Novel Antimalarial Compounds Isolated in a Survey of Self-Medicative Behavior of Wild Chimpanzees in Uganda

Abstract

Following a veterinary and behavioral survey of chimpanzees from a natural population in Uganda, leaf samples of Trichilia rubescens were collected because of the unusual method of ingestion observed. The methanolic crude extract of T. rubescens leaves exhibited significant antimalarial activity in vitro. Bioassaydirected fractionation provided two new limonoids, trichirubines A and B. A greater understanding of the role of secondary compounds in the primate diet may be helpful in recovering naturally occurring compounds of medicinal significance for human medicine.Plant parts which have no apparent nutritive value and/or are rich in secondary compounds are ingested by chimpanzees (10,14,21,22). Medicinal benefits of such ingestion have been suggested (8,9,20) by the observations of two unusual behaviors proposed to control intestinal parasite infection, namely swallowing whole bristly leaves and chewing the bitter pith of Vernonia amygdalina (7,8,18,19). There is no chemical evidence to suggest a role of secondary compounds correlated with the leaf-swallowing behavior: more likely there is a mechanical effect of the surface of the whole rough hispid leaves leading to the expulsion of parasites. Instead of a physical effect, the benefit of bitter pith chewing is pharmacologically based on the activity of steroid glucosides (10,14). In order to provide new information about self-medicative behavior of chimpanzees (Pan troglodytes schweinfurthii) and the phytochemistry of the plants ingested, field studies were conducted in Kanyawara, Kibale National Park, Uganda. The survey included behavioral data collection, as well as fecal and urine analysis of samples coming from identified chimpanzees. Particular attention was focused on sick individuals and unusual or occasional feeding behaviors. We report herein the bioassaydirected fractionation of the crude extracts of the plant leaves of Trichilia rubescens and elucidation of the structure of two limonoids, namely trichirubines A and B, which possess a significant anti-Plasmodium activity.The study was conducted in the Kibale National Park (766 km 2 between 0°13 to 0°41ЈN and 30°19Ј to 30°22ЈE) in western Uganda. Data were collected between December 2000 and March 2001 (dry season) and in October 2001 (rainy season). The area contains mid-altitude moist forest, secondary forest, grassland, swamps, and plantations of Eucalyptus and pines, and it includes elements of lowland tropical rainforest, montane rainforest, and mixed deciduous rainforest. The elevation is between 800 and 1,500 m, and the rainfall averages 1,700 mm per year.The Kanyawara community of wild chimpanzees (P. troglodytes schweinfurthii), including about 50 individuals, was observed. Feeding behaviors were recorded by 10-min focal-animal sessions and ad libitum observations (1). Health state was monitored daily by noninvasive methods consisting of clinical observations, coprological study of 252 stool samples, and urinalysis of 76 samples. We focused our behavioral observations on ill chimpanzees and u...

Self-medication and homeostatic behaviour in herbivores: learning about the benefits of nature’s pharmacy

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Selecting Medicinal Plants for Development of Phytomedicine and Use in Primary Health Care

“…According to Albuquerque and Hanazaki (2008) this approach intends to evaluate the use of secondary metabolites by animals or other non-nutritional substances from plants, aiming to combat diseases or controlling them, as it can be seen in the works developed by Carrai (2003) and Krief (2004). In the latter, it was observed that leaves of Trichilia rubescens Oliv.…”

As pesquisas etnodirigidas na descoberta de novos fármacos de interesse médico e farmacêutico: fragilidades e pespectivas

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