Three plant extracts Hypericum mysorense, Hypericum hookerianum and Usnea complanta, exhibited significant antiviral activity, at a concentration non toxic to the cell line used.
Online PR News – 12-January-2010 – – Antiviral activity of medicinal plants of Nilgiris
P. Vijayan, C. Raghu, G. Ashok, S.A. Dhanaraj & B. Suresh
JSS College of Pharmacy, TN, India
Plants have been used as folk remedies and ethnobotanical literature has described the usage of plant extracts, infusions and powders for centuries for diseases now known to be of viral origin. There is an increasing need for search of new compounds with antiviral activity as the treatment of viral infections with the available antiviral drugs is often unsatisfactory due to the problem of viral resistance coupled with the problem of viral latency and conflicting efficacy in recurrent infection in immune-compromised patients. Herpes simplex viruses (HSV) are ubiquitous agents which cause a variety of diseases ranging in severity from mild to severe, and in certain cases, these may even become life threatening, especially in immune-compromised patients. After primary infection, HSV persists in the host for the lifetime. HSV infection is thus considered lifelong infection.
Nucleoside analogues such as aciclovir (ACV), penciclovir etc., are the only approved drugs for the treatment of HSV infections. However, the widespread use of nucleoside based drugs has led to the emergence of resistance in HSV. This indicates the need for search of newer antiviral agents to treat such infections.
The present study was undertaken to test the extracts of 18 plants for their antiviral activity against herpes simplex virus type I (HSV-1, a DNA virus).
Material & Methods
The plant materials were collected from in and around Ootacamund, Tamil Nadu, India and were authenticated by the Botanical Survey of India, Government Arts College, Ootacamund where sample specimens were deposited. Extracts of different plants were prepared by using Soxhlet extraction unit as per the standard procedure. The essential oils from different parts of plants were isolated by water distillation using Clavenges apparatus.
Sixteen wells were used for each concentration of the test sample. The morphology of the cells was inspected daily and observed for microscopically detectable alterations, i.e.,loss of monolayer, granulation and vacuolization in the cytoplasm.
The cultures were treated with different dilutions of plant extracts in fresh maintenance medium and incubated at 37ºC for five days. Every 24 h the observation was made and cytopathic effects were recorded. Anti-HSV-1 activity was determined by the inhibition of cytopathic effect compared with control, i.e., the protection offered by the test samples to the cells was scored. In virus yield assay, reduction in the yield of virus when cells were treated with the plant extracts was determined.
List of selected medicinal plants -
Bacopa monnieri, Solanum trilobatum, Hibiscus vitifolius, Allium cepa, Derris brevipes, Hypericum mysorense, Hypericum hookerianum, Berberis tinctoria, Mahonia leschenaultia, Usnea complanta, Stirt Usneaceae, Tagetes minuta, Leucas lavandulaefolia, Melia dubia, Azadirachta indica, Santolina chamaecyparissus,
Cryptostegia grandiflora, Daucus carota, Rosmarinus officinalis,
Of the 18 plant extracts tested, three (H. mysorense, H. hookerianum and U. complanta) were found to exhibit potent antiviral activity. H. mysorense and H.hookerianum are used in the treatment for anxiety and inflammation traditionally. Hypericum perforatum from the same species is reported for its antiviral activity against human immunodeficiency virus (HIV) and hepatitis C virus. Three plant species Hypericums connatum, Hypericum caprifoliatum and Hypericum polyanthemum (Guttiferae), growing in Southern Brazil were chemically investigated and tested for their antiviral activity against feline immunodeficiency virus (FIV). Our results showed that H. mysorense and H. hookerianum suppressed HSV-1 infection.
The results from this preliminary investigation provide evidence of the importance of ethnopharmacology as a guide to the screening of biologically active plant materials. We used 100 per cent inactivation to define an extract with antiviral activity, but many extracts had partial antiviral activity. These extracts may have compounds that are true antiviral, but are present at quantities insufficient to inactivate all infectious virus particles. It is possible that the elucidation of active constituents in these plants may provide useful lead to the development of new and effective antiviral
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