Comparisons of AUC0–inf and Cmax values for sulfate conjugates demonstrated that exposure to pterostilbene sulfate was markedly higher than was exposure to resveratrol sulfate (Table 5). For both agents, these values appeared to be independent of the duration of dosing; however, these values did increase with dose level. In the case of resveratrol, glucuronide/parent AUC0–inf was similar after a single dose, but appeared to decrease with dose level after multiple doses. In contrast, the ratio for sulfate/parent increased with dose (Table 6) after both single and multiple doses. Exposure to the sulfate metabolite (relative to the parent or glucuronide) increased with dose for resveratrol, but decreased for pterostilbene (Table 6).
Comparisons of the AUC0–inf for Phase II metabolites after administration of the low doses of each agent demonstrated that exposure to resveratrol glucuronide was considerably greater than was exposure to pterostilbene glucuronide (Table 4). By contrast, at the high dose, a larger increase in levels of pterostilbene glucuronide resulted in the AUC0–inf for pterostilbene glucuronide approaching that of resveratrol glucuronide.