Beccaridiol, an unusual 28-nortriterpenoid from the leaves of Diplectria beccariana

A C29-triterpene, beccaridiol (1), a dihydrochalcone natural product, 2',4'-dihydroxy-3-(4-methoxyphenyl)-propiophenone (2), as well as three known compounds, 4'-hydroxy-1',2'-dihydro-beta-ionone, 4'-O-methyldavidigenin (3), and ursolic acid, have been isolated from an EtOAc-soluble extract of the leaves of Diplectria beccariana. Beccaridiol (1) was characterized as an ursane-type 28-nortriterpene possessing an unusual aromatic E-ring by spectroscopic data interpretation. The relative configuration of this unusual isolate was established by analyzing the observed NOESY NMR correlations, and the absolute stereochemistry of 1 was then determined based on the circular dichroism (CD) spectrum of its 2,3-di-p-bromobenzoate (1b) derivative. All isolates were evaluated for their potential cancer chemopreventive properties utilizing a cell culture assay to determine quinone reductase induction.     

Synthesis and cytotoxicity of epoxide and pyrazole analogs of the combretastatins

Twenty-six epoxide and corresponding pyrazole derivatives, of the structurally related chalcones and combretastatin A-4 (CA-4), were synthesized and tested for in vitro cytotoxicity. These molecules were synthesized by epoxidation of the relevant chalcones, followed by reaction with hydrazine. The structures of epoxides 3 and 7, and pyrazole 17, were confirmed by X-ray diffraction studies. The relatively coplanar conformation of a 3',3',4',4',5',5'-hexamethoxypyrazole 17 was in good agreement with the shape for 3',3',4',4',5'-pentamethoxypyrazole 16, which was determined from molecular mechanics optimization. In vitro cytotoxicity of each class of compounds was obtained using a 72 h continuous exposure MTT assay against two murine cancer cell lines; B16 melanoma and L1210 leukemia. The effect of substitution in the A-ring is addressed: three methoxy groups versus two, generally increased cytotoxicity across both cell lines. In the majority of cases, the pyrazoles are generally more active than the epoxides, with the most active, 5-(3'-amino-4'-methoxyphenyl)-3-(3',4',5'-trimethoxyphenyl)pyrazole 21, possessing an IC(50) value of 5 and 2.4 microM (B16 and L1210, respectively). Due to their planar conformations, the pyrazoles are typically less active than the corresponding chalcones, which adopt angular conformations similar to CA-4. B-ring modifications confirmed that in general the amino compounds are more active than the corresponding nitro compounds. Varying the number and orientation of methoxy groups on the A-ring did not produce any significant differences in toxicity in the cell lines studied.     

Synthesis and antiproliferative activity of 2-aryl-4-oxo-thiazolidin-3-yl-amides for prostate cancer

We have previously described serine amide phosphates (SAPs) as a novel class of cytotoxic agents for prostate cancer. Several of them showed potent cytotoxicity against human prostate cancer cell lines, but were not selective in non-tumor cells. To improve the selectivity and further enhance the potency, we designed a new series of 2-aryl-4-oxo-thiazolidin-3-yl amides. The current work describes synthesis, SAR, and biological evaluation of these compounds for their ability to inhibit the growth of prostate cancer cells. The antiproliferative effects of synthesized compounds were examined in five human prostate cancer cell lines (DU-145, PC-3, LNCaP, PPC-1, and TSU), and in RH7777 cells (negative controls). From this study, three potent compounds (8, 20, and 21) have been detected, which are effective in killing prostate cancer cells with improved selectivity compared to SAPs.     

Clerodane diterpenoids from Pulicaria wightiana

Five clerodane diterpenoids have been isolated from the aerial parts of Pulicaria wightiana along with 3'5,6-trihydroxy-3,4',7-trimethoxyflavone and 2-methyl-5-hydroxy-chroman-4-one. The structures and stereochemistry of the compounds were established from spectral (mainly 1D and 2D NMR) studies. The last two compounds were not reported earlier from this plant. The antibacterial activity of the diterpenoids were studied.     

Synthesis and RT inhibitory activity evaluation of new pyrimidine-based seco-nucleosides

Eleven new 3',4'-seco acyclic nucleosides (4-14) were prepared by nucleophilic substitution of protected pyrimidine bases on ethyl 3,3-diethoxypropanoate (3). Structures were characterized spectroscopically and a brief analysis of their conformation in solution was performed by the vicinal coupling constants (3)JH2'aH3' and (3)JH2'bH3'. In solid state, compound 6 forms a homodimer linked by hydrogen bonding. In preliminary tests all compounds show low toxicity and gentle activity against HIV-1 RT in vitro.     

Thalidomide analogues demonstrate dual inhibition of both angiogenesis and prostate cancer

The identification of agents with antiproliferative activity against endothelial cells has significant value for the treatment of many angiogenesis-dependent pathologies. Herein, we describe the discovery of a series of thalidomide analogues possessing inhibitory effects against both endothelial and prostate cancer cells. More specifically, several analogues exhibited low micromolar to mid-nanomolar potency in the inhibition of human microvascular endothelial cell (HMEC) proliferation, both in the presence and absence of vascular endothelial growth factor (VEGF), with the tetrafluorophthalimido class of compounds demonstrating the greatest potency. Additionally, all the compounds were screened against two different androgen independent prostate cancer cell lines (PC-3 and DU-145). Again, the tetrafluorophthalimido analogues exhibited the greatest effect with GI(50) values in the low micromolar range. Thalidomide was found to demonstrate selective inhibition of androgen receptor positive LNCaP prostate cancer cells. Furthermore, we showed that, as an example, tetrafluorophthalimido analogue 19 was able to completely inhibit the prostate specific antigen (PSA) secretion by the LNCaP cell line, while thalidomide demonstrated a 70% inhibition. We have also demonstrated that a correlation exists between HMEC and prostate cancer cell proliferation for this structural class. Altogether, our study suggests that these analogues may serve as promising leads for the development of agents that target both androgen dependent and independent prostate cancer and blood vessel growth.     

Growth inhibitory activities of oxyprenylated and non-prenylated naturally occurring phenylpropanoids in cancer cell lines

A series of 25 selected oxyprenylated natural phenylpropanoids were synthesized, and their growth inhibitory activities were evaluated in vitro together with 14 other commercially available non-alkylated compounds belonging to the same chemical series. The compounds were tested on six human cancer cell lines using MTT colorimetric assays. The data reveal that of the six chemical groups (G) studied, coumarins (G1), cinnamic and benzoic acids (G2), chalcones (G3), acetophenones (G4), anthraquinones (G5), and cinnamaldehydes and cinnamyl alcohols (G6), G2-related compounds displayed the weakest growth inhibitory activities in vitro, whereas G5-related compounds displayed the highest activities. Quantitative videomicroscopy analyses were then carried out on human U373 glioblastoma cells, which are characterized by various levels of resistance to different pro-apoptotic stimuli. These analyses revealed that compounds 20 (4,2′,4′-trihydroxychalcone), and 30 and 31 (two cinnamaldehydes) were cytostatic and able to overcome the intrinsic resistance of U373 cancer cells to pro-apoptotic stimuli.     

A new anti-tubulin agent containing the benzo[b]thiophene ring system.

A new type of inhibitor of tubulin polymerization was discovered based on the 3-aroyl-2-arylbenzo[b]thiophene molecular skeleton. The lead compound in this series, 2-(4'-methoxyphenyl)-3-(3',4',5'-trimethoxybenzoyl)-6-methoxybe nzo[b]thiophene 1, inhibited tubulin polymerization, caused an increase in the mitotic index of CA46 Burkitt lymphoma cells, and inhibited the growth of several human cancer cell lines.     

Synthesis and inhibition of cancer cell proliferation of (1,3')-bis-tetrahydroisoquinolines and piperazine systems

Some (1,3')-bis-tetrahydroisoquinolines were reported as scaffold intermediates for the synthesis of pentacyclic piperazine core alkaloids and their cytotoxicity against cancerous cell lines was evaluated. The NMR and X-ray structural assignments revealed an anti C3-C11 backbone stereochemistry of piperazine structures. Inhibition of cancer cell proliferation of (1,3')-bis-tetrahydroisoquinoline scaffolds and pentacyclic piperazine systems was assessed against three human cancer cell lines (K562 myelogenous leukemia, A549 lung carcinoma, MCF-7 breast adenocarcinoma) and both mouse tumor cell lines of blood (P388) and lymphocytic (L1210) leukemia with considerable activity against the latter. The cell cycle analysis was also studied by flow cytometry measurement on K562 cell line.     

Inhibition of purified rabbit muscle phosphorylase a and phosphorylase b by polychlorinated biphenyls, polychlorinated biphenylols and polybrominated biphenyls

Polychlorinated biphenyls, polychlorinated biphenylols and polybrominated biphenyls inhibited both rabbit muscle phosphorylase a and phosphorylase b (1,4-alpha-D-glucan:orthophosphate alpha-d-glucosyltransferase, EC 2.4.1.1). The degree of inhibition was dependent upon the relative hydrophobicity of the compounds and steric hinderance. 2,4,5,2',4',5'-Hexabromobiphenyl and Firemaster BP-6 were the most effective inhibitors (Ki, 15 . 10(-6) M). Phosphorylase b was inhibited by compounds of all three groups. 2,4,5,2',4',5'-Hexachlorobiphenyl and 2,4,5,2',4',5'-hexabromobiphenyl did not significantly inhibit phosphorylase a. All of the compounds inhibited phosphorylase a less than phosphorylase b, except 2',3',4',5,5'-pentachloro-2-biphenylol, which was equally effective on each enzyme. Kinetic analysis showed the inhibition was non-competitive and mixed. The results indicate that the compounds bind to hydrophobic site(s) on phosphorylase, access to which is limited by phosphorylation of serine 24.     

Synthesis and biological activity of acetyl-protected hydroxybenzyl diethyl phosphates (EHBP) as potential chemotherapeutic agents

Several acetyl-protected hydroxybenzyl diethyl phosphates (EHBPs) that are capable of forming quinone methide intermediates were synthesized and their cell growth inhibitory properties were evaluated in four different human cancer cell lines. Compounds 1, 1a, and 1b, corresponding to (4-acetyloxybenzyl diethylphosphate), (3-methyl-4-acetyloxybenzyl diethylphosphate), and (3-chloro-4-acetyloxybenzyl diethylphosphate), were significantly more potent than compounds 2 and 3, (2-acetyloxybenzyl diethylphosphate) and (3-acetyloxybenzyl diethylphosphate), respectively. Using HT-29 human colon cancer cells, compounds 1 and 3 increased apoptosis, inhibited proliferation, and caused a G(2)/M block in the cell cycle. Our data suggest that these compounds merit further investigation as potential anti-cancer agents.     

Structure-activity relationships in glycosylated 2-phenyl-indoles, 2-phenyl-benzo[b]thiophenes and 2-phenyl-benzo[b]furans as DNA binding and potential antitumor agents

In earlier investigations we have described the synthesis and biological evaluation of a panel of novel glycosylated heteroaromatics (1-12). It was found that these compounds can bind to DNA in vitro and are cytotoxic against several cancer cell lines at low micromolar concentration. We report here structure-activity studies of these molecules with respect to DNA binding and cytotoxicity. In particular the structure of the linker moiety between the carbohydrate and the intercalator, the stereochemistry at the anomeric position, and the substituents and stereochemistry at C-4 in one of the carbohydrate residues (4-amino-2,3,4,6-tetradeoxy-α-L-threo-hexopyranose) are investigated. All these structural features were identified to have a clear influence on DNA binding; however, only the substituents at C-4 in the carbohydrate residue exhibited an obvious impact on cytotoxicity. It was found that the amino group at C-4 was favored over all other substituents with regard to both DNA binding and cytotoxicity. The information gathered from these structure-activity investigations suggested that future work on the preparation of additional analogues should focus on molecules containing an amino sugar moiety.     

MiR‐34b‐3p represses cell proliferation,cell cycle progression and cell apoptosis in non‐small‐cell lung cancer (NSCLC) by targeting CDK4

Lung cancer is the most common incident cancer, with a high mortality worldwide, and non‐small‐cell lung cancer (NSCLC) accounts for approximately 85% of cases. Numerous studies have shown that the aberrant expression of microRNAs (miRNAs) is associated with the development and progression of cancers. However, the clinical significance and biological roles of most miRNAs in NSCLC remain elusive. In this study, we identified a novel miRNA, miR‐34b‐3p, that suppressed NSCLC cell growth and investigated the underlying mechanism. miR‐34b‐3p was down‐regulated in both NSCLC tumour tissues and lung cancer cell lines (H1299 and A549). The overexpression of miR‐34b‐3p suppressed lung cancer cell (H1299 and A549) growth, including proliferation inhibition, cell cycle arrest and increased apoptosis. Furthermore, luciferase reporter assays confirmed that miR‐34b‐3p could bind to the cyclin‐dependent kinase 4 (CDK4) mRNA 3′‐untranslated region (3′‐UTR) to suppress the expression of CDK4 in NSCLC cells. H1299 and A549 cell proliferation inhibition is mediated by cell cycle arrest and apoptosis with CDK4 interference. Moreover, CDK4 overexpression effectively reversed miR‐34‐3p‐repressed NSCLC cell growth. In conclusion, our findings reveal that miR‐34b‐3p might function as a tumour suppressor in NSCLC by targeting CDK4 and that miR‐34b‐3p may, therefore, serve as a biomarker for the diagnosis and treatment of NSCLC.     

miR-376b controls starvation and mTOR inhibition-related autophagy by targeting ATG4C and BECN1

Macroautophagy (autophagy) is the major intracellular degradation pathway for long-lived proteins and organelles. It helps the cell to survive a spectrum of stressful conditions including starvation, growth factor deprivation and misfolded protein accumulation. Moreover, abnormalities of autophagy play a role in major health problems including cancer and neurodegenerative diseases. Yet, mechanisms controlling autophagic activity are not fully understood. Here, we describe hsa-miR-376b (miR-376b) as a new microRNA (miRNA) regulating autophagy. We showed that miR-376b expression attenuated starvation- and rapamycin-induced autophagy in MCF-7 and Huh-7 cells. We discovered autophagy proteins ATG4C and BECN1 (Beclin 1) as cellular targets of miR-376b. Indeed, upon miRNA overexpression, both mRNA and protein levels of ATG4C and BECN1 were decreased. miR-376b target sequences were present in the 3' UTR of ATG4C and BECN1 mRNAs and introduction of mutations abolished their miR-376b responsiveness. Antagomir-mediated inactivation of the endogenous miR-376b led to an increase in ATG4C and BECN1 levels. Therefore, miR-376b controls autophagy by directly regulating intracellular levels of two key autophagy proteins, ATG4C and BECN1.     

Novel piperazine–chalcone hybrids and related pyrazoline analogues targeting VEGFR-2 kinase; design,synthesis, molecular docking studies,and anticancer evaluation

New piperazine–chalcone hybrids and related pyrazoline derivatives have been designed and synthesised as potential vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors. The National Cancer Institute (NCI) has selected six compounds to evaluate their antiproliferative activity in vitro against 60 human cancer cells lines. Preliminary screening of the examined compounds indicated promising anticancer activity against number of cell lines. The enzyme inhibitory activity against VEGFR-2 was evaluated and IC₅₀ of the tested compounds ranged from 0.57 µM to 1.48 µM. The most potent derivatives Vd and Ve were subjected to further investigations. A cell cycle analysis showed that both compounds mainly arrest HCT-116 cell cycle in the G2/M phase. Annexin V-FITC apoptosis assay showed that Vd and Ve induced an approximately 18.7-fold and 21.2-fold total increase in apoptosis compared to the control. Additionally, molecular docking study was performed against VEGFR (PDB ID: 4ASD) using MOE 2015.10 software and Sorafenib as a reference ligand.     

Photochemical synthesis and anticancer activity of barbituric acid,thiobarbituric acid,thiosemicarbazide, and isoniazid linked to 2-phenyl indole derivatives

2-Phenyl-1H-indole-3-carbaldehyde-based barbituric acid, thiobarbituric acid, thiosemicarbazide, isoniazid, and malononitrile derivatives were synthesized under photochemical conditions. The antitumor activities of the synthesized compounds were evaluated on three different human cancer cell lines representing prostate cancer cell line DU145, Dwivedi (DWD) cancer cell lines, and breast cancer cell line MCF7. All the screened compounds possessed moderate anticancer activity, and out of all the screened compounds, 5-{1[2-(4-chloro-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2b) and 5-{1[2-(4-methoxy-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2d) exhibited marked antitumor activity against used cell lines. Additionally, barbituric acid derivatives were selective to inhibit cell line DWD and breast cancer cell lines.     

Transcriptional analysis of VEGF-D and TGFβ genes in MCF7 cells exposed to saponin isolated from Holothuria leucospilota (sea cucumber)

Background:

Marine natural products contain a wide range of bioactive compounds with therapeutic properties that have revealed crucial properties in the treatment of some diseases. Some of these compounds have recently received considerable attention for drug discovery. In this study we examined the anti-angiogenic effect of saponin isolated from Holothuria leucospilota (sea cucumber) through evaluation of vascular endothelial growth factor D (VEGF-D) and transforming growth factor-β (TGFβ) expression in a breast cancer cell line.

Methods:

To investigate the effect of SCS on VEGF-D and TGF-β expression in breast cancer cells, the cells were treated with various concentrations of sample. After 48 h the viability of the cells was evaluated by trypan blue staining, and VEGF-D and TGFβ mRNA expression was were evaluated by real time-PCR.

Results:

Our results revealed that SCS can suppress cell viability and VEGF-D and TGFβ mRNA expression in breast cancer cells. Sea cucumber saponin at a concentration of 12 μg/ml inhibited VEGF-D and TGFβ expression more than 90% compared with controls.

Conclusion:

Findings suggest that SCS could inhibit tumor growth via inhibition of angiogenesis.Key Words: Sea cucumber, Saponin, Angiogenesis, Anticancer     

Synthesis and cytotoxic activity evaluation of indolo-, pyrrolo-, and benzofuro-quinolin-2(1H)-ones and 6-anilinoindoloquinoline derivatives

Certain indolo-, pyrrolo-, and benzofuro-quinolin-2(1H)-ones 4a,b, 6, 8, 16a-c and 6-anilinoindoloquinoline derivatives 10a,b, 11a,b, 12a,b have been synthesized and evaluated in vitro against a 3-cell lines panel consisting of MCF7 (Breast), NCI-H460 (Lung), and SF-268 (CNS). Those active compounds 4a,b, 6, 8, 10a,b, 11a,b, 12a,b were then evaluated in the full panel of 60 human tumor cell lines derived from nine cancer cell types. The results have shown that cytotoxicity decreases in the order of 6-anilinoindoloquinolines>indoloquinolin-2(1H)-ones>pyrroloquinolin-2(1H)-ones>benzofuroquinolin-2(1H)-ones. Among them, 1-[3-(11H-indolo[3,2-c]quinolin-6ylamino)phenyl]ethanone oxime hydrochloride (11a) and its 2-chloro derivative (11b) were most active, with mean GI(50) values of 1.70 and 1.35 microM, respectively. Both compounds 11a,b were also found to inhibit the growth of SNB-75 (CNS cancer cell) with a GI(50) value of less than 0.01 microM, and, therefore, were selected for further evaluation for in vivo antitumor activity.     

Diaryldimethylpiperazine ligands with mu- and delta-opioid receptor affinity: Synthesis of (+)-4-[(alphaR)-alpha-(4-allyl-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide and (-)-4-[(alphaR)-alpha-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide

We have explored the synthesis of compounds that have good affinity for both mu- and delta-opioid receptors from the (alphaR,2S,5S) class of diaryldimethylpiperazines. These non-selective compounds were related to opioids that have been found to interact selectively with mu- or delta-opioid receptors as agonists or antagonists. In our initial survey, we found two compounds, (+)-4-[(alphaR)-alpha-(4-allyl-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide (14) and its N-H relative, (-)-4-[(alphaR)-alpha-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide (15), that interacted with delta-receptors with good affinity, and, as we hoped, with much higher affinity at mu-receptors than SNC80. The relative configuration of the benzylic position in (+)-4-[(alphaR)-alpha-(4-allyl-(2S,5S)-dimethyl-1-piperazinyl)-(3-methoxyphenyl)methyl]-benzyl alcohol (10) was determined by X-ray crystallographic analysis of a crystal that was an unresolved twin. The absolute stereochemistry of that benzylic stereogenic center was unequivocally derived by the X-ray crystallographic analysis from the two other centers of asymmetry in the molecule that were known. Those were established from the synthesis via a dipeptide cyclo-L-Ala-L-Ala in which the absolute stereochemistry was established.