WHO: Recommendation of increased use of traditional natural products in the fight against influenza

Hong Kong/China - As from now on the WHO public health research agenda for influenza also includes the exploration of natural products, both in terms of prophylaxis and therapy [1], reported Prof. Dr. Stephan Ludwig, FluResearchNet, University of Muenster/Germany, at an international scientific congress in Hong Kong [2]. His keynote address drew attention to the ongoing and groundbreaking research approaches into antiviral drugs also based on natural products that are studied at his academic institute - which includes the prevention of influenza infections by nonspecifically blocking viral adhesion through herbal extracts.


Cistus incanus spp. Pandalis

The well-known potential of several plant extracts for antimicrobial activity is found in many of the traditional indications described in detail by the current WHO monographs on 118 selected medicinal plants [3]. The virus inhibiting activity of several herbal extracts tested so far is mainly caused by the high concentration of polyphenols, e.g. in the special rockrose extract Cystus052 [3]. The postulated effect is mainly a non-specific blockade of viral surface proteins by the extract, according to Ludwig. In the case of influenza A viruses, the polyphenols inhibit the viral hemagglutinin. Exactly that missing specificity determines both the broad antiviral spectrum and - in contrast to neuraminidase inhibitors - the missing development of resistance during treatment with the aforementioned special extracts of Cistus incanus [5]. This herbal extract, according to the studies at the University of Muenster, has an extremely high content of polymeric polyphenols. In addition, the treatment with Cystus052 had no effects on cellular viability and metabolism, intracellular signaling or cytokine responses. Thus, Ludwig equally assumes a non-specific binding of viruses by the extract ingredients and an absence of pharmacological effect on cells. The unspecific action of the Cistus extract tested in Muenster also accounts for the nearly complete lack of the emergence of resistant viral strains, unlike neuraminidase inhibitors. Meanwhile other groups of scientists could also demonstrate antiviral as well as therapeutic effects by the same special Cistus-extract in animal models and clinical studies. Either with distinct infection-blocking effects (animal model [6]) or by shortening the duration of symptoms and accelerated amelioration of symptoms (RCT [7]).

In Ludwig's opinion there are several substances promising to be efficient tools in the war on influenza while turning practical medicine away from classical immunological concepts for prevention or established post-infectious therapeutic approaches. Doing this, Ludwig emphasized, will be a true paradigm change at least in antiviral research. Although a few phytotherapeutic approaches are already present, medical products from traditional medicine should be given more attention. Not only to comply with WHO recommendations with regard to low resource areas in the world, but also to provide more secure options for influenza prophylaxis and therapy than before. Of course, to follow the WHO recommendations, also more controlled clinical trials with natural products are needed in future.

[1] Global Influenza Programme (WHO): WHO public health research agenda for influenza. WHO Press, Genf, 2010 (http://bit.ly/d2df1C).
[2] Congress: "Options for the Control of Influenza VII". Organizer: International Society for Influenza and other Respiratory Virus Diseases (isirv.org), Hongkong, 2010, September 3-7. (http://www.controlinfluenza.com/webcasts/optionsvii).
[3] World Health Organization: WHO monographs on selected medicinal plants (Vol. 1-4). Genf, 1999-2005.
[4] Hudson JB: The use of herbal extracts in the control of influenza. J Med Plants Res. 2009 Dec;3(13):1189-95.
[5] Ehrhardt C, Hrincius ER, Korte V, Mazur I, Droebner K, Poetter A, Dreschers S, Schmolke M, Planz O, Ludwig S: A polyphenol rich plant extract, CYSTUS052, exerts anti influenza virus activity in cell culture without toxic side effects or the tendency to induce viral resistance. Antiviral Res. 2007 Oct;76(1):38-47.
[6] Droebner K, Ehrhardt C, Poetter A, Ludwig S, Planz O: CYSTUS052, a polyphenol-rich plant extract, exerts anti-influenza virus activity in mice. Antiviral Res. 2007 Oct;76(1):1-10.
[7] Kalus U, Grigorov A, Kadecki O, Jansen JP, Kiesewetter H, Radtke H: Cistus incanus (CYSTUS052) for treating patients with infection of the upper respiratory tract. A prospective, randomised, placebo-controlled clinical study. Antiviral Res. 2009 Dec;84(3):267-71.

Additional informations
WHO: "Improve clinical management of patients: [...] Although antiviral drugs can reduce the duration and severity of illness and help control outbreaks, they are not widely used for treatment or prophylaxis in both under- and well-resourced countries during annual epidemics. They must be taken soon after the onset of illness and resistance can develop. Expansion and optimization of the current repertoire of antiviral drugs and development of clinical research to assess efficacy of putative adjuvant treatment modalities such as immunomodulators, passive immunotherapy and traditional medicine that are suitable for use in under-resourced areas would be most beneficial. [...] Develop novel and effective treatment strategies including adjunctive treatments (e.g. immunomodulators, immunoglobulin, natural products) that are applicable in low resource settings and easy to administer in pediatric and intensive care settings. [...]"
Source: Global Influenza Programme (WHO): WHO public health research agenda for influenza. WHO Press, Geneva, 2010 (http://bit.ly/d2df1C).

Autor/In: Rainer H. Bubenzer, Heilpflanzen-Welt (26.10.2010)