The present invention is directed in part tomethods of preventing or reducing colon carcinogenesiscomprising administering to a patient at risk of colorectalcancer, a pharmaceutical preparation comprising disclosedchemopreventive. In another aspect, the invention is directedto methods attenuation of oxygen free radicals comprisingadministrating to a patient in need thereof an antioxidanteffective amount of a compound represented by formula(I), (IIa) or (IIb) as disclosed herein.