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.

Outer membrane protein N expressed in Gram-negative bacterial strain of Escherichia coli BL21 (DE3) Omp8 Rosetta strains under osmoregulation by salts, sugars, and pHs.

This study presented the expression of the outer membrane protein N in E. coli BL21 (DE3) Omp8 Rosetta under its growth condition and by osmoregulation. The effects of osmotic stress caused by salts, sugars, or pH values on the survival of the target Gram-negative bacterial strain of E. coli BL21 (DE3) Omp8 Rosetta and OmpN expression remain unknown. Here, tryptone yeast extract with varied salts and concentrations was initially used to generate an LB broth medium. To show how salts and concentration affect bacterial growth, the optical density at 600 nm was measured. The findings supported the hypothesis that salts and concentrations control bacterial growth. Moreover, a Western blotting study revealed that OmpN overexpression was present in all tested salts after stimulation with both glucose and fructose after being treated individually with anti-OmpN and anti-histidine tag polyclonal antibodies on transferred nitrocellulose membrane containing crude OmpN. Following the presence of the plasmid pET21b(+)/ompN-BOR into E. coli BL21 (DE3) Omp8 Rosetta, which was expressed in the recombinant OmpN protein (BOR), OmpN expression was demonstrated for all monovalent cations as well as MgCl2. All of the tested salts, except for BaCl2, NaH2PO4, and KH2PO4, showed overexpression of recombinant BOR after Isopropyl ß-D-1-thiogalactopyranoside (IPTG) induction. Using CH3COONa, both with and without IPTG induction, there was very little bacterial growth and no OmpN expression. With NaCl, a pH value of 7 was suitable for bacterial development, whereas KCl required a pH value of 8. According to this research, bacterial growth in addition to salts, sugars, and pH values influences how the OmpN protein is produced.

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.

Histone Deacetylase Inhibitory Activity and Antiproliferative Potential of New [6]-Shogaol Derivatives.

Twenty newly synthesized derivatives of [6]-shogaol (4) were tested for inhibitory activity against histone deacetylases. All derivatives showed moderate to good histone deacetylase inhibition at 100 µM with a slightly lower potency than the lead compound. Most potent inhibitors among the derivatives were the pyrazole products, 5j and 5k, and the Michael adduct with pyridine 4c and benzothiazole 4d, with IC50 values of 51, 65, 61 and 60 µM, respectively. They were further evaluated for isoform selectivity via a molecular docking study. Compound 4d showed the best selectivity towards HDAC3, whereas compound 5k showed the best selectivity towards HDAC2. The potential derivatives were tested on five cancer cell lines, including human cervical cancer (HeLa), human colon cancer (HCT116), human breast adenocarcinoma cancer (MCF-7), and cholangiocarcinoma (KKU100 and KKU-M213B) cells with MTT-based assay. The most active histone deacetylase inhibitor 5j exhibited the best antiproliferative activity against HeLa, HCT116, and MCF-7, with IC50 values of 8.09, 9.65 and 11.57 µM, respectively, and a selective binding to HDAC1 based on molecular docking experiments. The results suggest that these compounds can be putative candidates for the development of anticancer drugs via inhibiting HDACs.

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.