Acute oral toxicity and neurobehavioural toxicological effects of hydroethanolic extract of Boophone disticha in rats

Boophone disticha (B. disticha) has been used systemically in traditional medical practice in Zimbabwe and neighbouring countries for the management of various central nervous system conditions including hysteria. Abuse of the plant by teenagers in Zimbabwe for its claimed hallucinogenic effects has also been reported, with the advent of serious toxicity in some cases. In the present work, we describe the acute toxicity and neurotoxicological effects of a freeze dried hydro-ethanolic plant extract of the bulb of B. disticha. Thirty-three adult (6—12 weeks old), non-pregnant female Sprague Dawley rats were used for the oral LD₅₀ estimation. Animals were given doses of 50, 120, 240, 360, 500 and 700 mg/kg and were observed using a modified Functional Observation Battery (FOB) for behavioural toxicity. The estimated oral LD₅₀ of the plant extract was between 120 and 240 mg/kg. For doses of 240 mg/kg and less, signs of toxicity began approximately 10 minutes after gavage, and the most prominent initial signs were head tremors (at 50 mg/kg) and body tremors, severe body tremors(>360 mg/kg) followed by convulsions. Generally, symptoms of toxicity lasted approximately 2 hours for doses of 240 mg/kg and less; and 3 hours for doses over 240 mg/kg for animals that survived. These results point to a rapid gastrointestinal absorption of the active principles in the plant extract. The most prominent neurotoxicological effects were increased flaccid limb paralysis and spastic hind-limb paralysis. Tachypnoea was noted at low doses and higher doses produced laboured breathing. The retropulsion observed with higher doses could indicate the reported hallucinogenic effects of the plant extract.