Tetra- and pentacyclic triterpene acids from the ancient anti-inflammatory remedy frankincense as inhibitors of microsomal prostaglandin E(2) synthase-1.

ABSTRACT: The microsomal prostaglandin E2 synthase (mPGES)-1 is the terminal enzyme in the biosynthesis of prostaglandin (PG)E2 from cyclooxygenase (COX)-derived PGH2. We previously found that mPGES-1 is inhibited by boswellic acids (IC50 = 3-30 ?M), which are bioactive triterpene acids present in the anti-inflammatory remedy frankincense. Here we show that besides boswellic acids, additional known triterpene acids (i.e., tircuallic, lupeolic, and roburic acids) isolated from frankincense suppress mPGES-1 with increased potencies. In particular, 3?-acetoxy-8,24-dienetirucallic acid (6) and 3?-acetoxy-7,24-dienetirucallic acid (10) inhibited mPGES-1 activity in a cell-free assay with IC50 = 0.4 ?M, each. Structure-activity relationship studies and docking simulations revealed concrete structure-related interactions with mPGES-1 and its cosubstrate glutathione. COX-1 and -2 were hardly affected by the triterpene acids (IC50 > 10 ?M). Given the crucial role of mPGES-1 in inflammation and the abundance of highly active triterpene acids in frankincence extracts, our findings provide further evidence of the anti-inflammatory potential of frankincense preparations and reveal novel, potent bioactivities of tirucallic acids, roburic acids, and lupeolic acids.

SUBMITTER: Verhoff M 

PROVIDER: S-EPMC4074212 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature