Cytostatic and apoptosis-inducing activity of boswellic acids toward malignant cell lines in vitro

Boswellic acids from frankincense were indentified as the active compounds which inhibit leukotriene biosynthesis, 5-lipoxygenase and exert antiproliferative activity toward a variety of malignant cells. Because of the relevance for the clinical application, we tested the ethanolic extract of Boswellia serrata gum resin containing a defined amount of boswellic acids for its cytotoxic, cytostatic and apoptotic activity on five leukemia (HL-60, K 562, U937, MOLT-4, THP-1) and two brain tumor (LN-18, LN-229) cell lines by WST-1 assay and flow cytometry. The Boswellia serrata extract induced dose-dependent antiproliferative effects on all human malignant cells tested with GI50 values (extract concentration producing 50% cell growth inhibition) between 57.0 and 124.1 micrograms/ml. In three haematological cell lines (K562, U937, MOLT-4) the effect of total extract expressed in GI50 was 2.8-, 3.3- and 2.3-times more potent (p < 0.05) than pure 3-O-acetyl-11-keto-beta-boswellic acid (AKBA). Morphological changes after 24-27 hours and the detection of apoptotic cells by AnnexinV-binding and/or by the detection of propidium iodide-labelled DNA with flow cytometry, confirmed the apoptotic cell death. The results of this study suggest the effectiveness of Boswellia serrata extract with defined content of boswellic acids.