Pycnogenol is a patented formulation of Pine Bark Extract which is standardized to 65-75% Procyanidin compounds by weight. Procyanidins are chain-like structures consisted of catechins similar to some found in green tea (the green tea catechins that do not have 'gallate' in their names). Pycnogenol is similar to grape seed extract and cocoa polyphenols as those are the three most common sources of Procyanidins.
Pycnogenol's benefits include increased blood flow (via a mechanism related to increased nitric oxide levels) and improved blood glucose control. The former exerts cardioprotective effects and may help with erectile dysfunction, while the latter appears to be anti-diabetic.
There are many human trials conducted on Pycnogenol, but a good deal of them have industry funding. Although industry funding doesn't necessarily invalidate published results, it should always be noted. Although the range of Pycnogenol research has significant breadth, it also has a relative lack of study replication. Some of the studies of Pycnogenol in autoimmune disease are also open-label, meaning that neither the researchers nor the subjects are blinded to treatments. While promising, these results need to be interpreted with a degree of caution since this type of experimental design fails to control for placebo effects or any unconscious bias that may be harbored by researchers analyzing the data. The one topic that appears to have been replicated numerous times is the effects on erectile dysfunction, with the caveat that all of the studies are confounded with the inclusion of l-arginine. So the effects of Pycnogenol alone on erectile dysfunction are still unknown.
Pycnogenol does appear to possess dual anti-oxidant and anti-inflammatory properties, with the latter being confirmed in humans and possibly being subject to a build-up effect over time. The low-dose buildup effect of Pycnogenol as an anti-inflammatory agent would make it useful in a multinutrient format, but it may not be the most potent anti-inflammatory in isolation. The degree of measured anti-inflammatory potential on COX enzymes (targets of Aspirin) are still lower than Aspirin itself.
Although not the most potent anti-inflammatory agent out there, Pycnogenol has shown some efficacy in alleviating symptoms in patients with autoimmune disease. Although the type of rampant inflammation during a flare far-exceeds the ability of pycnogenol, it has shown some efficacy for patients in remission phases of their disease, where symptoms tend to be driven by lower-level, chronic inflammation. One preliminary study has shown that pycnogenol may be particularly effective for relieving dry eye/dry mouth symptoms associated with Sjogren’s syndrome, a common autoimmune condition in women.