- Effect of polyphenolic extract, Pycnogenol(R), on the level of 8-oxoguanine in children suffering from attention deficit/hyperactivity disorder. Chovanov??, Z., Muchov??, J., Sivonov??, M., Dvor??kov??, M., Zitnanov??, I., Waczul??kov??, I., Trebatick??, J., Skod??cek, I., Durackov??, Z. Free Radic. Res. (2006)