Induction of retinoid X receptor activity and consequent upregulation of p21WAF1/CIP1 by indenoisoquinolines in MCF7 cells

Carbonylative Transformations Using a DMAP-Based Pd-Catalyst through Ex Situ CO Generation

A phosphine-free, efficient protocol for aminocarbonylation and carbonylative Suzuki-Miyaura coupling has been developed using a novel palladium complex, [PdII(DMAP)2(OAc)2]. The complex was successfully synthesized using a stoichiometric reaction between PdII(OAc)2 and DMAP in acetone at room temperature and characterized using single-crystal X-ray analysis. Only 5 mol % catalyst loading was sufficient for effective carbonylative transformations. "Chloroform-COware" chemistry was utilized for safe and facile insertion of the carbonyl unit using chloroform as an inexpensive CO source in a two-chamber setup. Various value-added pharmaceutically relevant compounds such as CX-516, CX-546, and farampator were synthesized using the technique. Furthermore, the commercially designed COware was engineered to COware-RB setup for sequential one-pot synthesis of indenoisoquinolines (topoisomerase I inhibitors).

Synthesis and Biological Activity of a New Indenoisoquinoline Copper Derivative as a Topoisomerase I Inhibitor

Topoisomerases are interesting targets in cancer chemotherapy. Here, we describe the design and synthesis of a novel copper(II) indenoisoquinoline complex, WN198. The new organometallic compound exhibits a cytotoxic effect on five adenocarcinoma cell lines (MCF-7, MDA-MB-231, HeLa, HT-29, and DU-145) with the lowest IC50 (0.37 ± 0.04 μM) for the triple-negative MDA-MB-231 breast cancer cell line. Below 5 µM, WN198 was ineffective on non-tumorigenic epithelial breast MCF-10A cells and Xenopus oocyte G2/M transition or embryonic development. Moreover, cancer cell lines showed autophagy markers including Beclin-1 accumulation and LC3-II formation. The DNA interaction of this new compound was evaluated and the dose-dependent topoisomerase I activity starting at 1 μM was confirmed using in vitro tests and has intercalation properties into DNA shown by melting curves and fluorescence measurements. Molecular modeling showed that the main interaction occurs with the aromatic ring but copper stabilizes the molecule before binding and so can putatively increase the potency as well. In this way, copper-derived indenoisoquinoline topoisomerase I inhibitor WN198 is a promising antitumorigenic agent for the development of future DNA-damaging treatments.

Investigation of Chemopreventive and Antiproliferative Potential of Dicliptera roxburghiana

CONTEXT

Carcinogenesis causes much human misery. It is a process involving multistage alterations. Medicinal plants are candidates for beneficial anticancer agents.

OBJECTIVES

Investigation of anticancer proficiencies of the plant Dicliptera roxburghiana.

MATERIAL AND METHODS

Crude extract and derived fractions were inspected for their inhibitory potential against nuclear factor KB (NFκB), nitric oxide synthase inhibition, aromatase inhibition and induction of quinone reductase 1 (QR 1). Antiproliferative activity was determined by using various cancer cell lines for example hormone responsive breast cancer cell line MCF-7, estrogen receptor negative breast cancer cell line MDA-MB-231, murine hepatoma cells Hepa 1c1c7, human neuroblastoma cells SK-N-SH and neuroblastoma cells MYCN-2.

RESULTS

Ethyl acetate and n-butanol fractions of D. roxburghiana were strongly active against NFκB with IC₅₀ of 16.6 ± 1.3 and 8.4 ± 0.7 µg/ml respectively with 100% survival. Chloroform fraction of the plant exhibited an induction ratio of 2.4 ± 0.09 with CD value of 17.7 µg/ml. Regarding the nitrite assay, the n-hexane fraction exhibited significant inhibition of NO activity with IC₅₀ of 17.8 ± 1.25 µg/ml. The n-butanol fraction exhibited strong antiproliferative activity against IcIc-7 cell lines with IC₅₀ values of 13.6 ± 1.91 µg/ml; against MYCN-2 a cytotoxic effect developed with dose dependence, with IC₅₀ of 12.6 ± 1.24 µg/ml. In antiproliferative activity against SK-N-SH cell lines, chloroform, ethyl acetate and n-butanol fractions were efficiently active with IC₅₀ values of 11.2 ± 0.84, 14.6 ± 1.71 and 16.3 ± 1.57 respectively.

DISCUSSION AND CONCLUSION

It was demonstrated that various fractions of D. roxburghiana displayed appreciable anticancer characteristics and could be a potent source for the development of anticancer leads.

Design and Synthesis of Indenoisoquinolines Targeting Topoisomerase I and Other Biological Macromolecules for Cancer Chemotherapy

The discovery that certain indenoisoquinolines inhibit the religation reaction of DNA in the topoisomerase I-DNA-indenoisoquinoline ternary complex led to a structure-based drug design research program which resulted in three representatives that entered Phase I clinical trials in cancer patients at the National Cancer Institute. This has stimulated a great deal of interest in the design and execution of new synthetic pathways for indenoisoquinoline production. More recently, modulation of the substitution pattern and chemical nature of substituents on the indenoisoquinoline scaffold has resulted in a widening scope of additional biological targets, including RXR, PARP-1, MYC promoter G-quadruplex, topoisomerase II, estrogen receptor, VEGFR-2, HIF-1α, and tyrosyl DNA phosphodiesterases 1 and 2. Furthermore, convincing evidence has been advanced supporting the potential use of indenoisoquinolines for the treatment of diseases other than cancer. The rapidly expanding indenoisoquinoline knowledge base has provided a firm foundation for further advancements in indenoisoquinoline chemistry, pharmacology, and therapeutics.

Synthesis and biological evaluation of (3/4-(pyrimidin-2-ylamino)benzoyl)-based hydrazine-1-carboxamide/carbothioamide derivatives as novel RXRα antagonists

Abnormal alterations in the expression and biological function of retinoid X receptor alpha (RXRα) have a key role in the development of cancer. Potential modulators of RXRα as anticancer agents are explored in growing numbers of studies. A series of (4/3-(pyrimidin-2-ylamino)benzoyl)hydrazine-1-carboxamide/carbothioamide derivatives are synthesised and evaluated for anticancer activity as RXRα antagonists in this study. Among all synthesised compounds, 6A shows strong antagonist activity (half maximal effective concentration (EC₅₀) = 1.68 ± 0.22 µM), potent anti-proliferative activity against human cancer cell lines HepG2 and A549 cells (50% inhibition of cell viability (IC₅₀) values < 10 µM), and low cytotoxic property in normal cells such as LO2 and MRC-5 cells (IC₅₀ values > 100 µM). Further bioassays indicate that 6A inhibits 9-cis-RA-induced activity in a dose-dependent manner, and selectively binds to RXRα-=LΒD with submicromolar affinity (Kd = 1.20 × 10⁻⁷ M). 6A induces time-and dose-dependent cleavage of poly ADP-ribose polymerase, and significantly stimulates caspase-3 activity, leading to RXRα-dependent apoptosis. Finally, molecular docking studies predict the binding modes for RXRα-LBD and 6A.

Natural and synthetic retinoid X receptor ligands and their role in selected nuclear receptor action

Important key players in the regulatory machinery within the cells are nuclear retinoid X receptors (RXRs), which compose heterodimers in company with several diverse nuclear receptors, playing a role as ligand inducible transcription factors. In general, nuclear receptors are ligand-activated, transcription-modulating proteins affecting transcriptional responses in target genes. RXR molecules forming permissive heterodimers with disparate nuclear receptors comprise peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptor (FXR), pregnane X receptor (PXR) and constitutive androstan receptor (CAR). Retinoid receptors (RARs) and thyroid hormone receptors (TRs) may form conditional heterodimers, and dihydroxyvitamin D₃ receptor (VDR) is believed to form nonpermissive heterodimer. Thus, RXRs are the important molecules that are involved in control of many cellular functions in biological processes and diseases, including cancer or diabetes. This article summarizes both naturally occurring and synthetic ligands for nuclear retinoid X receptors and describes, predominantly in mammals, their role in molecular mechanisms within the cells. A focus is also on triorganotin compounds, which are high affinity RXR ligands, and finally, we present an outlook on human microbiota as a potential source of RXR activators. Nevertheless, new synthetic rexinoids with better retinoid X receptor activity and lesser side effects are highly required.

Antiinflammatory lanostane triterpenoids from Ganoderma lucidum

Phytochemical and biological studies of the methanolic extracts from Ganoderma lucidum (Polyporaceae) have led to the identification and isolation of a new lanostane triterpenoid, ganosidone A (1), and its eight known derivatives (2‒9). The structure of new compound was determined by HREIMS, 1 D and 2 D NMR experiments and by comparing the acquired physicochemical data with the published values. All the compounds were evaluated for cancer chemopreventive potential based on their ability to inhibit nitric oxide (NO) production induced by lipopolysaccharides (LPS) in mouse macrophage RAW 264.7 cells in vitro. Notably, at a concentration of 50 μM, compounds 4 and 7 inhibited NO production by 86.5% and 88.2%, respectively.

NLS-RARα contributes to differentiation block and increased leukemogenic potential in vivo

The fusion oncogene, promyelocytic leukemia (PML)-retinoic acid receptor-α (RARα), is crucial for acute promyelocytic leukemia (APL) pathogenesis. Previous studies have reported that PML-RARα is cleaved by neutrophil elastase (NE), an early myeloid-specific serine protease, leading to translocation of the nuclear localization signal (NLS) of the PML protein to the N-terminal of RARα. This study was designed to evaluate the value of NLS-RARα in the early diagnosis of APL. To investigate the potential functional role of NLS-RARα in leukemogenesis, HL-60 and U937 cell lines were transfected with NLS-RARα lentivirus and negative control (LVNC). The results showed that the induced expression of NLS-RARα down-regulated expressions of CD11b, CD11c, and CD14 compared to the LVNC group induced by 1α, 25-dihydroxyvitamin D₃(1,25(OH)₂D₃). This suggested that NLS-RARα overexpression inhibited granulocytic and monocytic differentiation of myeloid leukemia cells. In addition, Wright-Giemsa staining, flow cytometry, respiratory burst assay, and NBT reduction assay all confirmed the importance of NLS-RARα in differentiation. The mechanistic investigations revealed that induced NLS-RARα expression inhibited 1,25(OH)₂D₃-induced granulocytic differentiation by regulating the cell cycle regulators p19^INK4D, p21^WAF1/CIP1, cyclinD1, cyclin E1, and pRB. Furthermore, the cleaved protein NLS-RARα enhanced the oncogenicity of U937 cells in NOD/SCID mice. These findings collectively demonstrated that NLS-RARα blocked granulocytic and monocytic differentiation of myeloid leukemia cells by inhibiting the downstream targets of the RARα signal pathway and the cell cycle. This may provide a promising new target and method for diagnosing and treating APL.

Alternative retinoid X receptor (RXR) ligands

Retinoid X receptors (RXRs) control a wide variety of functions by virtue of their dimerization with other nuclear hormone receptors (NRs), contributing thereby to activities of different signaling pathways. We review known RXR ligands as transcriptional modulators of specific RXR-dimers and the associated biological processes. We also discuss the physiological relevance of such ligands, which remains frequently a matter of debate and which at present is best met by member(s) of a novel family of retinoids, postulated as Vitamin A5. Through comparison with other natural, but also with synthetic ligands, we discuss high diversity in the modes of ligand binding to RXRs resulting in agonistic or antagonistic profiles and selectivity towards specific subtypes of permissive heterodimers. Despite such diversity, direct ligand binding to the ligand binding pocket resulting in agonistic activity was preferentially preserved in the course of animal evolution pointing to its functional relevance, and potential for existence of other, species-specific endogenous RXR ligands sharing the same mode of function.

A review of the molecular design and biological activities of RXR agonists

An attractive approach to combat disease is to target theregulation of cell function. At the heart of this task are nuclear receptors (NRs); which control functions such as gene transcription. Arguably, the key player in this regulatory machinery is the retinoid X receptor (RXR). This NR associates with a third of the NRs found in humans. Scientists have hypothesized that controlling the activity of RXR is an attractive approach to control cellular functions that modulate diseases such as cancer, diabetes, Alzheimer's disease and Parkinson's disease. In this review, we will describe the key features of the RXR, present a historic perspective of the first RXR agonists, and discuss various templates that have been reported to activate RXR with a focus on their molecular structure, biological activity, and limitations. Finally, we will present an outlook of the field and future directions and considerations to synthesize or modulate RXR agonists to make these compounds a clinical reality.

Phytochemical profile of genotypes of Euterpe edulis Martius - Juçara palm fruits

Juçara fruit (Euterpe edulis) has received attention due to its similarities to Euterpe oleracea (Açaí). The aim of this study was to evaluate the cytotoxicity, bioactive compounds, antioxidant capacities and chemopreventive activities of the fruit pulps of six populations of E. edulis (J1-J6) and one population of E. espiritosantense from different ecological regions. ESI(-)-FT-ICR-MS was used to evaluate the pulp composition. The varieties J1 and J4 presented higher polyphenol contents, while J2 and J5 showed higher anthocyanin contents. ESI-FT-ICR MS identified cyanidin-3-rutinoside (J1, J2, J3, J4, J5, J7), protocatechuic acid, methylhydroxybenzoate hexoside and rutin (J1 to J7) and malvidin-glicoside (J2 to J5). The J2, J3, J4, J5 and J6 samples inhibited inducible nitric oxide synthase (iNOS). The chemoprevention biomarker quinone reductase was significantly induced by J6. Pulp from plants J3, J4, J6 and J7 significantly reduced the inflammatory cytokine TNF-α, and J6 was selected as having the most potential for cultivation and consumption.

NF-κB inhibitors, unique γ-pyranol-γ-lactams with sulfide and sulfoxide moieties from Hawaiian plant Lycopodiella cernua derived fungus Paraphaeosphaeria neglecta FT462

LC-UV/MS-based metabolomic analysis of the Hawaiian endophytic fungus Paraphaeosphaeria neglecta FT462 led to the identification of four unique mercaptolactated γ-pyranol-γ-lactams, paraphaeosphaerides E-H (1-4) together with one γ-lactone (5) and the methyl ester of compound 2 (11). The structures of the new compounds (1-5 and 11) were elucidated through the analysis of HRMS and NMR spectroscopic data. The absolute configuration was determined by chemical reactions with sodium borohydride, hydrogen peroxide, α-methoxy-α-(trifluoromethyl)phenylacetyl chlorides (Mosher reagents), and DP4 + NMR calculations. All the compounds were tested against STAT3, A2780 and A2780cisR cancer cell lines, E. coli JW2496, and NF-κB. Compounds 1 and 3 strongly inhibited NF-κB with IC50 values of 7.1 and 1.5 μM, respectively.

The Daniel K. Inouye College of Pharmacy Scripts: Poha Berry (Physalis peruviana) with Potential Anti-inflammatory and Cancer Prevention Activities

The Daniel K. Inouye College of Pharmacy, during a historic event in Spring 2016, graduated the first two students in the Pacific region to earn a PhD in pharmaceutical sciences at the University of Hawai'i at Hilo. The college offers PhD programs in these five disciplines: Cancer Biology, Medicinal Chemistry, Pharmaceutics, Pharmacognosy, and Pharmacology. One of the Pharmacognosy dissertations focused on plant-derived natural products with potential anti-inflammatory and cancer chemopreventive activities. Physalis peruviana (Pp) L. originated in tropical South America. It has become naturalized and is found readily on the Island of Hawai'i. The edible fruits are commonly known as cape gooseberry or poha in Hawai'i. In part of our study, three new withanolides, physaperuvin G (1), physaperuvins I-J (2-3), along with four known withanolides, namely, 4β-hydroxywithanolide E (4), withaperuvin C (5), and physalactone (6), coagulin (7) were isolated from the aerial parts of P. peruviana. In addition, two known compounds, phyperunolide F (8), and withanolide S (9), were isolated and identified from the poha berry fruits. The structures and absolute stereochemistry of new compounds from poha were elucidated by several spectroscopy methods: Nuclear Magnetic Resonance (NMR) spectroscopy, X-ray diffraction, and mass spectrometry analyses. All isolated poha compounds (aerial parts and fruits) were evaluated for their anti-inflammatory activity with lipopolysaccharide (LPS)-activated murine macrophage RAW 264.7 cells, and tumor necrosis factor alpha (TNF-α)-activated nuclear factor-kappa B (NF-κB) with transfected human embryonic kidney cells 293. Most of the isolated natural compounds showed activity with these assays. Additional studies were performed with models of colon cancer. Specifically, 4β-hydroxywithanolide E (4HWE) inhibited the growth of colon cancer monolayer and spheroid cultures. The compound induced cell cycle arrest at low concentrations and apoptosis at higher concentrations. These data suggest the ingestion of poha berries may have some effect on the prevalence of colon cancer. Additionally, poha isolates compounds were evaluated for their growth inhibitory effects with U251MG glioblastoma and MDA-MB-231 breast cancer cells that harbor aberrantly-active signal transducer and activation of transcription 3 (STAT3), compared to normal NIH-3T3 mouse fibroblasts. This work has led to the filing of three provisional patents with the University of Hawai'i Office of Technology Transfer and Economic Development.

Fraxinus xanthoxyloides leaves reduced the level of inflammatory mediators during in vitro and in vivo studies

Background

Different parts of Fraxinus xanthoxyloides Wall. (Oleaceae) are used traditionally in the treatment of internal wounds, bone fracture, pain, jaundice, malaria and in pneumonia. These ailments involve protective and essential mechanisms of the organism in response to infection, injury and trauma. However, prolonged inflammation may lead to inflammatory disorders. The present investigation was carried to evaluate the crude methanol extract of F. xanthoxyloides leaves and its fractions for their anti-inflammatory and analgesic effects.

Methods

Methanol extract of F. xanthoxyloides leaves was fractionated through liquid-liquid partition on escalating polarity of solvents. Acetic acid and thermal responses were used to evaluate the analgesic effects of extract/fractions in rat. Anti-inflammatory effects were monitored through in vitro; TNF-α activated NFkB in 293/NFkB-Luc HEK cells and LPS-activated nitric oxide (NO) assay in RAW 264.7 cells. For in vivo studies carrageenan induced paw edema model was used in rat. Both in vitro and in vivo studies have indicated that chloroform fraction exhibited superior anti-inflammatory effects to other extract/fractions and therefore, was used in air pouch model in rat to estimate the inhibition in leukocyte migration and synthesis of inflammatory mediators. In addition, phytochemical investigation of crude extract was carried out by GC-MS analysis.

Results

GC-MS studies of crude extract revealed the presence of various classes of which terpenoids (26.61 %), lactam (16.47 %), esters (15.81 %), phenols (8.37 %), and steroid (6.91 %) constituted the major categories. Among the extracts chloroform fraction (200 mg/kg bw) significantly (P <0.001) increased the percent latency time (76.13 ± 4.49 %) in hot plate test after 120 min and decreased (P <0.001) the count of writhes (77.23 ± 5.64 %) as compared to other extracts. The in vitro studies indicated that chloroform fraction at 15 μg/ml more effectively inhibited the TNF-α induced synthesis of NFkB (85.0 ± 8.12 %, IC₅₀ = 5.98 μg/ml) and LPS-instigated nitric oxide (78.23 ± 2.39 %, IC₅₀ = 6.59 μg/ml) synthesis. Although all the extract/fractions showed a dose dependent increase in inhibition of edema formation however, chloroform fraction (4^th h = 77.64 ± 3.04 %) at 200 mg/kg bw exhibited relatively higher (P <0.001) anti-inflammatory activity in carrageenan-induced paw edema in rat. Moreover, chloroform fraction had the ability to decrease (P <0.001) the influx of leukocytes and the concentration of inflammatory mediators; TNF-α, NO, IL-6 and PGE₂ in air pouch exudate.

Conclusion

The study demonstrates the therapeutic potential of F. xanthoxyloides leaves against the inflammatory disorders suggesting the presence of active constituents in chloroform fraction.

Evidence supporting the conceptual framework of cancer chemoprevention in canines

As with human beings, dogs suffer from the consequences of cancer. We investigated the potential of a formulation comprised of resveratrol, ellagic acid, genistein, curcumin and quercetin to modulate biomarkers indicative of disease prevention. Dog biscuits were evaluated for palatability and ability to deliver the chemopreventive agents. The extent of endogenous DNA damage in peripheral blood lymphocytes from dogs given the dietary supplement or placebo showed no change. However, H₂O₂-inducible DNA damage was significantly decreased after consumption of the supplement. The expression of 11 of 84 genes related to oxidative stress was altered. Hematological parameters remained in the reference range. The concept of chemoprevention for the explicit benefit of the canine is compelling since dogs are an important part of our culture. Our results establish a proof-of-principle and provide a framework for improving the health and well-being of “man’s best friend”.

Skeletal muscle PGC-1α controls whole-body lactate homeostasis through estrogen-related receptor α-dependent activation of LDH B and repression of LDH A

The peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) controls metabolic adaptations. We now show that PGC-1α in skeletal muscle drives the expression of lactate dehydrogenase (LDH) B in an estrogen-related receptor-α-dependent manner. Concomitantly, PGC-1α reduces the expression of LDH A and one of its regulators, the transcription factor myelocytomatosis oncogene. PGC-1α thereby coordinately alters the composition of the LDH complex and prevents the increase in blood lactate during exercise. Our results show how PGC-1α actively coordinates lactate homeostasis and provide a unique molecular explanation for PGC-1α-mediated muscle adaptations to training that ultimately enhance exercise performance and improve metabolic health.

Design, synthesis, and biological evaluation of indenoisoquinoline rexinoids with chemopreventive potential

Nuclear receptors, such as the retinoid X receptor (RXR), are proteins that regulate a myriad of cellular processes. Molecules that function as RXR agonists are of special interest for the prevention and control of carcinogenesis. The majority of these ligands possess an acidic moiety that is believed to be key for RXR activation. This communication presents the design, synthesis, and biological evaluation of both acidic and nonacidic indenoisoquinolines as new RXR ligands. In addition, a comprehensive structure-activity relationship study is presented that identifies the important features of the indenoisoquinoline rexinoids. The ease of modification of the indenoisoquinoline core and the lack of the necessity of a carboxyl group for activity make them an attractive and unusual family of RXR agonists. This work establishes a structural foundation for the design of new and novel rexinoid cancer chemopreventive agents.

Preliminary evaluation for cancer chemopreventive and cytotoxic potential of naturally growing ethnobotanically selected plants of Pakistan

CONTEXT

Natural products are a very productive source of leads for the development of medicines. Six Pakistani plants were chosen for study based on ethnobotanical data.

OBJECTIVE

Exploration of important medicinal plants of Pakistan for cancer treatment.

MATERIALS AND METHODS

The crude extracts of the six plants and their fractions were tested for inhibition of nuclear factor κB (NFκB), aromatase, and nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage RAW 264.7 cells, induction of quinone reductase 1 (QR1), agonism of retinoid X receptor, and growth inhibition with MCF-7, LU-1 and MDA-MB-231 cancer cells.

RESULTS

Two samples of Withania coagulans (Stocks) Dunal (Solanaceae) demonstrated inhibition of TNF-α induced activity of NFκB with IC₅₀ values of 2.6 and 4.3 µg/mL, respectively. Two fractions from W. coagulans and Euphorbia wallichii Hook F. (Euphorbiaceae) aerial parts inhibited aromatase with IC₅₀ values of 17.0 and 17.7 µg/mL, respectively. A total of 13 samples (five from E. wallichii, one from Acer oblongifolium Hort. ex Dippel (Aceraceae), one from Aster thomsonii C. B. Clarke (Asteraceae) and six from W. coagulans aerial parts with fruits) inhibited NO production with IC₅₀ values ranging from 1.3 to 15.6 µg/mL. Fourteen samples demonstrated induction of QR1 with CD ranging from 1.0 to 20.6 µg/mL, and a total of eight extracts and fractions inhibited the proliferation of cancer cells in culture with IC₅₀ values ranging from 1.2 to 7.8 µg/mL.

DISCUSSION AND CONCLUSION

Selected plants can be a valuable source of chemopreventive and anticancer products. W. coagulans aerial parts showed the strongest activity.

Biologically active withanolides from Withania coagulans

Bioassay-directed isolation and purification of the crude extract of Withania coagulans, using two assays for cancer chemopreventive mechanisms, led to the isolation of three new steroidal lactones, withacoagulin G (1), withacoagulin H (2), and withacoagulin I (3), along with six known derivatives (4-9). The structures and absolute stereochemistry of these compounds were determined on the basis of spectroscopic analyses, including 1D and 2D NMR, mass spectrometry, and CD analyses. The structure of 1 was confirmed using X-ray diffraction methods. Compounds 1-9 inhibited nitric oxide production in lipopolysaccharide-activated murine macrophage RAW 264.7 cells with IC(50) values in the range of 1.9-38.2 μM. Compounds 1 and 2 were the most active (IC(50) 3.1 and 1.9 μM, respectively). Withanolides 1-9 exhibited inhibition of tumor necrosis factor-α (TNF-α)-induced nuclear factor-kappa B (NF-κB) activation with IC(50) values in the range of 1.60-12.4 μM.

Synthesis and biological evaluation of indenoisoquinolines that inhibit both tyrosyl-DNA phosphodiesterase I (Tdp1) and topoisomerase I (Top1)

Tyrosyl-DNA phosphodiesterase I (Tdp1) plays a key role in the repair of damaged DNA resulting from the topoisomerase I (Top1) inhibitor camptothecin and a variety of other DNA-damaging anticancer agents. This report documents the design, synthesis, and evaluation of new indenoisoquinolines that are dual inhibitors of both Tdp1 and Top1. Enzyme inhibitory data and cytotoxicity data from human cancer cell cultures were used to establish structure-activity relationships. The potencies of the indenoisoquinolines against Tdp1 ranged from 5 μM to 111 μM, which places the more active compounds among the most potent known inhibitors of this target. The cytotoxicity mean graph midpoints ranged from 0.02 to 2.34 μM. Dual Tdp1-Top1 inhibitors are of interest because the Top1 and Tdp1 inhibitory activities could theoretically work synergistically to create more effective anticancer agents.

Identification, synthesis, and biological evaluation of the metabolites of 3-amino-6-(3'-aminopropyl)-5H-indeno[1,2-c]isoquinoline-5,11-(6H)dione (AM6-36), a promising rexinoid lead compound for the development of cancer chemotherapeutic and chemopreventive agents

Activation of the retinoid X receptor (RXR), which is involved in cell proliferation, differentiation, and apoptosis, is a strategy for cancer chemotherapy and chemoprevention, and 3-amino-6-(3'-aminopropyl)-5H-indeno[1,2-c]isoquinoline-5,11-(6H)dione (AM6-36) (3) is among the few RXR ligands known. The presently reported studies of 3 include its binding to human plasma proteins, metabolic stability using human liver microsomes, metabolism by human liver microsomes and hepatocytes, and in vivo disposition in rat serum, liver, and mammary tissue. Compound 3 was 75% bound to human plasma proteins, and its metabolic stability was much greater than propranolol. One phase I metabolite was formed by human liver microsomes, seven phase I and II metabolites were formed by human hepatocytes, and five metabolites were detected in rat serum and liver after oral administration. The putative metabolites predicted using LC-MS-MS were synthesized to confirm their structures and to provide sufficient material for investigation of induction of RXRE transcriptional activity and inhibition of NFκB.

Induction of apoptosis by 3-amino-6-(3-aminopropyl)-5,6-dihydro-5,11-dioxo-11H-indeno[1,2-c]isoquinoline via modulation of MAPKs (p38 and c-Jun N-terminal kinase) and c-Myc in HL-60 human leukemia cells

Recently, we reported that 3-amino-6-(3-aminopropyl)-5,6-dihydro-5,11-dioxo-11H-indeno[1,2-c]isoquinoline (AM6-36), sharing structural similarity with naturally occurring isoquinolines, induced activities mediated by retinoid X receptor (RXR) response element accompanied by antiproliferative effects on breast cancer cells. To further characterize the biologic potential of AM6-36, we currently report studies conducted with HL-60 human leukemia cells. AM6-36 significantly inhibited cellular proliferation in a dose- and time-dependent manner with an IC(50) value of 86 nM. When evaluated at low test concentrations (≤0.25 μM), AM6-36 induced arrest in the G2/M phase of the cell cycle. At higher concentrations (1 and 2 μM), the response shifted to apoptosis, which was consistent with the effect of AM6-36 on other apoptotic signatures including an increase of apoptotic annexin V(+) 7-AAD(-) cells, loss of mitochondrial membrane potential, induction of poly(ADP-ribose) polymerase cleavage, and activation of several caspases. These apoptotic effects are potentially due to up-regulation of p38 MAPK and JNK phosphorylation and down-regulation of c-Myc oncogene expression. Taken together, AM6-36 might serve as an effective anticancer agent by inducing G2/M cell cycle arrest and apoptosis through the activation of MAPKs and inhibition of c-Myc.