oPC's derived commercially from grape seeds and the bark of pine trees, is a mixture of antioxidant molecules, variously called proanthocyanidins, procyanidins, proanthocyanidolic oligomers (PCO) or Oligomeric Procyanthocyanidins (OPC).oPC, as it's commonly called in scientific circles, is expert at treating vascular diseases because it actually increases the structural strength of weakened blood vessels. It also has other biological activity. OPC is one of the most potent antioxidants known -- fifty times as powerful as vitamin E, according to some tests. OPC's can help neutralize the underlying chemical cause (free radicals) that promotes most diseases.oPC's derived commercially from grape seeds and the bark of pine trees, is a mixture of antioxidant molecules, variously called proanthocyanidins, procyanidins, proanthocyanidolic oligomers (PCO) or Oligomeric Procyanthocyanidins (OPC).oPC, as it's commonly called in scientific circles, is expert at treating vascular diseases because it actually increases the structural strength of weakened blood vessels. It also has other biological activity. OPC is one of the most potent antioxidants known -- fifty times as powerful as vitamin E, according to some tests. OPC's can help neutralize the underlying chemical cause (free radicals) that promotes most diseases.oPC's derived commercially from grape seeds and the bark of pine trees, is a mixture of antioxidant molecules, variously called proanthocyanidins, procyanidins, proanthocyanidolic oligomers (PCO) or Oligomeric Procyanthocyanidins (OPC).