Oxidative stress is considered to contribute to degenerative disease. The urinary excretion of the DNA repair product 8-hydroxy-2′-deoxyguanosine (8-OHdG) is proposed as a noninvasive biomarker of current oxidative stress in vivo. We investigated the effect of an antioxidant mixture on urinary 8-OHdG excretions in 12 otherwise healthy smokers. During the intervention period for 2 weeks, subjects consumed four capsules of PICACE^® (Pycnogenol^® 15 mg/capsule, Vitamin E; 56.1 mg/capsule, Squalene; 138.9 mg/capsule) per day. On days 0 (pre-internal use), 3, 7, 14, and 44, morning urine samples were collected. The urinary 8-OHdG was measured using high-performance liquid chromatography (HPLC). The urinary 8-OHdG level on day 3 was significantly reduced compared to day 0. The level of 8-OHdG after a washout period for PICACE^® (days 44) returned to day 0 baseline. These preliminary data suggest that PICACE^® supplements can protect smokers from oxidative stress and possibly reduce disease risk caused by free radicals associated with smoking.

Information regarding drug interactions is useful for avoiding adverse effects from medicinal drug administration, and similar information is obviously desirable for health food products and supplements. When examining findings related to drug-supplement interactions, it is vital to understand pharmacokinetics such as drug absorption, distribution, metabolism, and excretion. The interaction disposition of one particular drug is primarily related to inhibition and induction of the drug-metabolizing enzyme cytochrome P450 (CYP). Thus, experiments evaluating the expression level of CYP isoforms in human hepatic microsomes and their relative ratio in drugs metabolized by them would be useful. However, investigations of drug-supplement interactions such as inhibition tests using the cDNA-expressed human CYP and specific substrates in combination are scarce. It is essential to consider studies for averting such interactions and to disseminate information for improving safety.