Synthesis of new analogs of AKBA and evaluation of their anti-inflammatory activities

A new series of 11-keto-beta-boswellic acid and 3-O-acetyl-11-keto-beta-boswellic acid analogs (5, 7, 8, 10, 13, 18a-d, 27a-c, 28a-d) were synthesized by modification of hydroxyl and acid functional moieties of boswellic acids. The structures of these analogs were confirmed by spectral data analysis (H-1, C-13 NMR and mass). Compounds 18b, 27a and 8 showed potent 5-lipoxygenase enzyme inhibitory activity (IC50: 19.53, 20.31 and 44.14 mu g/mL). The computational studies revealed that selectivity of AKBA is due to its fitment into the 5-LOX receptor, which is missing for the other enzymes like 12-LOX, COX-1 and COX-2. Our study found potentiating effects of 2-formyl and 3-keto substituents in reviving inactive AKBA analogues possessing essential COOH group at 4th position. (C) 2016 Elsevier Ltd. All rights reserved.