Identification of diphenylalkylisoxazol-5-amine scaffold as novel activator of cardiac myosin.

To identify novel potent cardiac myosin activator, a series of diphenylalkylisoxazol-5-amine compounds 4-7 have been synthesized and evaluated for cardiac myosin ATPase activation. Among the 37 compounds, 4a (CMA at 10 µM = 81.6%), 4w (CMA at 10 µM = 71.2%) and 6b (CMA at 10 µM = 67.4%) showed potent cardiac myosin activation at a single concentration of 10 µM. These results suggested that the introduction of the amino-isoxazole ring as a bioisostere for urea group is acceptable for the cardiac myosin activation. Additional structure-activity relationship (SAR) studies were conducted. Para substitution (-Cl, -OCH3, -SO2N(CH3)2) to the phenyl rings or replacement of a phenyl ring with a heterocycle (pyridine, piperidine and tetrahydropyran) appeared to attenuate cardiac myosin activation at 10 µM. Additional hydrogen bonding acceptor next to the amino group of the isoxazoles did not enhance the activity. The potent isoxazole compounds showed selectivity for cardiac myosin activation over skeletal and smooth muscle myosin, and therefore these potent and selective isoxazole compounds could be considered as a new series of cardiac myosin ATPase activators for the treatment of systolic heart failure.

Design and synthesis of sulfonamidophenylethylamides as novel cardiac myosin activator.

The sulfonamidophenylethylamide analogues were explored for finding novel and potent cardiac myosin activators. Among them, N-(4-(N,N-dimethylsulfamoyl)phenethyl-N-methyl-5-phenylpentanamide (13, CMA at 10 µM = 48.5%; FS = 26.21%; EF = 15.28%) and its isomer, 4-(4-(N,N-dimethylsulfamoyl)phenyl-N-methyl-N-(3-phenylpropyl)butanamide (27, CMA at 10 µM = 55.0%; FS = 24.69%; EF = 14.08%) proved to be efficient cardiac myosin activators both in in vitro and in vivo studies. Compounds 13 (88.2 + 3.1% at 5 µM) and 27 (46.5 + 2.8% at 5 µM) showed positive inotropic effect in isolated rat ventricular myocytes. The potent compounds 13 and 27 were highly selective for cardiac myosin over skeletal and smooth muscle myosin, and therefore these potent and selective amide derivatives could be considered a new class of cardiac myosin activators for the treatment of systolic heart failure.

Exploration of diphenylalkyloxadiazoles as novel cardiac myosin activator.

To explore novel cardiac myosin activator, a series of diphenylalkyl substituted 1,3,4-oxadiazoles and 1,2,4-oxadiazoles have been prepared and tested for cardiac myosin ATPase activation in vitro. In all cases, three carbon spacer between the oxadiazole core and one of the phenyl ring was considered crucial. In case of 1,3,4-oxadiazole, zero to two carbon spacer between oxadiazole core and other phenyl ring are favorable. Phenyl ring can be replaced by cyclohexyl moiety. In case of 1,2,4-oxadiazole, zero or one carbon spacer between the oxadiazole and other phenyl ring are favorable. Introduction of hydrogen bonding donor (NH) group at the 2nd position of the 1,3,4-oxadiazole enhances the activity. Substitutions on either of the phenyl rings or change of phenyl ring to other heterocycle are not tolerated for both the oxadiazoles. The prepared oxadiazoles showed selective activation for cardiac muscle over smooth and skeleton muscles.

Novel analogs of N-acylhydroxyethylaminomethyl-4H-chromen-4-one scaffold as IL-5 inhibitors.

A number of N-acyl substituted hydroxyethylaminomethyl-4H-chromen-4-ones 6a-u were prepared and evaluated for their IL-5 inhibitory activity. Among them, the compound 6r (95.0% inhibition at 30µM, IC50=10.0µM, ClogP=4.1549) showed most potent inhibitory activity. The structure activity relationship revealed that the bulkier or hydrophobic substituents at urea, carbamate or amide group resulted in good inhibitory activity against IL-5. Moreover, electron donating group at phenyl ring (6g and 6s) is much more active than electron withdrawing group (6f). Finally, replacement of cyclohexylmethoxy group at 5th position of ring A with bulky aliphatic substituents resulted in the loss of activity.

Exploration of 2-benzylbenzimidazole scaffold as novel inhibitor of NF-κB.

For finding the novel inhibitor of nuclear factor κB activity, a series of benzimidazole derivatives were rationally designed, synthesized and systematically studied for their in vitro activities against LPS induced NF-κB inhibition in RAW 264.7 cells using the SEAP assay based on the flexible chalcone JSH ((E)-1-(2-hydroxy-6-(isopentyloxy)phenyl)-3-(4-hydroxy phenyl)prop-2-en-1-one) which was previously reported. Although most of the benzimidazole derivatives showed strong inhibitory activity in low micromolar potency, 2-(4-methoxybenzyl)-1H-benzo[d]imidazole (3m; IC50=1.7 µM) and 2-(2-methoxybenzyl)-1H-benzo[d]imidazole (3n; IC50=2.4 µM) showed the best inhibition. The structure activity relationship revealed that 2-benzylbenzimidazole scaffold with hydrogen bonding acceptor on phenyl ring appears as a pharmacophore.

Exploration of benzamidochromenone derivatives with conformational restrictor as interleukin-5 inhibitors.

Novel amidochromen-4-one analogs 8a-k and 9a-f were prepared and studied for their IL-5 inhibitory activity. Among the synthesized compounds, (6-benzamido-2-cyclohexyl-4-oxo-4H-chromen-3-yl)methyl acetate (8a, 95% inhibition at 30 µM, IC50=6.1 µM) exhibited potent IL-5 inhibitory activity. The conformational restrictor at position 2 like bulky cyclohexyl group is favorable for the formation of effective conformer of side chain small ester like acetoxymethyl at position 3 of these chromenone analogs 8. In addition the hydrophobic planarity of benzamido group at position 6 should be important for the potent IL-5 inhibitory activity. Since replacing acetoxymethyl moiety with hydroxymethyl group at position 3 of chromenone decreases the activity, which indicates that the location of hydrogen bonding group should be near 4 atom distances away from chromenone ring is more optimum for the activity. Therefore, these benzamidochromen-4-one analogs 8 are novel scaffold for finding potent interleukin-5 inhibitors.

Synthesis and SAR studies of bis-chromenone derivatives for anti-proliferative activity against human cancer cells.

A novel family of 3-((4-oxo-4H-chromen-3-yl)methyl)-4H-chromen-4-one (bis-chromone) derivatives were designed, synthesized and studied for their anti-cancer activity using the XTT assay for the growth inhibition against various human cancer cells. Among them, 3-((5-(cyclohexylmethoxy)-4-oxo-4H-chromen-3-yl)methyl)-7-methoxy-4H-chromen-4-one and 3-((5-(cyclohexylmethoxy)-4-oxo-4H-chromen-3-yl)methyl)-7-hydroxy-4H-chromen-4-one showed micromolar level of in vitro anti-proliferative activity against human cancer cell lines. The SAR studies indicated bis-chromone as a basic scaffold to design anticancer agents. The 5-cyclohexylmethoxy on the first chromenone ring and electron donating group such as CH3, OCH3 or hydrogen bonding group (OH) on the other chromenone ring of bis-chromone increased the activity. However, saturation of one of chromenone to chromanone in bis-chromones decreased the activity.

Anti-proliferative effect of chalcone derivatives through inactivation of NF-κB in human cancer cells.

To investigate the anti-proliferative effect of NF-κB inhibitor, a series of analogs of (E)-1-(2-hydroxy-6-(isopentyloxy)phenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one (5a) were prepared and evaluated for their NF-κB inhibition and anti-proliferative activity against various human cancer cell lines. Compounds (E)-1-(2-(3,3-dimethylbutoxy)-6-hydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one (5e) and (E)-4-(3-(2-(3,3-dimethylbutoxy)-6-hydroxyphenyl)-3-oxoprop-1-enyl)benzenesulfonamide (5p) showed good NF-κB inhibition as well as potent anti-proliferative activity. SAR studies showed that all the compounds with potent or moderate NF-κB inhibition displayed good anti-proliferative activity. All the analogs (5b-r) maintained a good correlation between their NF-κB inhibition and anti-proliferative activity though the extent is not directly proportional to each other.

Design and synthesis of novel chromenone derivatives as interleukin-5 inhibitors.

A novel series of chromenone analogs were synthesized and evaluated for their inhibitory activity against interleukin-5. Among them 5-(cyclohexylmethoxy)-3-[3-hydroxy-3-(4-hydroxyphenyl)propyl]-4H-chromen-4-one (9b, 94% inhibition at 30 µM, IC(50) = 4.0 µM) and 5-(cyclohexylmethoxy)-3-[3-hydroxy-3-(4-methoxyphenyl)propyl]-4H-chromen-4-one (9c, 94% inhibition at 30 µM, IC(50) = 6.5 µM) showed the most potent activity. According to the SAR studies introduction of propanone unit in between chromenone and ring B as in 5-(cyclohexylmethoxy)-3-[3-(4-phenyl)-3-oxopropyl]-4H-chromen-4-ones (8) moderately increased the activity. However, the reduction of these propanones 8 to propanols 9 remarkably enhanced the activity. A small substituent at position 4 of ring B in 9, especially with hydrogen bonding capability, provides favorable contribution. Disappearance of IL-5 inhibitory activity upon saturation of chroman-4-one of 9 to chroman-4-ones 10 proves the critical importance of planar chromen-4-one unit of this scaffold in the IL-5 inhibition.

Study on anti-proliferative effect of benzoxathiole derivatives through inactivation of NF-κB in human cancer cells.

To investigate the anti-proliferative effect of a newly discovered NF-kB inhibitor, 6,6-dimethyl-2-(phenylimino)-6,7-dihydrobenzo[d][1,3]oxathiol-4(5H)-one (1a), a series of its analogs (1b-n) were prepared and evaluated for their NF-κB inhibition and anti-proliferative activity against various human cancer cell lines. Slight variation of hydrophobicity by replacement of dimethyl group of 1a at 6-position with bulky isopropyl group and introduction of para-fluoro substitution on 2-phenyl group showed good NF-κB inhibitory activity and anti-proliferative activity. However, excessive increase in hydrophobicity with 2,4,6-trichloro substituents on phenyl group resulted in the loss of both the activities. From the SAR results, 2-phenylimino-6,7-dihydrobenzo[d][1,3]oxathiol-4(5H)-one was identified as the lead scaffold for investigating new anticancer agent through inactivation of NF-κB.

Novel interleukin-5 inhibitors based on hydroxyethylaminomethyl-4H-chromen-4-one scaffold.

Hydroxyethylaminomethyl-4H-chromenones were previously discovered as fairly strong IL-5 inhibitor. For determination of detail structure activity relationship, N-substituted hydroxyethylaminomethylchromenones 4a-n were prepared and evaluated for their IL-5 inhibitory activity. Shifting the hydrophobic group to nitrogen from 1-position of hydroxyethylamino moiety of hydroxyethylaminomethyl-4H-chromenones enhances the activity. The increment in bulkiness or hydrophobicity of alkyl side chain at amino group increases the activity. The same level of activity of 5-(cyclohexylmethoxy)-3-(N-benzyl-2-hydroxyethylaminomethyl)-4H-chromenone analogs regardless of hydrophobic or hydrophilic substituents at 4th position of phenyl ring might infer the existence of tunnel structure in the putative receptor for accepting these side chains.

Structure-activity relationship study of arylsulfonylimidazolidinones as anticancer agents.

In an effort to find novel N-arylsulfonylimidazolidinones as highly potent anticancer agent, the structure-activity relationship of ethyl 2-methyl-4-(2-oxo-4-phenylimidazolidin-1-ylsulfonyl)phenylcarbamate was explored through synthesis and evaluation of in vitro cytotoxicity of its analogs against HCT116, A549 and NCL-H460 cancer cell lines. Among the synthesized derivatives, the carbamate analogs (4a-f and 4k-p) exhibited superior cytotoxicity to doxorubicin for all cancer cell lines. The SAR studies of these derivatives confirm that the intact 4-phenyl-l-benzenesulfonylimidazolidinone has a pivotal role as a basic pharmacophore and hydrophobic substitutions only at 2-position of 1-aminobenzenesulfonyl moiety are beneficial for the enhancement of the activity.

Biodegradable Polymeric Nanoparticles for Drug Delivery to Solid Tumors.

Advances in nanotechnology have favored the development of novel colloidal formulations able to modulate the pharmacological and biopharmaceutical properties of drugs. The peculiar physico-chemical and technological properties of nanomaterial-based therapeutics have allowed for several successful applications in the treatment of cancer. The size, shape, charge and patterning of nanoscale therapeutic molecules are parameters that need to be investigated and modulated in order to promote and optimize cell and tissue interaction. In this review, the use of polymeric nanoparticles as drug delivery systems of anticancer compounds, their physico-chemical properties and their ability to be efficiently localized in specific tumor tissues have been described. The nanoencapsulation of antitumor active compounds in polymeric systems is a promising approach to improve the efficacy of various tumor treatments.

Design and synthesis of sulfonamidophenylethylureas as novel cardiac myosin activator.

To optimize the lead urea scaffold 1 and 2 as selective cardiac myosin ATPase activator, a series of urea derivatives have been synthesized to explore its structure activity relationship. Among them N,N-dimethyl-4-(2-(3-(3-phenylpropyl)ureido)ethyl)benzenesulfonamide (13, CMA = 91.6%, FS = 17.62%; EF = 11.55%), N,N-dimethyl-4-(2-(1-methyl-3-(3-phenylpropyl)ureido)ethyl)benzene sulfonamide (40, CMA = 52.3%, FS = 38.96%; EF = 24.19%) and N,N-dimethyl-4-(2-(3-methyl-3-(3-phenylpropyl)ureido)ethyl)benzenesulfonamide (41, CMA = 47.6%, FS = 23.19%; EF = 15.47%) proved to be efficient to activate the cardiac myosin in vitro and in vivo. Further the % change in ventricular cell contractility at 5 µM of 13 (47.9 ± 3.2), 40 (45.5 ± 2.4) and 41 (63.5 ± 2.2) showed positive inotropic effect in isolated rat ventricular myocytes. The potent compounds 13, 40, 41 were highly selective for cardiac myosin over skeletal and smooth muscle myosin, thus proving them these new urea derivatives is a novel scaffold for discovery of cardiac myosin activators for the treatment of systolic heart failure.

Discovery of novel 3-(hydroxyalkoxy)-2-alkylchromen-4-one analogs as interleukin-5 inhibitors.

A series of novel chromen-4-one analogs 9a-d and 10a-u was designed, synthesized and evaluated for their IL-5 inhibitory activity. Most of the chromen-4-one analogs showed strong inhibitory activity in low micro molar potency. Among them, 5-(cyclohexylmethoxy)-3-(3-hydroxypropoxy)-2-isopropyl-4H-chromen-4-one (10t, 90.0% inhibition at 30 µM, IC50 = 5.5 µM, CLogP = 4.76887) and 2-cyclohexyl-5-(cyclohexylmethoxy)-3-(3-hydroxypropoxy)-4H-chromen-4-one (10u, 95.5% inhibition at 30 µM, IC50 = 3.0 µM, CLogP = 5.96187) showed the best inhibition. The structure activity relationship reveals that the hydrophobic cyclohexylmethoxy group at the position 5 of the chromen-4-one ring A is preferable than at position 6 and the dual hydrogen bonding acceptor property on the chromen-4-one ring should be important for the inhibitory activity. In addition, the optimum length of the side chain at position 3 of chromen-4-one ring is critical for the donation of hydrogen to the binding site and the 3-hydroxypropoxy group showed the best activity. Moreover, the conformational restrictor (isopropyl, cyclohexyl group) at position 2 is much more favorable for the formation of effective conformer of side chain with hydrogen bonding donor property of these chromen-4-one analogs.

Exploration of SAR for novel 2-benzylbenzimidazole analogs as inhibitor of transcription factor NF-κB.

A novel series of 2-benzylbenzimidazole analogs was designed, synthesized and investigated for their in vitro activities against LPS induced NF-κB inhibition in RAW 264.7 cells using the SEAP assay. Among them, 4-((4-(cyclohexylmethoxy)-1H-benzo[d]imidazol-2-yl)methyl)phenol (6e, >100% inhibition at 30 µM, IC50 = 3.0 µM), 4-((5-(cyclohexylmethoxy)-1H-benzo[d]imidazol-2-yl)methyl)phenol (6j, 96% inhibition at 30 µM, IC50 = 4.0 µM) and 2-((4-(cyclohexylmethoxy)-1H-benzo[d]imidazol-2-yl)methyl)phenol (6k, 95% inhibition at 30 µM, IC50 = 5.0 µM) showed strong inhibitory activity. The structure activity relationship confirmed that the substitution on benzimidazole ring A with hydrophobic cyclohexylmethoxy group at position 4 or 5 markedly enhances the activity. In addition, the hydrophilic hydrogen bonding donor group (OH) at position 2 or 4 on phenyl ring B connected with one methylene spacer to the benzimidazole ring is favorable for the inhibitory activity. However, hydrophobic (-OCH3 and -Cl) groups on phenyl ring B decrease the activity.

Exploration of flexible phenylpropylurea scaffold as novel cardiac myosin activators for the treatment of systolic heart failure.

A series of flexible urea derivatives have been synthesized and demonstrated as selective cardiac myosin ATPase activator. Among them 1-phenethyl-3-(3-phenylpropyl)urea (1, cardiac myosin ATPase activation at 10 µM = 51.1%; FS = 18.90; EF = 12.15) and 1-benzyl-3-(3-phenylpropyl)urea (9, cardiac myosin ATPase activation = 53.3%; FS = 30.04; EF = 18.27) showed significant activity in vitro and in vivo. The change of phenyl ring with tetrahydropyran-4-yl moiety viz., 1-(3-phenylpropyl)-3-((tetrahydro-2H-pyran-4-yl)methyl)urea (14, cardiac myosin ATPase activation = 81.4%; FS = 20.50; EF = 13.10), and morpholine moiety viz., 1-(2-morpholinoethyl)-3-(3-phenylpropyl)urea (21, cardiac myosin ATPase activation = 44.0%; FS = 24.79; EF = 15.65), proved to be efficient to activate the cardiac myosin. The potent compounds 1, 9, 14 and 21 were found to be selective for cardiac myosin over skeletal and smooth myosins. Thus, these urea derivatives are potent scaffold to develop as a newer cardiac myosin activator for the treatment of systolic heart failure.

Discovery of enantioselectivity of urea inhibitors of soluble epoxide hydrolase.

Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) in the metabolic pathway of arachidonic acid and has been considered as an important therapeutic target for chronic diseases such as hypertension, diabetes and inflammation. Although many urea derivatives are known as sEH inhibitors, the enantioselectivity of the inhibitors is not highlighted in spite of the stereoselective hydrolysis of EETs by sEH. In an effort to explore the importance of enantioselectivity in the urea scaffold, a series of enantiomers with the stereocenter adjacent to the urea nitrogen atom were prepared. The selectivity of enantiomers of 1-(α-alkyl-α-phenylmethyl)-3-(3-phenylpropyl)ureas showed wide range differences up to 125 fold with the low IC50 value up to 13 nM. The S-configuration with planar phenyl and small alkyl groups at α-position is crucial for the activity and selectivity. However, restriction of the free rotation of two α-groups with indan-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl moiety abolishes the selectivity between the enantiomers, despite the increase in activity up to 13 nM. The hydrophilic group like sulfonamido group at para position of 3-phenylpropyl motif of 1-(α-alkyl-α-phenylmethyl-3-(3-phenylpropyl)urea improves the activity as well as enantiomeric selectivity. All these ureas are proved to be specific inhibitor of sEH without inhibition against mEH.

Exploration of Pharmacophore in Chrysosplenol C as Activator in Ventricular Myocyte Contraction.

Chrysosplenol C (4',5,6-trihydroxy-3,3',7-trimethoxyflavone) isolated from Miliusa balansae has unique structural features as a reversible inotropic agent independent of ß-adrenergic signaling and with selective activation of cardiac myosin ATPase. Hence, a series of chrysosplenol analogues were synthesized and explored for identification of pharmacophore that is essential for the increasing contractility in rat ventricular myocytes. Analogue 7-chloro-2-(3-hydroxyphenyl)-3-methoxy-4H-chromen-4-one showed highly potent contractility (54.8% at 10 µM) through activating cardiac myosin ATPase (38.7% at 10 µM). Our systematic structure-activity relationship study revealed that flavonoid nucleus of chrososplenol C appears to be an essential basic skeleton and hydrophobic substituent at position 7 of chromenone such as methoxy or chloro enhances the activity. Additionally, our ATPase study suggested that these chrysosplenol analogues have selectivity toward cardiac myosin activation. Thus, the novel flavonone with 3-/7-hydrophobic substituent and 3'-hydrogen bonding donor function is a novel scaffold for discovery of a new positive inotropic agent.

Investigation of amino acid conjugates of (S)-1-[1-(4-aminobenzoyl)-2,3-dihydro-1H-indol-6-sulfonyl]-4-phenyl-imidazolidin-2-one (DW2282) as water soluble anticancer prodrugs.

The amino acid-conjugates (1a-k) with eleven amino acids attached to primary amine of (S)-1-[1-(4-aminobenzoyl)-2,3-dihydro-1H-indol-6-sulfonyl]-4-phenyl-imidazolidin-2-one (DW2282, 1) were prepared and studied for their prodrug characteristics and anti-cancer activity against SW620 cell line. All the amino acid derivatives showed not only improved water solubility but also displayed potent anti-cancer activity in vitro. Among these amino acid-conjugates the compounds, DW2282-L-Ala (1b), DW2282-L-Phe (1e), DW2282-L-Leu (1g) and DW2282-L-Met (1h) showed good reconversion within 8 h (104.76%, 84.03%, 95.02% and 78.34%, respectively) to the parent drug in human plasma. In addition, the compounds 1e, 1g and 1j also showed good bioavailability profile along with potent in vivo anticancer activity.