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Toxicity and Carcinogenicity of Some South Mrican Cycad (<i>Encephalartos</i>) Species
Abstract
The carcinogenicity of 4 species of South African cycads is reported for the first time. Different quantities of the various parts of the cones of Encephalartos umbe/uziensis, E. villosus, E. lebomboensis and E. laevifolius were incor-porated into the diet of rats for varying periods of time. Renal nephroblastomas were produced in some rats receiving mixtures of the kernel and outer flesh of the seeds of E. umbe/uziensis, outer flesh only of E. villosus, E. lebomboensis and E. laevifolius, and the kernel of E. laevifolius. The latter also caused the development of a renal carcinoma in one rat. Hepatocellular carcinomas were present in some rats which had received mixtures of the kernel and outer flesh of E. umbe/uziensis and E. villosus. All 4 cycads tested caused acute intoxication in rats, and this resulted in centrilobular hepatocellular necrosis, while chronic intoxication produced nodular hyperplasia of the liver and hyperplastic and hypertrophic alterations in the kidney tubular epithelium. Chronic changes in the liver and kidney were seen in some of the rats fed the peduncles and/or scales of 2 of the cycad species.
