The Effects of Abscisic Acid on Angiogenesis in Both ex vivo and in vivo Assays

BACKGROUND: Angiogenesis is a complex biological process wherein novel capillary blood vessels mature from pre-existing vasculature for delivering tissues with oxygen and nutrients. Natural molecules that have anti-angiogenic activity and toxicity can raise the focus on using plant sources as essential therapeutic agent. OBJECTIVE: The current research was intended to estimate the probable anti-angiogenic activity of abscisic acid alone and in combination with prednisolone, a well-known angiostatic glucocorticoid. Methods: two months old albino rats were used in this study. ABA and prednisolone stock solutions were prepared and added after embedding aortic rings in growth media. The ex vivo rat aorta ring assay (RAR) was applied to explore the anti-angiogenic effect of ABA. The in vivo chorioallantoic membrane assay (CAM) was applied to quantify the blood vessels inhibition zone by ABA effect. That zone was calculated as the mean inhibition region on eggs in mm ± SD. RESULTS: Abscisic acid screened byex vivo and in vivo assays, revealed a significant dose-dependent blood vessels inhibition in comparison to the negative control with IC50= 7.5µg/ml and a synergism effect when combined with prednisolone. CONCLUSION: The synergism activity of ABA with prednisolone can significantly inhibit blood vessels growth in RAR and CAM assays. These results shed the light on the potential clinic values of ABA, and prednisolone combination in angiogenesis-dependent tumors.