Sparstolonin B Inhibits Pro-Angiogenic Functions and Blocks Cell Cycle Progression in Endothelial Cells

Abstract

Sparstolonin B (SsnB) is a novel bioactive compound isolated from Sparganium stoloniferum, an herb historically used in Traditional Chinese Medicine as an anti-tumor agent. Angiogenesis, the process of new capillary formation from existing blood vessels, is dysregulated in many pathological disorders, including diabetic retinopathy, tumor growth, and atherosclerosis. In functional assays, SsnB inhibited endothelial cell tube formation (Matrigel method) and cell migration (Transwell method) in a dose-dependent manner. Microarray experiments with human umbilical vein endothelial cells (HUVECs) and human coronary artery endothelial cells (HCAECs) demonstrated differential expression of several hundred genes in response to SsnB exposure (916 and 356 genes, respectively, with fold change ≥2, p<0.05, unpaired t-test). Microarray data from both cell types showed significant overlap, including genes associated with cell proliferation and cell cycle. Flow cytometric cell cycle analysis of HUVECs treated with SsnB showed an increase of cells in the G1 phase and a decrease of cells in the S phase. Cyclin E2 (CCNE2) and Cell division cycle 6 (CDC6) are regulatory proteins that control cell cycle progression through the G1/S checkpoint. Both CCNE2 and CDC6 were downregulated in the microarray data. Real Time quantitative PCR confirmed that gene expression of CCNE2 and CDC6 in HUVECs was downregulated after SsnB exposure, to 64% and 35% of controls, respectively. The data suggest that SsnB may exert its anti-angiogenic properties in part by downregulating CCNE2 and CDC6, halting progression through the G1/S checkpoint. In the chick chorioallantoic membrane (CAM) assay, SsnB caused significant reduction in capillary length and branching number relative to the vehicle control group. Overall, SsnB caused a significant reduction in angiogenesis (ANOVA, p<0.05), demonstrating its ex vivo efficacy.

Determination of sparstolonin B by ultra‐high performance liquid chromatography coupled with triple quadrupole mass spectrometry: application to pharmacokinetic study of sparstolonin B in rat plasma

“…1; Liang et al, 2011). Selectively, it can block TLR2-and TLR4-mediated macrophages inflammatory responses (Liang et al, 2011), attenuate hypoxia-reoxygenation-induced cardiomyocyte inflammation (Liu et al, 2014b), suppress lipopolysaccharide-induced inflammation in human umbilical vein endothelial cells (Liang et al, 2013, b) and inhibit pro-angiogenic functions and blocks cell cycle progression in endothelial cells (Bateman et al, 2013). Several chemical constituents such as trans-stilbenoids, triterpenoids, flavonoids and phenolic acids have been reported (Nakajima et al, 1987;Powell et al, 1987;Kang et al, 2008;Zhang and Wang, 2009;Cui et al, 2012).…”

“…1; Liang et al, 2011). The dried tuber of Scirpus yagara Ohwi is a widely used traditional Chinese medicine (TCM), which is used for the treatment of several inflammatory diseases and tumors in China (Qiu et al, 2008;Bateman et al, 2013;Kumar et al, 2014). Several chemical constituents such as trans-stilbenoids, triterpenoids, flavonoids and phenolic acids have been reported (Nakajima et al, 1987;Powell et al, 1987;Kang et al, 2008;Zhang and Wang, 2009;Cui et al, 2012).…”

“…Recent research has characterized SsnB as a selective Toll-like receptor 2 (TLR2) and TLR4 antagonist. Selectively, it can block TLR2-and TLR4-mediated macrophages inflammatory responses (Liang et al, 2011), attenuate hypoxia-reoxygenation-induced cardiomyocyte inflammation (Liu et al, 2014b), suppress lipopolysaccharide-induced inflammation in human umbilical vein endothelial cells (Liang et al, 2013, b) and inhibit pro-angiogenic functions and blocks cell cycle progression in endothelial cells (Bateman et al, 2013). Furthermore, SsnB can induce reactive oxygen species generation and promote apoptotic cell death in neuroblastoma cells of different genetic backgrounds (Kumar et al, 2014).…”

Total synthesis of Sparstolonin B, a potent anti-inflammatory agent

“…[1][2][3] TLRs play an essential part in the perception of microbes and shape the complex host responses that occur during infection. 4 However, the signalling initiated by TLRs is a double-edged sword since a prolonged and exaggerated response can cause tissue and organ damage.…”

“…Bronsted and Lewis acids such as Yb(OTf) 3 , Zn(OTf) 3 and ZnCl 2 were screened in order to improve the yield. In the presence of 1.0 equivalent of ZnCl 2 , we found the yield of SsnB could be improved to 60% when 30 mg of 5 was used.…”