The proanthocyanidins (a subclass of the flavonoid family) are the main active ingredients of Pycnogenol. 

The first scientist who worked on the investigation of the biological effects of Pycnogenol was Dr.Jack Masquelier of the University of Bordeaux in France. The investigation began after studying some historical reports on an unknown component, which came from the bark of the Maritime Pine and used in the Middle Ages to treat scurvy from which seafarers suffering of this era and focused on naturally derived proanthocyanidins in Pycnogenol , and antioxidant properties. Indeed in vitro studies have demonstrated that Pycnogenol has strong antioxidant properties similar to those of vitamins C and E.