The biological activity of pycnogenol is due to its diverse and rich content of polyphenols.[1] Following ingestion, some of these compounds are metabolized by bacteria in the colon into other bioactive compounds that can be absorbed. For example, bacteria can convert the procyanidins in pycnogenol into the compound M1 (δ-(3,4-dihydroxy-phenyl)-γ-valerolactone), which is thought to strongly contribute to its overall biological effects.[2][3]
Pycnogenol seems to decrease pain and inflammation by reducing the activity of certain pathways in the body that lead to the production of pro-inflammatory compounds, including nuclear factor kappa B (NF-κB) and cyclooxygenase (COX)-1 and COX-2 enzymes.[4][5] As an antioxidant, in vitro and animal research suggests that pycnogenol may directly scavenge free radicals, regenerate other antioxidants in the body (e.g., vitamin C, vitamin E, and glutathione), and increase the activity of antioxidant enzymes.[6][7][8] The above effects, as well as pycnogenol's ability to enhance nitric oxide synthesis and increase capillary integrity, may contribute to reduced capillary permeability and increased blood flow.[9][10]