Toxicity evaluation and anti-ischemic stroke activity of selected natural extracts in zebrafish

Natural products are used in the discovery of novel therapeutic agents. Ischemic stroke is a neurological disorder caused by the obstruction of cerebral blood vessels, sometimes leading to paralysis and potentially death. Despite the complexity of this condition, therapeutic options are limited and typically associated with severe side effects, including intracranial hemorrhage. The present study aimed to explore the toxicity and anti-ischemic stroke activity of aqueous extracts from the aerial parts of gotu kola (Centella asiatica; CA), moringa leaves (Moringa oleifera; MO), turmeric rhizomes (Curcuma longa; CL), black pepper seeds (Piper nigrum; PN), and snakehead fish fillets (Channa striata; CS) in zebrafish. Toxicity tests were conducted in zebrafish embryos for 96 h. Ischemic stroke was induced in zebrafish larvae incubated in ponatinib (Pon) solution. In total, three concentrations of each extract, namely ¼ of the 10% lethal concentration (LC₁₀), ½ LC₁₀ and LC₁₀, were derived from toxicity testing and applied in anti-ischemic stroke assays. All extracts were considered non-toxic as their LC₅₀ values were >100 µg/ml. At certain concentrations, the extracts decreased hatching (>625 µg/ml CA and CL, >250 µg/ml MO, and >125 µg/ml CS) and survival rates (>625 µg/ml CA, >250 µg/ml MO, >156.25 µg/ml, >125 µg/ml PN and CS) and resulted in morphological deformity. Moreover, CA, MO, CL and CS, especially at their highest concentrations, significantly decreased the area of cerebral thrombosis compared with the Pon group. CA, MO, PN and CS ameliorated locomotor deficits following ischemia, as evidenced by significant improvements in average speed and total distance traveled. Among all extracts, CS at 29 µg/ml showed the greatest potential for development as an ischemic stroke treatment, exhibiting the strongest effects in preventing blood vessel blockage and restoring locomotor function following ischemia.