Constituents in purple sweet potato leaves inhibit in vitro angiogenesis with opposite effects ex vivo

Objective: The aim of this study was to investigate the in vitro effect of polyphenols in purple sweet potato leaves (PSPLs) on angiogenesis in human umbilical vascular endothelial cells (HUVECs). The ex vivo effect was test in human serum collected from the subjects who consumed 200 g of PSPL in a low polyphenol diet versus a low polyphenol diet. Methods: Methanolic extract from PSPLs and human sera from subjects were treated with HUVECs and the effects of cell proliferation, migration, tube formation, and matrix metalloproteinase activity were investigated. Results: The PSPL polyphenols at 0.2 to 0.6 mM gallic acid equivalents inhibited proliferation, migration, and tube formation of vascular endothelial growth factor-treated HUVECs. Further, the activity of secreted matrix metalloproteinase-2 was decreased by at least 13.8%. However, 5% PSPL serum increased migration and tube formation of HUVECs by 110% and 56.9%, respectively, compared with serum from subjects on the low polyphenol diet. Further, the activity of matrix metalloproteinase-9 was increased by 128% in the PSPL serum. Conclusion: These results suggest that PSPL polyphenols inhibited in vitro angiogenesis, but PSPL constituents might shift serum biochemistries to be more proangiogenic.