Design, synthesis, and structure–activity relationship studies of novel millepachine derivatives as potent antiproliferative agents

Discovery of novel dual tubulin and MMPs inhibitors for the treatment of lung cancer and overcoming drug resistance

Nowadays, hybrid molecule with dual targets activity or effect is regarded as an effective strategy for combating the drug resistance development in cancer therapy. Herein, novel of bifunctional conjugates targeting tubulin and MMPs inhibitors were synthesized. Among them, 15j exhibited robust anticancer activity in vitro and in vivo, with IC50 values of 0.154-0.296 μM against four human cancer cells and a 74.7 % (@20 mg/kg) tumor growth inhibition in vivo without obvious systemic toxicity. Mechanistic studies indicated that 15j exerted inhibitory effects on both tubulin polymerization, MMP-2 and MMP-9 activity. Moreover, 15j remarkably inhibited cell proliferation, migration and invasion, and accordingly disrupted the NF-κB signaling transduction. Furthermore, 15j effectively initiated mitochondria-dependent apoptotic pathway by causing mitochondrial dysfunction, promoting the accumulation of reactive oxygen species, and inducing DNA damage. Collectively, these results demonstrated that 15j, as a tubulin/MMPs dual-targeting inhibitor, has exhibited significant potential for the lung cancer therapy.

Design and bio-evaluation of novel millepachine derivatives targeting tubulin colchicine binding site for treatment of osteosarcoma

Microtubules are recognized as an appealing target for cancer treatment. We designed and synthesized of novel tubulin colchicine binding site inhibitors based on millepachine. Biological evaluation revealed compound 5h exhibited significant antiproliferative activity against osteosarcoma cell U2OS and MG-63. And compound 5h also remarkably inhibited tubulin polymerization. Further investigations indicated compound 5h not only arrest U2OS cells cycle at the G2/M phases, but also induced U2OS cells apoptosis in dose-dependent manners. Moreover, compound 5h was verified to inhibit cell migration and angiogenesis of HUVECs, induce mitochondrial membrane potential decreased and promoted the elevation of ROS levels. Furthermore, compound 5h exhibited remarkable effects on tumor growth in vivo, and the TGI rate was up to 84.94 % at a dose of 20 mg/kg without obvious toxicity. These results indicated that 5h may be an appealing tubulin inhibitor for treatment of osteosarcoma.

Evaluation of 3,5-Diphenyl-2-Pyrazolines for Antimitotic Activity by Inhibition of Tubulin Polymerization

Chalcones have a skeleton of diphenyls connected via an α,β-unsaturated carbonyl group. Many chalcone derivatives have been shown to interact with tubulin. Based on previous reports, chalcones derived by substitution of a carbonyl group with 2-pyrazoline can be expected to inhibit tubulin polymerization. Therefore, 3,5-diphenyl-2-pyrazolines were prepared to investigate their ability to inhibit tubulin polymerization. The clonogenic long-term survival assay showed that derivative 4, 5-(3,5-dimethoxyphenyl)-3-(2-methoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide, was the most effective at inhibiting the clonogenicity of HCT116 human colon cancer cells. Derivative 4 induced G2/M cell cycle arrest. In addition, derivative 4 caused dispersed microtubules, a disorganized spherical arrangement of chromosomes, and inhibition of mitotic spindle formation. The binding mode between tubulin and derivative 4 was elucidated by in silico molecular docking. Derivative 4 was superimposed with colchicine and entered the colchicine-binding site well. These results suggest that derivative 4 inhibits tubulin polymerization by binding to the colchicine binding site of tubulin, thus preventing mitotic spindle formation during mitosis in HCT116 colon cancer cells. We propose that derivative 4 could be used as a promising antimitotic chemotherapeutic agent.

A review on synthetic chalcone derivatives as tubulin polymerisation inhibitors

Microtubules play an important role in the process of cell mitosis and can form a spindle in the mitotic prophase of the cell, which can pull chromosomes to the ends of the cell and then divide into two daughter cells to complete the process of mitosis. Tubulin inhibitors suppress cell proliferation by inhibiting microtubule dynamics and disrupting microtubule homeostasis. Thereby inducing a cell cycle arrest at the G2/M phase and interfering with the mitotic process. It has been found that a variety of chalcone derivatives can bind to microtubule proteins and disrupt the dynamic balance of microtubules, inhibit the proliferation of tumour cells, and exert anti-tumour effects. Consequently, a great number of studies have been conducted on chalcone derivatives targeting microtubule proteins. In this review, synthetic or natural chalcone microtubule inhibitors in recent years are described, along with their structure-activity relationship (SAR) for anticancer activity.

The effect and mechanism of millepachine-disrupted spindle assembly in tumor cells

Millepachine (MIL) is a bioactive natural product that shows great potential for cancer treatment. Previous studies showed that MIL was a novel cancer drug candidate with a special structure. To provide reference for the research and development of MIL, we further investigated the mechanism of MIL inducing G2/M arrest and found MIL disrupted spindle assembly in tumor cells. In this study, we investigated the disrupting spindle assembly effects of MIL with a focus on its potential mechanism of action. First, we indicated that MIL did not inhibit microtubule polymerization from the results of in-vivo microtubule nucleation assay and microtubule polymerization in-vitro assay but delayed this process by inhibiting the production of ATP in tumor cells. Thereafter, we investigated the effect of MIL on the mitotic spindle. We found that MIL induced multipolar spindles by inhibiting the activity of Eg5 and inhibited mitotic spindle formation and chromatin condensation by the activation of the spindle assembly checkpoint (SAC) in tumor cells. These results established a novel function of MIL in regulating the assembly of mitotic spindle. As Eg5 and SAC are antitumor targets, effect of MIL on the Eg5 protein and SAC activation hinted that MIL has novel application in the development of antitumor drugs.

(E)-N-Aryl-2-oxo-2-(3,4,5-trimethoxyphenyl)acetohydrazonoyl cyanides as tubulin polymerization inhibitors: Structure-based bioisosterism design, synthesis, biological evaluation, molecular docking and in silico ADME prediction

A series of (E)-N-Aryl-2-oxo-2-(3,4,5-trimethoxyphenyl)acetohydrazonoyl cyanides have been synthesized and evaluated for their anticancer activity in human hepatocellular liver carcinoma HepG2 and breast adenocarcinoma MCF-7 cell lines. Among all the tested compounds, compound 3a, 3e and 3n displayed more activity than lead compound with IC₅₀ value of 0.26-0.61 μM. Meanwhile, these compounds (3a, 3e and 3n) showed potent antiproliferative activity against a panel of cancer cells and the HCT-8/T multidrug resistant cell line with IC₅₀ values in the range of 0.077- 7.44 μM. Flow cytometric analyses revealed that compound 3n induced cell cycle arrest in G2/M phases in a dose dependent manner. The compound 3n also displayed potent tubulin polymerization inhibition with an IC₅₀ value of 0.9 µM, with ten folds more active than colchicine (IC₅₀ = 9 μM). Molecular docking studies revealed that compound 3n efficiently interacted with the colchicine binding site of tubulin through hydrophobic, cation-π and hydrogen bond interaction. Furthermore, in silico pharmacokinetic prediction shown that these compounds have a good ADME-related physicochemical parameters. These results demonstrate that 3n exhibits potent cytotoxicity in cancer cells by targeting the colchicine binding site of tubulin and potentially acts as a therapeutic lead compound for the development of anticancer drugs.

Synthesis and Antiproliferative Activity of Minor Hops Prenylflavonoids and New Insights on Prenyl Group Cyclization

Synthesis of minor prenylflavonoids found in hops and their non-natural derivatives were performed. The antiproliferative activity of the obtained compounds against some human cancer cell lines was investigated. Using xanthohumol isolated from spent hops as a lead compound, a series of minor hop prenylflavonoids and synthetic derivatives were obtained by isomerization, cyclisation, oxidative-cyclisation, oxidation, reduction and demethylation reactions. Three human cancer cell lines-breast (MCF-7), prostate (PC-3) and colon (HT-29)-were used in antiproliferative assays, with cisplatin as a control compound. Five minor hop prenyl flavonoids and nine non-natural derivatives of xanthohumol have been synthetized. Syntheses of xanthohumol K, its dihydro- and tetrahydro-derivatives and 1″,2″,α,β-tetrahydroxanthohumol C were described for the first time. All of the minor hops prenyl flavonoids exhibited strong to moderate antiproliferative activity in vitro. The minor hops flavonoids xanthohumol C and 1″,2″-dihydroxanthohumol K and non-natural 2,3-dehydroisoxanthohumol exhibited the activity comparable to cisplatin. Results described in the article suggest that flavonoids containing chromane- and chromene-like moieties, especially chalcones, are potent antiproliferative agents. The developed new efficient, regioselective cyclisation reaction of the xanthohumol prenyl group to 1″,2″-dihydroxantohumol K may be used in the synthesis of other compounds with the chromane moiety.

Dual-targeting antitumor hybrids derived from Pt(IV) species and millepachine analogues

Many strategies have been developed to circumvent the shortcomings of Pt(II)-based chemotherapy, but the inherent problems still have not been effectively resolved. Here we report a new series of dual-targeting Pt(IV) prodrugs, conjugates of millepachine analogues with the related Pt(IV) complexes derived from cisplatin or oxaliplatin, respectively, which can inhibit tubulin polymerization and induce DNA damage. Among them, compound 19 possessed excellent antitumor activities against the tested human cancer cell lines, and arrested the cell cycle at the G2/M phases and ultimately induced cell apoptosis. Interestingly, its low cytotoxicity toward two human normal cells and sensitivity toward two cisplatin-resistant cells revealed the possibility for cancer therapy. More importantly, 19 displayed excellent antitumor efficacy in the SK-OV-3 xenograft model better than cisplatin and the corresponding millepachine analogue. Our research provided an efficient strategy for multi-targeting antitumor drug development.

Synthesis, biological evaluation and molecular docking studies of a new series of chalcones containing naphthalene moiety as anticancer agents

A series of chalcones containing naphthalene moiety 4a-4p have been synthesized, characterized by ¹H NMR and ¹³C NMR and evaluated for their in vitro anticancer activity. The majority of the screened compounds displayed potent anticancer activity against both HCT116 and HepG2 human cancer cell lines. Among the series, compound 4h with a diethylamino group at the para position of the phenyl ring exhibited the most potent anticancer activity against HCT116 and HepG2 cell lines with IC₅₀ values of 1.20 ± 0.07 and 1.02 ± 0.04 μM, respectively. The preliminary structure-activity relationship has been summarized. Tubulin polymerization experiments indicated that 4h effectively inhibited tubulin polymerization and flow cytometric assay revealed that 4h arrests HepG2 cells at the G2/M phase in a dose-dependent manner. Furthermore, molecular docking studies suggested that 4h binds to the colchicine binding site of tubulin.

Tubulin inhibitors targeting the colchicine binding site: a perspective of privileged structures

The vital roles of microtubule in mitosis and cell division make it an attractive target for antitumor therapy. Colchicine binding site of tubulin is one of the most important pockets that have been focused on to design tubulin-destabilizing agents. Over the past few years, a large number of colchicine binding site inhibitors (CBSIs) have been developed inspired by natural products or synthetic origins, and many moieties frequently used in these CBSIs are structurally in common. In this review, we will classify the CBSIs into classical CBSIs and nonclassical CBSIs according to their spatial conformations and binding modes with tubulin, and highlight the privileged structures from these CBSIs in the development of tubulin inhibitors targeting the colchicine binding site.

Indole molecules as inhibitors of tubulin polymerization: potential new anticancer agents, an update (2013–2015)

Discovery of new indole-based tubulin polymerization inhibitors will continue to dominate the synthetic efforts of many medicinal chemists working in the field. The indole ring system is an essential part of several tubulin inhibitors identified in the recent years. The present review article will update the synthesis, anticancer and tubulin inhibition activities of several important new indole classes such as 2-phenylindoles (28, 29 & 30), oxindoles (35 & 38), indole-3-acrylamides (44), indolines (46), aroylindoles (49), carbozoles (75, 76 & 82), azacarbolines (87) and annulated indoles (100–105).

Recent advances of cytotoxic chalconoids targeting tubulin polymerization: Synthesis and biological activity

Since microtubules have an important role in mitosis and other vital cellular functions, tubulin-targeting chemotherapy has been received growing attention in anticancer drug design and development. It was found that a number of naturally occurring compounds including distinct chalcones exert their effect by inhibition of tubulin polymerization. After the identification of tubulin polymerization as potential target for chalcone-type compounds, extensive researches have been made to design and synthesis of new anti-tubulin chalconoids. Although diverse chalcones have found to be potent anticancer agents but in the present review, we focused on the recently reported tubulin polymerization inhibitors from chalcone origin and related synthetic compounds, and their detailed synthetic methods and biological activities.

Synthesis, Evaluation, and Mechanism Study of Novel Indole-Chalcone Derivatives Exerting Effective Antitumor Activity Through Microtubule Destabilization in Vitro and in Vivo

Twenty-nine novel indole-chalcone derivatives were synthesized and evaluated for antiproliferative activity. Among them, 14k exhibited most potent activity, with IC50 values of 3-9 nM against six cancer cells, which displayed a 3.8-8.7-fold increase in activity when compare with compound 2. Further investigation revealed 14k was a novel tubulin polymerization inhibitor binding to the colchicine site. Its low cytotoxicity toward normal human cells and nearly equally potent activity against drug-resistant cells revealed the possibility for cancer therapy. Cellular mechanism studies elucidated 14k arrests cell cycle at G2/M phase and induces apoptosis along with the decrease of mitochondrial membrane potential. Furthermore, good metabolic stability of 14k was observed in mouse liver microsomes. Importantly, 14k and its phosphate salt 14k-P inhibited tumor growth in xenograft models in vivo without apparent toxicity, which was better than the reference compound CA-4P and 2. In summary, 14k deserves consideration for cancer therapy.

Recent developments in biological activities of chalcones: a mini review

Chalcones represent key structural motif in the plethora of biologically active molecules including synthetic and natural products. Synthetic manipulations of chalcones or their isolation from natural sources are being investigated worldwide for the development of more potent and efficient drugs for the treatment of several dreadful diseases such as cancer, diabetes, HIV, tuberculosis, malaria etc. Over the past few years, a large volume of research papers and review articles highlighting the significance of chalcone derivatives has been compiled in the literature. The present review article focuses on the recent developments (2010-2014) on various pharmacological and medicinal aspects of chalcones and their analogues.

Design, synthesis and biological evaluation of a series of pyrano chalcone derivatives containing indole moiety as novel anti-tubulin agents

A new series of pyrano chalcone derivatives containing indole moiety (3-42, 49a-49r) were synthesized and evaluated for their antiproliferative activities. Among all the compounds, compound 49b with a propionyloxy group at the 4-position of the left phenyl ring and N-methyl-5-indoly on the right ring displayed the most potent cytotoxic activity against all tested cancer cell lines including multidrug resistant phenotype, which inhibits cancer cell growth with IC50 values ranging from 0.22 to 1.80μM. Furthermore, 49b significantly induced cell cycle arrest in G2/M phase and inhibited the polymerization of tubulin. Molecular docking analysis demonstrated the interaction of 49b at the colchicine binding site of tubulin. In experiments in vivo, 49b exerted potent anticancer activity in HepG2 human liver carcinoma in BALB/c nude mice. These results indicated these compounds are promising inhibitors of tubulin polymerization for the potential treatment of cancer.