In conclusion, the anti-HSV compound from P. vulgaris is a
lignin-polysaccharide complex with potent activity against HSV-1 and
HSV-2. Its mode of action appears to be inhibiting viral binding and
penetration into host cells.

The chemical nature, the mode of action, and the in vitro and in vivo
anti-HSV activities of the polysaccharide from Prunella vulgaris were
characterized. The polysaccharide was isolated by ethanol
precipitation, dialysis, CTAB precipitation, and gel exclusion
chromatography. The isolated compound (PPS-2b) was a
lignin-carbohydrate complex with a molecular weight of 8500. The
carbohydrate moiety was composed of glucose, galactose, mannose,
galacturonic acid, rhamnose, xylose, and arabinose with glucose as the
major sugar. In plaque reduction assay, PPS-2b showed activities
against HSV-1 and HSV-2. The anti-HSV activity could be abolished by
periodate oxidation. Mechanism studies showed that PPS-2b inactivated
HSV-1 directly, blocked HSV-1 binding to Vero cells, and inhibited
HSV-1 penetration into Vero cells. A similar inhibition was observed
with a gC-deficient strain of HSV-1. The in vivo activities of a
Prunella cream formulated with a semi-purified fraction was assessed in
a HSV-1 skin lesion model in guinea pigs and a HSV-2 genital infection
model in BALB/c mice. Guinea pigs that received the Prunella cream
treatment showed a significant reduction (P<0.01) in skin lesions.
Mice that received the Prunella cream treatment showed a significant
reduction (P<0.01) in mortality.

PMID: 17475343 [PubMed - indexed for MEDLINE