Evaluation of developmental toxicity and apoptotic induction of the aqueous extract of Millettia pachycarpa using zebrafish as model organism

Abstract

Extensive and indiscriminate use of synthetic compounds and natural compounds obtained from plant sources have resulted in serious threats to the aquatic ecosystem and human health. Aqueous extract of the root of the plant, Milletia pachycarpa Benth, is currently used for killing fish in the state of Manipur, India. Moreover, this plant is also used as traditional medicine in this region. Although it is widely used in traditional medicine, there is limited information available regarding the adverse effects and mechanism underlying its toxicity. This study examined the effects of exposure to aqueous extract of M. pachycarpa (AEMP) on early embryonic development of zebrafish embryos and mechanisms underlying toxicity. Zebrafish embryos treated with different concentrations of the AEMP produced embryonic lethality and developmental defects. The 96-hr-LC₅₀ of AEMP was found to be 4.276 µg/mL. Further, multiple developmental abnormalities such as pericardial edema, yolk sac edema, spinal curvature, swim bladder deflation, decreased heart rate, and delayed hatching were also observed in a dose-dependent manner. Zebrafish embryo showing moderate-to-severe developmental defects following AEMP exposure cannot swim properly. Further, this study examined oxidative stress and apoptosis in embryos exposed to AEMP. Enhanced production of ROS and apoptosis was found in brain, trunk, and tail of zebrafish embryos treated with AEMP. Data suggest that oxidative stress and apoptosis are associated with AEMP-induced embryonic lethality and developmental toxicity in zebrafish embryos.

Keywords:

• developmental toxicity
• apoptosis
• oxidative stress
• Millettia pachycarpa
• zebrafish
• pericardial edema

Acknowledgements

We thank Department of Life Sciences, Manipur University, Canchipur, India, and UGC for providing financial assistance during the research period. Financial assistance from the Indian Institute of Science (IISc), University Grant Commission – Departmental Research Support and Department of Science and Technology – Fund for Improvement of S&T Infrastructure in Higher Educational Institutions, Government of India, is also acknowledged. We thank Ms Meenakshi Sen and Ms Deepti Bapat at IISc Confocal Facility for their help in taking confocal images.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We thank Department of Life Sciences, Manipur University, Canchipur, India, and UGC for providing financial assistance during the research period. Financial assistance from the Indian Institute of Science (IISc), University Grant Commission – Departmental Research Support and Department of Science and Technology – Fund for Improvement of S&T Infrastructure in Higher Educational Institutions, Government of India, is also acknowledged.