Formation Of Nicotinic Acid Research Articles

Optimization of vanadium oxide catalyst for the oxidation of 3-methylpyridine into nicotinic acid

Upon modification of V2O5 with SnO2 or ZrO2, increase in the activity and selectivity of the vanadium-oxide catalyst in the vapor-phase oxidation of 3-methylpyridine into nicotinic acid were observed. It was shown that the promoting effects of SnO2 and ZrO2 were the result of increases under their influence of the proton affinity of the vanadyl oxygen and decreases in the enthalpy of deprotonation of the methyl group of the substrate, connected by a nitrogen atom with the Lewis acidic center (vanadium ion). The given characteristics were calculated by the density functional theory quantum-chemical method. Modification of binary V2O5?SnO2 and V2O5?ZrO2?catalysts by TiO2 addition resulted in a further increase in the nucleophility of the vanadyl oxygen and, as a consequence, an increase in the catalytic activity and selectivity for nicotinic acid formation.

Gas Phase Catalytic Oxidation of β-Picoline to Nicotinic Acid: Catalysts, Mechanism and Reaction Kinetics

An overview of the fundamental studies on a new method of nicotinic acid synthesis by the gas phase catalytic oxidation of β-picoline by oxygen is presented. The nature of active component in vanadia catalysts and reactivity of vanadium species are considered. Common features and differences in the mechanistic steps of nicotinic acid formation on various catalysts investigated by in situ FTIR spectroscopy are discussed. Effects of the reaction mixture components on the yield of nicotinic acid are considered in detail. Attention is paid to the kinetic equations of β-picoline oxidation on vanadia-titania catalysts.

Mechanism of the oxygen involvement in nicotinic acid formation under β-picoline oxidation on V-Ti-O catalyst

Mechanism of the oxygen involvement in nicotinic acid formation under β-picoline oxidation on vanadia-titania catalyst was studied by in situ FTIR spectroscopy and kinetic method in temperature range of 120–300 °C. The formation of nicotinic acid proceeds via a consecutive transformation of the surface carbonil-like and carboxylate complexes stabilized at reduced vanadium. Catalyst oxygen includes in formation of these complexes. Carboxylate is a direct precursor of nicotinic acid, it turns into nicotinic acid in the presence of the gas-phase oxygen in joint step of catalyst reoxidation–acid desorption. Significant concentration ratio of oxygen to β-picoline (C O2:C βP > 16:1) is necessary to effective running reaction. This factor can be explained by the reaction mechanism. The variety of oxygen functions and of oxygen species require the maximum oxidized state of the catalyst and explain the necessity of a high oxygen excess in the reaction mixture.

Pyridine salvage and nicotinic acid conjugate synthesis in leaves of mangrove species

The metabolic fate of [carbonyl- 14C]nicotinamide was surveyed in leaf disks of seven mangrove species, Bruguiera gymnorrhiza, Rhizophora stylosa, Kandelia obovata, Sonneratia alba, Pemphis acidula, Lumnitzera racemosa and Avicennia marina, with and without 250 mM NaCl. Uptake of [ 14C]nicotinamide by leaf disks was stimulated by 250 mM NaCl in K. candel, R. stylosa, A. marina and L. racemosa. [Carbonyl- 14C]nicotinamide was converted to nicotinic acid and was utilised for the synthesis of nucleotides and nicotinic acid conjugates. Formation of nicotinic acid by the deaminase reaction was rapid; there was little accumulation of nicotinamide in the disks 3 h after administration. Radioactivity from [carbonyl- 14C]nicotinamide was incorporated into pyridine nucleotides (mainly NAD and NADP) in all mangrove leaves, and the rates varied from 2% (in L. racemosa) to 15% ( S. alba) of the total radioactivity taken up. NaCl generally reduced nicotinic acid salvage for NAD and NADP. In all mangrove leaf disks, the most heavily labelled compounds (up to 70% of total radioactivity) were trigonelline ( N-methylnicotinic acid) and/or nicotinic acid N-glucoside. Trigonelline was formed in all mangrove plants, but N-glucoside synthesis was found only in leaves of A. marina and K. obovata. In A. marina, incorporation of radioactivity into N-glucoside (51%) was much greater than incorporation into trigonelline (2%). In general, NaCl stimulates the synthesis of these pyridine conjugates. The rate of decarboxylation of nicotinic acid in roots of A. marina seedlings was much greater than for the corresponding reaction observed in leaves.

Kinetics of the β-picoline oxidation to nicotinic acid over vanadia-titania catalyst. 2. Effect of dioxygen and β-picoline

The effect of the dioxygen and β-picoline concentrations on the oxidation of β-picoline to nicotinic acid was studied at 270°C over a 20% V2O5-80% TiO2 (wt. %) catalyst. The study was performed in a differential reactor at constant concentrations of water and nicotinic acid. A considerable excess of dioxygen was shown to be necessary for the formation of nicotinic acid. It was found that the rates of β-picoline transformation into nicotinic acid, pyridine-3-carbaldehyde, pyridine-3-nitrile, pyridine and carbon oxides as well as selectivities to products and the catalyst state depend strongly on the ratio of dioxygen to β-picoline concentrations. The minimum admissible ratio of these concentrations under industrial conditions was determined.

Tryptophan metabolism along the kynurenine pathway in diet-induced and genetic hypercholesterolemic rabbits

Background The activity of nicotinic acid in hypercholesterolemia has been poorly understood. In man, nicotinic acid derives for the most part from tryptophan along the tryptophan–nicotinic acid pathway, also called the kynurenine pathway, kynurenine being the key metabolite in this process. In the present paper, we investigated if, in animals with hypercolesterolemia, degradation of tryptophan to nicotinic acid along the kynurenine pathway was perturbated. Methods Liver, kidney and intestine enzyme activities of the tryptophan–nicotinic acid pathway in normolipidemic, diet-induced hyperlipidemic New Zealand and heritable hypercholesterolemic Watanabe (WHHL) rabbits were determined. Results Liver tryptophan 2,3-dioxygenase (TDO) activity was present only as a holoenzyme and was higher in the controls than in the hyperlipidemic and Watanabe rabbits, but no difference was present between the group fed an atherogenic hyperlipidic diet and the WHHL rabbits. Small intestine indole 2,3-dioxygenase (IDO) did not vary significantly among the three groups but was higher in comparison with liver TDO activity. In liver, kynurenine 3-monooxygenase and kynurenine-oxoglutarate transaminase activities did not show any significant difference among the three groups of rabbits. Kynureninase and 3-hydroxyanthranilate 3,4-dioxygenase activities per g of fresh tissue decreased significantly in the group of hyperlipidemic and in WHHL rabbits. In the kidneys, kynurenine 3-monooxygenase and kynureninase activity did not change significantly in the three groups of rabbits; kynurenine-oxoglutarate transaminase activity per g of fresh tissue decreased in both hyperlipidemic groups, but no significant difference was observed between hyperlipidemic and Watanabe rabbits. 3-Hydroxyanthranilate 3,4-dioxygenase activity in kidney was decreased markedly in hyperlipidemic and Watanabe rabbits, but there was no difference between the two hypercholesterolemic groups. Aminocarboxymuconate-semialdehyde decarboxylase activity did not change. Thus 3-hydroxyanthranilate 3,4-dioxygenase may be an important regulatory mechanism in the control of the flow of tryptophan along the kynurenine pathway to NAD in hypercholesterolemic rabbits. Conclusions This study first demonstrates that in rabbits, hypercholesterolemia, both diet- or genetically induced, can influence the enzyme activities of the tryptophan–nicotinic acid pathway leading to a decreased formation of nicotinic acid, and thus NAD.

HPLC/diode-array applied to the thermal degradation of trigonelline, nicotinic acid and caffeine in coffee

A simultaneous determination of trigonelline, nicotinic acid and caffeine was performed in samples of arabica and robusta coffees, before and after roasting at either different temperatures (160–240°C) or different periods of time exposures, in order to study their thermal degradation. A reverse-phase HPLC/Diode-array detector method was used. The results were compared with a model dry system roast of the compounds under study, individually and in mixture. The loss of trigonelline was strongly dependent upon the degree of roast and was associated with the formation of nicotinic acid. A slight decrease in caffeine was verified in both species. This study showed diversified behavior of the compounds when in their native form or in an artificial mixture, eliciting the chemical environmental influence. Rate constants for the chemical reactions at 240°C were determined.

Nitrile Hydratase-Catalyzed Production of Nicotinamide from 3-Cyanopyridine in Rhodococcus rhodochrous J1

Nitrile hydratase, which occurs abundantly in cells of Rhodococcus rhodochrous J1 isolated from soil samples, catalyzes the hydration of 3-cyanopyridine to nicotinamide. By using resting cells, the reaction conditions for nicotinamide production were optimized. Under the optimum conditions, 100% of the added 12 M 3-cyanopyridine was converted to nicotinamide without the formation of nicotinic acid, and the highest yield achieved was 1,465 g of nicotinamide per liter of reaction mixture containing resting cells (1.48 g as dry cell weight) in 9 h. The nicotinamide produced was crystallized and then identified physicochemically. The further conversion of the nicotinamide to nicotinic acid was due to the low activity of nicotinamide as a substrate for the amidase(s) present in this organism.

Trigonelline Content in Coffee Beans and the Thermal Conversion of Trigonelline into Nicotinic Acid during the Roasting of Coffee Beans

The trigonelline content in coffee was determined by the microbiological assay method after demethylating the compound. The content was proved to be extremely high (up to 1 % on the wet basis). When trigonelline was heated to above 180°C, it was converted into nicotinic acid. Although the conversion rate was low, a nutritionally significant amount of nicotinic acid was formed during roasting coffee beans because of the high content of trigonelline in coffee beans. The optimum heating condition for nicotinic acid formation was found at 220°C for 20 min.

Trigonelline content in coffee beans and the thermal conversion of trigonelline into nicotinic acid during the roasting of coffee beans.

The trigonelline content in coffee was determined by the microbiological assay method after demethylating the compound. The content was proved to be extremely high (up to 1 % on the wet basis). When trigonelline was heated to above 180°C, it was converted into nicotinic acid. Although the conversion rate was low, a nutritionally significant amount of nicotinic acid was formed during roasting coffee beans because of the high content of trigonelline in coffee beans. The optimum heating condition for nicotinic acid formation was found at 220°C for 20 min.

Degradation of nicotinamide adenine dinucleotide in cell suspension cultures

Metabolites of [carbonyl- 14C]-NAD in cell suspension cultures of mung bean, soybean and garbanzo bean are trigonelline and compounds of the pyridine nucleotide cycle. Degradation of nicotinate does not occur. In parsley cell cultures nicotinate degradation and formation of nicotinic acid N-α- l-arabinoside were observed. These conjugates are alternative reservoir forms of nicotinic acid. The adenine moiety of NAD is degraded in cell cultures via hypoxanthine-xanthine-allantoin-allantoic acid, with accumulation of the latter two compounds.

The Enthalpies of Combustion and Formation of Nicotinic Acid and Creatinine.

The enthalpies of combustion of nicotinic acid and creatinine have been determined in an adiabatic rotating-bomb calorimeter. The enthalpies of formation have been obtained by combination of the experimental data with the accepted values for the enthalpies of formation of carbon dioxide and water. The results of other investigations on creatinine are discussed briefly. The resulting values and their estimated uncertainties are as follows: [Table: see text].

Tryptophan metabolism in some intestinal helminthiases

Tryptophan is metabolized to nicotinic acid in man through the formylkynurenine pathway. Disordered metabolism of this amino acid with the accumulation of intermediate metabolites (some of which are carcinogenic) had been encountered in patients with bilharzia. The aim of this work was to investigate the possibility that some intestinal helminths— Ascaris lumbricoides and Ancylostoma duodenale—may induce disordered tryptophan metabolism in the human host. Results revealed that infection with either A. lumbricoides (7 cases), or A. duodenale (8 cases) induced functional pyridoxine deficiency in the host. This deficiency was evidenced by the accumulation of certain metabolites along the tryptophan-nicotinic-acid pathway. The abnormal pattern encountered in these cases could be partially improved by pyridoxine supplements. Furthermore, this impairment in the reactions leading to the formation of nicotinic acid from its precursor, did not manifest itself by clinical symptoms of pellagra in the host.

The transmethylation processes in the aqueous humour and in the lens

Some nicotinic acid derivatives have been determined chromatographically in the aqueous humour and in the lenses of normal human and ox eyes and eyes with cataract. In these two tissues transmethylation and formation of nicotinic acid and its derivatives from tryptophan occur regularly in normal eyes. In eyes with cataract, transmethylation does not occur and nicotinic acid is not formed from tryptophan.

The Tryptophane-Nicotinic Acid Relationships andAlkaloid Biosynthesis in Certain Solanaceae

Tryptophane feedings in concentrations of from 0.1 Gm. to 0.6 Gm. per liter were found to stimulate nicotinic acid formation in tomato and Datura stramonium. However, no direct effect could be found on Datura alkaloid formation. In the latter case there was evidence that some relationship existed between nicotinic acid levels and those of alkaloid. As nicotinic acid decreased alkaloid increased and vice versa.

Application of chromatography. XXX. Studies on tryptophan metabolism in the culture of Eremothecium ashbyii.

In isolating a green fluorescent substance (G compound) from the mycelium of Er. ashbyii, yellow crystals, m.p. 223∼224°(decomp.), [α]20D-43.2°, were also separated and this substance was established as l-3-hydroxykynurenine. Study of the mycelium and broth of Er. ashbyii by two-dimentional paper chromatography detected only tryptophan and l-hydroxykynurenine as amino acid of tryptophan series, kynurenine being never detected. The two compounds were found from a comparatively early stage of the culture and they were readily distinguished by the color reaction with p-dimethy1-aminobenzaldehyde (Ehrlich reagent). Formation of riboflavin, l-hydroxykynurenine, and nicotinic acid was also investigated at intervals during the culture and it was found that riboflavin increased in proportion to the increase of l-hydroxykynurenine, but the formation of nicotinic acid factor seemed to have no quantitative relation to them. A leuco strain of Er. ashbyii obtained by successive culture of the yellow strain was also cultivated on the same medium and it was found that in addition to a slightly smaller production of the mycelium, the production of riboflavin and l-hydroxykynurenine was extremely low, compared with their production in the yellow strain. From such a fact it was presumed that the metabolism of kynurenine to l-hydroxykynurenine in the yellow strain is very active and that this oxidative process in the living body requires a large quantity of riboflavin.

Biogenesis of nicotine.

FOLLOWING the demonstration that the amino-acid tryptophane can readily be converted by barley plants into the alkaloid gramine1, the study of the biogenesis of alkaloids carried on here has included investigations into the possibility that nicotine may arise from tryptophane in a manner similar to the formation of nicotinic acid in animals and microorganisms2. Recent discussions of this possibility3,4 prompt me to describe part of these investigations.

Kynurenine as an Intermediate in the Formation of Nicotinic Acid from Tryptophane by Neurospora

These experiments lend stroiig support to the view that Neurospora converts tryptophane to nicotinic acid by way of kynurenine.