Toxicity of Anthraquinones: Differential Effects of Rumex Seed Extracts on Rat Organ Weights and Biochemical and Haematological Parameters

The genus Rumex and related species such as Rheum and Polygonum are widely used as medicinal herbs and foods. They contain anthraquinones (AQ) such as emodin and chrysophanol as active ingredients, and there is concern about the toxicity of these compounds. This study evaluated the chronic effects of Rumex patientia seed aqueous and ethanolic extracts, in male and female rats separately, on organ weights and over 30 haematological, biochemical and histological parameters, immediately after 14-week administration and after a further period of 15 days without drug treatment. Adverse changes were associated with long-term AQ administration, and these focussed on the liver, lung and kidney, but after 15-day convalescence, most had reverted to normal. In general, male rats appeared to be more susceptible than female rats at similar doses. The water extract produced no irreversible changes, which may reflect the lower dose of the AQ constituents or the presence of different ancillary compounds, and supports the traditional method of extracting Rumex seeds with water. In conclusion, ethanolic extracts of R. patientia caused irreversible pathological changes at very high doses (4000mg/kg), but lower doses and aqueous extracts produced either non-significant or reversible changes. Long-term administration of high doses of AQ extracts over a long period of time should be avoided until further assurances can be given, and given other existing reports of reproductive toxicity, should be avoided altogether during pregnancy. Copyright © 2015 John Wiley & Sons, Ltd.