Antiviral potency of mistletoe (Viscum album ssp. album) extracts against human parainfluenza virus type 2 in Vero cells

Abstract

Various extracts from the leaves of mistletoe (Viscum album L. ssp. album) were investigated for their antiviral activity on human parainfluenza virus type 2 (HPIV-2) growth in Vero cells. Plant extracts were prepared using distilled water, 50% ethanol, petroleum ether, chloroform and acetone. The 50% effective dose (ED(50)) of aqueous extract for HPIV-2 replication was 0.53 +/- 0.12 micro g/mL, and the antiviral index (AI), which was based on the ratio of the 50% inhibitory concentration (CD(50)) for host cell viability to the ED(50) for parainfluenza virus replication, was 10.05. The aqueous extract was found to be the most selective inhibitor. Furthermore, the aqueous extract at a concentration of 1 micro g/mL was found to inhibit HPIV-2 replication and the virus production was suppressed to more than 99% without any toxic effect on host cells. The chloroform extract was also found to be moderately active. In an effort to further analyse the mechanism of antiviral activity, the effectiveness of the aqueous extract on different steps of virus replication was examined. The antiviral activity could neither be attributed to the direct inactivation of the HPIV-2 nor to the inhibition of adsorption to Vero cells. The active aqueous extract has shown a dose-dependent antiviral activity on virus replication.

Phytochemical profile and therapeutic potential ofViscum albumL.

“…austriacum, album and abietis showed in vitro activity against Mycobacterium tuberculosis H37Ra strains (Deliorman et al 2001). The aqueous extract from the leaves showed potent antivirus (against human parainfluenza virus type 2 -HPIV-2 replication) activity (Karagöz et al 2003). All activities of V. album are summarised in Table 1.…”

“…A hexane extract of mistletoe in an agar diffusion test exhibited moderate antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae and Proteus vulgaris, and antifungal activity against Candida albicans (Ertürk et al 2003 In vitro on HPIV-2 Karagöz et al (2003) Natural Product Research 9…”

Cytotoxic effect of mistletoe (Viscum album L.) extract on Jurkat cells and its interaction with doxorubicin

“…Mistletoe preparations and some of their components activate NK-cells, monocytes/macrophages, granulocytes, T-helper cells, induce cytokine release and apoptosis in vitro and in vivo (Hajto, 1986;Van Huyen et al, 2006;Gardin, 2008). It also exerts strong antiviral, hypoglycemic and antioxidant effect dependent on the host tree (Karagöz et al, 2003;Orhan et al, 2005).…”

Methods for Testing the Antimicrobial Activity of Extracts

“…These authors suggest that antiviral activity is more likely to be found in aqueous rather than ethanol extracts; this is in contrast to antibacterial and antifungal assays where activity is more commonly seen in solvent extracts and essential oils. However, other studies have identified activity in both aqueous and solvent (ethanol or methanol) extracts of a wide range of plants against the hepatitis C virus [74], HSV-1, VSV [75,76], and human parainfluenza virus type 2 (HPIV-2) [77]. Few plant extracts/essential oils have been shown to demonstrate antiviral activity in vivo [78,79] with work by Nawawi et al [76] showing that, as with other in vitro assays, activity in vitro is not always matched by a similar level of activity in vivo.…”