concentration = 100 mM) and low pH values (less than pH4). To support the assumption that the observed condensation of both precursors to 1-CTHH occurred intracellularly, the metabolism of tryptamine was studied. Two minutes after i.c.v. injection of [3H]tryptamine approximately 4% of the injected dose remained unchanged and 10% were metabolized to [3H]IAA. These findings suggest a rapid disappearance of [3H]tryptamine from the cerebrospinal fluid as well as a rapid penetration into the cerebral tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Use of p-aminophenyl D and L-lactic acids and p-aminophenyl pyruvic acid as effectors in the affinity chromatography of lactate dehydrogenase.

p-Aminophenyl pyruvic acid and D-p-amino-phenyllactic acid were immobilized on a new synthetic acrylic carrier bearing acylating N-succinimidyl ester groups. The derivatives obtained were used successfully to purify lactate dehydrogenase (LDH) by affinity chromatography, the elution being carried out by means of NADH or preferably L-phenyllactic acid. Moreover, the specific activity of the LDH contained in a human blood serum was increased 270 times, using L-p-aminophenyllactic acid immobilized on a mixed polyacrylic agarose carrier.

Animals↗