Antibacterial and Zebrafish-based Screening for Wnt Signal Inhibitory Activities of Syzygium polycephaloides (C.B. Robb. Merr.) Bark Extracts

Abstract

Syzygium polycephaloides, a plant native to Southeast Asia, is used to cure common illnesses. In this study, the methanolic bark extracts of S. polycephaloides was evaluated for their antibacterial activity and screened for their Wnt signal inhibitory activity using zebrafish-based assay. In the antibacterial assay, the extracts were tested against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeroginosa, and Escherichia coli using disk diffusion assay. On the other hand, zebrafish-based screening was used to determine the inhibitory potential of S. polycephaloides against the Wnt signal. Zebrafish embryos were treated with LiCl to upregulate the Wnt signal which produces eyeless phenotype. The methanolic extracts had antibacterial activity against the test microorganisms except P. aeruginosa. After fractionation, ethyl acetate (EtOAc) and aqueous fractions exhibited wide-spectrum antibacterial activity. For the Wnt signal inhibitory activity screening, the LiCl-treated embryos were rescued to their normal eye development after treatment with the S. polycephaloides bark extracts (100 g/mL). The results suggest that the extracts may have inhibited the Wnt signal. This study shows that the S. polycephaloides is a potent source of antibacterial compounds and Wnt inhibitors.

Keywords

• disk-diffusion assay
• lithium chloride
• xav939