Effect of rootstocks and harvesting time on the nutritional quality of peel and flesh of peach fruits.

The influence was evaluated of four rootstocks (Ishtara, Mr. S 2/5, GF 677 and Barrier 1) and of harvesting time (early, middle, late) on the quality characteristics and nutritional value (vitamin C, phenols, carotenoids, total antioxidant capacity) of 'Flavorcrest' peach. The better rootstocks were Mr. S 2/5 (low-vigour) and Barrier 1 (high-vigour). In particular, Flavorcrest fruit on Mr. S 2/5 and on Barrier 1 rootstocks had higher antioxidant capacities and also higher phytochemical content, although fruits on Mr. S 2/5 were less firm. Flesh firmness was best for fruits at mid-harvest (H2, 7 July 2006), whereas phytochemical contents were best at late harvest (H3, 13 July 2006), when, for all rootstocks, the best nutritional characteristics were also recorded. Total antioxidant capacity and phytochemical content were determined for the peel and flesh. The results show that removal of peel from peach results in a significant loss of total antioxidant capacity.

Sphingomyelinase metabolites control survival and apoptotic death in SH-SY5Y neuroblastoma cells.

There is increasing evidence that sphingolipids are involved in cell survival, differentiation or commitment to death. The effect of different sphingolipids and inhibitors of mitogen-activated protein kinase (MAPK) cascade on SH-SY5Y neuroblastoma cell death has been studied. Permeant ceramide analogues C2-Cer, C8-Cer, and C8-Cer-1-phosphate, but not dihydro C2-Cer induce apoptosis, as shown by Hoechst staining. Inhibition of ceramidase and sphingosine kinase, as well as incubation with sphingosine, decreases cell viability, measured as 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide reduction, whereas addition of sphingosine-1-phosphate increases proliferation. Both PD98059 (MAPKK inhibitor) and SB202190 (p38 MAPK inhibitor) decreased viability, but only SB202190 abolished the effect of ceramide. These results suggest that in SH-SY5Y neuroblastoma cells, death is signalled by increases in ceramide, ceramide-phosphate or sphingosine content through p38 MAPK pathway while survival requires MAPK and high sphingosine-1-phosphate/ceramide ratio.