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At least 109 records · Page 6Linked to original sources
PubMed1999

The form of nicotine in tobacco. Thermal transfer of nicotine and nicotine acid salts to nicotine in the gas phase.

Thermal transfer to nicotine in the gas phase from neat nicotine, from various nicotine carboxylic acid salts, and from endogenous nicotine in Burley, Bright, and Oriental tobacco samples has been examined by thermogravimetric/differential thermal analysis/mass spectroscopy and evolved gas analysis. Under the conditions used in these studies, the peak transfer temperatures of these substances to nicotine in the gas phase are nicotine and nicotine acetate, both ca. 110-125 degrees C; nicotine malates, ca. 110-210 degrees C for nicotine to malic acid ratios of 1:0.56 and 1:1 and ca. 160-210 degrees C for a nicotine to malic acid ratio of 1:2; (S)-nicotine bis[(2R,3R)-hydrogen tartrate] dihydrate, ca. 195-210 degrees C; and tobacco samples, a range of ca. 160-220 degrees C. These results suggest that nicotine is mostly protonated in tobacco leaf. In all cases, the temperature of the transfer of nicotine to the gas phase was found to be many hundreds of degrees below the temperatures observed around the coal of a burning cigarette (smolder, ca. 500-775 degrees C; dynamic smoking, 600 to over 950 degrees C). Within the narrow zone of a puffing cigarette that encompasses an intermediate temperature range (125-250 degrees C), kinetic data suggest that these temperatures are not sufficient to volatilize significant amounts of nonprotonated nicotine, assuming any exists at all, during the short puff duration (2 s). It is concluded that nonprotonated nicotine and protonated nicotine (salts of nicotine with natural tobacco carboxylic acids) will transfer nicotine to smoke with comparable yields and efficiencies during the smoking process.

Carboxylic Acids↗
PubMed1967

The plasma free fatty acid rebound induced by nicotinic acid.

The time course of the nicotinic acid-induced changes in levels of plasma free fatty acids (FFA) was examined. The plasma FFA response of fasted dogs to graded doses of nicotinic acid was shown to be biphasic: an initial depression of the level of plasma FFA was followed by a rebound elevation to supernormal levels. FFA rebound was not seen after the administration of the nicotinic acid homologue, pyridylacetic acid, or a variety of nicotinic acid metabolities. A similar pattern of FFA response was observed in fasted, normal rats. Adrenalectomy did not abolish the secondary elevation of FFA but did cause a somewhat delayed response. Hypophysectomy modified the time course of the response-the initial FFA decrease was prolonged-and the intensity of the FFA rebound was diminished. No rebound was observed in hypophysectomized, adrenalectomized rats. In normal rats, nicotinic acid caused a significant rise in the level of plasma corticosterone. A normal rebound pattern was observed in thyroidectomized rats. Reserpine, administered on a schedule designed to deplete catecholamine stores, altered the time course of plasma FFA changes only slightly. The results indicate that both the pituitary and adrenal functions are required for the expression of the rebound phenomenon after nicotinic acid administration.

Adrenalectomy↗
PubMed2001

An animal model of nicotinic-acid-induced vasodilation: effect of haloperidol, caffeine and nicotine upon nicotinic acid response.

BACKGROUND: The normal vasodilatory response to ingestion of nicotinic acid (NA) is impaired in some patients with schizophrenia. It is unclear whether the impairment is a feature of the disorder itself or to a confounding factor such as neuroleptics, caffeine or nicotine use. METHODS: To address this question in a controlled manner, we have developed an animal (rat) model of NA-induced vasodilation, in which response is monitored by measuring change in skin temperature. RESULTS: We observed that (i) acute administration of acetylsalicylic acid (100mg/kg), caffeine (2.5mg/kg) and haloperidol (0.1 or 0.5mg/kg) and (ii) chronic administration of haloperidol (0.2mg/kg/day) significantly inhibited NA (30 mg/kg) response, whereas neither acute (0.25mg/kg) or chronic (0.5mg/kg/day for 14 days) administration of nicotine, or chronic administration of caffeine (5mg/kg/day for 14 days) had any significant effect upon NA response. CONCLUSIONS: Our data suggest that at least one drug commonly used to treat schizophrenia (haloperidol) can interfere with the vasodilatory response to NA. Studies using non-medicated patients with schizophrenia are required to determine whether reduced vasodilatory response to NA in schizophrenia is a feature of the disorder or a consequence of treatment.

Animals↗
PubMed1971

Oxidation of nicotinic acid by a Bacillus species: purification and properties of nicotinic acid and 6-hydroxynicotinic acid hydroxylases.

The enzymes of a Bacillus species that hydroxylate nicotinic acid to 6-hydroxynicotinic acid and 6-hydroxynicotinic acid to 2,6-dihydroxynicotinic acid were purified and characterized. The purified enzymes contained approximately two molecules of flavine and eight molecules of iron per molecule of enzyme. The enzymes were large (molecular weight, 400,000 to 450,000) and appeared to consist of subunits.

Ammonium Sulfate↗
PubMed1963

Inhibition on bacteria by 5-fluoronicotinic acid and other analogues of nicotinic acid.

Streightoff, Frank (The Lilly Research Laboratories, Indianapolis, Ind.). Inhibition of bacteria by 5-fluoronicotinic acid and other analogues of nicotinic acid. J. Bacteriol. 85:42-48. 1963.-Several compounds related to 5-fluoronicotinic acid (5-FNA) have been demonstrated to inhibit Streptococcus sp. (Viridans group), Staphylococcus aureus, Escherichia coli, and Lactobacillus plantarum in vitro. The most active compounds were 5-FNA and 5-fluoronicotinamide (5-FNAM). The growth of Streptococcus sp. was inhibited more than 50% by 0.05 mug/ml of 5-FNA or 0.5 mug/ml of 5-FNAM. The inhibition of Streptococcus sp. from 1 part of 5-FNA or 5-FNAM was reversed by 4 and 2 parts of nicotinic acid, respectively. The inhibition of E. coli from 100 parts of 5-FNA or 5-FNAM was reversed by 1 part of nicotinic acid. Inhibitions by most other active compounds could be reversed by nicotinic acid. In experiments with mice, eight compounds related to 5-FNA had activity against Streptococcus pyogenes; 5-FNA, 5-FNAM, and 5-fluoro-N-dimethylaminomethylnicotinamide protected all mice at 83 mg/kg x two treatments subcutaneously. The action of 200 mg/kg x two treatments of 5-FNA was reversed by 20 mg/kg x two treatments of nicotinic acid. The activity of 5-FNA was not increased by modifications at the number 3 or 5 positions on the pyridine ring or by any other structural changes.

Animals↗
PubMed1983

In vivo conversion of tryptophan to nicotinic acid in rats studied by simultaneous incorporation of [3H]-tryptophan and [14C]-nicotinic acid into liver NAD and NADP.

This study was carried out with three groups of weanling rats. One group was fed a high-protein (20%) diet, another group a low-protein (2.5%) diet, the third group a high-protein diet in restricted amounts. After 4 weeks of feeding, rats were injected simultaneously with L-[G-3H]-tryptophan and [carboxyl-14C]-nicotinic acid. The ratio of incorporation of [3H]-tryptophan to that of [14C]-nicotinic acid into liver NAD and NADP was found to be higher in protein-restricted rats. On the other hand, the ratio was found to be reduced in diet-restricted group of rats compared with ad libitum fed or low-protein diet fed groups. These results suggest that the efficiency of conversion of tryptophan to NAD is increased in protein deficiency, but reduced in the diet restriction. These observations are in line with our earlier findings on the changes in liver quinolinate phosphoribosyltransferase (EC 2.4.2.19) activity following feeding of low-protein or restricted diets. It is suggested that this technique of measuring the incorporation of two isotopes from the substrates labelled with two different isotopes can be conveniently used as a tool to measure the relative contribution of tryptophan and nicotinic acid to the synthesis of nicotinamide nucleotides.

Animals↗