Selfheal (Prunella vulgaris) is a native British plant, found among short grass on waste ground, grassland and open spaces in woodland, where it raises its closely packed heads of bright purple flowers. Creeping stems spread the plant over wide areas, so that the flowers often carpet the ground along dry, grassy banks. The flowers are arranged around terminal spikes, but do not open at the same time, resulting in an extended flowering period, from June to September.
Selfheal has been used as a medicinal plant for centuries, often as an astringent, and was identified as the herb used by Dioscorides, the ancient Greek physician, to cure inflammation of the throat and tonsils. Its common name stems from its popularity as a plant used according to the old belief in the “Doctrine of signatures”, whereby a plant’s medicinal use to mankind was gauged by aspects of its appearance. In the case of Selfheal, the mouth-like structures of its flowers led to it being used as a remedy for sore throats and mouth ulcers.
The plant is still used extensively in Traditional Chinese medicine, and recent research has suggested it may also have anti-mutagenic properties, indicating a possible treatment for certain cancers. Other studies have shown it to possess a wide variety of pharmacological effects, including antioxidant, anti-inflammatory, astringent, and antimicrobial.
A number of antiviral studies of P. vulgaris extracts have been carried out and compounds active against both HIV and Herpes Simplex Virus have been identified. In particular, a sulphated polysaccharide named prunellin was found to inhibit HIV-1 replication in vitro, as well as being able to arrest cell to cell transmission of the virus, with relatively low cytoxicity.
Experiments conducted on rats into its immunomodulatory effects demonstrated an inhibition of passive anaphylaxis activated by IgE antibodies, and also inhibition of histamine release from mast cells. Interestingly, it was also discovered that the immunomodulatory effects of P. vulgaris seemed to act synergistically with its anti-viral effects. These combined properties suggest that it has great potential as a treatment for both viral infections and immunological disorders.