Bioactive constituents isolated from Atractylodes lancea (Thunb.) DC. rhizome exhibit synergistic effect against cholangiocarcinoma cell

BACKGROUND: Cholangiocarcinoma (CCA) is the primary type of bile duct cancer with high morbidity and mortality, particularly in patients with advanced-stage disease. Treatment of CCA remains unsatisfactory due to the lack of sensitive and specific diagnostic tool for early detection as well as effective chemotherapeutics. PURPOSE: To investigate cytotoxic interactions between the three major constituents of the rhizomes of Atractylodes lancea (Thunb.) DC., ie, β-eudesmol (BE), atractylodin (AT), and hinesol (HS), against CCA cell line. METHODS: Cytotoxic activities against the human CCA cells CL-6 of the dual (BE:AT, BE:HS, and AT:HS) and triple (BE:AT:HS) combinations were evaluated using MTT assay. The cytotoxic interaction of each dual combination was assessed at five concentration ratios (10:0, 7:3, 5:5, 3:7, and 0:10) using isobologram analysis. For triple combination, the concentration ratio used in the experiment was 1:1.5:2.5 (BE:AT:HS) and analysis of the interaction was performed using polygonogram analysis at the concentrations that inhibit cell growth by 50% and 90%, respectively. RESULTS: The BE:AT combination produced the additive effect with sum fractional inhibitory concentration of 0.967±0.02 (mean ± SD). The BE:HS and AT:HS combinations produced a synergistic effect with sum fractional inhibitory concentrations of 0.685±0.08 and 0.767±0.09, respectively. The mixture of the three compounds produced synergistic interaction with combination index values of 0.519±0.10 and 0.65±0.17 (mean ± SD) at the concentrations that inhibit cell growth at the 50% and 90% leveled, respectively. CONCLUSION: Results obtained would guide further development of Atractylodes lancea (Thunb.) DC. as potential anti-CCA chemotherapeutics concerning the appropriate pharmaceutical dosage form.