It is an epicatechin trimer found in grape (Vitis vinifera),[1] unripe apples,[2] and cinnamon.

[3] Procyanidin C1 can be isolated from grape seed extract.

The structure of benzylated procyanidin C2 was confirmed by comparing the 1H NMR spectra of protected procyanidin C2 that was synthesized by two different condensation approaches.

[5] Procyanidin C1 has been shown to be an effective senolytic agent in wild-type mice, with effects of increased lifespan, reduced senescence markers and making them fitter.

It was also found to greatly increase the effectiveness of chemotherapy in mice in which human prostate tumor cells were implanted.