PT  - JOURNAL ARTICLE
AU  - Phillip Krüger
AU  - Rambod Daneshfar
AU  - Gunter P. Eckert
AU  - Jochen Klein
AU  - Dietrich A. Volmer
AU  - Ute Bahr
AU  - Walter E. Müller
AU  - Michael Karas
AU  - Manfred Schubert-Zsilavecz
AU  - Mona Abdel-Tawab
TI  - Metabolism of Boswellic Acids in Vitro and in Vivo
AID  - 10.1124/dmd.107.018424
DP  - 2008 Jun 01
TA  - Drug Metabolism and Disposition
PG  - 1135--1142
VI  - 36
IP  - 6
4099  - http://dmd.aspetjournals.org/content/36/6/1135.short
4100  - http://dmd.aspetjournals.org/content/36/6/1135.full
SO  - Drug Metab Dispos2008 Jun 01; 36
AB  - Boswellia serrata resin dry extract is among the few herbal remedies designated with an orphan drug status for the treatment of peritumoral brain edema. In addition, boswellic acids (BAs), the main active ingredients of B. serrata extracts, have potent anti-inflammatory properties, and may represent promising agents for the treatment of inflammatory diseases. Pharmacokinetic studies, however, revealed poor bioavailability, especially of 11-keto-β-boswellic acid (KBA) and 3-acetyl-11-keto-β-boswellic acid (AKBA), the most potent BAs. To address the question of whether BAs are extensively metabolized, we determined the metabolic stability of KBA and AKBA in vitro, investigated the in vitro metabolism of BAs, and compared the metabolic profiles of KBA and AKBA with those obtained in rats in vivo. In rat liver microsomes and hepatocytes as well as in human liver microsomes, we found that KBA but not AKBA undergoes extensive phase I metabolism. Oxidation to hydroxylated metabolites is the principal metabolic route. In vitro, KBA yielded metabolic profiles similar to those obtained in vivo in rat plasma and liver, whereas no metabolites of AKBA could be identified in vivo. Furthermore, AKBA is not deacetylated to KBA. This study indicates that the efficacy of B. serrata extract may be enhanced by increasing the bioavailability of AKBA. The American Society for Pharmacology and Experimental Therapeutics