Procyanidin C1

Procyanidins are a sub class of proanthocyanidins (PACs), formed from (+) catechin and (-) epicatechin subunits. Depending on the nature of the interflavan bonds Procyanidins are categorized into A-type and B-type. B-type procyanidins have a single interflavan bond. A-type procyanidins differentiate themselves from B-type procyanidins by containing a second interflavan bond between at least one set of subunits. The most abundant B-type trimeric procyanidin is Procyanidin C1. It occurs naturally in popular dietary products such as apple skins, cocoa, and grapes. Procyanidin C1 (CAS 37064-30-5) is a linear chain comprising epicatechin subunits in the order: epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin. 

Procyanidin C1 (CAS 37064-30-5) is studied for its HIV-related and antioxidant activities.

The most abundant B-type linear procyanidins in their order of natural concentration include Procyanidin B1, Procyanidin C1, Cinnamtannin A2, and Procyanidin Pentamer E. There is a limited availability of isolates of longer chains of procyanidins because of their decreasing concentration with DP length as well as their difficulty to isolate. Some additional factors leading to difficulty in isolation include:

• larger DP procyanidins tend to have lower stability
• the complexity of the structural variations increases with DP

You can find additional procyanidin reference standards here.