Cytotoxic and Apoptotic Effect of Commercial Tinctures of Scutellaria baicalensis on Lung Cancer Cell Lines

Abstract

Article history: The cytotoxic and apoptotic potentials of four commercial tinctures of S. baicalensis (SB1, SB2, SB3 and SB4) were investigated on three human lung cancer cells SK-MES-1, SK-LU-1 and A549. The number of cells that survived treatment with different concentrations of the tincture in 24, 48 and 72 hours was quantified by the colorimetric MTT assay. Acridine orange/ Propidium iodide dye exclusion assay was used to test for apoptosis in 24 and 48 hours at 200 μg/ml concentration of the tinctures. All the tinctures except SB4 showed a dose and time-dependent effect on the cancer cells. The minimum cytotoxic concentration of SB1, SB2, and SB3 sample tinctures on the SK-MES-1 and SK-LU-1 cells was approximately 100 μg/ml in 48 hours. 100 μg/ml of SB1 and SB2 tinctures have significant (p<0.05) cytotoxic activity on the SK-MES-1 cells in 72 hours. The A549 cells were the least sensitive to toxicity as significant effect on growth inhibition was not seen until 300 μg/ml. Of all the tinctures, only the SB1 showed significant (p<0.05) cytotoxic activity on nontransforming normal dividing FS5 cells, pointing to the possibility of a non-specific side effect at 400 μg/ml. Estimating duration of effect from the time taken to reverse cell growth inhibition, SB1 tinctures had the longest effect of up to 72 hours on the SK- MES-1 cells. Other tinctures showed significant (p<0.05) time-dependdent inhibition of cell growth up to at least 48 hours. Typical apoptotic morphological changes were observed with SB1, SB2 and SB3 tinctures in 24 hours but were more pronounced after 48 hours. The tinctures showed variable characteristics in terms of their dose response, duration of action and potential side effects. There is therefore an urgent need to standardize and regulate the manufacture of herbal formulations and establish a scientific evidence base on the use of commercial formulations of S. baicalensis.