Parasitic diseases remain a major public health problem affecting hundreds of millions of people, particularly in tropical developing countries. The limited availability and affordability of pharmaceutical medicines means that the majority of the world's population depends on traditional medical remedies, and it is estimated that some 20,000 species of higher plant are used medicinally throughout the world. Many well-known drugs listed in the modern pharmacopoeia have their origins in nature, including, for example, quinine from the bark of the Cinchona tree for the treatment of malaria, which has been followed by the subsequent development of the synthetic derivatives chloroquine, amodiaquine, primaquine and mefloquine. More recently, the wider recognition of the antimalarial activity of artemisinin from the herb Artemisia annua has led current research to focus on the development of a large number of synthetic and semisynthetic compounds, which are more active than artemisinin. There is an increasing awareness of the potential of natural products, which may lead to the development of much-needed new antiparasitic drugs. In this chapter, we have drawn together a comprehensive list of medicinal plants and other natural products that have been shown to have activity against human and, to a lesser extent, animal parasites. In addition, some of the opportunities and difficulties in working with natural products have been reviewed and discussed, including the problems involved with evaluating complex mixtures of compounds which may occur in extracts, problems associated with differentiating between general cytotoxicity and genuine antiparasitic activity, and the hope that new technologies will rapidly accelerate new drug discovery and development in this field. Nevertheless, the way forward for natural product medicines, including the conservation of recognized natural products and protection of general biodiversity, the discovery and development process, and the promotion and usage of existing remedies, presents some difficult challenges. Following an initiative by the World Health Organization in August 2000, there is now the opportunity to evaluate scientifically many more traditional medicines and other natural products in validated antiparasite and toxicity screens, which will help establish which substances have potential for new pharmaceutical products. The use of 'untested' traditional medicines will no doubt continue, and there is an urgent need to distinguish between the efficacious and safe products and the ineffective and/or unsafe products, particularly since many remedies are being more widely promoted in developing countries.

Antiparasitic properties of medicinal plants and other naturally occurring products.

OBJECTIVE:To provide a brief overview of the chemical history, analysis, nomenclature, biology, pharmacology, and pharmacotherapy of capsaicin.DATA SOURCES:Chemical Abstracts, Biological Abstracts, and a MEDLINE search were used to identify pertinent literature; selected literature was used in this review.DATA EXTRACTION:Original articles, reviews, and abstracts of articles were used to select material pertinent to the objectives of the review. The volume of material available prohibits comprehensive data extraction.CONCLUSIONS:A history of the use of Capsicum spp. and the predominant active ingredient, capsaicin, the parent compound of a group of vanillyl fatty acid amides, is presented. Distinct structural differences are noted between this compound and the capsaicinoids, especially the synthetic analog nonivamide, which has appeared as an adulterant in capsaicin-labeled products. Analysis shows that although some of these synthetic analogs eventually may prove to be true natural products, conclusive ev...

Capsaicin: Identification, Nomenclature, and Pharmacotherapy

Acute toxicity and mutagenic activity of Mexican plants used in traditional medicine.

Traditional medicine caters for about 80% of the health care needs of many rural populations around the world, especially in developing countries. In addition, plant-derived compounds have played key roles in drug discovery. Malaria is currently a public health concern in many countries in the world due to factors such as chemotherapy faced by resistance, poor hygienic conditions, poorly managed vector control programmes and no approved vaccines. In this review, an attempt has been made to assess the value of African medicinal plants for drug discovery by discussing the anti-malarial virtue of the derived phytochemicals that have been tested by in vitro and in vivo assays. This survey was focused on pure compounds derived from African flora which have exhibited anti-malarial properties with activities ranging from “very active” to “weakly active”. However, only the compounds which showed anti-malarial activities from “very active” to “moderately active” are discussed in this review. The activity of 278 compounds, mainly alkaloids, terpenoids, flavonoids, coumarines, phenolics, polyacetylenes, xanthones, quinones, steroids, and lignans have been discussed. The first part of this review series covers the activity of 171 compounds belonging to the alkaloid and terpenoid classes. Data available in the literature indicated that African flora hold an enormous potential for the development of phytomedicines for malaria.

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The potential of anti-malarial compounds derived from African medicinal plants, part I: a pharmacological evaluation of alkaloids and terpenoids.

In vitro antimalarial activity of limonoids from Khaya grandifoliola C.D.C. (Meliaceae).

Hypoglycemic Activity of Triterpenes and Tannins from Sarcopoterium spinosum and two Sanguisorba Species

Trennung einiger Bestandteile des Lecithins mit Hilfe der Hochleistungs-Flüssigkeits-Chromatographie. II

The medicinal plants, Coutarea latiflora Sesse & Moc. ex. DC. (Hintonia latiflora Bullock) (Rubiaceae) and Exostema caribaeum (Jacq.) Roem. et Schult. (Rubiaceae) were examined for antimalarial properties. Among different crude solvent extracts of the stem bark, the hydrolysed ethyl acetate extracts were shown to have the most potent in vitro antimalarial activity. One compound isolated from the ether extract from Exostema caribaeum showed only moderate activity.

Lj. Kraus

Papers

Hypoglycemic Activity of Triterpenes and Tannins from Sarcopoterium spinosum and two Sanguisorba Species

Trennung einiger Bestandteile des Lecithins mit Hilfe der Hochleistungs-Flüssigkeits-Chromatographie. II

In vitro antimalarial activity of Coutarea latiflora and Exostema caribaeum extracts on Plasmodium falciparum.

Behaviour of vegetable phospholipids in thin-layer chromatography : Optimization of mobile phase, detection and direct evaluation

A neoflavonoid from Coutarea hexandra (Rubiaceae)