Synthesis and investigation of novel 6-(1,2,3-triazol-4-yl)-4-aminoquinazolin derivatives possessing hydroxamic acid moiety for cancer therapy

By merging the critical pharmacophore of EGFR/HER2 and HDAC inhibitors into one compound, a novel series of EGFR, HER-2, and HDAC multitarget inhibitors were synthesized. Compounds 9a–l contained 4-anilinoquinazolines with C-6 triazole-linked long alkyl chains of hydroxamic acid and displayed excellent inhibition against these enzymes (compound 9d exhibited the best inhibitory potency on wild-type EGFR, HDAC1, and HDAC6 with IC₅₀ values 0.12 nM, 0.72 nM and 3.2 nM individually). Furthermore, compounds 9b and 9d potently inhibited proliferation of five human cancer cell lines (with IC₅₀ values between 0.49 and 8.76 μM). Further mechanistic study revealed that compound 9d also regulated the phosphorylation of EGFR and HER2 and histone H3 hyperacetylation on the cellular level and induced remarkable apoptosis in BT-474 cells. Therefore, our study suggested that a system network-based multi-target drug design strategy might provided an alternate drug design method, by taking into account the synergy effect of EGFR, HER-2 and HDAC.     

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.     

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.     

Iodine catalyzed three component synthesis of 1-((2-hydroxy naphthalen-1-yl)(phenyl)(methyl))pyrrolidin-2-one derivatives: Rationale as potent PI3K inhibitors and anticancer agents

A series of 1-((2-hydroxynaphthalen-1-yl)(phenyl)(methyl))pyrrolidin-2-one derivatives by an efficient iodine catalyzed domino reaction involving various aromatic aldehydes, 2-pyrrolidinone and β-naphthol was achieved and the structures were elucidated by FTIR ¹H NMR, ¹³C NMR, and HRMS. Subsequently they were evaluated for cytotoxicity against breast cancer (MCF-7), colon cancer (HCT116) cell lines. In the cytotoxicity, the relative inhibition activity was remarkably found to be high in MCF-7 cell lines as 79% (4c), 83% (4f) and the IC₅₀values were 1.03 µM (4c), 0.98 µM (4f). Compounds 4a, 4e, 4k–m, and 4q were found to be inactive and rest showed a moderate activity. In order to get more insight into the binding mode and inhibitor binding affinity, compounds (4a–q) were docked into the active site phosphoinositide 3-kinase (PI3K) (PDB ID: 4JPS) which is a crucial regulator of apoptosis or programmed cell death. Results suggested that the hydrophobic interactions in the binding pockets of PI3K exploited affinity of the most favourable binding ligands (4c and 4f: inhibitory constant (ki) = 66.22 nM and 107.39 nM). The SAR studies demonstrated that the most potent compounds are 4c and 4f and can be developed into precise PI3K inhibitors with the capability to treat various cancers.     

Design,synthesis, and docking studies of afatinib analogs bearing cinnamamide moiety as potent EGFR inhibitors

Two series of afatinib derivatives bearing cinnamamide moiety (10a–n and 11a–h) were designed, synthesized and evaluated for the IC₅₀ values against four cancer cell lines (A549, PC-3, MCF-7 and Hela). Two selected compounds (10e, 10k) were further evaluated for the inhibitory activity against EGFR and VEGFR2/KDR kinases. Seven of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ values in single-digit μM to nanomole range. Three of them are equal to more active than positive control afatinib against one or more cell lines. The most promising compound 10k showed the best activity against A549, PC-3, MCF-7 and Hela cancer cell lines and EGFR kinase, with the IC₅₀ values of 0.07 ± 0.02 μM, 7.67 ± 0.97 μM, 4.65 ± 0.90 μM and 4.83 ± 1.28 μM, which were equal to more active than afatinib (0.05 ± 0.01 μM, 4.1 ± 2.47 μM, 5.83 ± 1.89 μM and 6.81 ± 1.77 μM), respectively. Activity of compounds 10e (IC₅₀ 9.1 nM) and 10k (IC₅₀ 3.6 nM) against EGFR kinase were equal to the reference compound afatinib (IC₅₀ 1.6 nM). Structure–activity relationships (SARs) and docking studies indicated that replacement of the aqueous solubility 4-(dimethylamino)but-2-enamide group by cinnamamide moiety didn’t decrease the antitumor activity. The results suggested that methoxy substitution had a significant impact on the activity and methoxy substituted on C-4 or C-2,3,4 position was benefit for the activity.     

Synthesis of new morpholine-connected pyrazolidine derivatives and their antimicrobial,antioxidant, and cytotoxic activities

A simple and convenient one-pot four-component synthesis of morpholine-connected pyrazolidine derivatives 2a–f and 4a–f was developed using direct metal-free catalysis, with the identities of the synthesized compounds confirmed by IR, NMR (¹H and ¹³C), mass spectrometry, and elemental analysis. The prepared compounds were inspected for antimicrobial, antioxidant, and cytotoxic activities.Antimicrobial and antifungal activities against five bacterial and four fungal pathogens, respectively, were investigated using the disc diffusion technique. In antibacterial activity, compounds 2d and 2f (MIC = 2 μg/mL) exhibited significantly higher activity than the standard ciprofloxacin. The results of antifungal assay showed that the activity of compound 4a (MIC = 0.5 μg/mL) was significantly higher than the standard clotrimazole. Antioxidant activity was screened based on ABTS⁺ radical scavenging and linoleic acid peroxidation performance. Compound 4a showed substantial antioxidant (91.3%) activities, as compared with the Trolox standard. Cytotoxicity was evaluated using HepG2 (liver), HeLa (cervical), and MCF-7 (breast) cancer cell lines, with high toxicities observed for 2b (GI₅₀ = 12.2 μm) and 4a (GI₅₀ = 07.8 μm).     

Synthesis,and docking studies of phenylpyrimidine-carboxamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety as c-Met inhibitors

Four series of phenylpyrimidine-carboxamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (14a–e, 15a–g, 16a–e and 17a–g) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7). Four selected compounds (15e, 16a–b and 17a) were further evaluated for the activity against c-Met kinase, HepG2 and Hela cell lines. Most of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ valuables in single-digit μM to nanomole range. Eleven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15e showed superior activity to Foretinib against A549, PC-3 and MCF-7 cell lines, with the IC₅₀ values of 0.14 ± 0.08 μM, 0.24 ± 0.07 μM and 0.02 ± 0.01 μM, which were 4.6, 1.6 and 473.5 times more active than Foretinib (0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that the replacement of phenylpicolinamide scaffold with phenylpyrimidine fragment of the target compounds was benefit for the activity. What’s more, the introduction of fluoro atom to the aminophenoxy part played no significant impact on the activity and any substituent group on aryl group is unfavourable for the activity.     

Natural abenquines and synthetic analogues: Preliminary exploration of their cytotoxic activity

In this study, we explore the cytotoxic activity of four natural abenquines (2a–d) and fourteen synthetic analogues (2e–j and 3a–h) against a panel of six human cancer cell lines using a SRB assay. It was found that most of the compounds revealed higher levels of cytotoxic activities than naturally occurring abenquines. The analogues carrying ethylpyrrolidinyl and ethylpyrimidinyl with either an acetyl group (2 h–i) or a benzoyl group (3f–g), were the most potent against all human cancer cell lines and displayed EC₅₀ between a range of 0.6–3.4 μM. Notably, of the compounds tested, compound 2i proved the most cytotoxic against both ovarian (A2780) and breast (MCF7) cells, showing EC₅₀ = 0.6 and 0.8 μM respectively. Likewise, the analogues 2i, 3f and 3 g showed strong activity against cell HT29 with EC₅₀ = 0.9 μM for these compounds.     

Discovery of a highly potent,selective and novel CDK9 inhibitor as an anticancer drug candidate

A series of novel hybrid structure derivatives, containing both LEE011 and Cabozantinib pharmacophore, were designed, synthesized and evaluated. Surprisingly, a compound 4d was discovered that highly exhibited effective and selective activity of CDK9 inhibition with IC₅₀ = 12 nM. It effectively induced apoptosis in breast and lung cancer cell lines at nanomolar level. Molecular docking of 4d to ATP binding site of CDK9 kinase demonstrated a new hydrogen bonding between F atom of 4-(3-fluorobenzyloxy) group and ASN116 residue, compared with the positive control, LEE011. The compound 4d could block the cell cycle both in G0/G1 and G2/M phase to prevent the proliferation and differentiation of cancer cells. Mice bared-breast cancer treated with compound 4d showed significant suppression of cancer with low toxicity. Taken together, this novel compound 4d could be a promising drug candidate for clinical application.     

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).     

Synthesis and biological evaluation of novel hydroxybenzaldehyde-based kojic acid analogues as inhibitors of mushroom tyrosinase

Two series of novel kojic acid analogues (4a–j) and (5a–d) were designed and synthesized, and their mushroom tyrosinase inhibitory activities was evaluated. The result indicated that all the synthesized derivatives exhibited excellent tyrosinase inhibitory properties having IC₅₀ values in the range of 1.35 ± 2.15–17.50 ± 2.75 μM, whereas standard inhibitor kojic acid have IC₅₀ values 20.00 ± 1.08 μM. Specifically, 5-phenyl-3-[5-hydroxy-4-pyrone-2-yl-methylmercap-to]-4-(2,4-dihydroxyl-benzylamino)-1,2,4-triazole (4f) exhibited the most potent tyrosinase inhibitory activity with IC₅₀ value of 1.35 ± 2.15 μM. The kinetic studies of the compound (4f) demonstrated that the inhibitory effects of the compound on the tyrosinase were belonging to competitive inhibitors. Meanwhile, the structure-activity relationship was discussed.     

Design and synthesis of 4-morpholino-6-(1,2,3,6-tetrahydropyridin-4-yl)-N-(3,4,5-trimethoxyphenyl)-1,3,5-triazin-2-amine analogues as tubulin polymerization inhibitors

A series of thirty-seven 1,3,5-triazine analogues have been synthesized, characterized and evaluated for their antiproliferative activity against a panel of four different human cancer cell lines such as HeLa, HepG2, A549 and MCF-7. Most of the 1,3,5-triazine analogues exhibited promising antiproliferative activity against tested cancer cell lines. Among all the synthesized compounds, 8j showed potent activity against the cancer cell lines such as HeLa, HepG2, A549 and MCF-7 with IC₅₀ 12.3 ± 0.8, 9.6 ± 0.4, 10.5 ± 1.0 and 11.7 ± 0.5 μM respectively. 8j was taken up for elaborate biological studies and the cells in the cell cycle were arrested in G2/M phase. In addition, 8j was examined for its effect on the microtubule system with a tubulin polymerization assay, immunofluorescence. 8j showed remarkable inhibition of tubulin polymerization. Molecular docking studies were also carried out to understand the binding pattern. The studies suggested that 8j has a good binding affinity of ?7.949 towards nocodazole binding site of tubulin while nocodazole has ?7.462.     

Design,synthesis, and docking studies of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety as c-Met inhibitors

Four series of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (12a–e, 13a–f, 14a–f and 15a–i) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7) and c-Met kinase. Five selected compounds (13b, 15b, 15d, 15e and 15f) were further evaluated for the activity against HepG2 and Hela cell lines. Eighteen of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ valuables in single-digit μM to nanomole range. Seven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15f showed superior activity to Foretinib, with the IC₅₀ values of 1.04 ± 0.11 μM, 0.02 ± 0.01 μM and 9.11 ± 0.55 μM against A549, PC-3 and MCF-7 cell lines, which were 0.62 to 19.5 times more active than Foretinib (IC₅₀ values: 0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that replacement of quinoline nucleus of the previous active compounds with 1H-pyrrolo[2,3-b]pyridine moiety maintained even improved the potent cytotoxic activity. The results suggested that the introduction of fluoro atoms to the aminophenoxy part of target compounds or the phenyl group of pyrimidine substituted on C-4 position was benefit for the activity.     

Synthesis of novel forskolin isoxazole derivatives with potent anti-cancer activity against breast cancer cell lines

Forskolin C₁-isoxazole derivatives (3,5-regioisomers) (11a–e, 14, 15a–h and 15, 16a–g) were synthesized regioselectively by adopting 1,3-dipolar cycloadditions. These derivatives were tested using estrogen receptor positive breast cancer cell lines MCF-7 and BT-474. Majority of the compounds exhibited activity against the p53-positive MCF-7 breast cancer cells but not against the p53-negative BT-474 breast cancer cells. Among forskolin derivatives, compounds 11a, 11c, 14a, 14f, 14g, 14h, 15b, 16g and 17b exhibited higher anti-cancer activity against MCF-7 cell line with an IC₅₀ ≤ 1 µM. The derivative 14f exhibited highest activity in both p53-positive (MCF-7) and p53-negative (BT-474) breast cancer cell lines with an IC₅₀ of 0.5 µM.     

Synthesis,activity and docking studies of phenylpyrimidine–carboxamide Sorafenib derivatives

Two series of Sorafenib derivatives bearing phenylpyrimidine–carboxamide moiety (16a–g and 17a–p) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, MCF-7 and PC-3). Two selected compounds (17f and 17n) were further evaluated for the activity against VEGFR2/KDR kinase. More than half of the synthesized compounds showed moderate to excellent activity against three cancer cell lines. Compound 17f showed equal activity to Sorafenib against MCF-7 cell line, with the IC₅₀ values of 6.35 ± 0.43 μM. Meanwhile, compound 17n revealed more active than Sorafenib against A549 cell line, with the IC₅₀ values of 3.39 ± 0.37 μM. Structure–activity relationships (SARs) and docking studies indicated that the second series (17a–p) showed more active than the first series (16a–g). What’s more, the introduction of fluoro atom to the phenoxy part played no significant impact on activity. In addition, the presence of electron-donating on aryl group was benefit for the activity.     

Design,synthesis and cytotoxic activities of scopoletin-isoxazole and scopoletin-pyrazole hybrids

12 novel scopoletin-isoxazole and scopoletin-pyrazole hybrids were designed, synthesized and their chemical structures were confirmed by HR-MS, IR, ¹H NMR and ¹³C NMR spectra. The anticancer activities of the newly synthesized compounds were evaluated in vitro against three human cancer cell lines including HCT-116, Hun7 and SW620 by MTT assay. The screening results showed that six compounds (9a, 9c, 9d, 12a, 18b and 18d) exhibited potent cytotoxic activities with IC₅₀ values below 20 μM. Besides, we have further evaluated the growth inhibitory activities of six compounds against the human normal tissue cell lines HFL-1. Especially, compound 9d displayed significant anti-proliferative activity with IC₅₀ values ranging from 8.76 μM to 9.83 μM and weak cytotoxicity with IC₅₀ value of 90.9 μM on normal cells HFL-1, which suggested that isoxazole-based hybrids of scopoletin were an effective chemical modification to improve the anticancer activity of scopoletin.     

New potently bioactive alkaloids from Crinum erubescens

Antimalarial bioassay-guided fractionation of the swamp lily Crinum erubescens led to the isolation of four compounds with potent antiplasmodial activity. Compounds 1 and 2 were determined from their spectroscopic data to be the known pesticidal compound cripowellin A and the known pesticidal and antiproliferative compound cripowellin B. 1D and 2D-NMR techniques were used to determine the identities of 3 and 4 as the new compounds cripowellin C and D. A fifth compound was identified as the known alkaloid hippadine, which was inactive against Plasmodium falciparum. The antiplasmodial IC₅₀ values of compounds 1–4 were determined to be 30 ± 2, 180 ± 20, 26 ± 2, and 260 ± 20 nM, respectively, and their antiproliferative IC₅₀ values against the A2780 human ovarian cancer cell line were 11.1 ± 0.4, 16.4 ± 0.1, 25 ± 2, and 28 ± 1 nM.     

Synthesis and biological evaluation of N9-cis-cyclobutylpurine derivatives for use as cyclin-dependent kinase (CDK) inhibitors

A novel 6-aminopurine scaffold bearing an N9-cis-cyclobutyl moiety was designed using structure-based molecular design based on two known CDK inhibitors, dinaciclib and Cmpd-27. A series of novel 6-aminopurine compounds was prepared for structure–activity relationship (SAR) studies of CDK2 and CDK5 inhibitors. Among the compounds synthesized, compound 8l displayed potent CDK2 and CDK5 inhibitory activities with low nanomolar ranges (IC₅₀ = 2.1 and 4.8 nM, respectively) and showed moderate cytotoxicity in HCT116 colon cancer and MCF7 breast cancer cell lines. Here, we report the synthesis and evaluation of novel 6-aminopurine derivatives and present molecular docking models of compound 81 with CDK2 and CDK5.     

Synthesis and in vitro cytotoxic evaluation of new 1H-benzo[d]imidazole derivatives of dehydroabietic acid

A series of new 1H-benzo[d]imidazole derivatives of dehydroabietic acid were designed and synthesized as potent antitumor agents. Structures of the target molecules were characterized using MS, IR, ¹H NMR, ¹³C NMR and elemental analyses. In the in vitro cytotoxic assay, most compounds showed significant cytotoxic activities against two hepatocarcinoma cells (SMMC-7721 and HepG2) and reduced cytotoxicity against noncancerous human hepatocyte (LO2). Among them, compound 7b exhibited the best cytotoxicity against SMMC-7721 cells (IC₅₀: 0.36 ± 0.13 μM), while 7e was most potent to HepG2 cells (IC₅₀: 0.12 ± 0.03 μM). The cell cycle analysis indicated that compound 7b caused cell cycle arrest of SMMC-7721 cells at G2/M phase. Further, compound 7b also induced the apoptosis of SMMC-7721 cells in Annexin V-APC/7-AAD binding assay.