Toxicity of Methanolic Extract of Fruits of Catunaregam spinosa (Rubiaceae) on Danio rerio Embryos

Aims: Catunaregam spinosa is an exotic plant in Sri Lanka. Fruits of this plant contain saponins, steroids, flavonoids possessing piscicidal property. Since years ago C. spinosa employs in the fishery industry, especially in rural areas. This study was established to evaluate the toxicity and the teratogenic effects of fruits of C. spinosa on D. rerio embryos.

Methodology: Semi-static renewal method was conducted to determine the median lethal concentration. Concentrations of 15.0, 17.0, 19.0, 21.0, 23.0 and 25.0 mg L-1 were tested with twenty embryos per treatment. Each concentration was triplicated. Dilution water and 3, 4- Dichloroaniline at 4.0 mg L-1 were tested for negative and positive controls respectively. Four apical observations and teratogenic effects were examined at 24, 48, 72 and 96 h time intervals.

Results: Embryos exposed to 19.5 mg L-1 concentration exhibited 50% mortality at p = 0.05 significance level. Embryos exposed to high concentrations exhibited more teratogenic deformities with a high mortality rate. Negative control recorded >90 % survival rate and positive control 95.0% lethality after 96 h exposure. Hatchability was negatively correlated with the concentration of the extract.

Conclusion: Methanolic fruit extract of C. spinosa showed concentration-dependent mortality and the teratogenic effects on D. rerio embryos. It could be concluded that the fruits of C. spinosa show moderate piscicidal activity.