Antiviral activity of Isatidis Radix derived glucosinolate isomers and their breakdown products against influenza A in vitro/ovo and mechanism of action.

ETHNOPHARMACOLOGICAL RELEVANCE: Isatidis Radix, the sun-dried roots of Isatis indigotica Fortune ex Lindl., is one of the most usually used traditional Chinese medicines. For centuries, the herb has been employed in clinical practice for treatment of virus infection and inflammation. However, its active ingredients remain unclear. AIM OF THE STUDY: In the present study, the anti-influenza virus activity of epiprogoitrin, progoitrin, epigoitrin and goitrin, the Isatidis Radix derived glucosinolate isomers and their breakdown products, was firstly evaluated in vitro and in ovo and their mechanism of action was investigated. MATERIALS AND METHODS: Epiprogoitrin, progoitrin, epigoitrin and goitrin were isolated from Isatidis Radix by chiral separation. In vitro and in ovo evaluations were performed on Madin-Darby canine kidney (MDCK) cells and embryonated eggs respectively, both using protocols including prevention, treatment and virus neutralization. Hemagglutination (HA) and neuraminidase (NA) inhibition assays were performed for further understanding of the antiviral mechanism. RESULTS: Isatidis Radix derived glucosinolate isomers and their breakdown products all exhibited dose-dependent inhibition effect against influenza A virus (H1N1) without toxicity. The antiviral potency of the components was in the order of progoitrin > goitrin > epigoitrin > epiprogoitrin. The attachment of the constituents to the viral envelope conduced to the mechanism of their antiviral action without disturbing viral adsorption or budding. CONCLUSION: Taken together, these results are promising for further development of Isatidis Radix and may contribute an adjunct to pharmacotherapy for influenza virus infection.

Anti-NDV activity of baicalin from a traditional Chinese medicine in vitro.

The purpose of this study was to investigate the anti-Newcastle disease virus (NDV) activities of baicalin from Scutellaria baicalensis, a Traditional Chinese Medicine in vitro. Chicken embryo fibroblasts (CEFs) were infected with NDV, and quantitative analysis of apoptotic cells was performed using flow cytometry. Cytotoxicity and anti-viral activities of baicalin were studied using the MTT method. The results showed that the maximal safe concentrations of baicalin to CEFs was 1 × 2(-2) mg/ml. Baicalin could directly kill NDV, inhibit the infectivity of NDV to CEF and block intracellular NDV. It inhibited the apoptosis of NDV-infected CEFs and suppressed the spread of NDV. These results indicate that baicalin has strong anti-NDV activity and has the potential for use as components of an antiviral drug.

Evaluation of the use of different solvents to extract the four main components of Yinqiaosan and their in vitro inhibitory effects on influenza-A virus.

High-performance liquid chromatography coupled with an ultraviolet detector was used to quantitatively determine the amount of caffeoylquinic acid, arctium lappa glycoside, aurantiamarin and forsythin present in five solvent extracts (water, 30% ethanol, 50% ethanol, 70% ethanol and 95% ethanol) of Yinqiaosan (YQS). The calibration curves of the four components were linear (r(2) > 0.998) over the concentration range of 0.9-151.5 microg/mL. This method showed good repeatability with relative standard deviations of less than 2.9% and mean recoveries of 91.3-100.5%. We established the relative amounts of each of the four main ingredients in YQS for all five solvent extracts. The direct inhibitory effects of the five YQS extracts on influenza-A virus in vitro and the therapeutic effects on infected embryonated hen eggs were evaluated. YQS extracted in 50% ethanol and used at concentrations of 500 mg/mL and 250 mg/mL exerted the greatest therapeutic effect in infected embryonated hen eggs and was significantly superior to ribavirin (p < 0.05). Therefore, the 50% ethanol extract of YQS seems to be the most effective for the inhibition of influenza-A virus. Based on these results, further studies are warranted to evaluate the use of YQS extracts as a possible therapy for influenza.

Influenza infection of the embryonated hen's egg/an alternative model for in vivo evaluation of antiviral compounds.

The embryonated hen's egg can be infected with influenza A virus in laboratory experiments leading to death of chick embryos within 8 days post infection. This model can be used for rapid and reliable in vivo evaluation of potential anti-influenza inhibitors. It offers a realistic alternative to experiments with small laboratory rodents. By an example of treatment with the antiviral drugs amantadine (CAS 665-66-7), rimantadine (CAS 1501-84-4) and zanamivir (CAS 139110-80-8), it could be demonstrated that chick embryos survive a lethal influenza A virus infection when these drugs are administered immediately before or after the infective agent is inoculated. In conclusion, the use of influenza virus-infected chick embryos for evaluation of new antiviral substances can lead to a considerable reduction in the number of small laboratory rodents required.