Herbal Medicine to treat Tropical Infectious Diseases – “Old Hat” or New Hope?

Neglected Tropical Diseases (NTDs) are a group of about 20 transmissible conditions affecting mainly populations living in poor socioeconomic conditions, often in remote rural areas of tropical countries. Lowering the development and production costs of new drugs is particularly important when dealing with these diseases because new treantments not only have to be safe and efficacious but must also be affordable as well as easy to use for the affected people. To this end, drug repositioning or repurposing is a promising approach to find new therapy options at dramatically reduced develoment costs. As a result of a screening of established and commerically available herbal medicinal products (HMPs) for activity against the infectious agents responsible for the NTDs Human African Trypanosomiasis, Chagas Disease, Visceral Leishmaniasis as well as Malaria, various preparations showed interesting activity in vitro. Among these, Arnica tincture (Ph. Eur.) stood out with particularly strong activity against Trypanosoma brucei but also against Leishmania donovani [1]. Following the EMA recommendation that Arnica should not be used internally, the tincture was tested in an animal model for its therapeutic potential against cutaneous Leishmaniasis (CL). The cure rate of Gold Hamsters with CL caused by Leishmania braziliensis as well as L. tropica treated topically with Arnica tincture was distinctly better than that of the standard drug, meglumine antimoniate (Glucantime), injected into the lesion [2, 3]. A first observational study with human patients is therefore being conducted and appears to lead to a very high rate of definite cures. Of the 7 patients which have currently finished the study (June 2024), all were cured and no relapses were registered after 30 or 45 days of topical AT treatment followed by 180 days post-treatment observation. Three further patients, currently under post treatement observation, have shown initial cure or improvement. These results are extremely promising in view of the severeness of this skin infection and the difficulties in finding/developing new, safe and efficacious treatments. Repositioning of AT as a new treatment for CL still requires extended clinical trials with a higher number of patients and more complex cases of CL, which are therefore currently in preparation.