Toxicological evaluation, antioxidant and in vivo antipsychotic activities of Acanthospermum hispidum DC. and Clerodendrum capitatum (Willd.) Schumach. & Thonn. leaf extracts

Background: Nature provides substances for the treatment of diseases and ailments including psychosis. Acanthospermum hispidum and Clerodendrum capitatum have been reported in ethnobotany for the management of psychosis and Central Nervous System Disorder.

Objective: This study evaluated the leaf extracts of Acanthospermum hispidum (AH) and Clerodendrum capitatum(CC) for their toxicity, antioxidant and antipsychotic activities.

Methods: The methods used were brine shrimp lethality assay for the cytotoxicity and acute toxicity test was conducted using Lorke's method. The antioxidant activity was measured using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), while total phenolic content (TPC) was determined using Folin-Ciocalteu reagent. Antipsychotic property was evaluated in mice using antagonism of ketamine-induced stereotype behaviours and inhibition of hyperlocomotion.

Results: Extract of CC was non-toxic (LC50: 936.3±56.7 µg/mL), while that of AH was relatively toxic (LC50: 402.3±9.1 µg/mL). Acute toxicity (LD50) of >5000.0 and 2154.1 mg/kg b.w. were obtained for CC and AH, respectively. Acanthospermum hispidum had higher, free radical scavenging activity (IC50: 33.9±1.6 µg/mL) and TPC (240.3±4.6 µg GAE/g) than CC (IC50: 219.0±12.0 µg/mL; TPC: 117.9±1.3 µgGAE/g). Crude extract of AH (125-500 mg/kg p.o) significantly suppressed stereotype behaviours induced by ketamine (20 mg/kg i.p) in mice as compared with CC (125-500 mg/kg p.o), suggesting the antipsychotic effect of these plant extracts. The extracts further produced a significant reduction in spontaneous motor activities of the mice.

Conclusion: Leaf extracts of Acanthospermum hispidum and Clerodendrum capitatum demonstrated cytotoxic, antioxidant and significant antipsychotic activity in mice.