Inhibiting Angiogenesis by Anti-Cancer Saponins: From Phytochemistry to Cellular Signaling Pathways

Saponins are one of the broadest classes of high-molecular-weight natural compounds, consisting mainly of a non-polar moiety with 27 to 30 carbons and a polar moiety containing sugars attached to the sapogenin structure. Saponins are found in more than 100 plant families as well as found in marine organisms. Saponins have several therapeutic effects, including their administration in the treatment of various cancers. These compounds also reveal noteworthy anti-angiogenesis effects as one of the critical strategies for inhibiting cancer growth and metastasis. In this study, a comprehensive review is performed on electronic databases, including PubMed, Scopus, ScienceDirect, and ProQuest. Accordingly, the structural characteristics of triterpenoid/steroid saponins and their anti-cancer effects were highlighted, focusing on their anti-angiogenic effects and related mechanisms. Consequently, the anti-angiogenic effects of saponins, inhibiting the expression of genes related to vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-α (HIF-1α) are two main anti-angiogenic mechanisms of triterpenoid and steroidal saponins. The inhibition of inflammatory signaling pathways that stimulate angiogenesis, such as pro-inflammatory cytokines, mitogen-activated protein kinase (MAPKs), and phosphoinositide 3-kinases/protein kinase B (PI3K/Akt), are other anti-angiogenic mechanisms of saponins. Furthermore, the anti-angiogenic and anti-cancer activity of saponins was closely related to the binding site of the sugar moiety, the type and number of their monosaccharide units, as well as the presence of some functional groups in their aglycone structure. Therefore, saponins are suitable candidates for cancer treatment by inhibiting angiogenesis, for which extensive pre-clinical and comprehensive clinical trial studies are recommended.

The effect of quercetin supplementation on selected markers of inflammation and oxidative stress

BACKGROUND

Athletes use flavonoids as antioxidant to enhance endurance and physical performance. In vitro data indicate flavonoids have antioxidative and antiinflammatory functions but data in human studies are limited. The aim of this study was to determine the effects of a 2-month flavonoid quercetin supplementation on oxidative stress and inflammatory biomarkers in nonprofessional athletes with regular exercise.

MATERIALS AND METHODS

The randomized double-blind clinical trial was done among subjects with systematic and regular exercise for 8 weeks in four groups, each containing 15 individuals: 500 mg quercetin + 250 mg vitamin C as pro-oxidant (Q+C), 500 mg of quercetin alone (Q), 250 mg of vitamin C alone (C), and placebo (Control). IL-6, CRP, E-selectin and F2-isoprostane were measured before and after intervention.

RESULTS

In 60 participants with mean (±SD) age of 21.0 ± 1.6 years, statistically significant within group differences were observed in IL-6 (P<0.1), CRP (P<0.01) and F2-isoprostane for group 1 and pre- and postchanges in E-selectin was marginally significant for all study groups (P<0.1). Group 1 had marginally smaller F2-isoprostane (P<0.1) and interleukin 6 than control group (P<0.05) and there were marginally differences in CRP between respondents in group 1 and 2 with the control group (P<0.1).

CONCLUSIONS

Eight-week supplementation with quercein-vitamin C was effective in reducing oxidative stress and reducing inflammatory biomarkers including CRP and IL-6 with little effect on E-selectin in healthy subjects.

Flavonol Glycosides from Euphorbia microsciadia Bioss. with their Immunomodulatory Activities

FOUR KNOWN FLAVONOIDS

quercetin 3-O-β-D-rutinoside (Q3Rut), myricetin 3-O-β-D-galactopyranoside (M3Gal), quercetin 3-O-β-D-galactopyranoside (Q3Gal) and quercetin 3-O-β-D-glucopyranoside (Q3Glc), for the first time were isolated from aerial parts of Euphorbia microsciadia. The chemical structure of them was elucidated on the basis of 1 and 2 D-NMR spectra and different spectroscopic techniques. The immunomodulatory activities of isolated compounds were compared using standard T-cell proliferation assay. These data showed that lymphocyte suppression activity of flavonoids (1-4) were comparatively lower than prednisolon as a standard drug. Immunosuppressive activity of flavonoids with hydroxyl groups at both 3'-and 4'-positions in their B-ring (Q3Gal) were more than those with 3'-,4'-and 5'-hydroxyl substitution (M3Gal). In these compounds, Q3Gal showed the most inhibitory activity, whereas M3Gal showed the least lymphocyte antiprolifeartive activity.