Dual inhibitory action

Dual inhibition of 5-LO and HLE enzymes is unique to the Boswellic acids

Boswellic acids have been found to inhibit 5-lipoxygenase (5-LO) , as well as, human leukocyte elastase (HLE), the serine protease produced and released by polymorphonuclear leukocytes (PMNLs) which has been suggested to play a role in several diseases (pulmonary emphysema, cystic fibrosis, chronic bronchitis, acute respiratory distress syndrome, glomerulonephritis, and rheumatic arthritis) due to its aggressive and destructive properties.

This dual inhibitory action of two pathophysiologically important enzyme activities (HLE and 5-LO) is unique to the pentacyclic triterpenes from the boswellic acid series. Several leukotriene biosynthesis inhibitors furnished no HLE inhibitory activity as shown below. β-boswellic acid, AKBA, ursolic acid, and amyrin significantly inhibited HLE. The HLE inhibition activity of AKBA and ursolic acid were comparable, however; ursolic acid’s mode of inhibition is competitive11.

HLE activity in the presence of leukotriene synthesis inhibitors and cyclic and noncyclic hydrophobic compounds