Procyanidin C1 is extracted from the fruits of Vitis vinifera L. It is a B type proanthocyanidin and found in grape. It belongs to a polyphenol flavonoid epicatechin trimer. It can decrease cytokine production of mast cells and Fc epsilon RI-mediated degranulation in vitro dose-dependently. It inhibits ROS generation in stimulated mast cells and the tyrosine phosphorylation of Syk and linker for activation of T cells. It may be used for the treatment of cardiovascular diseases and may be useful as a lead compound to develop inhibitors of cancer metastasis and other diseases related to EMT. It has HIV-related, antioxidant and anti-inflammatory effects. It also inhibits the activity of 15-lipoxygenase and α-glucosidase. It could scavenge 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radicals.