In vitro screening of traditional medicines for anti-HIV activity: Memorandum from a WHO meeting (*1)
Traditional medicines are being used empirically in many countries for the treatment of acquired immunodeficiency syndrome (AIDS). Evaluation of these treatments in persons infected with human immunodeficiency virus (HIV) is a new challenge, especially since 5-6 million people are estimated to be infected, and all possible resources must be made available for the benefit of the affected populations. In this context, there is a need to evaluate those elements of traditional medicine, particularly medicinal plants and other natural products, that might yield effective and affordable therapeutic agents. This will require a systematic approach.
Against this background, WHO's Global Programme on AIDS (GPA) and Traditional Medicine Programme (TRM) convened an informal Consultation in Geneva, from 6 to 8 February 1989, with the following objectives:
-- to review the status of research in traditional medicine as applied to HIV infection and AIDS;
-- to review current activities in the area of medicinal plants and other natural products in relation to in vitro and in vivo preclinical evaluation for antiretroviral or anti-reverse-transcriptase activity; and
-- to identify opportunities for collaborative work and make appropriate recommendations.
A variety of plant products are being used by AIDS patients without any experimental evidence of anti-HIV activity. They include garlic (Allium sativum), shiitake mushrooms (Lentinus edodes), papaya (Carica papaya), ginseng (Panax species), Aloe vera, Ukrain (Chelidonium majus), immunact (a Peruvian plant root), Japanese pine cone extract, various flower essences, Easter lily bulbs, Fu-zheng (a Chinese traditional principle of treatment), and Padma 28 (a Tibetan formula of several plants). A number of other marine, fungal and animal products have also been used.
Traditional medicines are employed for the treatment of AIDS in all WHO regions. In African countries, many patients with a hospital diagnosis of AIDS seek alternative treatment among traditional practitioners when they see no change in their condition. In some cases, follow-up studies are effected by physicians in AIDS clinics and counselling centres. Generally, traditional practitioners voluntarily come forward to offer their remedies for scientific evaluation, especially when they see that patients on such therapies continue to be maintained in a reasonable state. Observations have shown that certain plants appear to be common to most of the infusions or concoctions given to patients. Some of these have biological activities which qualify them as candidates for further study for anti-HIV activity. For example, Diospyros usambarensis (Ebenaceae) has been found to possess fungicidal and cytotoxic properties.
Traditional Chinese Medicine is being used in AIDS patients in the United Republic of Tanzania, with the collaboration of Chinese and Tanzanian scientists. The research protocol for these studies stipulates that every year, for three years, 200 AIDS patients at different stages of the disease would be treated, with the same number of patients to be used as controls. A basic therapeutic recipe is prescribed which, during the trial, could be modified depending on the clinical manifestations. Some of the preparations used in the basic recipes include Polyporus umbellatus, Cordyceps sinensis and Paeonia obovata. A special outpatient clinic has been set up for follow-up studies of discharged patients. Immunological parameters to determine the T-lymphocyte subsets have been established and are being monitored. So far, 17 seropositive patients have been treated and some symptomatic improvement claimed.
Only a few experimental studies to discover anti-HIV agents from medicinal plants and other natural products are in progress. …