Enhancement of Anticancer Potential of Pterostilbene Derivative by Chalcone Hybridization.

Pterostilbene, a natural metabolite of resveratrol, has been indicated as a potent anticancer molecule. Recently, several pterostilbene derivatives have been reported to exhibit better anticancer activities than that of the parent pterostilbene molecule. In the present study, a series of pterostilbene derivatives were designed and synthesized by the hybridization of pterostilbene, chalcone, and cinnamic acid. The cytotoxic effect of these hybrid molecules was determined using two oral cancer cell lines, HSC-3 and OECM-1. (E)-3-(2-((E)-4-Hydroxystyryl)-4,6-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (4d), with IC50 of 16.38 and 18.06 µM against OECM-1 and HSC-3, respectively, was selected for further anticancer mechanism studies. Results indicated that compound 4d effectively inhibited cell proliferation and induced G2/M cell cycle arrest via modulating p21, cyclin B1, and cyclin A2. Compound 4d ultimately induced cell apoptosis by reducing the expression of Bcl-2 and surviving. In addition, cleavage of PARP and caspase-3 were enhanced following the treatment of compound 4d with increased dose. To conclude, a number of pterostilbene derivatives were discovered to possess potent anticancer potentials. Among them, compound 4d was the most active, more active than the parent pterostilbene.

Discovery of an Orally Efficacious MYC Inhibitor for Liver Cancer Using a GNMT-Based High-Throughput Screening System and Structure-Activity Relationship Analysis.

Glycine-N-methyl transferase (GNMT) downregulation results in spontaneous hepatocellular carcinoma (HCC). Overexpression of GNMT inhibits the proliferation of liver cancer cell lines and prevents carcinogen-induced HCC, suggesting that GNMT induction is a potential approach for anti-HCC therapy. Herein, we used Huh7 GNMT promoter-driven screening to identify a GNMT inducer. Compound K78 was identified and validated for its induction of GNMT and inhibition of Huh7 cell growth. Subsequently, we employed structure-activity relationship analysis and found a potent GNMT inducer, K117. K117 inhibited Huh7 cell growth in vitro and xenograft in vivo. Oral administration of a dosage of K117 at 10 mpk (milligrams per kilogram) can inhibit Huh7 xenograft in a manner equivalent to the effect of sorafenib at a dosage of 25 mpk. A mechanistic study revealed that K117 is an MYC inhibitor. Ectopic expression of MYC using CMV promoter blocked K117-mediated MYC inhibition and GNMT induction. Overall, K117 is a potential lead compound for HCC- and MYC-dependent cancers.

Discovery of 4-Anilinoquinolinylchalcone Derivatives as Potential NRF2 Activators.

Activation of nuclear factor erythroid-2-related factor 2 (NRF2) has been proven to be an effective means to prevent the development of cancer, and natural curcumin stands out as a potent NRF2 activator and cancer chemopreventive agent. In this study, we have synthesized a series of 4-anilinoquinolinylchalcone derivatives, and used a NRF2 promoter-driven firefly luciferase reporter stable cell line, the HaCaT/ARE cells, to screen a panel of these compounds. Among them, (E)-3-{4-[(4-acetylphenyl)amino]quinolin-2-yl}-1-(4-fluorophenyl)prop-2-en-1-one (13b) significantly increased NRF2 activity in the HaCaT cell with a half maximal effective concentration (EC50) value of 1.95 µM. Treatment of compound 13b upregulated HaCaT cell NRF2 expression at the protein level. Moreover, the mRNA level of NRF2 target genes, heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and glucose-6-phosphate dehydrogenase (G6PD) were significantly increased in HaCaT cells upon the compound 13b treatment. The molecular docking results exhibited that the small molecule 13b is well accommodated by the bound region of Kelch-like ECH-associated protein 1 (Keap1)-Kelch and NRF2 through stable hydrogen bonds and hydrophobic interaction, which contributed to the enhancement of affinity and stability between the ligand and receptor. Compound 13b has been identified as the lead compound for further structural optimization.

A novel NOX2 inhibitor attenuates human neutrophil oxidative stress and ameliorates inflammatory arthritis in mice.

Neutrophil infiltration plays a significant pathological role in inflammatory diseases. NADPH oxidase type 2 (NOX2) is a respiratory burst oxidase that generates large amounts of superoxide anion (O2•-) and subsequent other reactive oxygen species (ROS). NOX2 is an emerging therapeutic target for treating neutrophilic inflammatory diseases. Herein, we show that 4-[(4-(dimethylamino)butoxy)imino]-1-methyl-1H-benzo[f]indol-9(4H)-one (CYR5099) acts as a NOX2 inhibitor and exerts a protective effect against complete Freund's adjuvant (CFA)-induced inflammatory arthritis in mice. CYR5099 restricted the production of O2•- and ROS, but not the elastase release, in human neutrophils activated with various stimulators. The upstream signaling pathways of NOX2 were not inhibited by CYR5099. Significantly, CYR5099 inhibited NOX2 activity in activated human neutrophils and in reconstituted subcellular assays. In addition, CYR5099 reduced ROS production, neutrophil infiltration, and edema in CFA-induced arthritis in mice. Our findings suggest that CYR5099 is a NOX2 inhibitor and has therapeutic potential for treating neutrophil-dominant oxidative inflammatory disorders.

Discovery of 2-Substituted 3-Arylquinoline Derivatives as Potential Anti-Inflammatory Agents Through Inhibition of LPS-Induced Inflammatory Responses in Macrophages.

We describe herein the preparation of certain 2-substituted 3-arylquinoline derivatives and the evaluation of their anti-inflammatory effects in LPS-activated murine J774A.1 macrophage cells. Among these newly synthesized 2-substituted 3-arylquinoline derivatives, 2-(4-methoxy- benzoyl)-3-(3,4,5-trimethoxyphenyl)quinoline (18a) and 2-(4-fluorobenzoyl)-3-(3,4,5-trimethoxy- phenyl)quinoline (18b) are two of the most active compounds which can inhibit the production of NO at non-cytotoxic concentrations. Our results have also indicated that compounds 18a and 18b significantly decrease the secretion of pro-inflammatory cytokines (TNF-á and IL-6), inhibit the expression of iNOS, suppress the phosphorylation of MAPKs, and attenuate the activity of NF-êB by LPS-activated macrophages. Through molecular docking analysis, we found that 18b could fit into the middle of the TNF-á dimer and form hydrophobic interactions with Leu55, Leu57 chain A and B, Tyr59, Val123 chain B and D, Ile 155. These results suggest that both 18a and 18b are potential lead compounds in inhibiting LPS-induced inflammatory responses. Further structural optimization to discover novel anti-inflammatory agents is ongoing.

Pharmacological inhibition of bacterial ß-glucuronidase prevents irinotecan-induced diarrhea without impairing its antitumor efficacy in vivo.

Irinotecan (CPT-11), a first-line chemotherapy for advanced colorectal cancer, causes serious diarrhea in patients receiving treatment. The underlying mechanism has been shown that the active metabolite of CPT-11, SN-38, is metabolized to the inactive metabolite SN-38 glucuronide (SN-38 G) during hepatic glucuronidation, and subsequently is exported into the intestine, where SN-38 G is hydrolyzed by bacterial ß-glucuronidase (ßG) to be SN-38, thus leading to intestinal toxicity. Thus, inhibition of the intestinal bacterial ßG activity is expected to prevent CPT-11-induced diarrhea. However, the effects of such inhibition on serum pharmacokinetics of SN-38, the key determinant of CPT-11 treatment, are uncertain. Here, we determined the effects of a potent E. coli ßG (eßG)-specific inhibitor pyrazolo[4,3-c]quinoline derivative (TCH-3562) for the potential use in preventing CPT-11-induced diarrhea. TCH-3562 exhibited efficacious inhibitory potency of endogenous ßG activity in two anaerobes, Eubacteriumsp. and Peptostreptococcus anaerobius. Oral administration of TCH-3562 also effectively reduced the bacterial ßG activity in mice intestine. Moreover, pharmacokinetic analysis of TCH-3562 revealed a relatively low amount of TCH-3562 was detected in the plasma whereas the majority of TCH-3562 was found in the feces. Importantly, co-treatment of CPT-11 and TCH-3562 did not decrease active SN-38 level in mice plasma. Finally, we established that TCH-3562 as an adjuvant treatment showed protective effects on CPT-11-induced diarrhea and had no negative effects on the therapeutic efficacy of CPT-11 in tumor-bearing mice. Therefore, inhibition of the intestinal bacterial ßG activity by the specific inhibitor, TCH-3562, is promising to prevent CPT-11-induced diarrhea while maintaining its anti-tumor efficacy that may have clinical potentials for the treatment with CPT-11.

Discovery of 3-Amino-2-Hydroxypropoxyisoflavone Derivatives as Potential Anti-HCV Agents.

Synthesis and anti-hepatitis C virus (anti-HCV) effects of certain 3-amino-2-hydroxy-propoxy isoflavone derivatives, 6a⁻i, were described. The known 3-(3,4-dimethoxyphenyl)-7-(oxiran-2-ylmethoxy)-4H-chromen-4-one (5) was reacted with substituted amines to give the desired isoflavone derivatives, 6a⁻i. Among them, 7-{3-[(3,4-dimethoxy-phenethyl)amino]-2-hydroxypropoxy}-3-(3,4-dimethoxyphenyl)-4H-chromen-4-one (6b) was the most active, exhibiting approximately 2-fold higher anti-HCV effects than standard antiviral drug ribavirin (EC50 of 6.53 vs. 13.16 µM). In addition, compound 6b was less cytotoxic than ribavirin. The selectivity index (SI) of 6b is approximately 2.6-fold higher than ribavirin. The compounds 6e, 6h, and 6i were also found to possess higher anti-HCV effects than ribavirin. Compound 6b was found to inhibit the HCV RNA expression in Ava5 cells in a dose-dependent manner; furthermore, we found that the antiviral mechanism of compounds 6b, 6e, 6h, and 6i gave rise to induction of HO-1 expression. With the HO-1 promoter-based analysis, we found compounds 6b, 6e, 6h, and 6i induced HO-1 expression through increasing Nrf-2 binding activity. Taken together, compound 6b may serve as a potential lead compound for developing novel anti-HCV agents.

Synthesis and Biological Evaluation of Thalidomide Derivatives as Potential Anti-Psoriasis Agents.

Several thalidomide derivatives were synthesized and evaluated for their anti-inflammatory activity. Introduction of the benzyl group to the parent thalidomide is unfavorable in which 2-(1-benzyl-2,6-dioxopiperidin-3-yl)isoindoline-1,3-dione (4a) was inactivated. However, the inhibitory activities on TNF-α and IL-6 expression in HaCaT cells were improved by the substitution of a chloro- or methoxy- group at the phenyl position of 4a. The IL-6 inhibitory activity decreased in an order of 5c (69.44%) > 4c (48.73%) > 6c (3.19%) indicating the 3-substituted derivative is more active than the 4-substituted counterpart, which in turn is more active than the 2-substituted counterpart. Among them, 2-[1-(3-chlorobenzyl)-2,6-dioxopiperidin-3-yl]isoindoline-1,3-dione (5c) was found to inhibit TNF-α and IL-6 expression in HaCaT cells with a higher potency than thalidomide and no significant cell cytotoxicity was detected at 10 µM. In psoriasis, Compound 5c reduced IL-6, IL-8, IL-1ß and IL-24 in imiquimod-stimulated models. Our results indicated that compound 5c is a potential lead of novel anti-psoriasis agents. Structural optimization of compound 5c and its in vivo assay are ongoing.

Novel CIL-102 derivatives as potential therapeutic agents for docetaxel-resistant prostate cancer.

The standard-of-care treatment for metastatic prostate cancer (PCa) is androgen deprivation therapy (ADT). Nevertheless, most tumors eventually relapse and develop into lethal castration-resistant prostate cancer (CRPC). Docetaxel is a FDA-approved agent for the treatment of CRPC; however, the tumor often quickly develops resistance to this drug. Thus, there is an immediate need for novel therapies to treat docetaxel-resistant PCa. In this study, we modified the structure of CIL-102 and investigated the efficacy of the derivatives against CRPC and docetaxel-resistant PCa. These novel CIL-102 derivatives inhibit CRPC tumorigenicity, including proliferation, migration and colony formation, and importantly, selectively inhibit CRPC cell proliferation over non-cancerous prostate epithelia. Computational modeling indicated the derivatives bind to ß-tubulin and immunocytochemistry revealed the depolymerization of microtubules upon treatment. Western blot analyses reveal that pro-apoptotic and anti-oxidant pathways are activated, and MitoSOX and DCF-DA analyses confirmed increased reactive oxygen species (ROS) production upon treatments. Furthermore, CIL-102 derivatives effectively reduce the proliferation of docetaxel-resistant CR PCa cell lines. Our data indicate the potential of these compounds as promising therapeutic agents for CRPC as well as docetaxel-resistant CRPC.

Discovery of Pyrazolo[4,3-c]quinolines Derivatives as Potential Anti-Inflammatory Agents through Inhibiting of NO Production.

The synthesis and anti-inflammatory effects of certain pyrazolo[4,3-c]quinoline derivatives 2a⁻2r are described. The anti-inflammatory activities of these derivatives were evaluated by means of inhibiting nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Among them, 3-amino-4-(4-hydroxyphenylamino)-1H-pyrazolo[4,3-c]-quinoline (2i) and 4-(3-amino-1H-pyrazolo[4,3-c]quinolin-4-ylamino)benzoic acid (2m) exhibited significant inhibition of LPS-stimulated NO production with a potency approximately equal to that of the positive control, 1400 W. Important structure features were analyzed by quantitative structure⁻activity relationship (QSAR) analysis to give better insights into the structure determinants for predicting the inhibitory effects on the accumulation of nitric oxide for RAW 264.7 cells in response to LPS. In addition, our results indicated that their anti-inflammatory effects involve the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) protein expression. Further studies on the structural optimization are ongoing.

Specific Inhibition of Bacterial ß-Glucuronidase by Pyrazolo[4,3-c]quinoline Derivatives via a pH-Dependent Manner To Suppress Chemotherapy-Induced Intestinal Toxicity.

The direct inhibition of bacterial ß-glucuronidase (ßG) activity is expected to reduce the reactivation of glucuronide-conjugated drugs in the intestine, thereby reducing drug toxicity. In this study, we report on the effects of pyrazolo[4,3-c]quinolines acting as a new class of bacterial ßG-specific inhibitors in a pH-dependent manner. Refinement of this chemotype for establishing structure-activity relationship resulted in the identification of potential leads. Notably, the oral administration of 3-amino-4-(4-fluorophenylamino)-1H-pyrazolo[4,3-c]quinoline (42) combined with chemotherapeutic CPT-11 treatment prevented CPT-11-induced serious diarrhea while maintaining the antitumor efficacy in tumor-bearing mice. Importantly, the inhibitory effects of 42 to E. coli ßG was reduced as the pH decreased due to the various surface charges of the active pocket of the enzyme, which may make their combination more favorable at neutral pH. These results demonstrate novel insights into the potent bacterial ßG-specific inhibitor that would allow this inhibitor to be used for the purpose of reducing drug toxicity.

Discovery of Indeno[1,2-c]quinoline Derivatives as Potent Dual Antituberculosis and Anti-Inflammatory Agents.

A series of indeno[1,2-c]quinoline derivatives were designed, synthesized and evaluated for their anti-tuberculosis (anti-TB) and anti-inflammatory activities. The minimum inhibitory concentration (MIC) of the newly synthesized compound was tested against Mycobacterium tuberculosis H37RV. Among the tested compounds, (E)-N'-[6-(4-hydroxypiperidin-1-yl)-11H-indeno[1,2-c]quinolin-11-ylidene]isonicotino-hydrazide (12), exhibited significant activities against the growth of M. tuberculosis (MIC values of 0.96 µg/mL) with a potency approximately equal to that of isoniazid (INH), an anti-TB drug. Important structure features were analyzed by quantitative structure-activity relationship (QSAR) analysis to give better insights into the structure determinants for predicting the anti-TB activity. The anti-inflammatory activity was induced by superoxide anion generation and neutrophil elastase (NE) release using the formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF)-activated human neutrophils method. Results indicated that compound 12 demonstrated a potent dual inhibitory effect on NE release and superoxide anion generation with IC50 values of 1.76 and 1.72 µM, respectively. Our results indicated that compound 12 is a potential lead compound for the discovery of dual anti-TB and anti-inflammatory drug candidates. In addition, 6-[3-(hydroxymethyl)piperidin-1-yl]-9-methoxy-11H-indeno[1,2-c]quinolin-11-one (4g) showed a potent dual inhibitory effect on NE release and superoxide anion generation with IC50 values of 0.46 and 0.68 µM, respectively, and is a potential lead compound for the discovery of anti-inflammatory drug candidates.

TCH1036, a indeno[1,2-c]quinoline derivative, potentially inhibited the growth of human brain malignant glioma (GBM) 8401 cells via suppression of the expression of Suv39h1 and PARP.

A newly synthesized Indeno[1,2-c]quinoline derivative, which has previously been found to potentially trap DNA-topoisomerase cleavage complexes more effectively than camptothecin, could effectively inhibit the proliferation of a variety of cancers, such as breast cancer treated with TCH1030. In this study, we further explore the activity of the TCH1036, TCH1259 and TCH1030 compounds in suppressing the growth of human brain malignant glioma (GBM) 8401 cells, in addition to elucidating the related mechanisms. According to tests of cytotoxicity, the GBM cells were more sensitive to the inhibitory effects of the TCH1036 compound than to those of the other two compounds. Moreover, the accumulation of GBM cells in the sub-G1 and G2/M phases was clearly induced by the TCH1036 compound in a dose-dependent manner. A screening of the majority of histone-modifier enzymes indicated that the expression of Suv39h1 in the GBM cells was attenuated by treatment with each of the TCH compounds, an observation which was further confirmed by Western blotting. The increase in active-form caspase 3 in the GBM cells treated with TCH compounds caused a high degree of poly (ADP-ribose) polymerase (PARP) cleavage and also enhanced the high ratio of hypodiploid GBM cells in the sub-G1 phase. In molecular docking simulations, it was observed that the stable forms of the TCH compounds could successfully insert into the catalytic pocket of PARP, with the highest affinity being between PARP and the TCH1036 compound. These findings suggested that the TCH1036 compound would be a promising compound in the treatment of brain malignant glioma.

Amsacrine analog-loaded solid lipid nanoparticle to resolve insolubility for injection delivery: characterization and pharmacokinetics.

Amsacrine analog is a novel chemotherapeutic agent that provides potentially broad antitumor activity when compared to traditional amsacrine. However, the major limitation of amsacrine analog is that it is highly lipophilic, making it nonconductive to intravenous administration. The aim of this study was to utilize solid lipid nanoparticles (SLN) to resolve the delivery problem and to investigate the biodistribution of amsacrine analog-loaded SLN. Physicochemical characterizations of SLN, including particle size, zeta potential, entrapment efficiency, and stability, were evaluated. In vitro release behavior was also measured by the dialysis method. In vivo pharmacokinetics and biodistribution behavior of amsacrine analog were investigated and incorporated with a non invasion in vivo imaging system to confirm the localization of SLN. The results showed that amsacrine analog-loaded SLN was 36.7 nm in particle size, 0.37 in polydispersity index, and 34.5±0.047 mV in zeta potential. More than 99% of amsacrine analog was successfully entrapped in the SLN. There were no significant differences in the physicochemical properties after storage at room temperature (25°C) for 1 month. Amsacrine analog-loaded SLN maintained good stability. An in vitro release study showed that amsacrine analog-loaded SLN sustained a release pattern and followed the zero equation. An in vivo pharmacokinetics study showed that amsacrine analog was rapidly distributed from the central compartment to the tissue compartments after intravenous delivery of amsacrine analog-loaded SLN. The biodistribution behavior demonstrated that amsacrine analog mainly accumulated in the lungs. Noninvasion in vivo imaging system images also confirmed that the drug distribution was predominantly localized in the lungs when IR-780-loaded SLN was used.

Discovery of indeno[1,2-b]quinoxaline derivatives as potential anticancer agents.

We have synthesized certain indeno[1,2-b]quinoxaline derivatives for antiproliferative evaluation. Among them, 11-{[3-(dimethylamino)propoxy]imino}-N-[3-(dimethylamino) propyl]-11H-indeno[1,2-b]quinoxaline-6-carboxamide (10a) was active against the growth of MDA-MB231, PC-3, and Huh-7 with IC50 values of 0.87 (selectivity index, SI = 36.22), 0.82 (SI = 38.43), and 0.64 µM (SI = 49.23) respectively. Compound 10a was inactive against the growth of normal human fetal lung fibroblast cell line (MRC-5) with an IC50 value of 31.51 µM. Its analogs, 10b and 10c, were also active against the growth of MB231, PC-3, and Huh-7 with IC50 values of <1.0 µM in each case. Our results have also indicated compounds 10a-10c exhibited comparable inhibitory activities against topo I and topo II with the positive compound 2 at a concentration of 10 µM. Mechanism studies indicated that compound 10a induced cell cycle arrest at S phase via activation of caspase-3, -7 and an increase in the protein expression of Bad and Bax but a decrease in expression of Bcl-2 and PARP, which consequently cause cell death. In addition, compound 10a attenuated the levels of phosphorylated Src, Akt-1, and Akt-2 protein levels but did not affect the total protein expression of Akt. We have also implanted human hepatocellular carcinoma cells into the yolk sac of zebrafish larvae and incubated larvae with various concentrations of 10a. Our results of the zebrafish xenograft assay confirmed the anti-tumor effect of 10ain vivo.

Novel oxime-bearing coumarin derivatives act as potent Nrf2/ARE activators in vitro and in mouse model.

We have designed and synthesized certain novel oxime- and amide-bearing coumarin derivatives as nuclear factor erythroid 2 p45-related factor 2 (Nrf2) activators. The potency of these compounds was measured by antioxidant responsive element (ARE)-driven luciferase activity, level of Nrf2-related cytoprotective genes and proteins, and antioxidant activity. Among them, (Z)-3-(2-(hydroxyimino)-2-phenylethoxy)-2H-chromen-2-one (17a) was the most active, and more potent than the positive t-BHQ in the induction of ARE-driven luciferase activity. Exposure of HSC-3 cells to various concentrations of 17a strongly increased Nrf2 nuclear translocation and the expression level of Nrf2-mediated cytoprotective proteins in a concentration-dependent manner. HSC-3 cells pretreated with 17a significantly reduced t-BOOH-induced oxidative stress. In the animal experiment, Nrf2-mediated cytoprotective proteins, such as aldo-keto reductase 1 subunit C-1 (AKR1C1), glutathione reductase (GR), and heme oxygenase (HO-1), were obviously elevated in the liver of 17a-treated mice than that of control. These results suggested that novel oxime-bearing coumarin 17a is able to activate Nrf2/ARE pathway in vivo and are therefore seen as a promising candidate for further investigation.

Discovery of 3-phenylquinolinylchalcone derivatives as potent and selective anticancer agents against breast cancers.

A number of 3-phenylquinolinylchalcone derivatives were synthesized and evaluated in vitro for their antiproliferative activities against three breast cancer cell lines (MCF-7, MDA-MB-231, and SKBR-3), and a non-cancer normal epithelial cell line (H184B5F5/M10). Among them, (E)-3-[3-(4-methoxyphenyl)quinolin-2-yl]-1-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (7) was active against the growth of MCF-7, MDA-MB-231, and SKBR-3 with IC50 values of 1.05, 0.75, and 0.78 µM respectively without significant cytotoxicity to the normal H184B5F5/M10 cell line and therefore, was selected as a new lead for further mechanism studies. Results indicated that compound 7 inhibited the polymerization of tubulins, induced G2/M cell cycle arrest via modulation of the cyclin B1, cdk1 and CDC25. Compound 7 ultimately induced cell apoptosis by the increase of apoptotic protein Bax and the decrease of anti-apoptotic protein Bcl-2. In addition, PARP was cleaved while caspase-3 and -8 activities were induced after the treatment of compound 7 for 24 h in a concentration-dependent manner. Thus, compound 7 induces cell cycle arrest at G2/M phase via cleavage of PARP, induces caspase-3 and -8 activities and consequently to cause the cell death. Further study on the structure optimization of 7 is ongoing.

Discovery of oxime-bearing naphthalene derivatives as a novel structural type of Nrf2 activators.

Recent studies have demonstrated that oxidative stress insult is one of major causes of tumor formation. Therefore, identify the effective anti-oxidative agents as a preventive approach to stop cancer progression has widely explored. Although, many potent anti-oxidative ingredients in the natural products have been identified but the amount from the nature source hindrances the clinical application. Compound which can activate Nrf2 signaling pathway result unregulated the cellular antioxidant-responses has been demonstrated as an effective chemopreventive approach for cancer treatment. In the present study, certain oxime-bearing naphthalene derivatives were synthesized and evaluated for their Nrf2 activation and anti-proliferative activities. Results indicated (E)-1-(naphthalen-2-yloxy)propan-2-one oxime (11) which increased 2.04-fold Nrf2/ARE-driven luciferase activity was more active than its 1-substituted isomer 10 (1.17-fold) and t-BHQ (1.77-fold), the known Nrf2 activator. The activities were further increased by the replacement of the peripheral methyl group with the phenyl ring in which (Z)-2-(naphthalen-2-yloxy)-1-phenylethanone oxime (13a) exhibited 3.49-fold potency of the positive control. It is worth to mention that compounds 11, 13a, and 13b which showed significant Nrf2 activation are non-cytotoxic to the tested cells with IC50>50µM. This observation strongly suggested that these compounds can be used for chemoprevention. Mechanism studies indicated that these compounds were capable of inducing the phosphorylation of Nrf2 protein at serine 40 which led to the activation of the Nrf2 transcriptional activity.

Discovery of benzo[f]indole-4,9-dione derivatives as new types of anti-inflammatory agents.

Certain benzo[f]indole-4,9-dione derivatives were synthesized and evaluated for their inhibitory effects on superoxide anion generation and neutrophil elastase (NE) release in formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF)-activated human neutrophils. Results indicated that (Z)-1-benzyl-4-(hydroxyimino)-1H-benzo[f]indol-9(4H)-one (10) showed a potent dual inhibitory effect on NE release and superoxide anion generation with IC50 value of 2.78 and 2.74 µM respectively. The action mechanisms of 10 in human neutrophils were further investigated. Our results showed that compound 10 did not alter fMLF-induced phosphorylation of Src (Src family Y416). Notably, phosphorylation of Akt (S473) and mobilization of [Ca2+]i caused by fMLF was inhibited by compound 10. Further structural optimization of 10 is ongoing.

Discovery of Novel N-alkyl 4-anilinofuro[2,3-b]quinoline Derivatives (CIL-102 Derivatives) Against Castration-resistant Human Prostate Cancers.

A number of N-alkylated 4-anilinofuro[2,3-b]quinoline derivatives were synthesized and evaluated in vitro against PC-3, A549, and MCF-7 cancer cells and M-10 normal human mammary epithelial cells. The known antimitotic CIL-102 was moderately active against the growth of PC-3 prostate cancer cells with an IC50 value of 2.69 µM while it was more potent against the growth of A549, MCF-7 and M-10 cells with IC50 values of 0.61, 0.31 and 0.95 µM, respectively. However, the cytotoxic profiles of its N-alkylated derivatives, 6a - 6c, were reversed and strongly inhibited PC-3 cell growth with IC50 values of less than 1.0 µM but only weakly against the growth of A549, MCF-7 and M-10 cells. These results indicated that N-alkylation of CIL-102 increased not only selectivity but also the antiproliferative potency against PC-3 cell growth. Among these derivatives synthesized, N-(4-acetylphenyl)-N-(furo[2,3-b]quinolin- 4-yl)methylamine (6a) and its N-ethyl counterpart 6b are the two most active CIL-102 derivatives against PC-3 cell growth with IC50 value of 0.22 and 0.20 µM, respectively. Compound 6a is less cytotoxic to normal human M-10 cells than 6b and therefore was selected for further mechanism studies. The flow cytometry studies clearly indicated that compound 6a induced cell accumulation in G2/M phase in a dose-dependent manner after 24 h-treatment. While the proliferation of LNCaP C-81 prostate cancer cells was also strongly suppressed by compound 6a; compound 11a exhibited better selective activity toward LNCaP C-81 prostate cancer cells over RWPE-1 non-cancerous prostate epithelia. Thus, this group of compounds has a potential of serving as therapeutic agents toward advanced castration-resistant prostate cancers.