In Vitro Cytotoxic and Toxicological Activities of Ethanolic Extract of Kaempferia Galanga Linn. And Its Active Component, Ethyl-P-Methoxycinnamate, Against Cholangiocarcinoma

Objective: To evaluate the cytotoxic, apoptotic, mutagenic and immunomodulatory activities of Kaempferia galanga Linn. (KG) extract and ethyl-p-methoxycinnamate (EPMC) in vitro.

Methods: The present study investigated the cytotoxic [using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide test], apoptotic (using a mitochondrial membrane potential assay), mutagenic (using a micronucleus test) and immunomodulatory (using flow cytometry) activities of the ethanolic extract of KG and its bioactive component, EPMC, against two cholangiocarcinoma (CCA) cell lines, CL-6 and HuCCT1, and one normal human cell line, OUMS-36T-1F.

Results: Both KG extract and EPMC exhibited moderate cytotoxic activity against both CCA cells. The cytotoxic activity was supported by their concentration-dependent induction of apoptosis. CL-6 was most sensitive (3-4 fold) and selective to 5-fluorouracil (5-FU), compared with KG extract and EPMC [median half inhibiting concentration (IC₅₀) and selectivity index (SI) were 23.01 μg/mL and 17.32; 78.41 μg/mL and 4.44; 100.76 μg/mL and 2.20, respectively for 5-FU vs. KG extract vs. EPMC]. HuCCT1 was relatively more sensitive and selective to 5-FU and EPMC than KG extract [median IC₅₀ and SI were 66.03 μg/mL and 6.04; 60.90 μg/mL and 3.65; 156.60 μg/mL and 2.23, respectively for 5-FU vs. EPMC vs. KG extract]. EPMC produced relatively potent cytotoxic activity against polymorphonuclear cells (IC₅₀ = 92.20 μg/mL). KG extract and EPMC exhibited concentration-dependent mutagenic activity, as well as inhibition of tumor necrosis factor-α and interleukin-6.

Conclusion: Considering cytotoxic, apoptotic, immunomodulatory and mutagenic activities, further development of KG as a drug candidate is likely to focus on the oral pharmaceutical formulation of a standardized KG extract rather than isolated compounds.

Keywords: Apoptosis; Cholangiocarcinoma; Cytotoxicity; Immunomodulatory activity; Kaempferia galanga Linn.; Mutagenicity.