Effect of postharvest nicotinamide treatment on NAD plus metabolism and redox status in strawberry fruit during storage

The increased activity of PARP enzymes is associated with a deficiency of NAD+, as well as with a loss of NADPH and ATP, and consequent deterioration of the redox state in fruits. In this study, we checked whether treatment with nicotinamide (NAM) would affect PARP-1 expression and NAD+ metabolism in strawberry fruit during storage. For this purpose, strawberry fruits were treated with 10 mM NAM and co-treated with NAM and UV-C, and then stored for 5 days at 4 degrees C. Research showed that nicotinamide contributes to reducing oxidative stress level by reducing PARP-1 mRNA gene expression and the protein level resulting in higher NAD+ availability, as well as improving energy metabolism and NADPH levels in fruits, regardless of whether they are exposed to UVC. The above effects cause fruits treated with nicotinamide to be characterised by higher anti-radical activity, and a lower level of reactive oxygen species in the tissue.