4-(3-Alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamide salts: Novel hydrosoluble prodrugs of antimitotics selectively bioactivated by the cytochrome P450 1A1 in breast cancer cells.

4-(3-Alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides (PAIB-SAs) are members of a new family of prodrugs bioactivated by cytochrome P450 1A1 (CYP1A1) in breast cancer cells into their potent 4-(2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamide metabolites (PIB-SAs). One of the predominant problems for the galenic formulation and administration of PAIB-SAs in animal studies is their poor hydrosolubility. To circumvent that difficulty, we report the design, the synthesis, the chemical characterization, the evaluation of the aqueous solubility, the antiproliferative activity and the mechanism of action of 18 new Na+, K+ and Li+ salts of PAIB-SAs. Our results evidenced that the latter exhibited highly selective antiproliferative activity toward MCF7 and MDA-MB-468 breast cancer cells expressing endogenously CYP1A1 compared to insensitive MDA-MB-231 and HaCaT cells. Moreover, PAIB-SA salts 1-18 are significantly more hydrosoluble (3.9-9.4 mg/mL) than their neutral counterparts (< 0.0001 mg/mL). In addition, the most potent PAIB-SA salts 1-3 and 10-12 arrested the cell cycle progression in the G2/M phase and disrupted the cytoskeleton's dynamic assembly. Finally, PAIB-SA salts are N-dealkylated by CYP1A1 into their corresponding PIB-SA metabolites, which are potent antimitotics. In summary, our results show that our water-soluble PAIB-SA salts, notably the sodium salts, still exhibit potent antiproliferative efficacy and remain prone to CYP1A1 bioactivation. In addition, these PAIB-SA salts will allow the development of galenic formulations suitable for further biopharmaceutical and pharmacodynamic studies.

Homologation of the Alkyl Side Chain of Antimitotic Phenyl 4-(2-Oxo-3-alkylimidazolidin-1-yl)benzenesulfonate Prodrugs Selectively Targeting CYP1A1-Expressing Breast Cancers Improves Their Stability in Rodent Liver Microsomes.

Phenyl 4-(2-oxo-3-alkylimidazolidin-1-yl)benzenesulfonates (PAIB-SOs) are a new family of antimitotic prodrugs bioactivated in breast cancer cells expressing CYP1A1. In this study, we report that the 14C-labeled prototypical PAIB-SO [14C]CEU-818 and its antimitotic counterpart [14C]CEU-602 are distributed in whole mouse body and they show a short half-life in mice. To circumvent this limitation, we evaluated the effect of the homologation of the alkyl side chain of the imidazolidin-2-one moiety of PAIB-SOs. Our studies evidence that PAIB-SOs bearing an n-pentyl side chain exhibit antiproliferative activity in the nanomolar-to-low-micromolar range and a high selectivity toward CYP1A1-positive breast cancer cells. Moreover, the most potent n-pentyl PAIB-SOs were significantly more stable toward rodent liver microsomes. In addition, PAIB-SOs 10 and 14 show significant antitumor activity and low toxicity in chorioallantoic membrane (CAM) assay. Our study confirms that homologation is a suitable approach to improve the rodent hepatic stability of PAIB-SOs.

Branched alkyl of phenyl 4-(2-oxo-3-alkylimidazolidin-1-yl)benzenesulfonates as unique cytochrome P450 1A1-activated antimitotic prodrugs: Biological evaluation and mechanism of bioactivation.

We recently discovered a new family of prodrugs deriving from phenyl 4-(2-oxo-3-imidazolidin-1-yl)benzenesulfonates (PIB-SOs) bioactivatable by cytochrome P450 1A1 (CYP1A1) into potent antimitotics referred to as phenyl 4-(2-oxo-3-alkylimidazolidin-1-yl)benzenesulfonates (PAIB-SOs). PAIB-SOs display significant selectivity toward human breast cancer cells based on the N-dealkylation of PAIB-SOs into their corresponding PIB-SOs by CYP1A1. In this study, we have evaluated the molecular mechanism of the bioactivation of PAIB-SOs into PIB-SOs by branching the linear alkyl chain on the imidazolidin-2-one (IMZ) moiety of PAIB-SOs by branched alkyl groups such as isopropyl, isobutyl and sec-butyl. Our results show that PAIB-SOs bearing an isobutyl group on the IMZ moiety and either a methoxy, a chloro or a bromo group at positions 3, 3,5 or 3,4,5 on the aromatic ring B exhibit antiproliferative activity ranging from 0.13 to 6.9 µM and selectivity toward MCF7 and MDA-MB-468 mammary cancer cells comparatively to other cell lines tested. Moreover, the most potent and selective PAIB-SOs bearing an isobutyl group and either a 3,5-Cl (44), 3,5-Br (45) or a 3,4,5-OMe (46) on the IMZ moiety exhibit antiproliferative activity in the sub-micromolar range and high selectivity ratios toward mammary cancer cells. They stop the cell cycle of MCF7 cells in the G2/M phase and disrupt their cytoskeleton. Furthermore, our studies evidenced that PAIB-SOs bearing either an isopropyl, a sec-butyl or an isobutyl group are hydroxylated on the carbon atom adjacent to the IMZ (Cα-OH) but only PAIB-SOs bearing an isobutyl group are bioactivated into PIB-SOs. Finally, PAIB-SOs 45 and 46 exhibit low toxicity toward normal cells and chick embryos and are thus promising antimitotic prodrugs highly selective toward CYP1A1-expressing breast cancer cells.

Preparation and biological evaluation of new antimicrotubule agents: Modification of the imidazolidin-2-one moiety of phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates.

We prepared and biologically evaluated 32 novel molecules named phenyl 4-(dioxoimidazolidin-1-yl)benzenesulfonates (PID-SOs) and ethyl 2-(3-(4-(phenoxysulfonyl)phenyl)ureido)acetates (EPA-SOs). The antiproliferative activity of PID-SOs and EPA-SOs was assessed on four cancer cell lines (HT-1080, HT-29, M21, and MCF7). The most potent PID-SOs bearing an imidazolidin-2,4-dione group show antiproliferative activity in the nanomolar to low micromolar range (0.066 - 6 µM) while EPA-SOs and PID-SOs bearing an imidazolidin-2,5-dione moiety are mostly not active, exhibiting antiproliferative activity over 100 µM. The most potent PID-SOs (16-18) arrest the cell cycle progression in G2/M phase and interact with the colchicine-binding site leading to the microtubule and cytoskeleton disruption. Moreover, their antiproliferative activity is not impaired in vinblastine-, paclitaxel-, and multidrug-resistant cell lines. Finally, our study confirms that PID-SOs bearing the imidazolidin-2,4-dione moiety are a new family of promising antimitotics.

Pyrrole Hemithioindigo Antimitotics with Near-Quantitative Bidirectional Photoswitching that Photocontrol Cellular Microtubule Dynamics with Single-Cell Precision*.

We report the first cellular application of the emerging near-quantitative photoswitch pyrrole hemithioindigo, by rationally designing photopharmaceutical PHTub inhibitors of the cytoskeletal protein tubulin. PHTubs allow simultaneous visible-light imaging and photoswitching in live cells, delivering cell-precise photomodulation of microtubule dynamics, and photocontrol over cell cycle progression and cell death. This is the first acute use of a hemithioindigo photopharmaceutical for high-spatiotemporal-resolution biological control in live cells. It additionally demonstrates the utility of near-quantitative photoswitches, by enabling a dark-active design to overcome residual background activity during cellular photopatterning. This work opens up new horizons for high-precision microtubule research using PHTubs and shows the cellular applicability of pyrrole hemithioindigo as a valuable scaffold for photocontrol of a range of other biological targets.

A facile synthesis of diaryl pyrroles led to the discovery of potent colchicine site antimitotic agents.

Three different series of cis-restricted analogues of combretastatin A-4 (CA-4), corresponding to thirty-nine molecules that contained a pyrrole nucleus interposed between the two aryl rings, were prepared by a palladium-mediated coupling approach and evaluated for their antiproliferative activity against six human cancer cell lines. In the two series of 1,2-diaryl pyrrole derivatives, results suggested that the presence of the 3',4',5'-trimethoxyphenyl moiety at the N-1 position of the pyrrole ring was more favorable for antiproliferative activity. In the series of 3,4-diarylpyrrole analogues, three compounds (11i-k) exhibited maximal antiproliferative activity, showing excellent antiproliferative activity against the CA-4 resistant HT-29 cells. Inhibition of tubulin polymerization of selected 1,2 pyrrole derivatives (9a, 9c, 9o and 10a) was similar to that observed with CA-4, while the isomeric 3,4-pyrrole analogues 11i-k were generally from 1.5- to 2-fold more active than CA-4. Compounds 11j and 11k were the only compounds that showed activity as inhibitors of colchicine binding comparable to that CA-4. Compound 11j had biological properties consistent with its intracellular target being tubulin. This compound was able to block the cell cycle in metaphase and to induce significant apoptosis at a concentration of 25 nM, following the mitochondrial pathway, with low toxicity for normal cells. More importantly, compound 11j exerted activity in vivo superior to that of CA-4P, being able to significantly reduce tumor growth in a syngeneic murine tumor model even at the lower dose tested (5.0 mg/kg).

Eg5 targeting agents: From new anti-mitotic based inhibitor discovery to cancer therapy and resistance.

Eg5, the product of Kif11 gene, also known as kinesin spindle protein, is a motor protein involved in the proper establishment of a bipolar mitotic spindle. Eg5 is one of the 45 different kinesins coded in the human genome of the kinesin motor protein superfamily. Over the last three decades Eg5 has attracted great interest as a promising new mitotic target. The identification of monastrol as specific inhibitor of the ATPase activity of the motor domain of Eg5 inhibiting the Eg5 microtubule motility in vitro and in cellulo sparked an intense interest in academia and industry to pursue the identification of novel small molecules that target Eg5 in order to be used in cancer chemotherapy based on the anti-mitotic strategy. Several Eg5 inhibitors entered clinical trials. Currently the field is faced with the problem that most of the inhibitors tested exhibited only limited efficacy. However, one Eg5 inhibitor, Arry-520 (clinical name filanesib), has demonstrated clinical efficacy in patients with multiple myeloma and is scheduled to enter phase III clinical trials. At the same time, new trends in Eg5 inhibitor research are emerging, including an increased interest in novel inhibitor binding sites and a focus on drug synergy with established antitumor agents to improve chemotherapeutic efficacy. This review presents an updated view of the structure and function of Eg5-inhibitor complexes, traces the possible development of resistance to Eg5 inhibitors and their potential therapeutic applications, and surveys the current challenges and future directions of this active field in drug discovery.

A Pyranoxanthone as a Potent Antimitotic and Sensitizer of Cancer Cells to Low Doses of Paclitaxel.

Microtubule-targeting agents (MTAs) remain a gold standard for the treatment of several cancer types. By interfering with microtubules dynamic, MTAs induce a mitotic arrest followed by cell death. This antimitotic activity of MTAs is dependent on the spindle assembly checkpoint (SAC), which monitors the integrity of the mitotic spindle and proper chromosome attachments to microtubules in order to ensure accurate chromosome segregation and timely anaphase onset. However, the cytotoxic activity of MTAs is restrained by drug resistance and/or toxicities, and had motivated the search for new compounds and/or alternative therapeutic strategies. Here, we describe the synthesis and mechanism of action of the xanthone derivative pyranoxanthone 2 that exhibits a potent anti-growth activity against cancer cells. We found that cancer cells treated with the pyranoxanthone 2 exhibited persistent defects in chromosome congression during mitosis that were not corrected over time, which induced a prolonged SAC-dependent mitotic arrest followed by massive apoptosis. Importantly, pyranoxanthone 2 was able to potentiate apoptosis of cancer cells treated with nanomolar concentrations of paclitaxel. Our data identified the potential of the pyranoxanthone 2 as a new potent antimitotic with promising antitumor potential, either alone or in combination regimens.

Calibrated liposomal release of the anti-mitotic agent BI-2536 increases the targeting of mitotic tumor cells.

Cancer drugs which are specifically targeted at mitosis have generally under-delivered as a class. One likely reason is that only a small percentage of cancer cells in a tumor are actually dividing at any moment. If this is the case, then prolonged bioavailability in the tumor should significantly increase the efficacy of antimitotic agents. Here, we show that if the Plk1 inhibitor BI 2536 is co-encapsulated in a liposome with a pair of anions, its release rate is dependent on both the identity and stoichiometry of the anions. We created a library of liposomes with varying release rates using this approach and found that liposomal drug release rates correlated inversely with in vitro cancer cell killing. Xenografted mice treated with a single dose of slow-releasing liposomal BI 2536 experienced tumor volume decreases lasting 12 days and complete responses in 20% of mice. Treatment with two doses a week apart increased the response rate to 75%. This approach, which we termed Paired Anion Calibrated Release (PACeR), has the potential to revive the clinical utility of antimitotic cancer drugs which have failed clinical trials.

Pyrrolo[2',3':3,4]cyclohepta[1,2-d][1,2]oxazoles, a New Class of Antimitotic Agents Active against Multiple Malignant Cell Types.

A new class of pyrrolo[2',3':3,4]cyclohepta[1,2-d][1,2]oxazoles was synthesized for the treatment of hyperproliferative pathologies, including neoplasms. The new compounds were screened in the 60 human cancer cell lines of the NCI drug screen and showed potent activity with GI50 values reaching the nanomolar level, with mean graph midpoints of 0.08-0.41 µM. All compounds were further tested on six lymphoma cell lines, and eight showed potent growth inhibitory effects with IC50 values lower than 500 nM. Mechanism of action studies showed the ability of the new [1,2]oxazoles to arrest cells in the G2/M phase in a concentration dependent manner and to induce apoptosis through the mitochondrial pathway. The most active compounds inhibited tubulin polymerization, with IC50 values of 1.9-8.2 µM, and appeared to bind to the colchicine site. The G2/M arrest was accompanied by apoptosis, mitochondrial depolarization, generation of reactive oxygen species, and PARP cleavage.

Discovery of dihydrofuranoallocolchicinoids - Highly potent antimitotic agents with low acute toxicity.

Two series of heterocyclic colchicinoids bearing ß-methylenedihydrofuran or 2H-pyran-2-one fragments were synthesized by the intramolecular Heck reaction. Methylenedihydrofuran compounds 9a and 9h were found to be the most cytotoxic among currently known colchicinoids, exhibiting outstanding antiproliferative activity on tumor cell lines in picomolar (0.01-2.1 nM) range of concentrations. Compound 9a potently and substoichiometrically inhibits microtubule formation in vitro, being an order of magnitude more active in this assay than colchicine. Derivatives 9a and 9h revealed relatively low acute toxicity in mice (LD50 ≥ 10 mg/kg i.v.). The X-Ray structure of colchicinoid 9a bound to tubulin confirmed interaction of this compound with the colchicine binding site of tubulin.

Synthesis and Antiproliferative Screening Of Novel Analogs of Regioselectively Demethylated Colchicine and Thiocolchicine.

Colchicine, a pseudoalkaloid isolated from Colchicum autumnale, has been identified as a potent anticancer agent because of its strong antimitotic activity. It was shown that colchicine modifications by regioselective demethylation affected its biological properties. For demethylated colchicine analogs, 10-demethylcolchicine (colchiceine, 1) and 1-demethylthiocolchicine (3), a series of 12 colchicine derivatives including 5 novel esters (2b-c and 4b-d) and 4 carbonates (2e-f and 4e-f) were synthesized. The antiproliferative activity assay, together with in silico evaluation of physicochemical properties, confirmed attractive biological profiles for all obtained compounds. The substitutions of H-donor and H-acceptor sites at C1 in thiocolchicine position provide an efficient control of the hydration affinity and solubility, as demonstrated for anhydrate 3, hemihydrate 4e and monohydrate 4a.

Determining the affinity of anti-mitotic compounds binding to colchicine binding site of tubulin by affinity probe capillary electrophoresis.

The colchicine binding site of tubulin is often used to screen the anti-mitotic compounds, which are widely used as anti-cancer therapies. In the present work, an affinity probe capillary electrophoresis (APCE) method was developed for determining the affinity of anti-mitotic compounds. To this end, a fluorescently labeled affinity probe, 5-carboxyfluorescein-colchicine (F-colchicine), was prepared for the affinity competition experiment. The probe can form a stable complex with tubulin with the binding stoichiometry of 0.75, and the dissociation constant Kd of the complex was determined as 5.7 × 10-5 mol/L. In the affinity competition experiment, F-colchicine was incubated with tubulin and the test compound in the solution. The F-colchicine-tubulin complexes and free F-colchicine were quickly separated by CE and the concentration of free F-colchicine was accurately determined with the laser induced fluorescence detection. The affinity constant of the tested compound can be measured with the affinity competition binding curve. The enantiomers of the anti-mitotic compound were evaluated by using the method. The binding affinity of the enantiomers displayed an enantioselective manner. Compared to other affinity binding assay methods, our method is more straightforward, more accurate, and more cost-effective.

The pyrrolopyrimidine colchicine-binding site agent PP-13 reduces the metastatic dissemination of invasive cancer cells in vitro and in vivo.

Standard chemotherapies that interfere with microtubule dynamics are a chemotherapeutic option used for the patients with advanced malignancies that invariably relapse after targeted therapies. However, major efforts are needed to reduce their toxicity, optimize their efficacy, and reduce cancer chemoresistance to these agents. We previously identified a pyrrolo[2,3d]pyrimidine-based microtubule-depolymerizing agent (PP-13) that binds to the colchicine site of ß-tubulin and exhibits anticancer properties in solid human cancer cells, including chemoresistant subtypes. Here, we investigated the therapeutic potential of PP-13 in vitro and in vivo. PP-13 induced a mitotic blockade and apoptosis in several cancer cells cultured in two-dimensions or three-dimensions spheroids, in conjunction with reduced cell proliferation. Capillary-like tube formation assays using HUVECs showed that PP-13 displayed antiangiogenic properties. It also inhibited cancer cell motility and invasion, in in vitro wound-healing and transwell migration assays. Low concentration PP-13 (130 nmol.L-1) treatment significantly reduced the metastatic invasiveness of human cancer cells engrafts on chicken chorioallantoic membrane. In nude mice, 0.5 or 1 mg.kg-1 PP-13 intraperitoneally administered three-times a week reduced the sizes of paclitaxel-refractory orthotopic breast tumors, delayed the progression of metastasis, and decreased the global metastatic load compared to 0.5 mg.kg-1 paclitaxel or vehicle alone. PP-13 did not show any apparent early adverse effect in vivo. These data suggest that PP-13 is a promising alternative to standard chemotherapy in antimitotic drug-refractory tumors, especially through its impact on metastasis.

Synthesis and biological evaluation of N-biphenyl-nicotinic based moiety compounds: A new class of antimitotic agents for the treatment of Hodgkin Lymphoma.

We previously demonstrated that some N-biphenylanilides caused cell-cycle arrest at G2/M transition in breast cancer cells. Among them we choose three derivatives, namely PTA34, PTA73 and RS35 for experimentation in solid tumor cell lines, classical Hodgkin Lymphoma (cHL) cell lines and bona fide normal cell lines. Almost all tumor cells were sensitive to compounds in the nanomolar range whereas, they were not cytotoxic to normal ones. Interestingly the compounds caused a strong G2/M phase arrest in cHL cell lines, thus, here we investigated whether they affected the integrity of microtubules in such cells. We found that they induced a long prometaphase arrest, followed by induction of apoptosis which involved mitochondria. PTA73 and RS35 induced the mitotic arrest through the fragmentation of microtubules which prevented the kinethocore-mitotic spindle interaction and the exit from mitosis. PTA34 is instead a tubulin-targeting agent because it inhibited the tubulin polymerization as vinblastine. As such, PTA34 maintained the Cyclin B1-CDK1 regulatory complex activated during the G2/M arrest while inducing the inactivation of Bcl-2 through phosphorylation in Ser70, the degradation of Mcl-1 and a strong activation of BIML and BIMS proapoptotic isoforms. In addition PTA34 exerted an antiangiogenic effect by suppressing microvascular formation.

Synthesis and biological evaluation of 1-benzyl-N-(2-(phenylamino)pyridin-3-yl)-1H-1,2,3-triazole-4-carboxamides as antimitotic agents.

A library of 1-benzyl-N-(2-(phenylamino)pyridin-3-yl)-1H-1,2,3-triazole-4-carboxamides (7a-al) have been designed, synthesized and screened for their anti-proliferative activity against some selected human cancer cell lines namely DU-145, A-549, MCF-7 and HeLa. Most of them have shown promising cytotoxicity against lung cancer cell line (A549), amongst them 7f was found to be the most potent anti-proliferative congener. Furthermore, 7f exhibited comparable tubulin polymerization inhibition (IC50 value 2.04 µM) to the standard E7010 (IC50 value 2.15 µM). Moreover, flow cytometric analysis revealed that this compound induced apoptosis via cell cycle arrest at G2/M phase in A549 cells. Induction of apoptosis was further observed by examining the mitochondrial membrane potential and was also confirmed by Hoechst staining as well as Annexin V-FITC assays. Furthermore, molecular docking studies indicated that compound 7f binds to the colchicine binding site of the ß-tubulin. Thus, 7f exhibits anti-proliferative properties by inhibiting the tubulin polymerization through the binding at the colchicine active site and by induction of apoptosis.

Natural products as new antimitotic compounds for anticancer drug development.

Cell cycle control genes are frequently mutated in cancer cells, which usually display higher rates of proliferation than normal cells. Dysregulated mitosis leads to genomic instability, which contributes to tumor progression and aggressiveness. Many drugs that disrupt mitosis have been studied because they induce cell cycle arrest and tumor cell death. These antitumor compounds are referred to as antimitotics. Vinca alkaloids and taxanes are natural products that target microtubules and inhibit mitosis, and their derivatives are among the most commonly used drugs in cancer therapy worldwide. However, severe adverse effects such as neuropathies are frequently observed during treatment with microtubule-targeting agents. Many efforts have been directed at developing improved antimitotics with increased specificity and decreased likelihood of inducing side effects. These new drugs generally target specific components of mitotic regulation that are mainly or exclusively expressed during cell division, such as kinases, motor proteins and multiprotein complexes. Such small molecules are now in preclinical studies and clinical trials, and many are products or derivatives from natural sources. In this review, we focused on the most promising targets for the development of antimitotics and discussed the advantages and disadvantages of these targets. We also highlighted the novel natural antimitotic agents under investigation by our research group, including combretastatins, withanolides and pterocarpans, which show the potential to circumvent the main issues in antimitotic therapy.

Design and 22-step synthesis of highly potent D-ring modified and linker-equipped analogs of spongistatin 1.

Spongistatin 1 is among the most potent anti-proliferative agents ever discovered rendering it an attractive candidate for development as a payload for antibody-drug conjugates and other targeted delivery approaches. Unfortunately, it is unavailable from natural sources and its size and complex stereostructure render chemical synthesis highly time- and resource-intensive. As a result, the design and synthesis of more acid-stable and linker functional group-equipped analogs that retain the low picomolar potency of the parent natural product requires more efficient and step-economical synthetic access. Using uniquely enabling direct complex fragment coupling crotyl- and alkallylsilylation reactions, we report a 22-step synthesis of a rationally designed D-ring modified analog of spongistatin 1 that is characterized by GI50 values in the low picomolar range, and a proof-of-concept result that the C(15) acetate may be replaced with linker functional group-bearing esters with only minimal reductions in potency.

Design, synthesis and biological evaluation of a novel library of antimitotic C2-aroyl/arylimino tryptamine derivatives that are also potent inhibitors of indoleamine-2, 3-dioxygenase (IDO).

A novel library of C2-substituted tryptamines (based on diverse C2-aroyl/arylimino indoles and indole-diketopiperazine hybrids) possessing antimitotic properties were designed, synthesized and screened for their inhibitory activity against tubulin polymerization, and against proliferation of A549 lung cancer, HeLa cervical cancer, MCF7 breast cancer and HePG2 liver cancer cell lines. The design of molecules were inspired from known antimitotic compounds and natural products. The molecular docking of the designed compounds indicated that they bind to the colchicin binding site of tubulin. They were synthesized by a unique iodine catalysed oxidative ring opening reaction of 1-aryltetrahydro-ß-carbolines. Among the compounds synthesized quite a few compounds induced cytotoxicity on the cancer cells by disrupting the tubulin polymerization. They were found to be non-toxic for healthy cells. Immuno Fluorescence study for the most active molecules (between ~6 µM concentration) against A549 and HeLa cells demonstrated complete disruption and shrinkage of the microtubule structures. These compounds also inhibited indoleamine-2, 3-dioxygenase with low micromolar IC50.

4-(3-Alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides as new antimitotic prodrugs activated by cytochrome P450 1A1 in breast cancer cells.

The role and the importance of the sulfonate moiety in phenyl 4-(2-oxo-3-alkylimidazolidin-1-yl)benzenesulfonates (PAIB-SOs) were assessed using its bioisosteric sulfonamide equivalent leading to new cytochrome P450 1A1 (CYP1A1)-activated prodrugs designated as 4-(3-alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides (PAIB-SAs). PAIB-SAs are active in the submicromolar to low micromolar range showing selectivity toward CYP1A1-expressing MCF7 cells as compared to cells devoid of CYP1A1 activity such as MDA-MB-231 and HaCaT cells. The most potent, PAIB-SA 13, bearing a trimethoxyphenyl group on ring B blocks the cell cycle progression in G2/M phase, disrupts the microtubule dynamics and is biotransformed by CYP1A1 into CEU-638, its potent antimicrotuble counterpart. Structure-activity relationships related to PAIB-SOs and PAIB-SAs evidenced that PAIB-SOs and PAIB-SAs are true bioisosteric equivalents fully and selectively activatable by CYP1A-expressing cells into potent antimitotics.