3,5-Bis(3-dimethylaminomethyl-4-hydroxybenzylidene)-4-piperidone and related compounds induce glutathione oxidation and mitochondria-mediated cell death in HCT-116 colon cancer cells

This study aims at investigating the cytotoxicity and some of the modes of action of 3,5-bis(3-dimethylamino-4-hydroxybenzylidene)-4-piperidone trihydrochloride 3 and two related compounds 2 (which lacks the dimethylaminomethyl groups) and 4 (which has an additional dimethylaminoethyl substituent in both aryl rings) in order to ascertain the contribution of dimethylaminoethyl substituent to bioactivity. The bioactivities of 2–4 were compared with curcumin 5. Both 2 and 3 displayed submicromolar GI₅₀ values towards HCT-116 cells and were significantly more potent than 4, 5 and 5-fluorouracil (5-FU). All of the compounds displayed greater toxicity towards HCT-116 cells than human CRL-1790 non-malignant colon cells. In HCT-116 cells, the compounds 2, 3 and 5 increased the ratio of oxidised to reduced glutathione and destabilized the mitochondrial membrane potential. Both 2 and 5 produced an increase in mitochondrial superoxide and a burst in intracellular reactive oxygen species in HCT 116 cells. In addition, 2 and 4 stimulated respiration in rat liver mitochondria while 2 and 5 induced mitochondrial swelling. The results suggest that 2 and 5 cause oxidation or cross-linking of the thiols which control the mitochondrial permeability transition.     

Novel DNA-directed alkylating agents: Design,synthesis and potent antitumor effect of phenyl N-mustard-9-anilinoacridine conjugates via a carbamate or carbonate linker

A series of phenyl N-mustard-9-anilinoacridine conjugates via a carbamate or carbonate linker was synthesized for antitumor evaluation. The carbamate or carbonate linker is able to lower the reactivity of the phenyl N-mustard pharmacophore and thus, these conjugates are rather chemically stable. The in vitro studies revealed that these derivatives possessed significant cytotoxicity with IC₅₀ in sub-micromolar range in inhibiting human lymphoblastic leukemia (CCRF-CEM), breast carcinoma (MX-1), colon carcinoma (HCT-116) and human non-small cell lung cancer (H1299) cell growth in vitro. Compounds 10a, 10b, 10e, 10i, and 15a were selected for evaluating their antitumor activity in nude mice bearing MX-1 and HCT-116 xenografts. Remarkably, total tumor remission was achieved by these agents with only one cycle of treatment. Interestingly, no tumor relapse was found in mice treated with 10a over 129 days. This agent is capable of inducing DNA interstrand cross-linking in human non-small lung cancer H1299 cells in a dose dependent manner by modified comet assay and has a long half-life in rat plasma.     

lH-Pyrazolo[3,4-b]quinolin-3-amine derivatives inhibit growth of colon cancer cells via apoptosis and sub G1 cell cycle arrest

A series of lH-pyrazolo[3,4-b]quinolin-3-amine derivatives were synthesized and evaluated for anticancer efficacy in a panel of ten cancer cell lines, including breast (MDAMB-231 and MCF-7), colon (HCT-116, HCT-15, HT-29 and LOVO), prostate (DU-145 and PC3), brain (LN-229), ovarian (A2780), and human embryonic kidney (HEK293) cells, a non-cancerous cell line. Among the eight derivatives screened, compound QTZ05 had the most potent and selective antitumor efficacy in the four colon cancer cell lines, with IC₅₀ values ranging from 2.3 to 10.2?µM. Furthermore, QTZ05 inhibited colony formation in HCT-116 cells in a concentration-dependent manner. Cell cycle analysis data indicated that QTZ05 caused an arrest in the sub G1 cell cycle in HCT-116 cells. QTZ05 induced apoptosis in HCT-116 cells in a concentration-dependent manner that was characterized by chromatin condensation and increase in the fluorescence of fluorochrome-conjugated Annexin V. The findings from our study suggest that QTZ05 may be a valuable prototype for the development of chemotherapeutics targeting apoptotic pathways in colorectal cancer cells.     

Aminoadamantanes containing monoterpene-derived fragments as potent tyrosyl-DNA phosphodiesterase 1 inhibitors

The ability of a number of nitrogen-containing compounds that simultaneously carry the adamantane and monoterpene moieties to inhibit Tdp1, an important enzyme of the DNA repair system, is studied. Inhibition of this enzyme has the potential to overcome chemotherapeutic resistance of some tumor types. Compound (+)-3c synthesized from 1-aminoadamantane and (+)-myrtenal, and compound 4a produced from 2-aminoadamantane and citronellal were found to be most potent as they inhibited Tdp1 with IC₅₀ values of 6 and 3.5 µM, respectively. These compounds proved to have low cytotoxicity in colon HCT-116 and lung A-549 human tumor cell lines (CC₅₀ > 50 µM). It was demonstrated that compound 4a at 10 µM enhanced cytotoxicity of topotecan, a topoisomerase 1 poison in clinical use, against HCT-116 more than fivefold and to a lesser extent of 1.5 increase in potency for A-549.     

Design and synthesis of novel 6-hydroxy-4-methoxy-3-methylbenzofuran-7-carboxamide derivatives as potent Mnks inhibitors by fragment-based drug design

A novel series of 6-hydroxy-4-methoxy-3-methylbenzofuran-7-carboxamide derivatives featured with various C-2 substituents were designed and synthesized as Mnks inhibitors through fragment-based drug design. Among them, 5b, 5i, 5o and 8k showed the best Mnk2 inhibitory activity with IC₅₀ values of 1.45, 1.16, 3.55 and 0.27?μM, respectively. And these compounds inhibited the activity of Mnk1 at the same time. Furthermore, compounds 5o and 8k exhibited anti-proliferative effects to human leukemia cancer THP-1 and MOLM-13 cell lines and colon cancer HCT-116 cell line. Moreover, Western blot assay suggested that 8k could decrease the levels of p-eIF4E in a dose-dependent manner in HCT-116 cells. Docking studies demonstrated strong interactions between 8k and Mnk2. Therefore, this unique benzofuran scaffold demonstrated great potential to be further explored as potent Mnks inhibitors with improved potency.     

Synthesis of (Z)-3-(arylamino)-1-(3-phenylimidazo[1,5-a]pyridin-1-yl)prop-2-en-1-ones as potential cytotoxic agents

The new derivatives based on (Z)-3-(arylamino)-1-(3-phenylimidazo[1,5-a]pyridin-1-yl)prop-2-en-1-one scaffold was synthesized and evaluated for their in vitro cytotoxic potential against a panel of cancer cell lines, viz., A549 (human lung cancer), HCT-116 (human colorectal cancer), B16F10 (murine melanoma cancer), BT-474 (human breast cancer), and MDA-MB-231 (human triple-negative breast cancer). Among them, many of the synthesized compounds exhibited promising cytotoxic potential against the panel of tested cancer cell lines with IC₅₀ <30 µM. Based on the preliminary screening results, the structure-activity relationship (SAR) of the compounds was established. Among the synthesized compounds, 15i displayed a potential anti-proliferative activity against HCT-116 cancer cell line with an IC₅₀ value of 1.21 ± 0.14 µM. Flow cytometric analysis revealed that compound 15i arrested the G0/G1 phase of the cell cycle. Moreover, increased reactive oxygen species (ROS) generation, clonogenic assay, acridine orange staining, DAPI nuclear staining, measurement of mitochondrial membrane potential (ΔΨm), and annexin V-FITC assays revealed that compound 15i promoted cell death through apoptosis.     

Novel hybrid molecules of 3,5-bis(benzylidene)-4-piperidones and dichloroacetic acid which demonstrate potent tumour-selective cytotoxicity

A novel class of hybrid molecules 2a-o was designed as candidate antineoplastic agents from dichloroacetic acid which is a known inhibitor of pyruvate dehydrogenase kinase and a number of cytotoxic 3,5-bis(benzylidene)-4-piperidones 1. In general these new hybrid molecules are potent cytotoxins towards human HCT116 colon cancer cells. A number of lead molecules emerged having the IC₅₀ values in the double digit nanomolar range. Most of these compounds are less toxic to human CRL1790 non-malignant colon cells and hence the selectivity index (SI) figures for most of the compounds are huge; in the case of 2c-g, m, n, the SI values are in excess of 100. Compounds 2g, 2j, 2m and 2n displayed >100-fold higher potency than the reference drug 5-FU. Quantitative structure-activity relationships revealed that the potencies of the compounds in series 2 increase as the magnitude of the Hammett σ and Taft σ* values rise. X-ray crystallographic of a representative compound 2c revealed various structural features which may influence cytotoxic potencies. Several representative compounds lowered the mitochondrial membrane potential and increased the production of reactive oxygen species in HCT116 cells. A minimal effect was noted in altering the percentage of cells in different phases of the cell cycle. Some future directions have been outlined for analog development.     

Synthesis and biological screening of new thiazolo[4,5-d]pyrimidine and dithiazolo[3,2-a:5′,4′-e]pyrimidinone derivatives as antimicrobial,antiquorum-sensing and antitumor agents

New thiazolopyrimidine and dithiazolopyrimidinone derivatives 2–11 were synthesized and estimated for antimicrobial activity against S. aureus, B. cereus, E. coli, C. albicans, A. fumigatus and A. terreus. The attained results proved that 4, 8a and 11g have significant effectiveness against S. aureus and B. cereus. On the other hand, 7, 10b, 10c and 11h exhibited prominent activity against B. cereus, whereas 8a, 10b and 11g were proved to be active against E. coli. From another point of view, 4 and 8a exhibited promising efficacy against A. fumigatus and A. terreus; moreover, 8a showed outstanding efficacy against C. albicans. Quorum-sensing inhibitory activity of the new compounds was esteemed against C. violaceum, where 7, 8a, 9b, 10a-c, 11d and 11g have acceptable efficacy. In vitro antitumor efficacy of the same compounds against HepG2, HCT-116 and MCF-7 cancer cell lines was also tested. Compounds 4 and 11h showed enhanced effectiveness against the three cell lines, whereas 10b displayed eminent activity against HCT-116 and MCF-7 cells. Moreover, 11a was found to have outstanding activity against MCF-7 cells, while 11i showed promising efficacy against HepG2 cells. The in vitro active antitumor compounds were evaluated for in vivo antitumor effectiveness against EAC in mice, as well as in vitro cytotoxicity against WI38 and WISH normal cells. Results manifested that 4 has the strongest in vivo activity, and that all investigated analogs are less cytotoxic than 5-FU against both normal cell lines. DNA-binding affinity of the active compounds was examined, where 4, 8a, 10c, 11d and 11g,h displayed strong affinity. In silico studies proved that majority of the analyzed compounds are in conformity with the optimum needs for good oral absorption.     

Design,synthesis and in vitro apoptotic mechanism of novel pyrrolopyrimidine derivatives

In this work we described the synthesis and evaluation of cytotoxic and apoptotic activity of novel pyrrolopyrimidine derivatives against A549, PC3 and MCF-7 cells. Among the synthesized compounds, 6b, 8a, 9a and 7a, 8b displayed the significant cytotoxic activities against A549 and PC3 cells with IC₅₀ value of 0.35, 1.48, 1.56 and 1.04, 1.89 µM, respectively. It was found that A549 cells were more sensitive to synthesized compounds than PC3 and MCF-7 cells. In order to evaluate the mechanism of cytotoxic activity in A549, compounds 6b, 8a and 9a were selected for further studies. Annexin V binding assay and western blot analysis results revealed that 6b, 8a and 9a induced apoptosis in A549 cells by intrinsic apoptotic pathway through the activation pro-apoptotic proteins such as Bim, Bax, Bak, Puma and deactivation of anti-apoptotic proteins including Bcl-2, Mcl-1 and Bcl-XL accompanied by the activation of caspase-3, caspase-9 and cleavage of PARP. Also, compounds 6b, 8a and 9a triggered apoptosis in HCT116 wt cells via activation of caspase-3 and caspase-9, but not in HCT116 Bax/Bak KO cells, indicating resistance to 6b, 8a and 9a treatment.     

Green chemoselective synthesis of thiazolo[3,2-a]pyridine derivatives and evaluation of their antioxidant and cytotoxic activities

The green chemoselective synthesis of thiazolo[3,2-a]pyridine derivatives was achieved in water via microwave-assisted three-component reactions of malononitrile, aromatic aldehydes and 2-mercaptoacetic acid with molar ratios of 2:1:1.5 and 2:2.2:1, respectively. These compounds were subject to the experiments of antioxidant activity and cytotoxicity to carcinoma HCT-116 cells and mice lymphocytes. Nearly all of the tested compounds possessed potent capacities for scavenging free radicals. In addition, most of these compounds showed cytotoxicity to HCT-116 cells and mice lymphocytes with no selectivity. Of these, only thiazolo[3,2-a]pyridine derivative 5d suggested selective cytotoxicity to tumor cell line HCT-116 cells.     

Apoptotic induction mediated p53 mechanism and Caspase-3 activity by novel promising cyanoacrylamide derivatives in breast carcinoma

New cyanoacrylamide derivatives were theoretically examined for their binding abilities to a protein model of apoptosis inhibitor proteins x-IAP and c-IAP1 using molecular modeling. The two compounds 5a and 5b proved promising IAP antagonists, where they have good binding affinity toward the selected active domains. Anticancer activity of all derivatives was performed on different human cancer cell lines (HCT116, Caco₂, and MCF7) as well as normal line (HBF4). Data revealed that breast carcinoma was more sensitive to the novel compounds than other lines especially compounds 5a and 5b, but all derivatives lost their cytotoxic effect in case of Caco2 cell line and they showed low cytotoxic effect toward HCT116 cells except compound 3. The flow cytometric analysis revealed that the two compounds 5a and 5b induced apoptosis to 46.5% and 54.8% respectively, relative to control 8.06%. In addition, PCR results indicated that the two compounds 5a and 5b induced the expression of p53 gene and decreased induction of BCL2 (anti-apoptotic gene), while the two compounds have no effect on the protein expression of Caspase-9. By monitoring the presence of Caspase-3 which was a mean to detect apoptotic death in breast carcinoma, the two compounds have stimulated the induction of apoptosis by increasing the production of Caspase-3 protein. Finally, it was concluded that the two compounds 5b and 5a have the most promising anti-cancer activity against human breast carcinoma (MCF7), and it is believed that the anticancer activities of these two compounds were due to being the most effective in the inhibition of a member of IAPs groups, leading to activation of p53 gene and the Caspase-3 dependent apoptosis.     

Design,synthesis and apoptosis-related antiproliferative activities of chelidonine derivatives

To get chelidonine derivatives with enhanced antiproliferative activity and selectivity, a series of nitric oxide donating derivatives (10a-f and 11a-j) were designed, synthesized and biologically evaluated. Compared with chelidonine, these compounds exhibited lower IC₅₀ values against human hepatoma cells HepG2, breast cancer cells MCF-7, colon cancer cells HCT-116, as well as leukemia cells K562. Compound 11j displayed the strongest antiproliferative activity with IC₅₀ values of 3.91, 6.90, 4.36 and 1.12 μM against the above four cells, respectively. Nevertheless, it showed an IC₅₀ value >40 μM against human peripheral blood mononuclear cells (PBMCs), which demonstrated high selectivity between normal and cancer blood cells. In further mechanism studies, 11j showed the capability to induce K562 cells apoptosis, S phase cell cycle arrest and mitochondrial membrane potential disorder. Besides, 11j was found to be effective in promoting the expression of proapoptotic protein Bad and suppressing the expression of anti-apoptotic proteins Bcl-xL, catalase, survivin, claspin and clusterin.     

Discovery of 1-benzoyl-3-cyanopyrrolo[1,2-a]quinolines as a new series of apoptosis inducers using a cell- and caspase-based high-throughput screening assay. 2: Structure–activity relationships of the 4-, 5-, 6-, 7- and 8-positions

As a continuation of our efforts to discover and develop the apoptosis inducing 1-benzoyl-3-cyanopyrrolo[1,2-a]quinolines as potential anticancer agents, we explored substitutions at the 4-, 5-, 6-, 7- and 8-positions of pyrrolo[1,2-a]quinoline. SAR studies showed that substitution at the 6-position by a small group such as Cl resulted in potent compounds. Substitutions at the 5- and 8-positions were tolerated while substitutions at the 4- and 7-position led to inactive compounds. Several compounds, including 2c, 3a, 3b and 3f, were found to be highly active against human breast cancer cells T47D with EC₅₀ values of 0.053–0.080 μM, but much less active against human colon cancer cells HCT116 and hepatocellular carcinoma cancer cells SNU398 in the caspase activation assay. Compound 3f also was found to be highly active with a GI₅₀ value of 0.018 μM against T47D cells in a growth inhibition assay.     

Synthesis and antitumor activities of novel dipeptide derivatives derived from dehydroabietic acid

A series of dipeptide derivatives from dehydroabietic acid were designed and synthesized as novel antitumor agents. The antitumor activities screening indicated that many compounds showed moderate to high levels of inhibition activities against NCI-H460, HepG2, SK-OV-3, BEL-7404, HeLa and HCT-116 cancer cell lines and that some displayed more potent inhibitory activities than commercial anticancer drug 5-fluorouracil. The mechanism of representative compound 7b was studied by AO/EB staining, Hoechst 33258 staining, JC-1 mitochondrial membrane potential staining, TUNEL assay, DNA ladder assay and flow cytometry, which exhibited that the compound could induce apoptosis in HeLa cells. Further investigation showed that compound 7b induced apoptosis of HeLa cells through a mitochondrial pathway.     

Discovery of certain benzyl/phenethyl thiazolidinone-indole hybrids as potential anti-proliferative agents: Synthesis,molecular modeling and tubulin polymerization inhibition study

A series of certain benzyl/phenethyl thiazolidinone-indole hybrids were synthesized for the study of anti-proliferative activity against A549, NCI-H460 (lung cancer), MDA-MB-231 (breast cancer), HCT-29 and HCT-15 (colon cancer) cell lines by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). We found that compound G37 displayed highest cytotoxicity with IC₅₀ value of 0.92 ± 0.12 µM towards HCT-15 cancer cell line among all the synthesized compounds. Moreover, compound G37 was also tested on normal human lung epithelial cells (L132) and was found to be safe in contrast to HCT-15 cells. The lead compound G37 showed significant G2/M phase arrest in HCT-15 cells. Additionally, compound G37 significantly inhibited tubulin polymerization with IC₅₀ value of 2.92 ± 0.23 µM. Mechanistic studies such as acridine orange/ethidium bromide (AO/EB) dual staining, DAPI nuclear staining, annexinV/propidium iodide dual staining, clonogenic growth inhibition assays inferred that compound G37 induced apoptotic cell death in HCT-15 cells. Moreover, loss of mitochondrial membrane potential with elevated intracellular ROS levels was observed by compound G37. These compounds bind at the active pocket of the α/β-tubulin with higher number of stable hydrogen bonds, hydrophobic and arene-cation interactions confirmed by molecular modeling studies.     

Synthesis,in vitro and in vivo evaluation of 3-arylisoquinolinamines as potent antitumor agents

In the search for potent water-soluble 3-arylisoquinolines, several 3-arylisoquinolinamines were designed and synthesized. Various substituted 3-arylisoquinolinamines exhibited strong cytotoxic activity against eight different human cancer cell lines. In particular, C-6 or C-7 dimethylamino-substituted 3-arylisoquinolinamines displayed stronger potency than the lead compound 7a. Interestingly, compounds 7b and 7c showed more effective activity against paclitaxel-resistant HCT-15 human colorectal cancer cell lines when compared to the original cytotoxic cancer drug, paclitaxel. We analyzed the cell cycle dynamics by flow cytometry and found that treatment of human HCT-15 cells with 3-arylisoquinolinamine 7b blocked or delayed the progression of cells from G0/G1 phase into S phase, and induced cell death. Treatment with compound 7b also significantly inhibited the growth of tumors and enhanced tumor regression in a paclitaxel-resistant HCT-15 xenograft model.     

Design,synthesis, docking studies and biological evaluation of novel chalcone derivatives as potential histone deacetylase inhibitors

A group of novel chalcone derivatives comprising hydroxamic acid or 2-aminobenzamide group as zinc binding groups (ZBG) were synthesized. The structure of the prepared compounds was fully characterized by IR, NMR and elemental microanalyses. Most of the tested compounds displayed strong to moderate HDAC inhibitory activity. Some of these compounds showed potent anti-proliferative activity against human HepG2, MCF-7 and HCT-116 cell lines. In particular, compounds 4a and 4b exhibited significant anti-proliferative activity against the three cell lines compared to SAHA as reference drug and displayed promising profile as anti-tumor candidates. The results indicated that these chalcone derivatives could serve as a promising lead compounds for further optimization as antitumor agents.     

Design,synthesis and cytotoxic activities of scopoletin-isoxazole and scopoletin-pyrazole hybrids

12 novel scopoletin-isoxazole and scopoletin-pyrazole hybrids were designed, synthesized and their chemical structures were confirmed by HR-MS, IR, ¹H NMR and ¹³C NMR spectra. The anticancer activities of the newly synthesized compounds were evaluated in vitro against three human cancer cell lines including HCT-116, Hun7 and SW620 by MTT assay. The screening results showed that six compounds (9a, 9c, 9d, 12a, 18b and 18d) exhibited potent cytotoxic activities with IC₅₀ values below 20 μM. Besides, we have further evaluated the growth inhibitory activities of six compounds against the human normal tissue cell lines HFL-1. Especially, compound 9d displayed significant anti-proliferative activity with IC₅₀ values ranging from 8.76 μM to 9.83 μM and weak cytotoxicity with IC₅₀ value of 90.9 μM on normal cells HFL-1, which suggested that isoxazole-based hybrids of scopoletin were an effective chemical modification to improve the anticancer activity of scopoletin.     

Synthesis and anti-proliferative activities of new derivatives of embelin

Embelin (1), a benzoquinone isolated from Embelia ribes is known to possess variety of biological activities. Despite of several promising biological activities, preclinical efforts on embelin were hampered because of its poor aqueous solubility. In order to address the solubility issue, herein, we have synthesized a series of Mannich products of embelin by treating it with various secondary amines. The synthesized compounds were screened for antiproliferative and antimicrobial activities. In cytotoxicity screening, the benzyl-piperidine linked derivative 8m was found to possess better antiproliferative activity compared to parent natural product embelin against a panel of cell lines including HCT-116, MCF-7, MIAPaCa-2 and PC-3 with IC₅₀ values of 30, 41, 34 and 36 μM, respectively. The mechanistic study of compound 8m revealed that it exhibits cytotoxicity via induction of apoptosis and mitochondrial membrane potential loss. Further, the compounds were tested for antimicrobial activity where dimethylamino- 8a and piperidine linked derivative 8b displayed antibacterial activity against Staphylococcus aureus with MIC values of 8 and 16 μg/mL, respectively. Mannich derivatives did now show improved aqueous solubility, however their hydrochloride salts 8a·HCl, 8b·HCl and 8m·HCl showed significantly improved aqueous solubility without affecting biological activities of parent Mannich derivatives.