Isolation of Nicotinic Acid (Vitamin B3) and N-Propylamine after Myosmine Peroxidation

Abstract

The alkaloid myosmine (3-(1-pyrroline-2-yl)pyridine) is widespread in biological matrixes including foodstuffs and tobacco products. Some in vitro tests in cellular systems showed mutagenic activity for myosmine. Myosmine activation including peroxidation mechanism employs unstable oxazirane intermediates. The formation of minor metabolite 3-hydroxymethyl-pyridine in rat metabolism experiments as well as in in vitro peroxidation assays suggests its further oxidation to nicotinic acid and possible concomitant formation of n-propylamine. A sensitive high-performance liquid chromatography-ultraviolet (HPLC-UV) method was developed for the direct analysis of n-propylamine in the peroxidation assay solution of myosmine employing derivatization with 3,5-dinitrobenzoyl chloride. Additionally, during peroxidation procedures, formation of 3-pyridylmethanol to nicotinic acid, the essential vitamin B3, was observed and characterized using HPLC-UV and gas chromatography/mass spectrometry. This new reaction pathway may present further contribution to our knowledge of myosmine's significance in human food including its activation in human organism, foodstuffs, and biological systems.

Biosynthesis of vitamin B3 and NAD+: incubating HepG2 cells with the alkaloid myosmine

“…The existence of 3-pyridinylaldehyde, which has been postulated in earlier studies of MYO peroxidation, has not yet been confirmed. 5 This strongly supports the conclusion that 3-pyridinylmethanol represents the intermediate in vitro as well as in vivo to perform NA synthesis. NA formation with administered MYO in HepG2 cells yields sufficient concentration to meet the demand of NAD + biosynthesis.…”

“…49 In vitro peroxidation of MYO has been shown to contribute to NA production under abiotic conditions. 3,5 Owing to the presence of reactive oxygen species and other peroxy-containing species in human saliva and blood, MYO reactions may be spontaneous, similar to the abiotic conditions mentioned herein, and may lead to the formation of NA in the absence of enzymatic oxidation.…”

“…Discovery of the organic synthesis of NA from MYO prompted the search of the biological oxidation of MYO to NA. 4 HepG2 cells were used as a biological oxidation model to check conversion of NA from MYO. As already mentioned, formation of NAD + from NA in HepG2 cells was not expected at the beginning of the study.…”

“…In vitro peroxidative synthesis of MYO was recently reported, and conversion of the alkaloid to the biologic active substance NA was demonstrated. 5 NA and its analogue amide form nicotinamide (NAM) are designated as niacin or commonly known as vitamin B 3 . The essential amino acid tryptophan (TRP) is assumed as a precursor of niacin in several micro-organisms, plants, and fungi species.…”

“…31,32 The novel in vitro peroxidation pathway from MYO to NA requires chemical degradation of the 3-pyrrolidine-pyridine structure to 3-pyridinylmethanol, and subsequent oxidation to NA + . 5 Thus, in the present study, the focus was to determine whether the 3-pyrrolidine-pyridine structure to the amide group of NAD of MYO can operate within cells containing an enzyme configuration 33,34 to generate NA and then NAD + via the reported Preiss-Handler pathway. Gene expression levels of the essential NAD + biosynthetic enzymes NAD synthetase (NADSYN), NAMPT, nicotinamide mononucleotide adenosyl transferase (NMNAT)1-3, nicotinate phosphoribosyl transferase (NAPRT), and nicotinamide riboside kinase (NRK) may be inhibited, utilized, or influenced by MYO.…”