Antiproliferative effects of some novel synthetic solanidine analogs on HL-60 human leukemia cells in vitro

There is increasing evidence of the direct antiproliferative effects of various steroidal structures, including cardenolides, steroidal alkaloids and sexual hormones. The aim of the present study was to characterize the antiproliferative effects of three synthetic solanidine analogs (1-3) on HL-60 human leukemia cells. The three compounds exerted similar cytostatic effects (IC(50) values: 1.27-2.94 μM after a 72-h exposure) and the most effective (2) was selected for further investigations. Incubation with compound 2 resulted in a marked chromatin condensation followed by a gradual increase in cell membrane permeability detected by Hoechst dye 33258-propidium iodide double staining. A flow cytometric analysis revealed a marked decrease in the G1 phase and substantial increases in the S and G2/M phases after 24-h incubation, while after 48 h the proportion of cells in the subG1 phase was increased significantly with a concomitant decrease in cells in the G1 and G2/M phases. Compound 2 at 6.0 μM significantly decreased the activity of ribonucleotide reductase and proved to be a potent antioxidant in the lipid peroxidation and DPPH assays (IC(50) values: 2.0 and 13.1 μM, respectively). The antiproliferative effect of the test compound on the non-cancerous human lung fibroblast cell line (MRC-5) was significantly weaker than that on the leukemia cells. These results lead to the conclusion that compound 2 induces a marked disturbance in the cell cycle, which is, at least partially, a consequence of the inhibition of DNA synthesis.     

Synthesis of chalcone-amidobenzothiazole conjugates as antimitotic and apoptotic inducing agents

A series of chalcone-amidobenzothiazole conjugates (9a-k and 10a,b) have been synthesized and evaluated for their anticancer activity. All these compounds exhibited potent activity and the IC(50) of two potential compounds (9a and 9f) against different cancer cell lines are in the range of 0.85-3.3 μM. Flow cytometric analysis revealed that these compounds induced cell cycle arrest at G2/M phase in A549 cell line leading to caspase-3 dependent apoptotic cell death. The tubulin polymerization assay (IC(50) of 9a is 3.5 μM and 9f is 5.2 μM) and immuofluorescence analysis showed that these compounds effectively inhibit microtubule assembly at both molecular and cellular levels in A549 cells. Further, Annexin staining also suggested that these compounds induced cell death by apoptosis. Moreover, docking experiments have shown that they interact and bind efficiently with tubulin protein. Overall, the current study demonstrates that the synthesis of chalcone-amidobenzothiazole conjugates as promising anticancer agents with potent G2/M arrest and apoptotic-inducing activities via targeting tubulin.     

Design and synthesis of benzo[c,d]indolone-pyrrolobenzodiazepine conjugates as potential anticancer agents

A series of benzo[c,d]indol-2(1H)one-PBD conjugates (11a-l) have been designed and synthesized as potential anticancer agents. These compounds were prepared by linking the C8-position of DC-81 with a benzo[c,d]indol-2(1H)one moiety through different alkane spacers in good yields and confirmed by (1)H NMR, mass and HRMS data. The DNA binding ability of these conjugates was evaluated by thermal denaturation studies and interestingly, compound 11l showed enhanced DNA binding ability. These compounds were also evaluated for their anticancer activity in selected human cancer cell lines of lung, skin, colon and prostate by using MTT assay method. These new conjugates showed promising anticancer activity with IC(50) values ranging from 1.05 to 36.49 μM. Moreover, cell cycle arrest in SubG1 phase was observed upon treatment of A549 cells with 1 and 2 μM (IC(50)) concentrations of compound 11l and it induced apoptosis. This is confirmed by Annexin V-FITC, Hoechst staining, caspase-3 activity as well as DNA fragmentation analysis.     

Design, synthesis and anticancer activity of novel dihydrobenzofuro[4,5-b][1,8]naphthyridin-6-one derivatives

On the basis of the chemical structures of psorospermin with a xanthone template and acronycine derivatives with an acridone template, rac-1 and rac-2 constructed on an 1,2-dihydrobenzofuro[4,5-b][1,8]naphthyridin-6(11H)-one scaffold were designed and synthesized as potential anticancer agents. Their anticancer activities were evaluated against five human cancer cell lines. Rac-2 showed similar anticancer activity to doxorubicin and rac-1 exhibited even higher anticancer activity against LNCaP (IC(50)=0.14 μM), DU145 (IC(50)=0.15 μM), PC3 (IC(50)=0.30 μM) and MCF-7 (IC(50)=0.26 μM) cancer lines than doxorubicin and rac-2. Also, rac-1 revealed very potent anticancer activity (IC(50)=0.15 μM) against MCF-7/ADR cell (doxorubicin-resistant breast cancer cell) lines and induced G2/M phase arrest of the cell cycle in MCF-7/ADR cells.     

Synthesis of 6-substituted 9-methoxy-11H-indeno[1,2-c]quinoline-11-one derivatives as potential anticancer agents

We have synthesized certain 6-substituted 9-methoxy-11H-indeno[1,2-c]quinolin-11-ones for antiproliferative evaluation. Results indicated that 6-alkylamine derivatives, 6-[2-(dimethylamino)ethylamino]-9-methoxy-11H-indeno[1,2-c]quinolin-11-one (5a) and its 6-[3-(dimethylamino)propylamino] derivative, 5b, were able to inhibit cells growth completely at a concentration of 100 μM while most of the 6-arylamine derivatives 6b-6h were inactive at the same concentration. Comparable mean GI(50) (drug molar concentration causing 50% cell growth inhibition) values for 5a (3.47 μM) and 5b (3.39 μM) indicated the cytotoxicity may not be affected by the length of alkyl substituents at C-6 position. Compound 5b, with a mean GI(50) value of 3.39 μM, was the most active and therefore was selected for further evaluation on its effects of H460 lung cancer cell cycle distribution. Results indicated that 5b induced cell cycle arrest in G2/M phase after 24h treatment, while the hypodiploid (sub-G0/G1 phase) cells increased. We found that H460 cell became shrinked after the treatment of 5b, indicating that apoptosis may be a mechanism by which 5b kills the cancer cells. DNA unwinding assay indicated that 5b may bind to DNA through intercalation. Our results have also demonstrated that PARP was cleaved while caspase-3 and caspase-8 activities were induced after the treatment of 5b at 10 μM for 24h. Thus, compound 5b intercalates DNA, induces cell cycle arrest at G2/M phase via cleavage of PARP, induces caspase-3 and caspase-8 activities, and consequently causes the cell death.     

The novel pyrimidine and purine derivatives of l-ascorbic acid: synthesis, one- and two-dimensional 1H and 13C NMR study, cytostatic and antiviral evaluation

The syntheses of the novel C-5 substituted pyrimidine derivatives of l-ascorbic acid containing free hydroxy groups at C-2' (6-10) or C-2' and C-3' (11-15) positions of the lactone ring are described. Debenzylation of the 6-chloro- and 6-(N-pyrrolyl)purine derivatives of 2,3-O,O-dibenzyl-l-ascorbic acid (16 and 17) gave the new compounds containing hydroxy groups at C-2' (18) and C-2' and C-3' (19 and 20). Z- and E-configuration of the C4'C5' double bond and position of the lactone ring of the compounds 6-9 were deduced from their one- and two-dimensional (1)H and (13)C NMR spectra and connectivities in NOESY and HMBC spectra. Compounds 15 and 18 showed the best inhibitory activities of all evaluated compounds in the series. The compound 15 containing 5-(trifluoromethyl)uracil showed marked inhibitory activity against all human malignant cell lines (IC(50): 5.6-12.8 microM) except on human T-lymphocytes. Besides, this compound influenced the cell cycle by increasing the cell population in G2/M phase and induced apoptosis in SW 620 and MiaPaCa-2 cells. The compound 18 containing 6-chloropurine ring expressed the most pronounced inhibitory activities against HeLa (IC(50): 6.8 microM) and MiaPaCa-2 cells (IC(50): 6.5 microM). The compound 20 with 6-(N-pyrrolyl)purine moiety showed the best differential inhibitory effect against MCF-7 cells (IC(50): 35.9 microM).     

Design, synthesis and CoMFA studies of N1-amino acid substituted 2,4,5-triphenyl imidazoline derivatives as p53-MDM2 binding inhibitors

A series of novel N1-amino-acid substituted 2,4,5-triphenyl imidazoline derivatives was designed and synthesized based on our previous studies. All synthesized target compounds were screened for their p53-MDM2 binding inhibitory activities and anti-proliferative activities against five cancer cell lines. Among them, twelve compounds displayed improved binding inhibitory activities and most compounds showed higher cell growth inhibition activities with IC(50) values in the low micromolar range. Compound 6c exhibited marked p53-MDM2 binding inhibitory activity (IC(50)=0.59 μM) which was eightfold more potent than that of Nutlin-1 (IC(50)=4.78 μM). CoMFA analysis was performed based on obtained biological data and resulted in a statistically significant CoMFA model with high predict abilities (q(2)=0.645, r(2)=0.979).     

Synthesis, structure-activity relationships and biological evaluation of caudatin derivatives as novel anti-hepatitis B virus agents

A series of caudatin derivatives were synthesized, and their anti-hepatitis B virus (HBV) activity was evaluated in HepG 2.2.15 cells. Most of the 3-O-substituted caudatin derivatives showed effective anti-HBV activity. Among the tested compounds, six compounds (2e-2h, 2l, 2r) exhibited significantly inhibitory activity against HBV DNA replication with IC(50) values in the range of 2.82-7.48 μM. Interestingly, two compounds (2e, 2f) had potent activity inhibiting not only the secretion of HBsAg (IC(50)=18.68 μM, 21.71 μM), HBeAg (IC(50)=13.16 μM, 33.73 μM), but also HBV DNA replication (IC(50)=7.48 μM, 3.63 μM). The structure-activity relationships (SARs) of caudatin derivatives had been discussed, which were useful for caudatin derivatives to be explored and developed as novel anti-HBV agents.     

Cycloalkyl-substituted aryl chloroethylureas inhibiting cell cycle progression in G0/G1 phase and thioredoxin-1 nuclear translocation

1-(2-Chloroethyl)-3-(4-cyclohexylphenyl)urea (cHCEU) has been shown to abrogate the presence of thioredoxin-1 into the nucleus through its selective covalent alkylation. In the present letter we have evaluated the structure-activity relationships of the substituents at positions 3 and 4 of the phenyl ring of cHCEU derivatives on cell cycle progression and thioredoxin-1 nuclear translocation. Active CEU derivatives exhibited GI(50) ranging from 1.9 to 49muM on breast carcinoma MCF-7, skin melanoma M21, and colon carcinoma HT-29 cells. On one hand, compounds 1, 2, 9c, 10c, 13, and 14 arrested the cell cycle in G(2)/M phase while CEUs 3, 4, 5c, 6c, 11c, and 12c blocked the cell division in G(0)/G(1) phase. On the other hand, CEUs 2-4, 5c, 7c, 8c, 11c, and 12c abrogated the translocation of thioredoxin-1 while the other CEU derivatives were inactive in that respect. Our results suggest that CEU substituted on the phenyl ring at position 3 or 4 by lower cycloalkyl or cycloalkoxy groups arrest cell progression in G(0)/G(1) phase through mechanism of action different from their antimicrotubule counterparts, presumably via thioredoxin-1 alkylation and modulation of its activity. The mechanism of action of these new molecules is still undetermined. However, the significant accumulation of cells in G(0)/G(1) phase suggests that these molecules may act similarly to known chemopreventive agents against cancers. In addition, the inhibition of Trx-1 nuclear localization also suggests the abrogation of an important chemoresistance mechanism towards a variety of chemotherapeutic agents.     

A Rhodanine Derivative CCR-11 Inhibits Bacterial Proliferation by Inhibiting the Assembly and GTPase Activity of FtsZ

A perturbation of FtsZ assembly dynamics has been shown to inhibit bacterial cytokinesis. In this study, the antibacterial activity of 151 rhodanine compounds was assayed using Bacillus subtilis cells. Of 151 compounds, eight strongly inhibited bacterial proliferation at 2 μM. Subsequently, we used the elongation of B. subtilis cells as a secondary screen to identify potential FtsZ-targeted antibacterial agents. We found that three compounds significantly increased bacterial cell length. One of the three compounds, namely, CCR-11 [(E)-2-thioxo-5-({[3-(trifluoromethyl)phenyl]furan-2-yl}methylene)thiazolidin-4-one], inhibited the assembly and GTPase activity of FtsZ in vitro. CCR-11 bound to FtsZ with a dissociation constant of 1.5 ± 0.3 μM. A docking analysis indicated that CCR-11 may bind to FtsZ in a cavity adjacent to the T7 loop and that short halogen-oxygen, H-bonding, and hydrophobic interactions might be important for the binding of CCR-11 with FtsZ. CCR-11 inhibited the proliferation of B. subtilis cells with a half-maximal inhibitory concentration (IC(50)) of 1.2 ± 0.2 μM and a minimal inhibitory concentration of 3 μM. It also potently inhibited proliferation of Mycobacterium smegmatis cells. Further, CCR-11 perturbed Z-ring formation in B. subtilis cells; however, it neither visibly affected nucleoid segregation nor altered the membrane integrity of the cells. CCR-11 inhibited HeLa cell proliferation with an IC(50) value of 18.1 ± 0.2 μM (～15 × IC(50) of B. subtilis cell proliferation). The results suggested that CCR-11 inhibits bacterial cytokinesis by inhibiting FtsZ assembly, and it can be used as a lead molecule to develop FtsZ-targeted antibacterial agents.     

Synthesis and anti-leishmanial activity of 1-aryl-β-carboline derivatives against Leishmania donovani

β-carbolines from various natural and synthetic sources have been known to show diverse biological activities. As a part of our current ongoing project to search for potent natural product-derived anti-leishmanial compounds, we have synthesized a series of substituted 1-aryl-β-carboline derivatives. A total of 22 compounds were synthesized and tested in vitro against Leishmania donovani, out of which 6 compounds (4, 5, 10, 11, 19 and 22) showed notably more activity than the standard miltefosine (IC(50) 12.07±0.82 μM), with compound 4 being the most potent (IC(50) 2.16±0.26 μM).     

Synthesis, structural elucidation, DNA-PK inhibition, homology modelling and anti-platelet activity of morpholino-substituted-1,3-naphth-oxazines

A number of new angular 2-morpholino-(substituted)-naphth-1,3-oxazines (compound 10b), linear 2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 13b-c), linear 6, 7 and 9-O-substituted-2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 17-22, 24, and 25) and angular compounds 14-16 and 23 were synthesised. The O-substituent was pyridin-2yl-methyl (15, 18, and 21) pyridin-3yl-methyl (16, 19, and 22) and 4-methylpipreazin-1-yl-ethoxy (23-25). Twelve compounds were tested for their inhibitory effect on collagen induced platelet aggregation and it was found that the most active compounds were compounds 19 and 22 with IC(50)=55±4 and 85±4 μM, respectively. Furthermore, the compounds were also assayed for their ability to inhibit DNA-dependent protein kinase (DNA-PK) activity. The most active compounds were 18 IC(50)=0.091 μM, 24 IC(50)=0.191 μM, and 22 IC(50)=0.331 μM. Homology modelling was used to build a 3D model of DNA-PK based on the X-ray structure of phosphatidylinositol 3-kinases (PI3Ks). Docking of synthesised compounds within the binding pocket and structure-activity relationships (SAR) analyses of the poses were performed and results agreed well with observed activity.     

Steroids from Commiphora mukul display antiproliferative effect against human prostate cancer PC3 cells via induction of apoptosis

Two new stigmastane-type steroids, stigmasta-5,22E-diene-3β,11α-diol (1) and stigmasta-5,22E-diene-3β,7α,11α-triol (2), together with eight known compounds, were isolated from the resinous exudates of Commiphora mukul. Their structures were established by extensive analysis of their HR-MS, 1D- and 2D-NMR (COSY, HMQC, HMBC and NOESY) spectra. The isolates were evaluated for their antiproliferative activities against four human cancer cell lines. Compound 2 demonstrated inhibitory effects with IC(50) values of 5.21, 9.04, 10.94 and 16.56 μM, respectively, against K562, MCF-7, PC3 and DU145 human cancer cell lines. Further study showed that 2 was able to enforce the PC3 cell cycle arrest in the G2/M phase, and induce the apoptosis of PC3 cells by activation of Bax, caspases 3 and 9, and by inhibition of Bcl-2. It was also found that 1 inhibited proliferation of PC3 cells via G0/G1 phase arrest of the cell cycle.     

Inhibitory effects of Mannich bases of heterocyclic chalcones on NO production by activated RAW 264.7 macrophages and superoxide anion generation and elastase release by activated human neutrophils

Some chalcones exert potent anti-inflammatory activities. Mannich bases of heterocyclic chalcones inhibited nitric oxide (NO) production in lipopolysaccharide and interferon-γ stimulated RAW 264.7 macrophages. Also Formyl-Met-Leu-Phe and cytochalasin B induced superoxide anion generation (O2·-) and elastase release in human neutrophils. Mannich bases of heterocyclic chalcone analogs exhibited potent inhibitory effects on NO production with IC(50) values ranges between 10.5 and 0.018 μM, O2·- generation (IC(50) 39.87-0.68 μM) and elastase release (IC(50) 39.74-0.95 μM). Compound 29 (IC(50) 0.055 μM) and 34 (IC(50) 0.018 μM) were showed excellent inhibition on NO production. On the other hand, compounds 2 and 8 showed potent inhibition on O2·- generation and elastase release. Therefore, these four compounds may be new leads for development of anti-inflammatory activities. The structure-activity relationships are also discussed.     

Synthesis and biological evaluation of tetracyclic thienopyridones as antibacterial and antitumor agents

A facile synthesis of model 4-oxopyrido[3',2':4,5]thieno[3,2-b]indole-3-carboxylic acids 9a-e was achieved via Stille arylation of 2-chloro-3-nitro-4-oxothieno[2,3-b]pyridine-5-carboxylate and a subsequent microwave-assisted phosphite-mediated Cadogan reaction. The new compounds were tested for their in vitro antimicrobial and antiproliferative activity. Compounds 9a-c and 9e exhibited very high potency against Gram positive Bacillus subtilis and Bacillus megaterium at concentrations 0.000015-0.007 μg/mL. They also displayed excellent activity towards other Gram positive bacilli and staphylococci and Gram negative Haemophilus influenzae, being in most cases superior or equal to commercial fluoroquinolones. Both 9a and 9c were inhibitors of the DNA gyrase activity. As concerns antitumor properties, compounds 9b-e showed growth inhibition of MCF-7 breast tumor and A549 non-small cell lung cancer cells with IC(50) 1.6-2.8 μM and 2.6-6.9 μM, respectively, coupled with absence of cytotoxicity towards normal cells. These compounds are promising as dual acting chemotherapeutics.     

Synthesis, biological evaluation and structure-activity relationships of glycyrrhetinic acid derivatives as novel anti-hepatitis B virus agents

Fifty-seven derivatives of glycyrrhetinic acid (GA) were synthesized, and their anti-hepatitis B virus (HBV) activity was evaluated in HepG 2.2.15 cells. Among them, sixteen compounds showed greater anti-HBV activity than GA, especially, compounds 29, 32, 35, 41 exhibited significantly inhibitory activities against HBV DNA replication with IC(50) values of 5.71, 5.36, 8.90 and 9.08 μM, respectively. The structure-activity relationships (SARs) of GA derivatives were discussed for exploring novel anti-HBV agents.     

Selective Induction of DNA Damage and Cell Cycle Arrest Mediated by Chromone-Triazole Dyads Derivatives: Effects on Breast and Prostate Cancer Cells

Chromones and triazoles are groups of heterocyclic compounds widely known to exhibit a broad spectrum of biological activities. The combination of these two pharmacophores could result in multiple mechanisms of action to increase the potency of anticancer drugs and reduce their side effects. The in vitro antitumor effect of eight chromone-based compounds was evaluated in breast (T-47D and MDA-MB-231) and prostate (PC3) cancer cell lines, and in non-cancerous human mammary epithelial cells (HuMEC) using a resazurin-based method. Flow cytometry was used to evaluate the cell cycle and cell death, and ɣ-H2AX detection to identify DNA damage. The compounds showed selective cytotoxicity against cancer cell lines, with (E)-2-(2-(5-(4-methoxyphenyl)-2H-1,2,3-triazol-4-yl)vinyl)-4H-chromen-4-one (compound 2 a ) being more potent in non-metastatic T-47D cells (IC₅₀ 0.65 μM). Replacing the hydrogen by a methyl group on the triazole ring in compound 2 b enhanced the cytotoxic activity up to IC₅₀ 0.24 μM in PC3, 0.32 μM in MDA-MB-231 and 0.52 μM in T-47D. Compound 2 b was 3-fold more potent than doxorubicin in PC3 (IC₅₀ 0.73 μM) and 4-fold in MDA-MB-231 (IC₅₀ 1.51 μM). The addition of tetrahydroisoindole-1,3-dione moiety in compound 5 did not improve its effectiveness in any of the cell lines but it exerted the lowest cytotoxic effect in HuMEC (IC₅₀ 221.35 μM). The compounds revealed different cytotoxic mechanisms: 2 a and 2 b induced G2/M arrest, and compound 5 did not affect the cell cycle.     

One-pot regioselective synthesis of tetrahydroindazolones and evaluation of their antiproliferative and Src kinase inhibitory activities

A number of 2-substituted tetrahydroindazolones were synthesized by three-component condensation reaction of 1,3-diketones, substituted hydrazines, benzaldehydes, and Yb(OTf)(3) as a catalyst in [bmim][BF(4)] ionic liquid using a simple, efficient, and economical one-pot method. The synthesized tetrahydroindazolones were evaluated for inhibition of cell proliferation of human colon carcinoma (HT-29), human ovarian adenocarcinoma (SK-OV-3), and c-Src kinase activity. 3,4-Dichlorophenyl tetrahydroindazolone derivative (15) inhibited the cell proliferation of HT-29 and SK-OV-3 cells by 62% and 58%, respectively. 2,3-Diphenylsubstituted tetrahydroindazolone derivatives, inhibited the cell proliferation of HT-29 cells by 65-72% at a concentration of 50 μM. In general, the tetrahydroindazolones showed modest inhibition of c-Src kinase where 4-tertbutylphenyl- and 3,4-dichlorophenyl- derivatives showed the inhibition of c-Src kinase with IC(50) values of 35.1 and 50.7 μM, respectively.     

Synthesis and in vitro evaluation of novel coumarin-chalcone hybrids as potential anticancer agents

A series of coumarin-chalcone hybrids have been synthesized and evaluated for their in vitro cytotoxicity against a panel of four human cancer cell lines and normal fibroblasts (NIH3T3). Among 21 compounds screened, three compounds (23, 25 and 26) showed IC(50) range from 3.59 to 8.12 μM. The most promising compound 26 showed around 30-fold more selectivity towards C33A (cervical carcinoma) cells over normal fibroblast NIH3T3 cells with an IC(50) value of 3.59 μM.