Cytotoxic triterpenoid saponins from the fruits of Aesculus pavia L

Continued chemical investigation on the fruits of North American Aesculus pavia L. resulted in the isolation and identification of 13 polyhydroxyoleanene pentacyclic triterpenoid saponins, named aesculiosides IIe-IIk (1-7), and IIIa-IIIf (8-13), together with 18 known compounds: aesculiosides Ia-Ie (14-18), IIa-IId (19-22), IVa-IVc (23-25), 3-O-[beta-D-galactopyranosyl(1-->2)]-alpha-L-arabinofuranosyl(1-->3)-beta-D-glucuronopyranosyl-21,22-O-diangeloyl-3beta,15 alpha,16 alpha,21 beta,22 alpha,28-hexahydroxyolean-12-ene (26), 3-O-[beta-D-glucopyranosyl(1-->2)]-alpha-L-arabinofuranosyl(1-->3)-beta-D-glucuronopyranosyl-21,22-O-diangeloyl-3beta,16 alpha,21 beta,22 alpha,24 beta,28-hexahydroxyolean-12-ene (27), 3-O-[beta-D-galactopyranosyl(1-->2)]-alpha-L-arabinofuranosyl(1-->3)-beta-D-glucuronopyranosyl-21,22-O-diangeloyl-3beta,16 alpha,21 beta,22 alpha,28-pentahydroxyolean-12-ene (28), R(1)-barrigenol (29), scopolin (30), and 5-methoxyscopolin (31). The structures of these compounds were elucidated by spectroscopic and chemical analyses. Compounds 14-22 and 26-28 were tested in vitro for their activity against 59 cell lines from nine different human cancers including leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate, and breast. It was found that compounds with two-acyl groups at C-21 and C-22 had cytotoxic activity for all cell lines tested with GI(50) 0.175-8.71 microM, while compounds without acyl groups at C-21 and C-22 had weak or no cytotoxic activity. These results suggest that the acyl groups at C-21 and C-22 are essential for their activity.     

Simple isoquinoline and benzylisoquinoline alkaloids as potential antimicrobial, antimalarial, cytotoxic, and anti-HIV agents

Twenty-six simple isoquinolines and 21 benzylisoquinolines were tested for antimicrobial, antimalarial, cytotoxic, and anti-HIV activities. Some simple isoquinoline alkaloids were significantly active in each assay, and may be useful as lead compounds for developing potential chemotherapeutic agents. These compounds include 13 (antimicrobial), 25, 26, and 42 (antimalarial), 13 and 25 (cytotoxic), and 28 and 29 (anti-HIV). A quaternary nitrogen atom of isoquinolium or dihydroisoquinolinium type may contribute to enhanced potency in the first three types of activities. In contrast, anti-HIV activity was found with tetrahydroisoquinoline and 6,7-dihydroxyisoquinolium salts.     

Synthesis and cytotoxicity of lupane-type triterpenoid glyceryl esters

A new series of betulinic acid and betulin derivatives were synthesized by introducing a D-glycerol moiety at the C-3 and/or C-28 positions of the lupane skeleton. The resulting glyceryl esters were evaluated in vitro for their cytotoxic activity against A549, DLD-1 and WS1 human cell lines. The structure-activity relationships study revealed that the incorporation of a glycerol unit at the C-3 or C-28 position of the lupane core resulted in compounds exhibiting potent cytotoxic activity together with decreased liposolubility.     

Synthesis of macrocyclic bisbibenzyl derivatives and their anticancer effects as anti-tubulin agents

Based on the core skeleton of the total synthesized bisbibenzyl marchantin C, riccardin D and plagiochin E, a series of brominated and aminomethylated derivatives of above three bisbibenzyls have been synthesized and their cytotoxic activity against KB, MCF-7 and PC3 cell lines has been preliminary evaluated. The bio-test results revealed that the brominated derivatives 21, 22, 24, 25 and 28 exhibited excellent antiproliferative activity, with IC(50) value lower than their parent compounds. As a most potent microtubule depolymerization agent, compound 28 was found to arrest cells at the G(2)/M phase of the cell cycle as determined by the flow cytometry assay in PC3 cell line. The remarkable biological profile and novel structure of these bisbibenzyl derivatives make them possible as promising candidates for clinical development as chemotherapeutic agents.     

New ursolic and betulinic derivatives as potential cytotoxic agents

Fifteen new ursolic and betulinic triterpenoids, bearing various functionalities at C-3 and C-28 were synthesized as potential cytotoxic agents. All compounds were obtained by a hemisynthetic route via ursolic and betulinic acids. Preliminary screening of these compounds on human HT 29 colon cancer cells revealed inhibitory activity for three of them. Beta-D-Glucopyranosyl-3beta-hydroxyurs-12(13)-en-28-oate 1c, 3beta-3-(3-pyridyl)-prop-2-enoyloxyurs-12(13)-en-28-oic acid 1i and the potassium salt of 3beta-cinnamoyloxylup-20(29)-en-28-oic acid 2d demonstrated cytotoxic activity in the micromolar range: 8.0, 45.0 and 8.0 microM, respectively.     

New ligand-based approach for the discovery of antitrypanosomal compounds

The antitrypanosomal activity of 10 already synthesized compounds was in silico predicted as well as in vitro and in vivo explored against Trypanosoma cruzi. For the computational study, an approach based on non-stochastic linear fingerprints to the identification of potential antichagasic compounds is introduced. Molecular structures of 66 organic compounds, 28 with antitrypanosomal activity and 38 having other clinical uses, were parameterized by means of the TOMOCOMD-CARDD software. A linear classification function was derived allowing the discrimination between active and inactive compounds with a confidence of 95%. As predicted, seven compounds showed antitrypanosomal activity (%AE>70) against epimastigotic forms of T. cruzi at a concentration of 100mug/mL. After an unspecific cytotoxic assay, three compounds were evaluated against amastigote forms of the parasite. An in vivo test was carried out for one of the studied compounds.     

Oleanane-type triterpenoids from Panax stipuleanatus and their anticancer activities

One newly (1) and 10 known oleanane-type triterpenoids (2-11) were isolated from the methanol extract of Panax stipuleanatus rhizomes. Based on their spectroscopic data, these compounds were identified as spinasaponin A methyl ester (1), pesudoginsenoside RP(1) methyl ester (2), spinasaponin A 28-O-glucoside (3), pseudoginsenoside RT(1) methyl ester (4), pseudoginsenoside RT(1) (5), stipuleanoside R(2) methyl ester (6), stipuleanoside R(2) (7), araloside A methyl ester (8), 3-O-β-D-glucopyranosyl (1→3)-β-D-glucuronopyranoside-28-O-β-D-glucopyranosyl oleanolic acid methyl ester (9), 3-O-β-D-xylopyranosyl (1→2)-β-D-glucopyranosyl-28-O-β-D-glucopyranosyl oleanolic acid (10), and chikusetsusaponin IVa (11). When the cytotoxic activities of the isolated compounds were evaluated, compound 1 exhibited significant cytotoxic activity with IC(50) values of 4.44 and 0.63 μM against HL-60 (leukemia) and HCT-116 (colon cancer) cell lines, respectively. Compound 2 showed potent cytotoxicity with an IC(50) of 6.50 μM against HCT-116, whereas it was less cytotoxic against HL-60 (IC(50)=41.45 μM). After HL-60 and HCT-116 were treated with compounds 1 and 2, increased production of apoptotic bodies was observed. Furthermore, compounds 1 and 2 in HCT-116 cells activated intrinsic and extrinsic apoptosis pathways by upregulating DR-5 and Bax, downregulating Bcl-2, activating caspase-9, and cleaving poly-ADP-ribose polymerase (PARP). We also observed the activation of ERK1/2 MAPK by both compounds in the HCT-116 cells. Together, compounds 1 and 2 might induce intrinsic and extrinsic apoptosis pathways through the activation of the ERK1/2 MAPK pathway in HCT-116 colon cancer cells. Structure-activity relationship analysis indicated that a carboxyl group at position-28 is potentially responsible for the cytotoxic effects.     

Syntheses of 2,4,6-trisubstituted pyrimidine derivatives as a new class of antifilarial topoisomerase II inhibitors

A series of 21 compounds of trisubstituted pyrimidine derivatives have been synthesized and evaluated for their in vitro topoisomerase II inhibitory activity against filarial parasite Setaria cervi. Out of these, seven compounds (8, 11-14, 25 and 28) have shown 60-80% inhibition at 40 and 20 microg/mL concentration. Five compounds (12, 13, 14, 25 and 28) exhibited 70-80% inhibition at 10 microg/mL concentration and three compounds (13, 14 and 28) have shown 40-60% inhibition at 5 microg/mL concentration. All the above mentioned compounds have shown better topo II inhibitory activity than standard antifilarial drug (DEC) and enzyme topo II inhibitors (Novobiocin, Nalidixic acid).     

Synthesis, evaluation and structural studies of antiproliferative tubulin-targeting azetidin-2-ones

A series of azetidin-2-ones substituted at positions 1, 3 and 4 of the azetidinone ring scaffold were synthesised and evaluated for antiproliferative, cytotoxic and tubulin-binding activity. In these compounds, the cis double bond of the vascular targeting agent combretastatin A-4 is replaced with the azetidinone ring in order to enhance the antiproliferative effects displayed by combretastatin A-4 and prevent the cis/trans isomerisation that is associated with inactivation of combretastatin A-4. The series of azetidinones was synthetically accessible via the Staudinger and Reformatsky reactions. Of a diverse range of heterocyclic derivatives, 3-(2-thienyl) analogue 28 and 3-(3-thienyl) analogue 29 displayed the highest potency in human MCF-7 breast cancer cells with IC(50) values of 7 nM and 10nM, respectively, comparable to combretastatin A-4. Compounds from this series also exhibited potent activity in MDA-MB-231 breast cancer cells and in the NCI60 cell line panel. No significant toxicity was observed in normal murine breast epithelial cells. The presence of larger, bulkier groups at the 3-position, for example, 3-naphthyl derivative 21 and 3-benzothienyl derivative 26, resulted in relatively lower antiproliferative activity in the micromolar range. Tubulin-binding studies of 28 (IC(50)=1.37 μM) confirmed that the molecular target of this series of compounds is tubulin. These novel 3-(thienyl) β-lactam antiproliferative agents are useful scaffolds for the development of tubulin-targeting drugs.     

卷柏化学成分及细胞毒活性研究(英文)

从卷柏(Selaginella tamariscina(Beauv.)Spring)中分离得到10个化合物,运用波谱手段分别鉴定为se-laginellin(1)、selaginellin A(2)、selaginellin B(3)、穗花杉双黄酮(4)、sequoiaflavone(5)、去甲银杏双黄酮(6)、银杏双黄酮(7)、异银杏双黄酮(8)、扁柏双黄酮(9)、异柳杉双黄酮(10)。其中化合物1、5和8为首次从该植物中分离得到。化合物1,4,7,8和9显示出选择性的细胞毒活性。     

Synthesis and evaluation of pyrazolo[3,4-b]pyridines and its structural analogues as TNF-alpha and IL-6 inhibitors

In the present article, we have synthesized three different series of pyrazolo[3,4-b]pyridines and their structural analogues using novel synthetic strategy involving one-pot condensation of 5,6-dihydro-4H-pyran-3-carbaldehyde/2-formyl-3,4,6-tri-O-methyl-D-glucal/chromone-3-carbaldehyde with heteroaromatic amines. All synthesized compounds were evaluated for their anti-inflammatory activity against TNF-alpha and IL-6. Out of 28 compounds screened, 40, 51, 52 and 56 exhibited promising activity against IL-6 with 60-65% inhibition at 10 microM concentration. Amongst these, 51, 52 and 56 showed potent IL-6 inhibitory activity with IC(50)'s of 0.2, 0.3 and 0.16 microM, respectively. Compound 56 was not cytotoxic in CCK-8 cells up to the concentration of >100 microM.     

Synthesis of 6-chloroisoquinoline-5,8-diones and pyrido[3,4-b]phenazine-5,12-diones and evaluation of their cytotoxicity and DNA topoisomerase II inhibitory activity

The substituted chloroisoquinolinediones and pyrido[3,4-b]phenazinediones were synthesized, and the cytotoxic activity and topoisomerase II inhibitory activity of the prepared compounds were evaluated. Chloroisoquinolinediones have been prepared by the reported method employing 6,7-dichloroisoquinoline-5,8-dione. The cyclization to pyrido[3,4-b]phenazinediones was achieved by adding the aqueous sodium azide solution to the dimethylformamide solution of corresponding chloroisoquinoline-5,8-dione. The cytotoxicity of the synthesized compounds was evaluated by a SRB (Sulforhodamine B) assay against various cancer cell lines such as A549 (human lung cancer cell line), SNU-638 (human stomach cancer cell), Col2 (human colon cancer cell line), HT1080 (human fibrosarcoma cell line), and HL-60 (human leukemia cell line). Almost all the synthesized pyrido[3,4-b]phenazinediones showed greater cytotoxic potential than ellipticine (IC(50)=1.82-5.97 microM). In general, the cytotoxicity of the pyrido[3,4-b]phenazinediones was higher than that of the corresponding chloroisoquinolinediones. The caco-2 cell permeability of selected compounds was 0.62 x 10(-6)-35.3 x 10(-6)cm/s. The difference in cytotoxic activity among tested compounds was correlated with the difference in permeability to some degree. To further investigate the cytotoxic mechanism, the topoisomerase II inhibitory activity of the synthesized compounds was estimated by a plasmid cleavage assay. Most of compounds showed the topoisomerase II inhibitory activity (28-100%) at 200 microM. IC(50) values for the most active compound 6a were 0.082 microM. However, the compounds were inactive for DNA relaxation by topoisomerase I at 200 microM.     

Synthesis and G-quadruplex stabilizing properties of a series of oxazole-containing macrocycles

The synthesis of 24-membered macrocycles containing four, six, and seven oxazole moieties is described. Selected compounds were evaluated for their ability to specifically bind and stabilize G-quadruplex DNA and for cytotoxic activity. An unexpected oxidative cleavage reaction afforded a macrocyclic imide that was also evaluated for G-quadruplex stabilizing and cytotoxic activity.     

Synthesis and in vitro anticancer activity of new gemcitabine-nucleoside analogue dimers containing methyltriazole or ester-methyltriazole linker

Two series of novel gemcitabine-nucleoside analogue dimers were synthesized using the ‘click’ chemistry approach. In the first series of dimers (21–30), the nucleoside units were connected with a stable methyltriazole 4N-3′(or 5′)C linker whereas in the second series (31–40) with a cleavable ester-methyltriazole 4N-3′(or 5′)C linker. Dimers 21–40 were evaluated for their cytotoxic activity in five human cancer cell lines such as cervical (HeLa), nasopharyngeal (KB), lung (A549), brain (U87), liver (HepG2) and normal dermal fibroblast cell line (HDF) using the sulforhodamine B (SRB) assay. Compound 29 comprising two gemcitabine (dFdC) units exhibited the highest activity among dimers 21–30. The activity of compound 29 was higher than that of dFdC in all the studied cancer cell lines. A similar order of activity was observed for compounds 25, 28, and 30. The best activity among all the dimers synthesized was displayed by compound 39, comprising two gemcitabine units with a cleavable linker. The activity of compound 39 was 5 to 9 times higher than that of dFdC, depending on the cell line. In addition, marked cytotoxic activity was shown by compounds 31, 36, 38, and 40.     

Synthesis and biological activity of 2,5-diaryl-3-methylpyrimido[4,5-c]quinolin-1(2H)-one derivatives

A series of 2,5-diaryl-3-methylpyrimido[4,5-c]quinolin-1(2H)-ones (7-30), variously substituted at the 2- and 5-phenyl moieties, were synthesized and evaluated for their in vitro cytotoxic activity against a PC3 cancer cell line. Cytotoxicity data revealed that the type of substituent as well as substitution pattern have variable influence on cytotoxic activity. Among the compounds tested, compounds (9), (13), (18), (19), and (23) demonstrated appreciable cytotoxic activity with mean IC(50) values of 2.0, 1.4, 1.6, 2.2, and 1.9microM, respectively. Methyl substitution at the 2-phenyl ring was found to yield the least active compounds. Two of the most potent compounds (13) and (18) were further investigated for inhibition of tubulin polymerization and found to have no activity at the concentrations used in the assay.     

Antitumor agents 251: synthesis, cytotoxic evaluation, and structure-activity relationship studies of phenanthrene-based tylophorine derivatives (PBTs) as a new class of antitumor agents

Polar phenanthrene-based tylophorine derivatives (PBTs) were designed, synthesized and evaluated as potential antitumor agents. These compounds contain a core phenanthrene structure and can be synthesized efficiently in excellent yield. The newly synthesized PBTs were evaluated for cytotoxic activity against the A549 human cancer cell line. Among them, N-(2,3-methylenedioxy-6-methoxy-phenanthr-9-ylmethyl)-L-2-piperidinemethanol (34) and N-(2,3-methylenedioxy-6-methoxy-phenanthr-9-ylmethyl)-5-aminopentanol (28) showed the highest potency with IC50 values of 0.16 and 0.27 microM, respectively, which are comparable to those of currently used antitumor drugs. A structure-activity relationship (SAR) study was also explored to facilitate the further development of this new compound class.     

N-Propargylic β-enaminones in breast cancer cells: Cytotoxicity,apoptosis, and cell cycle analyses

Breast cancer is one of the most common cancers worldwide and the discovery of new cytotoxic agents is needed. Enaminones are regarded to be a significant structural motif that is found in a variety of pharmacologically active compounds however the number of studies investigating the anticancer activities of N-propargylic β-enaminones (NPEs) is limited. Herein we investigated the potential cytotoxic and apoptotic effects of 23 different NPEs (1-23) on human breast cancer cells. Cytotoxicity was evaluated via MTT assay. Apoptotic cell death and cell cycle distributions were investigated by flow cytometry. CM-H2DCFDA dye was used to evaluate cellular ROS levels. Expression levels of Bcl-2, Bax, p21, and Cyclin D1 were measured by quantitative real-time PCR. ADME properties were calculated using the ADMET 2.0 tool. NPEs 4, 9, 16, and 21 showed selective cytotoxic activity against breast cancer cells with SI values >2. NPEs induced apoptosis and caused significant changes in Bcl-2 and Bax mRNA levels. The cell cycle was arrested at the G0/G1 phase and levels of p21 and Cyclin D1 were upregulated in both breast cancer cells. ROS levels were significantly increased by NPEs, suggesting that the cytotoxic and apoptotic effects of NPEs were mediated by ROS. ADME analysis revealed that NPEs showed favorable distributions in both breast cancer cell lines, meaning good lipophilicity values, low unfractionated values, and high bioavailability. Therefore, these potential anticancer compounds should be further validated by in vivo studies for their appropriate function in human health with a safety profile, and a comprehensive drug interaction study should be performed.     

Aneugenic effects of the genistein glycosidic derivative substituted at C7 with the unsaturated disaccharide

Genistein, due to its recognized chemopreventive and antitumour potential, is a molecule of interest as a lead compound in drug design. Recently, we found that the novel genistein derivative, [7-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-(1?→?4)-(6-O-acetyl-hex-2-ene-α-D-erythro pyranosyl)genistein, named G21, induced aberrations in mitotic spindle formation. In the presented study, we investigated the properties of G21 relevant to its genotoxic activity. The inhibition of topoisomerase IIα activity was evaluated in decatenation assay and immunoband depletion assay, the covalent DNA-topoisomerase IIα complexes and histone ?H2AX were detected immunofluorescently. Genotoxic effects of the tested compounds were assessed in micronucleation assay. The presence of centromeres in the micronuclei and the multiplication of centrosomes were evaluated in fluorescence immunolabelled specimens. The inhibition of tubulin polymerization was measured spectrophotometrically. We found that both tested drugs were able to inhibit topoisomerase II activity; however, G21, in contrast to genistein, blocked this enzyme at the concentration far exceeding cytotoxic IC(50). We also found that both compounds caused micronucleation in DU 145 prostate cancer cells, but in contrast to genistein, G21 exhibited aneugenic activity, manifested by the presence of centromeres in micronuclei formed in cells treated with the drug. Aneugenic properties of G21 resulted from the inhibition of tubulin polymerization and centrosome disruption, not observed in the presence of genistein. The study supports and extends our previous observations that the mechanisms of cytotoxicity of genistein and its new glycosidic derivative-G21 are significantly different.     

10-Formyl-5,10-dideaza-acyclic-5,6,7,8-tetrahydrofolic acid (10-formyl-DDACTHF): a potent cytotoxic agent acting by selective inhibition of human GAR Tfase and the de novo purine biosynthetic pathway

The synthesis of 10-formyl-DDACTHF (3) as a potential inhibitor of glycinamide ribonucleotide transformylase (GAR Tfase) and aminoimidazole carboxamide ribonucleotide transformylase (AICAR Tfase) is reported. Aldehyde 3, the corresponding gamma- and alpha-pentaglutamates 21 and 25 and related agents were evaluated for inhibition of folate-dependent enzymes including GAR Tfase and AICAR Tfase. The inhibitors were found to exhibit potent cytotoxic activity (CCRF-CEM IC(50) for 3=60nM) that exceeded their enzyme inhibition potency [K(i) (3)=6 and 1 microM for Escherichia coli GAR and human AICAR Tfase, respectively]. Cytotoxicity rescue by medium purines, but not pyrimidines, indicated that the potent cytotoxic activity is derived from selective purine biosynthesis inhibition and rescue by AICAR monophosphate established that the activity is derived preferentially from GAR versus AICAR Tfase inhibition. The potent cytotoxic compounds including aldehyde 3 lost activity against CCRF-CEM cell lines deficient in the reduced folate carrier (CCRF-CEM/MTX) or folylpolyglutamate synthase (CCRF-CEM/FPGS(-)) establishing that their potent activity requires both reduced folate carrier transport and polyglutamation. Unexpectedly, the pentaglutamates displayed surprisingly similar K(i)'s versus E. coli GAR Tfase and only modestly enhanced K(i)'s versus human AICAR Tfase. On the surface this initially suggested that the potent cytotoxic activity of 3 and related compounds might be due simply to preferential intracellular accumulation of the inhibitors derived from effective transport and polyglutamation (i.e., ca. 100-fold higher intracellular concentrations). However, a subsequent examination of the inhibitors against recombinant human GAR Tfase revealed they and the corresponding gamma-pentaglutamates were unexpectedly much more potent against the human versus E. coli enzyme (K(i) for 3, 14nM against rhGAR Tfase versus 6 microM against E. coli GAR Tfase) which also accounts for their exceptional cytotoxic potency.