Anti-influenza virus activity of two extracts of the blackcurrant (Ribes nigrum L.) from New Zealand and Poland.

We investigated the inhibitory effect of extracts of blackcurrant (Ribes nigrum L.) from New Zealand and Poland on 4 strains of influenza virus (IFV) by the inhibition of virus adsorption; pandemic flu from 2009-2010 (IFV-AH1pdm), Hong Kong flu (IFV-AH3), oseltamivir phosphate-resistant Russian flu (IFV-AH1tamr) and influenza virus type B (IFV-B). The inhibitory effect of the extracts of blackcurrant or blueberry on the infectivity of the virion were evaluated by the inhibition of virus adsorption on the cell surface (adsorption-inhibitory assay). Three percent solutions of the blackcurrant extracts from New Zealand and Poland were enough to disinfect more than half of IFV-AH1pdm and IFV-B, and 10% solutions from both regions disinfected all IFV strains completely. Our previous study showed that the antiviral effect of the blackcurrant differed according to viral species. Here we showed that although the antiviral effect of Blackcurrant was slightly different within viral strains from one species, the extract of Blackcurrant could disinfect all of 4 IFV strains we examined. The extracts of blackcurrant showed definite potential for use as a disinfectant and antiseptic agent to prevent IFV infection.

Relationship between polyphenol content and anti-influenza viral effects of berries.

BACKGROUND: Berries are known to have many kinds of biological activities. We focused on their antiviral effect, which has not yet been well evaluated. RESULTS: We compared the anti-influenza viral effects of berries belonging to the genus Vaccinium - 35 species of blueberry (Vaccinium cyanococcus), the Natsuhaze (Vaccinium oldhamii), bilberry (Vaccinium myrtillus) and cranberry (Vaccinium oxycoccos)- with those belonging to the genus Ribes, i.e. blackcurrant (Ribes nigrum). Only Elliott and Legacy among Northern Highbush varieties but many Rabbiteye varieties such as Austin, Baldwin, Brightblue, Festival, T-100 and Tifblue showed anti-influenza viral activity. Natsuhaze, bilberry, cranberry and blackcurrant had high antiviral effects. A relationship was observed between the antiviral effect and total polyphenol content. CONCLUSIONS: 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.

Anti-viral and anti-bacterial activities of an extract of blackcurrants (Ribes nigrum L.).

The inhibitory effects of an extract of the blackcurrant (Ribes nigrum L.) against pathogens associated with oral, nasopharyngeal and upper respiratory infectious diseases; namely respiratory syncytial virus (RSV), influenza virus A and B (IFV-A and IFV-B), adenovirus (AdV), herpes simplex virus type 1, Haemophilus influenzae type B, Streptococcus pneumoniae and Streptococcus mutans, were investigated. Less than 1% concentration of extract of blackcurrant inhibited replication of RSV, IFV-A and -B and HSV-1 by over 50% and a 10% extract inhibited adsorption of these viruses onto the cell surface by over 95%. The effects on AdV were much less pronounced; the half minimal inhibitory concentration of AdV replication was 2.54 ± 0.26, and a 10% concentration of the extract inhibited AdV adsorption on the cell surface by 72.9 ± 3.4%. The antibacterial activities of the blackcurrant were evaluated based on its efficacy as a disinfectant. A 10% extract disinfected 99.8% of H. Influenzae type B and 78.9% of S. pneumoniae in 10 min, but had no demonstrable effect against S. mutans. The blackcurrant extract still showed antiviral and antibacterial activities after the pH had been made neutral with sodium hydroxide, suggesting that these activities are not the result of acidic reactions or of components precipitated at a neutral pH. These findings demonstrate the potential of blackcurrant extract as a functional food for oral care.

Down-regulation of spontaneous Epstein-Barr virus reactivation in the P3HR-1 cell line by L-arginine.

We tested the hypothesis that inhibition of Epstein-Barr virus (EBV) reactivation is controlled in part by nitric oxide (NO) generated from L-arginine (Arg). The spontaneous reactivation of EBV in the Burkitt's lymphoma (BL) cell line P3HR-1 was inhibited when the cells were cultured in L-Arg-supplemented medium. The expression of EBV early antigen (EA), immediate-early BZLF1 mRNA and the protein ZEBRA, and production of infectious virus were reduced by L-Arg supplementation in a dose-dependent manner. We demonstrated that inducible NO synthase (iNOS) mRNA was constitutively expressed in P3HR-1 cells, as quantitated by the reverse transcription-polymerase chain reaction. L-Arg supplementation enhanced iNOS and NOx expression in the cells. A specific NOS inhibitor, NG-monomethyl-L-Arg enhanced the expression of ZEBRA and early BMRF1 protein EA-D in the cells. L-Arg supplementation also inhibited the spontaneous EBV reactivation in another BL cell line EB1 and a B lymphoblastoid cell line OB. These results indicated that L-Arg induces iNOS and generates NO, which inhibits EBV reactivation in EBV-positive cells.