Chemical comparison of Prunus africana bark and pygeum products marketed for prostate health

Abstract The bark of Prunus africana may contain atranorin, atraric acid, beta-sitosterol and its esters, ferulic acid and its esters, and N-butylbenzene sulfonamide, compounds that have been shown to improve the conditions of benign prostatic hyperplasia, enlarged prostate. An analytical scheme, involving liquid-solid extractions, saponifications, and LC-APCI-MS (triple quadrupole) analysis, was developed, optimized, and validated to determine the compounds at μg/g levels. Limits of quantification were in the low ng/mL range except for beta-sitosterol. All of the compounds plus two internal standards eluted in under 10 min on a phenyl-hexyl column with gradient elution involving water-methanol and acetonitrile. The mass fraction of the compounds in Prunus africana bark (four samples) and commercial pygeum products (seven samples), derived from bark, were compared. Bark and pygeum were similar in their content of atranorin and atraric acid, found at low μg/g levels, and in the fact that ferulic acid was almost totally (> 90%) in the form of esters. In contrast, the total amount of ferulic acid was on average four times higher in bark (450 μg/g) than in pygeum while the opposite was true for total beta-sitosterol. Some pygeum samples had levels of total beta-sitosterol above 10,000 μg/g while the compound in bark was relatively invariant at about 680 μg/g. The fraction of free beta-sitosterol varied significantly between bark (33%) and pygeum (nearly all). In pygeum, the measured total beta-sitosterol concentration generally followed the labeled values for phytosterol content. No N-butylbenzene sulfonamide was found in any of the bark and pygeum samples.