Evaluation and molecular docking study of two flavonoids from Oroxylum indicum (L.) Kurz and their semi-synthetic derivatives as histone deacetylase inhibitors.

Chrysin (5,7-dihydroxyflavone, 6) and galangin 3-methyl ether (5,7-dihydroxy-3-methoxy flavone, 7) were obtained from the leaves of Oroxylum indicum (L.) Kurz in 4% and 6% yields, respectively. Both compounds could act as pan-histone deacetylase (HDAC) inhibitors. Structural modification of these lead compounds provided thirty-eight derivatives which were further tested as HDAC inhibitors. Compounds 6b, 6c, and 6q were the most potent derivatives with the IC50 values of 97.29 ± 0.63 µM, 91.71 ± 0.27 µM, and 96.87 ± 0.45 µM, respectively. Molecular docking study indicated the selectivity of these three compounds toward HDAC8 and the test against HDAC8 showed IC50 values in the same micromolar range. All three compounds were further evaluated for the anti-proliferative activity against HeLa and A549 cell lines. Compound 6q exhibited the best activity against HeLa cell line with the IC50 value of 13.91 ± 0.34 µM. Moreover, 6q was able to increase the acetylation level of histone H3. These promising HDAC inhibitors deserve investigation as chemotherapeutic agents for treating cancer.

Tiliacora triandra Leaf Powder Ethanolic Extract in Combination with Cisplatin or Gemcitabine Synergistically Inhibits the Growth of Cholangiocarcinoma Cells In Vitro and in Nude Mouse Xenograft Models.

Background and Objectives: The treatments of cholangiocarcinoma (CCA) with Cisplatin (Cis) and Gemcitabine (Gem) often cause side effects and drug resistance. This study aimed to investigate the combined effects of Tiliacora triandra leaf powder ethanolic extract (TLPE) and Cis or Gem on CCA cells in vitro and in nude mouse xenografts. Materials and Methods: Antiproliferative activity was evaluated using MTT assay. Drug interaction was studied by Chou-Talalay method. Apoptosis induction and cell cycle arrest were analyzed by flow cytometry. Cell cycle and apoptosis regulating proteins were evaluated by western blot analysis. Results:Treatments with Cis or Gem in combination with TLPE significantly inhibited the growth of KKU-M213B and KKU-100 cells compared with single drug treatments. Synergistic drug interactions were observed with the dose reduction of Cis and Gem treatments. The safety of TLPE was demonstrated in vitro by the hemolytic assay. Synergistic combination treatments down-regulated Bcl2 and reduced the ratio of Bcl2/Bax in both CCA cells. TLPE enhanced tumor suppression of both Cis and Gem in nude mouse xenograft models. Combination treatments with Cis and TLPE reduced Cis toxicity, as demonstrated by the enhanced body weight change of the treated mice compared with the treatment with Cis alone. Furthermore, TLPE reduced hepatotoxicity caused by Gem treatment and reduced kidney and spleen toxicities caused by Cis treatment. Conclusion: These findings suggest that TLPE enhances the anticancer activity of Cis and Gem and reduces their toxicity both in vitro and in nude mouse xenograft models.

Ethanolic extract of Ya-nang (Tiliacora triandra) leaf powder induces apoptosis in cholangiocarcinoma cell lines via induction of hyperacetylation and inhibition of growth signaling.

Objective: To develop alternative medicine for reducing undesired side effects of chemotherapy in CCA patients, the anticancer activity of Tiliacora triandra leaf powder ethanolic (TLPE) extract against cholangiocarcinoma cell lines was investigated. Methods: Antiproliferation was studied using the MTT assay while apoptosis induction and cell cycle arrest were analyzed by flow cytometry. The levels of key proteins and phenolic acid content were analyzed by western blotting and reversed-phase HPLC, respectively. Results: TLPE extract inhibited CCA cell growth in a dose- and time-dependent manner, with IC50 values of 7.86 ± 0.05 µg/ml for KKU-M213B cells and 8.59 ± 0.36 µg/ml for KKU-100 cells at an exposure time of 72 h. TLPE extract inhibited the growth of CCA cell lines by inducing apoptosis of both cell lines and causing an increased population of KKU-100 cells at G0/G1 phase. TLPE extract up-regulated Ac-H3 but down-regulated p-ERK, p53, Bax, CDK4 and Bcl2 expressions in KKU-M213B cells. TLPE extract up-regulated Ac-H3, p21 and Bax but down-regulated p-ERK, p53, CDK4 and Bcl2 expressions in KKU-100 cells. Additionally, phenolic acids including p-hydroxybenzoic, vanillic, syringic, p-coumaric, ferulic and sinapinic acids were identified. Conclusion: These results suggest the possibility of developing T. triandra leaf powder ethanolic extract as a chemotherapeutic or chemoprevention agent for cholangiocarcinoma.

HDAC Inhibitory and Anti-Cancer Activities of Curcumin and Curcumin Derivative CU17 against Human Lung Cancer A549 Cells.

Previous research reported that the curcumin derivative (CU17) inhibited several cancer cell growths in vitro. However, its anticancer potential against human lung cancer cells (A549 cell lines) has not yet been evaluated. The purpose of this research was to examine the HDAC inhibitory and anti-cancer activities of CU17 compared to curcumin (CU) in A549 cells. An in vitro study showed that CU17 had greater HDAC inhibitory activity than CU. CU17 inhibited HDAC activity in a dose dependent manner with the half-maximal inhibitory concentration (IC50) value of 0.30 ± 0.086 µg/mL against HDAC enzymes from HeLa nuclear extract. In addition, CU17 could bind at the active pockets of both human class I HDACs (HDAC1, 2, 3, and 8) and class II HDACs (HDAC4, 6, and 7) demonstrated by molecular docking studies, and caused hyperacetylation of histone H3 (Ac-H3) in A549 cells shown by Western blot analysis. MTT assay indicated that both CU and CU17 suppressed A549 cell growth in a dose- and time-dependent manner. Besides, CU and CU17 induced G2/M phase cell cycle arrest and p53-independent apoptosis in A549 cells. Both CU and CU17 down-regulated the expression of p53, p21, Bcl-2, and pERK1/2, but up-regulated Bax expression in this cell line. Although CU17 inhibited the growth of lung cancer cells less effectively than CU, it showed less toxicity than CU for non-cancer cells. Accordingly, CU17 is a promising agent for lung cancer treatment. Additionally, CU17 synergized the antiproliferative activity of Gem in A549 cells, indicating the possibility of employing CU17 as an adjuvant treatment to enhance the chemotherapeutic effect of Gem in lung cancer.

Influence of side-chain changes on histone deacetylase inhibitory and cytotoxicity activities of curcuminoid derivatives.

Using curcuminoids as lead compounds, fifty-nine curcuminoid derivatives with different side chains at the phenolic moiety were synthesized. All compounds were investigated for their histone deacetylase (HDAC) inhibitory activities. The potent pan-HDAC inhibitors were further tested against three human cancer cell lines including Hela, HCT116 and MCF-7 with MTT-based assay. The bisethylamide 4z and the mono-sec-butyl derivative 5j manifested good antiproliferative activities against HCT116 cancer cells with the IC50 values as 14.60 ± 1.19 µg/mL and 7.33 ± 0.98 µg/mL, respectively. Molecular docking study of both compounds with Class I HDACs revealed that the compounds might bind tightly to the binding pocket of HDAC2. These findings suggested that these compounds can be putative candidates for the development of anticancer drugs via inhibiting HDACs.