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Results for “NICOTINIC ACID”

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At least 919 records · Page 51Linked to original sources
PubMed1989

[Determination of aspirin and nicotinic acid in plasma when used in combination].

An ultraviolet spectrophotometric method has been developed for indirect determination of aspirin (ASA) using the difference between total salicylic acid and free salicylic acid in rabbit plasma. Recoveries of salicylic acid were found to be above 98.4% and the method was linear from 8-160 micrograms with a correlation coefficient of 0.9999. The coefficient of variation was less than 3.85%. Using this method for ASA and Carlson's method for nicotinic acid (NA), the plasma concentrations of these two drugs were determined when they were used iv alone or in combination in rabbits. The results analysed by a micro-computer were fitted to a two compartment open model with first-order elimination. Among the pharmacokinetic parameters of NA, T1/2 (beta) and AUC0-infinity for the group (n = 6) treated with NA 50 mg/kg in combination with ASA 50 mg/kg were 2.3374 h and 361.63 micrograms.h/ml, respectively, both significantly different from those for the group (n = 6) treated with NA 50 mg/kg alone which were 0.9846 h and 157.71 micrograms.h/ml, respectively (p less than 0.01). For ASA, no significant differences were demonstrated. The mechanism and significance of the prolonged T1/2 (beta) of NA were discussed.

Animals↗
PubMed2005

The structure of a eukaryotic nicotinic acid phosphoribosyltransferase reveals structural heterogeneity among type II PRTases.

Nicotinamide adenine dinucleotide (NAD) is an essential cofactor for cellular redox reactions and can act as an important substrate in numerous biological processes. As a result, nature has evolved multiple biosynthetic pathways to meet this high chemical demand. In Saccharomyces cerevisiae, the NAD salvage pathway relies on the activity of nicotinic acid phosphoribosyltransferase (NAPRTase), a member of the phosphoribosyltransferase (PRTase) superfamily. Here, we report the structure of a eukaryotic (yeast) NAPRTase at 1.75 A resolution (locus name: YOR209C, gene name: NPT1). The structure reveals a two-domain fold that resembles the architecture of quinolinic acid phosphoribosyltransferases (QAPRTases), but with completely different dispositions that provide evidence for structural heterogeneity among the Type II PRTases. The identification of a third domain in NAPRTases provides a structural basis and possible mechanism for the functional modulation of this family of enzymes by ATP.

Adenosine Triphosphate↗
PubMed1989

Effect of nicotinic acid on microviscosity in mixed liposomal system of lecithin and sphingomyelin.

In rat liver plasma membrane, the molar ratio of sphingomyelin and phospholipid is approximately 1:4, whereas, the molar ratio of phospholipid and cholesterol is 3:1. Considering this ratio to be typical for a real biological membrane, we have studied the effect of anticholesterol and the vasodialatory drug nicotinic acid (NA) on the fluidity profile of a liposomal system of lipids mixed in this ratio using the fluorescence polarization probe 1,6-diphenyl-1-1,3,5-hexatriene. The study reveals that when NA is added to the aqueous dispersion of the mixed lipid system (molar ratio of lipid:NA, 1:1) it creates a more fluid environment for the probe molecule and modifies the fluidity profile of the cholesterol-incorporated liposomal system by eliminating the effect of cholesterol to some extent. The drug also affects the activation energy of diffusion of this system. These results on fluidity have been compared with those in cases of liposomes of individual lipids. The effect of NA on fluidity may be attributed to a mechanical interaction of the drug molecules with the lipid molecules.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Nutritional status of vitamin A, E, C, B1, B2, B6, nicotinic acid, B12, folate, and beta-carotene in young women.

To investigate the vitamin status of young Japanese women, dietary intakes of vitamin A, E, C, B1, B2, B6, B12, niacin, folate, and beta-carotene were assessed by a 3-d weighed food record in 150 female students aged 21-22. Whole blood levels of vitamin B1, B2, and nicotinic acid, and serum levels of retinol, alpha-tocopherol, vitamin B6, and beta-carotene were determined by HPLC. Vitamin B12 and folate in serum were measured by chemiluminescence immunoassay, and serum vitamin C was done by dinitrophenylhydrazine method. When the 6th revision RDAs for the Japanese (physical activity level 1) were applied, 46.7% of the females showed sufficient intake for vitamin A, 28.7% for E, 80.7%, for B1, 92.7% for B2, 54.7% for B6, 99.3% for niacin, 76.0% for B12, 34.0% for folate, and 54.0% for C. Fifty-nine percent of total vitamin A (microgRE) intakes were derived from beta-carotene. The mean+/- SD of energy intakes was low, 1.572+/-315 kcal. Significant correlations among intakes of energy and all these vitamins were found. Serum folate and ascorbic acid levels in the females with corresponding vitamin intakes above the RDA were significantly higher than in those with intakes below the RDA. There were significant correlations between blood vitamin levels and vitamin intakes in vitamin B12 (r=0.185), folate (r=0.255), vitamin C (r=0.272), and beta-carotene (r=0.319). Mean blood levels of folate, ascorbic acid, vitamin B2, B12, and beta-carotene were higher in the highest quartile of intake than in the lowest. The 95% confidence intervals of blood vitamin levels obtained from the females with sufficient vitamin intakes were nearly equal to those obtained from all subjects. Only a few females (0.7-4.7%) had their blood vitamin levels below the lower limits. Serum alpha-tocopherol levels were significantly correlated with serum levels of retinol, beta-carotene, and vitamin C. This data suggested that young women should increase suitable dietary food intakes in order to maintain good status of vitamin. Moreover, sufficient amount of physical activity would be expected for prevention of excessive energy intake.

Adult↗
PubMed2006

NAADP+ synthesis from cADPRP and nicotinic acid by ADP-ribosyl cyclases.

ADP-ribosyl cyclases (ADPRCs) are present from lower Metazoa to mammals and synthesize the Ca2+-active (di)nucleotides cyclic ADP-ribose (cADPR), NAADP+, and ADP-ribose (ADPR), involved in the regulation of important cellular functions. NAADP+ can be synthesized by ADPRCs from NADP+ through a base-exchange reaction, which substitutes nicotinamide for nicotinic acid (NA). Here we demonstrate that ADPRCs from both lower and higher Metazoa (including human CD38) can also synthesize NAADP+ starting from 2'-phospho-cyclic ADP-ribose (cADPRP) and NA. Comparison, on the two substrates cADPRP and NADP+, of the relative rates of the reactions introducing NA and hydrolyzing/cyclizing the substrate, respectively, indicates that with all ADPRCs tested cADPRP is preferentially transformed into NAADP+, while NADP+ is preferentially cyclized or hydrolyzed to cADPRP/2'-phospho-ADP-ribose. cADPRP was detectable in retinoic acid-differentiated, CD38+ HL-60 cells, but not in undifferentiated, CD38- cells. These results suggest that cADPRP may be a NAADP+ precursor in ADPRC+ cells.

ADP-ribosyl Cyclase↗
PubMed1995

[Modification of pyrimidine nucleosides using nicotinic acid derivatives].

Interaction of nicotinoyl chloride in situ with 2'-deoxyuridine, its 3'-O-acetyl-, or 5'-O-trityl derivatives led to 3'-O-nicotinoyl-, 5'-O-nicotinoyl-, 3',5'-di-O-nicotinoyl-, and N3,3'-di-O-nicotinoyl-2'-deoxyuridine. Similarly, 5'-O-nicotinoyl-6-azauridine resulted from the reaction of 2',3'-O-ethoxymethylidene-6-azauridine followed by the deprotection. Reaction of 5'-amino-5'-deoxy-2',3'-O-ethoxymethylidene-6-azauridine with nicotinic acid in the presence of 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline followed by the cleavage of the 2',3'-O-protecting group gave 5'-deoxy-5'-nicotinamido-6-azauridine. The same compound was obtained from 5'-amino-5'-deoxy-6-azauridine and N-succinimidyl nicotinate. Structures of the compounds obtained were corroborated by 1H NMR spectra. It is shown that 3',5'-di-O-nicotinoyl-2'- deoxyuridine and 5'-deoxy-5'-O-nicotinamido-6-azauridine are cytotoxic toward CaOv cells in vitro (CE50 10(-5) M).

Antineoplastic Agents↗
PubMed2005

Nicotinic acid limitation regulates silencing of Candida adhesins during UTI.

The adherence of Candida glabrata to host cells is mediated, at least in part, by the EPA genes, a family of adhesins encoded at subtelomeric loci, where they are subject to transcriptional silencing. We show that normally silent EPA genes are expressed during murine urinary tract infection (UTI) and that the inducing signal is the limitation of nicotinic acid (NA), a precursor of nicotinamide adenine dinucleotide (NAD+). C. glabrata is an NA auxotroph, and NA-induced EPA expression is likely the result of a reduction in NAD+ availability for the NAD+-dependent histone deacetylase Sir2p. The adaptation of C. glabrata to the host, therefore, involves a loss of metabolic capacity and exploitation of the resulting auxotrophy to signal a particular host environment.

Animals↗
PubMed2006

Unusual sterically controlled regioselective lithiation of 3-bromo-5-(4,4'-dimethyl)oxazolinylpyridine. Straightforward access to highly substituted nicotinic acid derivatives.

[Structure: see text] Lithiation of 5-bromonicotinic acid protected as secondary or tertiary amide as well as (4,4'-dimethyl)oxazoline with lithium amides is reported. The unusual C-2 and C-4 regioselective lithiation of 3-bromo-5-(4,4'-dimethyl)oxazolinylpyridine using LTMP versus LDA was observed, providing a new route to substituted nicotinic acid scaffolds. The methodology was applied to the synthesis of novel C-4 and C-6 arylated 5-bromonicotinic acids.

Lithium↗