Antiviral effects were found to differ markedly between berry species. Rabbiteye varieties tended to have higher antiviral effects than Northern, Southern and Half Highbush blueberry varieties. We also found that Natsuhaze, which has recently been harvested in Japan as a potential functional food, had an antiviral effect comparable to that of bilberry, cranberry and blackcurrant. There was a positive relationship between antiviral activity and polyphenol content, indicating the possibility that polyphenol is one of the key factors in the antiviral effects of berries.

SummaryThe purpose of the current study was to assess the involvement of the branched-chain amino acid leucine in the regulation of translation initiation in the liver and to compare the time course of leucine action on the translation initiation in the liver and skeletal muscle of rats. The phosphorylation of the eukaryotic initiation factor (eIF) 4E -binding protein 1 (4E-BP 1) frees eIF4E and stimulates protein synthesis by accelerating translation initiation. Phosphorylation of the 70-kDa ribosomal protein S6 kinase (S6K1) is thought to be involved in regulating the synthesis of certain ribosomal proteins and other selected proteins with polypyrimidine clusters near the transcription start site. Food-de prived (18h) male rats were orally administered 135mg/100g body weight L-leucine and sacrificed at 0, 1, 3, or 6h after administration. The oral administration of leucine resulted in an enhanced phosphorylation of 4E-BP1 and S6K1 in both the liver and skeletal muscle. A time-dependent change in the phosphorylation state of 4E-BP1 and S6K1 was more acute in the skeletal muscle than in the liver and closely paralleled the changes in plasma leucine concentration. Our results indicate that the primary mediator in 4E-BP 1 phosphorylation and S6K1 phosphorylation by the oral administration of leucine is an increase in the plasma concentration of leucine. Furthermore, our findings suggest differential sensitivity in the tissue response to oral administration of leucine.

The indispensable branched-chain amino acid leucine acts as a key regulator of mRNA translation by modulating the phosphorylation of proteins that represent impor ƒ¿-Ketoisocaproate Effect on 4E-BP1 and S6K1 Phosphorylation

SummaryLeucine performs a signaling role to enhance protein synthesis by phosphory lating eukaryotic initiation factor (eIF) 4E-binding protein 1 (4E-BP1) and 70-kDa riboso mal protein 56 kinase (56K1), two key regulatory proteins involved in the initiation of mRNA translation. The purpose of the current study was to assess whether the phosphory lation of 4E-BP1 and S6K1 was increased in skeletal muscle and liver by an oral administra tion of leucine to diabetic rats and to determine the in vivo contribution of insulin to a leucine-dependent induction of 4E-BP1 and S6K1 phosphorylation. Food-deprived (18h) normal and diabetic rats were orally administered 135mg/100g body weight L-leucine and sacrificed at 1h after administration. Leucine administration resulted in enhanced phos phorylation of 4E-BP1 and S6K1 in skeletal muscle and in liver of nondiabetic rats. The stimulatory action of leucine on the phosphorylation of 4E-BP1 and S6K1 in skeletal mus cle was not abolished in rats with streptozotocin-induced diabetes. In contrast, leucine ad ministration did not stimulate the phosphorylation of 4E-BP1 and S6K1 in the liver of dia betic rats. These findings suggest that in skeletal muscle, leucine functions as a nutritional signaling molecule that independently regulates the phosphorylation states of 4E-BP1 and S6K1. In contrast to skeletal muscle, insulin is essential in mediating the leucine-dependent induction of 4E-BP1 and S6K1 phosphorylation in liver.

We previously reported that extracts from plants of the Ericaceae genus Vaccinium, commonly known as the kind of blueberry, inhibited the early steps of influenza virus (IFV) infection to host cells, and that the activity was correlated with the total polyphenol content. Particularly potent inhibitory activity was observed for Vaccinium oldhamii. In this study, we identified the active components in Vaccinium oldhamii involved in the inhibition of IFV infection. We sequentially fractionated the Vaccinium oldhamii extract using a synthetic adsorbent resin column. High inhibitory activity was observed for the fractions eluted with 30%, 40%, and 50% ethanol, and three peaks (peak A, B, and C) considered to represent polyphenols were identified in the fractions by HPLC analysis. Among these peaks, high inhibitory activity was detected for peak A and B, but not for peak C. These peaks were analyzed by LC/MS, which revealed that peak A contained procyanidin B2 and ferulic acid derivatives, whereas peak B contained two ferulic acid O-hexosides, and peak C contained quercetin-3-O-rhamnoside and quercetin-O-pentoside-O-rhamnoside. It is already known that these polyphenols have anti-IFV activity, but we speculate that ferulic acid derivatives are the major contributors to the inhibition of the early steps of IFV replication, such as either adsorption or entry, observed for Vaccinium oldhamii.