Isolation and HPLC Estimation of Six Boswellic Acids from Boswellia serrata Extract†

Abstract

Boswellic acids are a complex mixture of pentacyclic triterpenic acids, consisting of six boswellic acids, namely, 11-keto-β-boswellic acid (1), 3-O-acetyl-11-keto-β-boswellic acid (2), α-boswellic acid (3), β-boswellic acid (4), 3-O-acetyl-α-boswellic acid (5), and 3-O-acetyl-β-boswellic acid (6). Six boswellic acids (1–6), antiinflammatory and anti-arthritic constituents of Boswellia serrata, have been isolated by a combination of column chromatography and preparative high performance liquid chromatography. The structures of these boswellic acids were characterized thoroughly by high resolution NMR and mass spectral data. The purity of the boswellic acids was analyzed by HPLC method. HPLC separation was performed on a C-18 column using mobile phase 0.1 % v/v phosphoric acid in water and acetonitrile, with detection at 210 and 248 nm. Commercially available varieties of boswellic acids were analyzed to detect the percentage of these six boswellic acids. The percentage of 11-keto-β-boswellic acid (1), 3-O-acetyl-11-keto-β-boswellic acid (2), α-boswellic acid (3), β-boswellic acid (4), 3-O-acetyl-α-boswellic acid (5), and 3-O-acetyl-β-boswellic acid (6) as estimated using their calibration curves were found to be 4.91 ± 0.066 to 5.66 ± 0.080,1.13 ± 0.043 to 3.38 ± 0.062, 5.61 ± 0.021 to 7.29 ± 0.051, 15.80 ± 0.018 to 20.99 ± 0.028, 1.64 ± 0.032 to 3.57± 0.082 and 6.89 ± 0.010 to 12.92 ± 0.015 in five different samples. The total percentages of boswellic acids are 35.98 ± 0.190 to 53.68 ± 0.325.