A simple, rapid, and reproducible reverse-phase high-performance liquid chromatographic method is developed for the estimation of boswellic acids, the active constituents in Boswellia serrata oleo- gum resin. The chromatographic separation is performed using a mobile phase consisting of acetonitrile–water (90:10, % v/v) adjusted to pH 4 with glacial acetic acid on a Kromasil 100 C18 analytical column with flow rate of 2.0 mL/min and detection at 260 nm. The elution times are 4.30 and 7.11 min for 11-keto β-boswellic acid (11-KBA) and 3-acetyl 11-keto β-boswellic acid (A-11-KBA), respectively. The calibration curve is linear in the 11.66–58.30 μg/mL and 6.50–32.50 μg/mL range for 11-KBA and A-11-KBA, respectively. The limits of detection are 2.33 μg/mL and 1.30 μg/mL for 11-KBA and A-11-KBA, respectively. The mean recoveries are 98.24% to 104.17% and 94.12% to 105.92% for 11-KBA and A-11-KBA, respectively. The inter- and intra-day variation coefficients are less than 5%. The present method is successfully applied for the estimation of boswellic acids from the market formulations containing Boswellia serrata extract. Introduction Sallaki is the oleo-gum resin obtained by incisions made on the trunk of the tree Boswellia serrata belonging to the family Burseraceae (1). It is popularly known as Indian olibanum, Frankincense, Salai gugal, Dhup, Loban, and Kundur. The oleo-gum resin of Boswellia serrata has been used in various Unani and Ayurvedic preparations as an anti-inflammatory agent (2–4). Sallaki is reported to contain monoterpenes, diter- penes, and triterpenes (2–4). The anti-inflammatory activity is attributed to the presence of four-pentacyclic triterpene acids [viz., β-boswellic acid (BA), 3-acetyl β-boswellic acid (ABA), 11- keto β-boswellic acid (11-KBA), and 3-acetyl 11-keto β- boswellic acid (A-11-KBA)] (5) (Figure 1). 11-KBA and A-11- KBA have pronounced anti-inflammatory activity (5). These boswellic acid derivatives were reported to inhibit 5-lipoxyge- nase (5–7), human leukocyte elastase (HLE) (8), and human topoisomerases I and IIα (9) activities. A survey of literature revealed that nonaqueous titration (10), reversed-phase high-performance liquid chromatographic (RP-HPLC) (11–12), high-performance thin-layer chromato- graphic (HPTLC) (13–16), and capillary electrochromato- graphic (17) methods are reported for the estimation of boswellic acids from Sallaki; whereas HPTLC (16), HPLC (18–20), gas chromatographic–mass spectrometric (21), and liquid chromatographic–mass spectrometric (22) methods are reported for their estimation in human plasma. The gradient HPLC (11) and HPTLC method (15,16) have so far been pub- lished for the estimation of 11-KBA and A-11-KBA from market formulation. The present paper aims at reporting a rapid Shailesh A. Shah 1,* , Ishwarsinh S. Rathod 1 , Bhanubhai N. Suhagia 1 , Saurabh S. Pandya 2 , and Vijay K. Parmar 2 1 Department of Quality Assurance, L.M. College of Pharmacy, Navrangpura, Ahmedabad-380 009, India and 2 Department of Pharmaceutical Chemistry, K.B. Institute of Pharmaceutical Education and Research, Sector-23, Gandhinagar-382023, India Reproduction (photocopying) of editorial content of this journal is prohibited without publisher’s permission. 735 Journal of Chromatographic Science, Vol. 46, September 2008 A Simple High-Performance Liquid Chromatographic Method for the Estimation of Boswellic Acids from the Market Formulations Containing Boswellia serrata Extract * Author to whom correspondence should be addressed: email shaileshah_lmcp@rediffmail.com. Abstract Figure 1. Chemical structures of pentacyclic triterpenic acids.