Procyanidin A1 is an A type proanthocyanidin dimer.
It is an epicatechin-(2òâÂÂ7,4òâÂÂ8)-catechin dimer found in Rhododendron spiciferum, in peanut skins and in Ecdysanthera utilis.
Procyanidin B1 can be converted into procyanidin A1 by radical oxidation using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals under neutral conditions.