Mechanism of Anti-Inflammatory Action
Inflammation is a complex process involving a series of actions and/or reactions and a broad range of biologically active substances (e.g. bradykinins, histamines, prostaglandins, thromboxanes, hydroxy-fatty acids, leukotrienes, lysosomal enzymes, and lymphokines) triggered by the body’s immunological response to tissue damage.2 Leukotrienes, important mediators in inflammatory and allergic processes, are produced from arachidonic acid, an essential fatty acid synthesized in the body, via the key enzyme 5-lipoxygenase (5-LO).2,3,4 Earlier work5 identified the boswellic acids (BAs), shown in Figure 1, as specific, nonredox inhibitors of 5-LO. Thus, they inhibit the production of inflammatory leukotrienes. Based on IC50 (effective inhibitory concentration of tested substance) values, acetyl-11-keto-b-boswellic acid (IV) alone provided the most potent inhibitory action due to its optimal structure.5,6

(I) b-boswellic acid

(II) acetyl-b-boswellic acid

(III) 11-keto-b-boswellic acid (KBA)

(IV) acetyl-11-keto-b-boswellic acid (AKBA)

(V) a-boswellic acid

(VI) g-boswellic acid

Figure 1. Structures of the pentacyclic triterpenic acids in Boswellia serrata:
(Compounds I-IV are the major pentacyclic triterpenic acids and are called the b-boswellic acids.)

It has been suggested that the boswellic acids inhibit 5-LO by one of two ways:
  • Directly interacting with 5-LO or
  • interacting with the five-lipoxygenase-activating protein (FLAP).5
urrent research provides additional information to clarify the mechanism by which boswellic acids inhibit 5-LO and reveals that these compounds are unique in their inhibition of 5-LO as well as another proinflammatory enzyme, human leukocyte elastase (HLE)7,9,11
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