Developing a zebrafish-based pipeline to investigate the biological properties of medicinal plant extracts from Northern Vietnam

Purpose: Traditional medicines have been used in Vietnam for thousands of years, and still play an essential role in healthcare. However, so far, there is no clear definition of circumstances in which plants can be collected, conserved, and extracted; viable models for a productive and sustainable exploitation of natural extracts are missing, sometimes leading to severe and unfavorable consequences on health. In this study, we aim to develop a cost-effective pipeline to assess the pharmaco-/toxicological properties of these medicinal materials using the zebrafish embryo as an in vivo model.
Methods: Medicinal plants extracts were prepared by incorporating in the design more standardized methods as the traditional ones, using increasing polarity solvents. After that, the zebrafish has been chosen as a whole animal model to determine the core of the biological properties of a specific extract. Embryotoxicity was analyzed by exposing extracts to zebrafish embryos, which were monitored at specific times during 4 days for survival and the presence of developmental malformations. In addition, the zebrafish transgenic line Tg(fli1:EGFP) displaying fluorescent endothelial cells was used to visualize blood vessels and detect effects on angiogenesis. Proof-of-concept experiments were done by passing samples from two plants: Caesalpinia sappan L. and Glochidion eriocarpum to evaluate its efficiency.
Results: Effects of C. sappan L. extract on zebrafish embryonic morphology and lethality were determined in the corresponding concentration-response curves (LC50=500 mg/L and EC50=40 mg/L). Analysis of transgenic zebrafish showed the anti-angiogenic properties in a dose dependent manner. In addition, the interaction between this plant extract and the embryo chorion was explored. On the other hand, G. eriocarpum extract exposure led to a biphasic response from the zebrafish embryos, suggesting a protective role of the embryonic chorion. Our results may contribute to the design of a rational high throughput pharmacological screening approach using the zebrafish model.