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.

Recently, the curcumin derivative CU17 possessing HDAC inhibitory activity has been shown to synergistically enhance the anti-proliferative activity of Gem against lung cancer cells. Nevertheless, the mechanism(s) underlying the synergistic anti-cancer effect remains to be investigated. This study aimed to investigate the mechanisms that underpin the anti-cancer activity of the combined Gem and CU17 against NSCLC A549 cells both in vitro and in mouse xenograft models. CU17 was successfully synthesized and subsequently investigated for its combination effects with Gem on inductions of cell cycle arrest and apoptosis in A549 cells. The combination treatment substantially decreased cell survival through S phase prolongation and G2/M phase cell cycle arrest via up-regulating the expressions of p21 and p53 proteins. Additionally, CU17 potentiated the apoptotic effect of Gem in A549 cells by increasing the Bax/Bcl-2 ratio. The co-treatment resulted in an up-regulation of pERK1/2 and Ac-H3 expression. An in vivo study demonstrated that CU17 significantly improved the anti-cancer effect of Gem in nude mice utilizing A549 cell xenografts. The hematoxylin and eosin (H&E) staining results indicated that CU17 decreased the toxicity of Gem to the liver, kidneys, and spleen. Overall, CU17 enhanced the effectiveness of Gem while decreasing its toxicity. This compound shows promise as a chemosensitizer for NSCLC treatment with Gem.

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.

Capsaicin and dihydrocapsaicin were modified at phenolic moieties and allylic of double-bond to provide seven capsaicin and dihydrocapsaicin derivatives. Their structures were assigned by spectroscopic techniques (1D-NMR and MS). All compounds were evaluated as histone deacetylase inhibitors via in vitro fluorometric assay at 100 µM. The results revealed that the chloranil derivatives were found to be best histone deacetylase inhibitors among the tested compounds with 86% and 87% inhibitions. In addition, molecular docking experiments of the active compounds with representatives of class I (HDAC1, HDAC2, HDAC3 and HDAC8), class IIa (HDAC4 and HDAC7) and class IIb (HDAC6) HDAC isoforms displayed potential isoform-selective HDAC inhibitors. Those data show a new method for providing the isoform-selective histone deacetylase inhibitors from common natural products.

A new glycoside, glutacoside (1), as well as 6 known compounds was isolated and identified from the root of Gluta usitata. Their structures were determined by Infrared spectroscopy, Mass spectroscopy, and 1-Dimensional and 2-dimensional nuclear magnetic resonance spectroscopy data. The histone deacetylase (HDAC) inhibitory and antioxidant activities of the obtained compounds were evaluated. Molecular docking experiments of the selected compound with representatives of class I (HDAC2 and HDAC8) and class II (HDAC4 and HDAC7) HDAC isoforms displayed potential isoform-selective HDAC inhibitors. Molecular docking data showed consistent results to the in vitro experiments with the highest potency against HDAC8. The docking studies suggested that the phenolic and carbonyl group can be favorably accommodated at the gorge region of the binding site. Furthermore, the phenolic groups also acted as major roles for antioxidant activities.

Background/Objectives: Drug resistance and severe side effects caused by gemcitabine (Gem) and cisplatin (CDDP) are common. This study aimed to investigate the combined effects of CU4c and Gem or CDDP on lung cancer cells in vitro and in nude mouse xenograft models. Methods: Antiproliferative activity and drug interaction were evaluated using MTT and Chou–Talalay methods, respectively. Apoptosis induction and cell cycle arrest were analyzed by flow cytometry. The expression levels of proteins were evaluated by Western blot analysis. The HDAC-inhibitory activity of CU4c was confirmed in vitro, in silico, and in A549 cells. Results: CU4c inhibited the proliferation of A549 cells in a dose- and time-dependent manner but had little effect on the growth of noncancerous Vero cells. CU4c synergistically enhanced the antiproliferative activities of CDDP (at 24 h) and Gem (at 48 and 72 h) against A549 cells. Combined CU4c and CDDP notably inhibited A549 proliferation by triggering cell cycle arrest at S and G2/M phases at 24 h with elevated levels of p21 and p53 proteins. Combined CU4c and Gem induced cell cycle arrest at both the S and G2/M phases at 48 h via upregulating the expression of the p21 protein. CU4c enhanced the apoptotic effects of CDDP and Gem by increasing the Bax/Bcl-2 ratio, pERK1/2, and Ac-H3 levels. Combined CU4c and Gem significantly reduced tumor growth while minimizing visceral organ damage in animal study. Conclusions: These results suggest that CU4c enhances the anticancer activity of CDDP and Gem and reduces the toxicity of Gem in animal studies.