Evaluation of chromic oxide, glycerol triether, and beta-sitosterol as fecal flow markers in two species of nonhuman primates.

Recovery of beta-sitosterol, glycerol triether (1-hexadecyl-2,3-didodecyl glycerol triether), and chromic oxide was studied in African green monkeys and stumptail macaques consuming diets containing 0.75 mg/Cal cholesterol and 38% of calories as safflower oil or butter. Following oral administration of these compounds, feces were collected daily for 9 days. For all animals, excretion of beta-sitosterol and glycerol triether paralleled one another almost exactly. Except for two animals, this was also true for chromic acid. Essentially 100% of the administered beta-sitosterol and 90-95% of the glycerol triether were recovered; excretion of these markers virtually was complete by day 3. Ninety-two percent of the beta-sitosterol was isolated in the nonsaponifiable lipid extract of the feces with less than 6% in the remaining aqueous phase. A maximum of 3.1% of the beta-sitosterol and 1.8% of the glycerol triether were found in the blood. For stumptail macaques, the major excretory form of beta-sitosterol was the 5 beta-derivative. African green monkeys were more variable; one animal excreted the bulk of the beta-sitosterol unchanged while others excreted greater than 80% as the ring-saturated 5 beta-derivative. Animals consuming the safflower oil containing diet consistently excreted a greater percentage of the beta-sitosterol unchanged, compared with those animals eating the butter containing diet. There was no evidence for steroid ring degradation in any of the animals used in this study.