Synthesis and structure–activity relationships of novel benzofuran farnesyltransferase inhibitors

A series of benzofuran-based farnesyltransferase inhibitors have been designed and synthesized as antitumor agents. Among them, 11f showed the most potent enzyme inhibitory activity (IC₅₀ = 1.1 nM) and antitumor activity in human cancer xenografts in mice.     

Search for novel histone deacetylase inhibitors. Part II: Design and synthesis of novel isoferulic acid derivatives

Previously, we described the discovery of potent ferulic acid-based histone deacetylase inhibitors (HDACIs) with halogeno-acetanilide as novel surface recognition moiety (SRM). In order to improve the affinity and activity of these HDACIs, twenty seven isoferulic acid derivatives were described herein. The majority of title compounds displayed potent HDAC inhibitory activity. In particular, IF5 and IF6 exhibited significant enzymatic inhibitory activities, with IC₅₀ values of 0.73 ± 0.08 and 0.57 ± 0.16 μM, respectively. Furthermore, these compounds showed moderate antiproliferative activity against human cancer cells. Especially, IF6 displayed promising profile as an antitumor candidate with IC₅₀ value of 3.91 ± 0.97 μM against HeLa cells. The results indicated that these isoferulic acid derivatives could serve as promising lead compounds for further optimization.     

Design,synthesis and anticancer activity of novel nopinone-based thiosemicarbazone derivatives

A series of new nopinone-based thiosemicarbazone derivatives were designed and synthesized as potent anticancer agents. All these compounds were identified by ¹H NMR, ¹³C NMR, HR-MS spectra analyses. In the in vitro anticancer activity, most derivatives showed considerable cytotoxic activity against three human cancer cell lines (MDA-MB-231, SMMC-7721 and Hela). Among them, compound 4i exhibited most potent antitumor activity against three cancer cell lines with the IC₅₀ values of 2.79 ± 0.38, 2.64 ± 0.17 and 3.64 ± 0.13 μM, respectively. Furthermore, the cell cycle analysis indicated that compound 4i caused cell cycle arrest of MDA-MB-231 cells at G2/M phase. The Annexin V-FITC/7-AAD dual staining assay also revealed that compound 4i induced the early apoptosis of MDA-MB-231 cells.     

Synthesis of novel strobilurin–pyrimidine derivatives and their antiproliferative activity against human cancer cell lines

A series of new strobilurin–pyrimidine analogs were designed and synthesized based on the structures of our previously discovered antiproliferative compounds I and II. Biological evaluation with two human cancer cell lines (A549 and HL60) showed that most of these compounds possessed moderate to potent antiproliferative activity. Two potent candidates (8f, IC₅₀ = 2.2 nM and 11d, IC₅₀ = 3.4 nM) were identified with nanomolar activity against leukemia cancer cell line HL60 for further development. This activity represents a 1000- to 2500-fold improvement compared to the parent compounds I and II and is 20- to 30-fold better than the chemotherapy drug, doxorubicin. The present work provides strong incentive for further development of these strobilurin–pyrimidine analogs as potential antitumor agents for the treatment of leukemia.     

Design,synthesis and biological evaluation of heterocyclic azoles derivatives containing pyrazine moiety as potential telomerase inhibitors

Three series of novel heterocyclic azoles derivatives containing pyrazine (5a–5k, 8a–8k and 11a–11k) have been designed, synthesized, structurally determined, and their biological activities were evaluated as potential telomerase inhibitors. Among the oxadiazole derivatives, compound 5c showed the most potent biological activity against SW1116 cancer cell line (IC₅₀ = 2.46 μM against SW1116 and IC₅₀ = 3.55 μM for telomerase). Compound 8h performed the best in the thiadiazole derivatives (IC₅₀ = 0.78 μM against HEPG2 and IC₅₀ = 1.24 μM for telomerase), which was comparable to the positive control. While compound 11f showed the most potent biological activity (IC₅₀ = 4.12 μM against SW1116 and IC₅₀ = 15.03 μM for telomerase) among the triazole derivatives. Docking simulation by positioning compounds 5c, 8h and 11f into the telomerase structure active site was performed to explore the possible binding model. The results of apoptosis demonstrated that compound 8h possessed good antitumor activity against HEPG2 cancer cell line. Therefore, compound 8h with potent inhibitory activity in tumor growth inhibition may be a potential antitumor agent against HEPG2 cancer cell. Therefore, the introduction of oxadiazole, thiadiazole and triazole structures reinforced the combination of our compounds and the receptor, resulting in progress of bioactivity.     

Synthesis and biological activities of a pH-dependently activated water-soluble prodrug of a novel hexacyclic camptothecin analog

CH0793076 (1) is a novel hexacyclic camptothecin analog showing potent antitumor activity in various human caner xenograft models. To improve the water solubility of 1, water-soluble prodrugs were designed to generate an active drug 1 nonenzymatically, thus expected to show less interpatient PK variability than CPT-11. Among the prodrugs synthesized, 4c (TP300, hydrochloride) having a glycylsarcosyl ester at the C-20 position of 1 is highly water-soluble (>10 mg/ml), stable below pH 4 and rapidly generates 1 at physiological pH in vitro. The rapid (ca. <1 min) generation of 1 after incubation of TP300 with plasma (mouse, rat, dog and monkey) was also demonstrated. TP300 showed a broader antitumor spectrum and more potent antitumor activity than CPT-11 in various human cancer xenograft models.     

Structure-based optimization and biological evaluation of trisubstituted pyrazole as a core structure of potent ROS1 kinase inhibitors

Recently inhibition of ROS1 kinase has proven to be a promising strategy for several indications such as glioblastoma, non-small cell lung cancer (NSCLC), and cholangiocarcinoma. Our team reported trisubstituted pyrazole-based ROS1 inhibitors by which two inhibitors showed good IC₅₀ values in enzyme-based screening. To develop more advanced ROS1 inhibitors through SAR this trisubstituted pyrazole-based scaffold has been built. Consequently, 16 compounds have been designed, synthesized and shown potent IC₅₀ values in the enzymatic assay, which are from 13.6 to 283 nM. Molecular modeling studies explain how these ROS1 kinase inhibitors revealed effectively the key interactions with ROS1 ATP binding site. Among these compounds, compound 9a (IC₅₀ = 13.6 nM) has exerted 5 fold potency than crizotinib and exhibited high degree of selectivity (selectivity score value = 0.028) representing the number of non-mutant kinases with biological activity over 90% at 10 μM.     

Synthesis and antitumor activities of novel hybrid molecules containing 1,3,4-oxadiazole and 1,3,4-thiadiazole bearing Schiff base moiety

A series of novel hybrid molecules containing 1,3,4-oxadiazole and 1,3,4-thiadiazole bearing Schiff base moiety were designed, synthesized and evaluated for their in vitro antitumor activities against SMMC-7721, MCF-7 and A549 human tumor cell lines by CCK-8 assay. The bioassay results demonstrated that most of the tested compounds showed potent antitumor activities, and some compounds exhibited stronger effects than positive control 5-fluorouracil (5-FU) against various cell lines. Among these compounds, compound 8d showed the best inhibitory effect against SMMC-7721 cells, with IC₅₀ value of 2.84 μM. Compounds 8k and 8n displayed highly effective antitumor activities against MCF-7 cells, with IC₅₀ values of 4.56 and 4.25 μM, respectively. Compounds 8a and 8n exhibited significant antiproliferative activity against A549 cells, with IC₅₀ values of 4.11 and 4.13 μM, respectively. The pharmacological results suggest that the substituents of phenyl ring on the 1,3,4-oxadiazole are vital for modulating antiproliferative activities against various tumor cell lines.     

Synthesis and biological evaluation of compounds which contain pyrazole,thiazole and naphthalene ring as antitumor agents

A series of compounds which contain pyrazole, thiazole and naphthalene ring (1a–7a, 1b–7b, 1c–7c, 1d–7d) were firstly synthesized and their anti-proliferative activity, EGFR inhibitory activity, cytotoxicity and inhibition to Hela cell migration were evaluated. Compound 2-(3-(3,4-dimethylphenyl)-5-(naphthalen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one (7d) displayed the most potent inhibitory activity (IC₅₀ = 0.86 μM for Hela and IC₅₀ = 0.12 μM for EGFR). Structure–activity relationship (SAR) analysis showed that the anti-proliferative activity was affected by A-ring-substituent (–OCH₃ > –CH₃ > –H > –Br > –Cl > –F). Docking simulation of compound 7d into EGFR active site showed that naphthalene ring of 7d with LYS721 formed two p–π bonds, which enhanced antitumor activity. Therefore, compound 7d may be developed as a potential antitumor agent.     

Synthesis,molecular docking and α-glucosidase inhibition of 2-((5,6-diphenyl-1,2,4-triazin-3-yl)thio)-N-arylacetamides

A novel series of 2-((5,6-diphenyl-1,2,4-triazin-3-yl)thio)-N-arylacetamides 5a–5q have been synthesized and evaluated for their α-glucosidase inhibitory activity. All newly synthesized compounds exhibited potent α-glucosidase inhibitory activity in the range of IC₅₀ = 12.46 ± 0.13–72.68 ± 0.20 μM, when compared to the standard drug acarbose (IC₅₀ = 817.38 ± 6.27 μM). Among the series, compound 5j (12.46 ± 0.13 μM) with strong electron-withdrawing nitro group on the arylacetamide moiety was identified as the most potent inhibitor of α-glucosidase. Molecular docking study was carried out to explore the binding interactions of these compounds with α-glucosidase. Our study identifies a novel series of potent α-glucosidase inhibitors for further investigation.     

SAR analysis and biological studies of synthesized podophyllum derivates obtained by N linkage modification at C-4 position

A series of C4-N-substituted podophyllum derivatives were synthesized and tested for cytotoxicity in HeLa, BGC-823, A549, Huh7 and MCF-7 cells by MTT assay. Pharmacologically, most derivatives displayed potent cytotoxicity against at least one of the tested tumor cell lines. Structure activity relationship (SAR) analysis suggests that compounds with imidogen exposed on the pyridine, rather than pyrimidine, exhibited significantly elevated potency. Moreover, the presence of a chlorine atom in the heterocyclic ring enhanced cytotoxicity, with the order 3-position > 4-position > 5-position > 6-position. Specifically, two compounds, 3g and 3h, with 2-amino-3-chloropyridine substituted into the podophyllotoxin (PPT) and 4′-O-demethylepipodophyllotoxin (DMEP) scaffolds were shown to have the most potent HeLa cells cytotoxicity compared to other synthesized derivatives or reference compounds PPT, DMEP and etoposide (VP-16). The compound 3g was shown to inhibit microtubule polymerization and compound 3h affected topoisomerase II catalytic activity. Both compounds resulted in G₂/M phase arrest and apoptosis, purportedly by increasing the expression of P53, followed by Bax up-regulation, Bcl-2 down-regulation, and caspase-3 activation. As a result of this work, we conclude that compounds 3g and 3h are more potent anticancer agents than VP-16, and that they work by different antitumor mechanisms.     

Design,synthesis and biological evaluation of new potent and highly selective ROS1-tyrosine kinase inhibitor

ROS1 protein is a receptor tyrosine kinase that has been reported mainly in meningiomas and astrocytomas, and until now, there is no selective inhibitor for this kinase. In this study, we illustrate for the synthesis of a highly potent and selective inhibitor for ROS1 kinase. The synthesized compound 1 was tested initially at a single dose concentration of 10 μM over 45 different kinases. At this concentration, a 94% inhibition of the enzymatic activity of ROS1 kinase was observed, while the inhibition in activity was below 30% in all of the other kinases. The pyrazole compound 1 was further tested in a 10-dose IC₅₀ mode and showed an IC₅₀ value of 199 nM for ROS1 kinase. The compound 1 can be used as a promising lead for the development of new selective inhibitors for ROS1 kinase, and it may open the way for new selective therapeutics for astrocytomas.     

Design and synthesis of pyrrolo[3,2-d]pyrimidine HER2/EGFR dual inhibitors: Improvement of the physicochemical and pharmacokinetic profiles for potent in vivo anti-tumor efficacy

During the course of our studies on a novel HER2/EGFR dual inhibitor (TAK-285), we found an alternative potent pyrrolo[3,2-d]pyrimidine compound (1a). To enhance the pharmacokinetic (PK) profile of this compound, we conducted chemical modifications into its N-5 side chain and conversion of the chemically modified compounds into their salts. Among them, 2cb, the tosylate salt of compound 2c, showed potent HER2/EGFR kinase inhibitory activity (IC₅₀: 11/11 nM) and cellular growth inhibitory activity (BT-474 cell GI₅₀: 56 nM) with a good drug metabolism and PK (DMPK) profile. Furthermore, 2cb exhibited significant in vivo antitumor efficacy in both mouse and rat xenograft models with transplanted 4-1ST gastric cancer cell lines (mouse, T/C = 0%, 2cb po bid at 100 mg/kg; rat, T/C: -1%, 2cb po bid at 25 mg/kg).     

Xanthine oxidase inhibitory terpenoids of Amentotaxus formosana protect cisplatin-induced cell death by reducing reactive oxygen species (ROS) in normal human urothelial and bladder cancer cells

The diterpenoids (+)-ferruginol (1), ent-kaur-16-en-15-one (2), ent-8(14),15-sandaracopimaradiene-2α,18-diol (3), 8(14),15-sandaracopimaradiene-2α,18,19-triol (4), and (+)-sugiol (5) and the triterpenoids 3β-methoxycycloartan-24(24¹)-ene (6), 3β,23β-dimethoxycycloartan-24(24¹)-ene (7), 3β,23β-dimethoxy-5α-lanosta-24(24¹)-ene (8), and 23(S)-23-methoxy-24-methylenelanosta-8-en-3-one (9), isolated from Amentotaxus formosana, showed inhibitory effects on xanthine oxidase (XO). Of the compounds tested, compound 5 was a potent inhibitor of XO activity, with an IC₅₀ value of 6.8 ± 0.4 μM, while displaying weak ABTS radical cation scavenging activity. Treatment of the bladder cancer cell line, NTUB1, with 3–10 μM of compound 5 and 10 μM cisplatin, and immortalized normal human urothelial cell line, SV-HUC1, with 0.3–1 μM and 10–50 μM of compound 5 and 10 μM cisplatin, respectively, resulted in increased viability of cells compared with cytotoxicity induced by cisplatin. Treatment of NTUB1 with 20 μM cisplatin and 10 or 30 μM of compound 5 resulted in decreased ROS production compared with ROS production induced by cisplatin. These results indicate that 10 or 30 μM of compound 5 in NTUB1 cells may mediate through the suppression of XO activity and reduction of reactive oxygen species (ROS) induced by compound 5 cotreated with 20 μM cisplatin and protection of subsequent cell death.     

Design,synthesis and in vitro anticancer activity of novel quinoline and oxadiazole derivatives of ursolic acid

A series of new quinoline derivatives of ursolic acid were designed and synthesized in an attempt to develop potential anticancer agents. The structures of these compounds were identified by ¹H NMR, ¹³C NMR, IR and ESI-MS spectra analysis. The target compounds were evaluated for their in vitro cytotoxicity against three human cancer cell lines (MDA-MB-231, Hela and SMMC-7721). From the results, compounds 3a–d displayed significant antitumor activity against three cancer cell lines. Especially, compound 3b was found to be the most potent derivative with IC₅₀ values of 0.61 ± 0.07, 0.36 ± 0.05, 12.49 ± 0.08 μM against MDA-MB-231, HeLa and SMMC-7721 cells, respectively, stronger than positive control etoposide. Furthermore, the Annexin V-FITC/PI dual staining assay revealed that compound 3b could significantly induce the apoptosis of MDA-MB-231 cells in a dose-dependent manner. The cell cycle analysis also indicated that compound 3b could cause cell cycle arrest of MDA-MB-231 cells at G0/G1 phase.     

Synthesis and biological evaluation of 1,2,3-triazole linked aminocombretastatin conjugates as mitochondrial mediated apoptosis inducers

A series of 1,2,3-triazole linked aminocombretastatin conjugates were synthesized and evaluated for cytotoxicity, inhibition of tubulin polymerization and apoptosis inducing ability. Most of the conjugates exhibited significant anticancer activity against some representative human cancer cell lines and two of the conjugates 6d and 7c displayed potent cytotoxicity with IC₅₀ values of 53 nM and 44 nM against A549 human lung cancer respectively, and were comparable to combretastatin A-4 (CA-4). SAR studies revealed that 1-benzyl substituted triazole moiety with an amide linkage at 3-position of B-ring of the combretastatin subunit are more active compared to 2-position. G2/M cell cycle arrest was induced by these conjugates 6d and 7c and the tubulin polymerization assay (IC₅₀ of 1.16 μM and 0.95 μM for 6d and 7c, respectively) as well as immunofluorescence analysis showed that these conjugates effectively inhibit microtubule assembly at both molecular and cellular levels in A549 cells. Colchicine competitive binding assay suggested that these conjugates bind at the colchicine binding site of tubulin as also observed from the docking studies. Further, mitochondrial membrane potential, ROS generation, caspase-3 activation assay, Hoechst staining and DNA fragmentation analysis revealed that these conjugates induce cell death by apoptosis.     

Ursolic acid derivatives induce cell cycle arrest and apoptosis in NTUB1 cells associated with reactive oxygen species

Twenty-three ursolic acid (1) derivatives 2–24 including nine new 1 derivatives 5, 7–11, 20–22 were synthesized and evaluated for cytotoxicities against NTUB1 cells (human bladder cancer cell line). Compounds 5 and 17 with an isopropyl ester moiety at C-17-COOH and a succinyl moiety at C-3-OH showed potent inhibitory effect on growth of NTUB1 cells. Compounds 23 and 24 with seco-structures prepared from 1 also showed the increase of the cytotoxicity against NTUB1 cells. Exposure of NTUB1 to 5 (40 μM) and 23 (20 and 50 μM) for 24 h significantly increased the production of reactive oxygen species (ROS) while exposure of NTUB1 to 5 (20 and 40 μM) and 23 (20 and 50 μM) for 48 h also significantly increased the production of ROS while exposure of cells to 17 did not increase the amount of ROS. Flow cytometric analysis exhibited that treatment of NTUB1 with 5 or 17 or 23 led to the cell cycle arrest accompanied by an increase in apoptotic cell death after 24 or 48 h. These data suggest that the presentation of G1 phase arrest and apoptosis in 5- and 23-treated NTUB1 for 24 h mediated through increased amount of ROS in cells exposed with 5 and 23, respectively, while the presence of G2/M arrest before accumulation of cells in sub-G1 phase in 5-treated cells for 48 h also due to increased amount of ROS in cells exposed with 5. The inhibition of tubulin polymerization and cell cycle arrest at G2/M following by apoptosis presented in the cell cycle of 23 also mediates through the increase amount of ROS induced by treating NTUB1 with 23 for 48 h.     

The sulfamide moiety affords higher inhibitory activity and oral bioavailability to a series of coumarin dual selective RAF/MEK inhibitors

Introducing a sulfamide moiety to our coumarin derivatives afforded enhanced Raf/MEK inhibitory activity concomitantly with an acceptable PK profile. Novel sulfamide 17 showed potent HCT116 cell growth inhibition (IC₅₀ = 8 nM) and good PK profile (bioavailability of 51% in mouse), resulting in high in vivo antitumor efficacy in the HCT116 xenograft (ED₅₀ = 4.8 mg/kg). We confirmed the sulfamide moiety showed no negative impact on tests run on the compound to evaluate DMPK (PK profiles in three animal species, CYP inhibition and CYP induction) and the safety profile (hERG and AMES tests). Sulfamide 17 had favorable properties that warranted further preclinical assessment     

Development of novel ferulic acid derivatives as potent histone deacetylase inhibitors

Histone deacetylase inhibitors (HDACIs) offer a promising strategy for cancer therapy. The discovery of potent ferulic acid-based HDACIs with hydroxamic acid or 2-aminobenzamide group as zinc binding group was reported. The halogeno-acetanilide was introduced as novel surface recognition moiety (SRM). The majority of title compounds displayed potent HDAC inhibitory activity. In particular, FA6 and FA16 exhibited significant enzymatic inhibitory activities, with IC₅₀ values of 3.94 and 2.82 μM, respectively. Furthermore, these compounds showed moderate antiproliferative activity against a panel of human cancer cells. FA17 displayed promising profile as an antitumor candidate. The results indicated that these ferulic acid derivatives could serve as promising lead compounds for further optimization.     

Aroylguanidine-based factor Xa inhibitors: The discovery of BMS-344577

We report the design and synthesis of a novel class of N,N′-disubstituted aroylguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The structure–activity relationships (SAR) investigation led to the discovery of the nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC₅₀ = 4 nM, EC_2×PT = 7 μM). However, the potent CYP3A4 inhibition activity (IC₅₀ = 0.3 μM) of 22 precluded its further development. Detailed analysis of the X-ray crystal structure of compound 22 bound to FXa indicated that the substituent at the 6-position of the nicotinoyl group of 22 would be solvent-exposed, suggesting that efforts to attenuate the unwanted CYP activity could focus at this position without affecting FXa potency significantly. Further SAR studies on the 6-substituted nicotinoyl guanidines resulted in the discovery of 6-(dimethylcarbamoyl) nicotinoyl guanidine 36 (BMS-344577, IC₅₀ = 9 nM, EC_2×PT = 2.5 μM), which was found to be a selective, orally efficacious FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models.