Abstract
Context: Oridonin, isolated from the leaves of Isodon rubescens (Hemsl.) H.Hara (Lamiaceae), has good antitumor activity. However, its safety in vivo is still unclear.Objective: To investigate the preliminary safety of oridonin in zebrafish.Materials and methods: Embryo, larvae and adult zebrafish (n = 40) were used. Low, medium and high oridonin concentrations (100, 200 and 400 mg/L for embryo; 150, 300 and 600 mg/L for larvae; 200, 400 and 800 mg/L for adult zebrafish) and blank samples were administered. At specific stages of zebrafish development, spontaneous movement, heartbeat, hatching rate, etc., were recorded to assess the developmental effects of oridonin. VEGFA, VEGFR2 and VEGFR3 gene expression were also examined.Results: Low-dose oridonin increased spontaneous movement and hatching rate with median effective doses (ED50) of 115.17 mg/L at 24 h post-fertilization (hpf) and 188.59 mg/L at 54 hpf, but these values decreased at high doses with half maximal inhibitory concentrations (IC50) of 209.11 and 607.84 mg/L. Oridonin decreased heartbeat with IC50 of 285.76 mg/L at 48 hpf, and induced malformation at 120 hpf with half maximal effective concentration (EC50) of 411.94 mg/L. Oridonin also decreased body length with IC50 of 324.78 mg/L at 144 hpf, and increased swimming speed with ED50 of 190.98 mg/L at 120 hpf. The effects of oridonin on zebrafish embryo development may be attributed to the downregulation of VEGFR3 gene expression.Discussions and conclusions: Oridonin showed adverse effects at early stages of zebrafish development. We will perform additional studies on mechanism of oridonin based on VEGFR3.
Highlights
Angiogenesis, the endothelium-derived development of new blood vessels, plays a crucial role in biological and pathological processes
The solution was serially diluted in 100% dimethyl sulfoxide (DMSO) that was 1000 times more concentrated to allow for a 1:1000 dilution with embryo medium (EM) (0.137 M NaCl, 5.4 mM KCl, 0.25 mM Na2HPO4, 0.44 mM KH2PO4, 1.3 mM CaCl2, 1.0 mM MgSO4 and 4.2 mM NaHCO3) (Westerfield 2000) to create a serial dilution with a final DMSO concentration of 1%
The first observed effect of oridonin on zebrafish embryo development was the influence on the spontaneous movement frequency from 24 to 30 hpf
Summary
Angiogenesis, the endothelium-derived development of new blood vessels, plays a crucial role in biological and pathological processes. Specific antiangiogenic agents are an attractive therapeutic approach in treating angiogenesis-dependent diseases, in solid tumour progression and diabetic retinopathy (Carmeliet and Jain 2011). Vascular endothelial growth factor (VEGF) is one of the most important and specific angiogenic factors that regulate normal physiological and pathological neovascularization. VEGFR2 and VEGFR3 are important receptors that mediate the angiogenic activity of VEGF through distinct signal transduction pathways that regulate endothelial cell proliferation, migration, differentiation and tube formation (Shibuya 2011). To discover safe and efficient agents for treating angiogenesis-related diseases, researchers have focused on developing small-molecule therapeutic strategies that target the VEGF signalling pathway (Siveen et al 2017)
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