Antiviral and Immunomodulatory Properties of Prunella vulgaris

Asian Journal of Traditional Medicinesacid in extracts of P. vulgaris consistently inhibited theinteraction between Lck SH2 and a peptide containingits consensus binding sequence at pYEEI. It was shownthat the inhibitory effect of rosmarinic acid was specificfor the SH2 domains of Src family protein tyrosinekinase. It was also found that rosmarinic acid inhibitedTCR-induced-Ca 2+ mobilization and IL-2 promoteractivation. Thus, this suggested the inhibition involvedthe membrane proximal site of TCR signaling andshowed that rosmarinic acid inhibited the expression ofcytokines, such as IL-2 and IFN-gamma [37] .Overall perspectivesThe above results provide ample evidence of theantiviral and immunomodulatory properties of P.vulgaris. Most importantly, its active components inaqueous extracts have been studied in detail and potentantiviral activity againt HIV, HSV and HSV mutantshave been demonstrated. Furthermore, severalcompounds like prunellin, tannins, polyphenols and itspolysaccharides exhibit strong inhibitory effects on HIVand HSV. The mechanisms of action may involvesuppression of the early or late stages of viral replication,integrase activity, blocking of surface glycoproteins andviral antigens. Interestingly, the immunomodulatoryeffects of P. vulgaris may act synergistically with itsanti-viral effects. The polysaccharide fractions of P.vulgaris could not only markedly stimulate theproduction of superoxide and nitrite, representing nitricoxide, from murine macrophage RAW264.7 and brainmacrophage BV2 cells, but also the protein levels ofinducible nitric oxide synthase (iNOS) and the mRNA ortumor necrosis factor alpha [35, 36] . The actions of P.vulgaris extracts on immune factors like histamine, IL-2,TNF-alpha, IgG, IgG1, IgG2b, nitric oxide, Src familyprotein kinase and T cell activation may be associatedwith specific cell targets during inflammatory andallergic actions. P. vulgaris exhibits significant dualproperties in the areas mentioned. These results confirmthat P. vulgaris is able to act as a new and effectiveantiviral agent with low toxicity. However, morein-depth studies on the chemical components of P.vulgaris need to be carried out to advance the search foreffective antiviral agents. Also, it is essential to carry outresearch on the co-administration of the active fractionswith currently used antiviral agents, a cocktail treatment,to examine their effect on HSV and HIV infections.Clinically, the extract of P. vulgaris has been developedand used in oral hygiene products for the control ofgingivitis and in eye drops for the treatment of keratitisdue to the herpes infection. Considering the differentpathways of transmission of viral infections, commonlythrough the mucosae (e.g. labial and genital herpes),novel topical agents with good antiviral andimmunomodulatory effects need to be developed toprevent sexually transmitted infections including HSVand HIV.To conclude, the combined properties of P. vulgarissuggest that it has great potential as a treatment for viralinfections as well as immunological disorders.References[1] World Health Organization. WHO Regional Publications,Western Pacific Series No.2, Medicinal Plants in China – Aselection of 150 commonly used species. 1989, P. 231[2] Namba T. The Encyclopedia of Wakan-Yaku (TraditionalSino-Japanese Medicines), vol. II. Hoikusha Publishing Co. Osaka,Japan. 1994. P.120-1[3] Shin TY, Kim YK, Kim HM. Inhibition of Immediate-typeallergic reactions by Prunella vulgaris in a murine model.Immunopharmacol Immunotoxicol 2001: 23(3): 423-35[4] Grieve M. A Modern Herbal. 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