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

Abstract

BackgroundIn the ‘kynurenine pathway’, it is reported that essential amino acid tryptophan (TRP) forms nicotinic acid (NA, vitamin B3) in biological systems. This pathway is part of the ‘de novo pathway’ to perform the nicotinamide adenine dinucleotide (NAD+)‐biosynthesis. Additionally, biosynthesis of the NAD+ via the ‘Preiss‐Handler pathway’ involves NA and its analogue nicotinamide (NAM) both designated as niacin. Previous attempts were successfully to convert MYO by organic synthesis to NA and assumption was, the alkaloid myosmine (MYO), which is in taken from food, can be converted into NA by biological oxidation.ResultIn the present study, incubation of HepG2 cells with MYO yielded NA. Moreover, a significant increase of NAD+ compared to the control has been found.ConclusionHence MYO could be assumed to be the hitherto unknown origin of an alternative NA‐biosynthesis additionally influencing NAD+‐biosynthesis positively. This novel MYO‐pathway may open new perspectives to improve knowledge and relevance of NA and NAD+‐biosynthesis and bioactivation in cells and moreover in food staples, food and diet.This article is protected by copyright. All rights reserved.