Apocynin, also known as acetovanillone, is a natural organic compound related to vanillin. It has been isolated from a variety of plant sources. Metabolites of apocynin are able to block the activity of NADPH oxidase, thus giving apocynin antioxidant and anti-inflammatory capabilities. Effects of apocynin on the concentration of reactive oxygen and nitrogen species in patients with asthma and chronic obstructive pulmonary disease were investigated in phase I clinical trials. In preclinical models, it was found that apocynin provides neuroprotective effects in models of stroke and Parkinson's disease.