Teratogenic Potential Of 4-O-Methylhonokiol On Japanese Medaka (Oryzias Latipes) Embryogenesis

The present study was aimed to evaluate the teratogenic potential of 4-O-methylhonokiol (4-O-MH), a neolignan isolated from Magnolia grandiflora seeds, using Japanese medaka embryogenesis as an experimental model. Fertilized medaka eggs (Iwamatsu stage 10) were exposed to 1, 2, 5, and 10 µM 4-O-MH for 0 – 6 day post fertilization (dpf) and the heart beats, vessel circulation, thrombus formation, hatching efficiency, and mortality were evaluated. Heartbeats were determined on 3 and 6 dpf embryos. Compared to control embryos, heartbeats were found to be decreased significantly in 2, 5, and 10 µM groups in 6 dpf. Thrombi were seen only in embryos exposed to 5 and 10 µM 4-O-MH that can cause significant delay in vessel circulation. The embryos exposed to 5 and 10 µM 4-O-MH for 0 – 6 dpf reduced hatching efficiency in comparison with the control, 1, and 2 µM groups. The calculated IC₅₀ as determined on 10 dpf from three independent experiments is 5.99 µM. These preliminary data suggested that 4-O-MH might be a teratogen with potential effect on the cardiovasculature and hatching and ultimately reduce the survivability of the embryos.

Acknowledgements: Thanks go to the United States Department of Agriculture, Agriculture Research Service, Specific Cooperative Agreement No.1UO1FD004246.