Acute and sub-acute oral toxicity of Brazilian red propolis in rats

Ethnopharmacological relevancePropolis is a bee product widely used in folk medicine due to its numerous pharmacological properties. However, samples from different regions can differ in chemical composition, effectiveness, and side effects. Despite the widespread use of Brazilian red propolis, which is an isoflavone-rich variety, its toxicity has not been carefully studied.Aims of the studyTo assess the acute and sub-acute toxicity of the hydroethanolic extract of red propolis (HERP) administered orally to rats.Materials and methodsHERP for the acute (300 mg/kg) and sub-acute (10, 100 and 200 mg/kg) toxicity studies was administered orally to rats according to OECD Guidelines 420 and 407, respectively. Clinical signs were identified, and hematological and biochemical analyses were performed. Water and food uptake as well as body and organ weights of animals were recorded.Results and conclusionsThe acute study revealed no lethal effects at 300 mg/kg of HERP, but toxic signs were observed, as HERP had an LD50 of more than 300 mg/kg, indicating a warning. The most toxic signals in sub-acute studies were observed in males at a dose of 200 mg/kg HERP. These results suggest estrogen-like activity, possibly from the isoflavones in HERP.

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