A novel class of inhibitors for human steroid 5alpha-reductase: synthesis and biological evaluation of indole derivatives. II

In a search for novel nonsteroidal inhibitors of human prostatic 5alpha-reductase, we found a new series of indole derivatives that showed potent inhibitory activities for the human enzyme. Among them, 4-[(1-benzyl-1H-indol-5-yl)oxyl-3-chlorobenzoic acid (2d, YM-32906) showed more potent inhibitory activity than finasteride with an IC50 value of 0.44 nM. 3-Chloro-4-[[1-(4-phenoxybenzyl)-1H-indol-5-yl]oxy]benzoic acid (2m) showed inhibitory activities for both human and rat prostatic 5alpha-reductase with IC50 values of 2.1 and 73 nM, respectively. The synthesis and structure-activity relationships of these indole derivatives are presented.     

A novel class of inhibitors for human and rat steroid 5alpha-reductases: synthesis and biological evaluation of indoline and aniline derivatives. III

While searching for novel nonsteroidal inhibitors of human and rat prostatic 5alpha-reductases, we found a new series of indoline and aniline derivatives that showed potent inhibitory activities for both enzymes. Among them, 3-chloro-4-?[1-(4-phenoxybenzyl)indolin-5-yl]oxylbenzoic acid (2e, YM-36117) showed a more potent inhibitory activity for the human enzyme than ONO-3805 with an IC50 value of 5.3 nM and a reduced rat prostatic dihydrotestosterone (DHT) concentration by oral administration. The synthesis and the structure-activity relationships of these indoline and aniline derivatives are presented.     

Synthesis of tricyclic compounds as steroid 5alpha-reductase inhibitors

A series of 4-phenoxybutyric acid derivatives attached to a tricyclic skeleton were prepared and evaluated as 5alpha-reductase inhibitors. Structure activity relationships for these compounds in terms of rat epididymis (type 2) 5alpha-reductase inhibitory activities reveal that 1) the substitution pattern at the 11-position of dibenz[b,e]oxepin influenced potency, 2) higher lipophilicity of the tricyclic skeleton improved potency, whereas the existence of a basic nitrogen atom in this skeleton was detrimental to potency, and 3) isobutyl substitution at the 8 positon of the azepine skeleton was tolerated. Among the tricyclic compounds studied, 4-[3-[5-benzyl-8-(2-methyl)propyl-10,11-dihydrodibenz[b,f]azepine- 2-carboxamido]phenoxy]butyric acid (26) was the most potent inhibitor of rat type 2 5alpha-reductase at 0.1 microM.     

4-(1-benzoylindol-3-yl)butyric acids and FK143: novel nonsteroidal inhibitors of steroid 5 alpha-reductase (II).

A novel series of indolebutyric acids with varying benzoyl substituents were synthesized to develop nonsteroidal inhibitors of steroid 5 alpha-reductase. We previously reported the discovery of a novel nonsteroidal 5 alpha-reductase inhibitor, FR119680, which had an IC50 value of 5.0 nM against the rat prostatic enzyme. However, this compound was not strongly active against the human prostatic enzyme. By further study of the structure-activity relationships we succeeded in producing the strongly active compound, FK143, 4-[3-[3-[bis(4-isobutylphenyl)-methylamino]benzoyl]-1H-indol-1-yl] butyric acid, with an IC50 value of 1.9 nM against the human enzyme. FK143 also has in vivo inhibitory activity against the castrated young rat model and it should therefore be an extremely useful agent for the treatment of benign prostatic hyperplasia.     

4-(Benzoylindolizinyl)butyric acids; novel nonsteroidal inhibitors of steroid 5alpha-reductase. III.

A novel series of indolizinebutyric acids with various benzoyl substituents was synthesized to develop nonsteroidal inhibitors of steroid 5alpha-reductase, and the structure-activity relationships in this series were studied. We previously reported the structure-activity relationships in a series of indolebutyric acids as well as the discovery of the novel nonsteroidal 5alpha-reductase inhibitor, FK143. We have now made other modifications to this compound to improve in vivo inhibitory activity. By altering the heterocyclic nucleus and changing the benzoyl substituent we have succeeded in identifying the strongly active compound, FK687, (S)-4-[1-[4-[[1-(4-isobutylphenyl)butyl]oxy]benzoyl]indolizin-3-yl]butyric acid, which displays strong in vitro inhibitory activity against the human enzyme and in vivo inhibitory activity against the castrated young rat model. This compound should be a useful agent for the treatment of benign prostatic hyperplasia.     

Synthesis of 2-phenylbenzofuran derivatives as testosterone 5 alpha-reductase inhibitor

A series of 2-phenylbenzofuran derivatives with a carbamoyl, alkylamino, or alkyloxy group at the 5 or 6 position of the benzofuran ring were synthesized and evaluated for rat and human testosterone 5 alpha-reductase inhibitory activities in vitro. Against rat enzyme, the carbamoyl derivatives had more potent inhibitory activities than the alkylamino or alkyloxy derivatives, and the 6-carbamoyl derivatives tended to be more potent than the 5-carbamoyl derivatives. Against human enzyme, the 6-substituted derivatives had more potent inhibitory activities than the 5-substituted derivatives. The 6-carbamoyl and 6-alkylamino derivatives tended to show stronger inhibitory activities against human type 1 enzyme than against type 2 enzyme, but they were not largely selective.     

Syntheses of (4,1-benzoxazepine-3-ylidene)acetic acid derivatives and their inhibition of squalene synthase

The (3,5-trans)-7-chloro-5-(2-chlorophenyl)-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepine-3-acetic acid derivatives 1 have been previously identified as potent squalene synthase inhibitors. A series of (4,1-benzoxazepin-3-ylidene)acetic acid derivatives were synthesized and evaluated for their inhibition of rat and human squalene synthase, and the (E)-isomers were found to exhibit potent inhibitory activity, with the same potency as 4,1-benzoxazepine-3-acetic acid derivatives. In contrast the (Z)-isomers did not exhibit significant inhibitory activity, and the active conformation of the 4,1-benzoxazepine-3-acetic acid derivatives was deduced from the folded conformation of the (E)-isomers.     

Synthesis and structure-activity relationship of N-arylrolipram derivatives as inhibitors of PDE4 isozymes

Structure activity studies of N-phenylrolipram derivatives have led to the identification of highly potent PDE4 inhibitors. The potential of these inhibitors for cellular activity was routinely assessed in an assay of fMLP induced oxidative burst in human eosinophils. Since first generation PDE4 inhibitors have been plagued with a number of unwanted side effects, parallel structure activity studies for competition with the [3H]-rolipram binding site in rat brain were performed. In this fashion 5-[4-(3-cyclopentyloxy-4-methoxyphenyl)-2-oxo-pyrrolidin-1-yl]-3-(3-methoxybenzyloxy)benzoic acid N',N'-dimethylhydrazide (22) was identified as a potent inhibitor of PDE4 which exhibits >1000 fold selectivity versus PDE3, and is a nanomolar inhibitor in all the cellular assays tested. Studies on the stereoselectivity of PDE4 inhibition of this class of rolipram based compounds revealed, that for example (S)-11 is a more potent inhibitor than (R)-11. This effect can also be observed in primary human cells where the (S)-enantiomer is about 10 fold more potent than the corresponding (R)-enantiomer.     

Renin inhibitors. II. Synthesis and structure-activity relationships of N-terminus modified inhibitors containing a homostatine analogue.

The synthesis and structure-activity relationships of N-terminus modified renin inhibitors containing the homostatin analogue, (2RS,4S,5S)-5-amino-2-ethyl-4-hydroxy-7-methyloctanoic acid, are described. The compounds having a 3-alkyl (or aryl)sulfonylpropionyl residue at the N-terminus are found to be potent inhibitors which contain two amino acids. (2RS,4S,5S)-N-Isobutyl-5-[N-[(2S)-3-ethylsulfonyl-2-(1- naphthylmethyl)propionyl]-L-norleucyl]-amino-2-ethyl-4-hydroxy-7- methyloctanamide (20) has an IC50 of 0.5 nM against human plasma renin and the oral bioavailability of 20 is 0.73% in rats. Interaction between renin and the N-terminus of 1 and 20 is discussed in molecular modeling studies.     

Cell-permeable esters of diazeniumdiolate-based nitric oxide prodrugs

Although O(2)-(2,4-dinitrophenyl) derivatives of diazeniumdiolate-based nitric oxide (NO) prodrugs bearing a free carboxylic acid group were activated by glutathione to release NO, these compounds were poor sources of intracellular NO and showed diminished antiproliferative activity against human leukemia HL-60 cells. The carboxylic acid esters of these prodrugs, however, were found to be superior sources of intracellular NO and potent inhibitors of HL-60 cell proliferation.     

Studies on antidiabetic agents. IX. A new aldose reductase inhibitor, AD-5467, and related 1,4-benzoxazine and 1,4-benzothiazine derivatives: synthesis and biological activity

N-Acetic acid derivatives (I) of 2-substituted 1,4-benzoxazines and benzothiazines were designed and synthesized for evaluation as new aldose reductase inhibitors. In general, 3-thioxo derivatives were more potent inhibitors of aldose reductase from human palcenta in vitro than the corresponding 3-oxo derivatives. While many compounds (I) were not very effective in inhibiting sorbitol accumulation in the rat sciatic nerve in vivo, the 3-thioxo compounds bearing an isopropyl group at the 2-position showed highly potent activity in the in vivo assay. Compound 46 (AD-5467) was selected from this series as a candidate for further development.     

Vertebrate collagenase inhibitor. II. Tetrapeptidyl hydroxamic acids.

To develop a potent and specific collagenase inhibitor, a series of tetrapeptidyl hydroxamic acids were synthesized, based on the previous findings with tripeptidyl derivatives (Chem. Pharm. Bull., 38, 1007-1011, 1990). Among the series of tetrapeptidyl derivatives synthesized, R-Gly-Pro-Leu-Ala-NHOH and R-Gly-Pro-D-Leu-D-Ala-NHOH were found to be highly specific and potent inhibitors against vertebrate collagenase with an IC50 of 10(-6) M order, where R stands for Boc or acyl group. Analysis of their structure-activity relationships showed a characteristic feature of the substrate-binding site of collagenase as follows: 1) the S1 subsite forms a shallow hydrophobic pocket, although glycine residue corresponds to the subsite of the natural collagen substrate: 2) the S2 subsite constitutes a bulky pocket with less requirement for hydrophobicity: 3) the S3 subsite preferentially accommodates Pro residue: and 4) the accommodation of the P4-P1 subsites of peptidyl collagenase inhibitor to the S4-S1 subsites is required to form a tight binding of its hydroxamic acid moiety to the zinc ion at the catalytic site of the enzyme. The introduction of an enantiometric dipeptide unit, D-Leu-D-Ala, to the P2-P1 subsites demonstrated an increased binding capacity to the extended S4-S1 subsites of collagenase, thus providing proteinase-resistant inhibitor.     

Studies on aldose reductase inhibitors from medicinal plant of "sinfito," Potentilla candicans, and further synthesis of their related compounds

For several years we have screened natural products having aldose reductase (AR) inhibitory activity. 3,3',4-Tri-O-methylellagic acid 4'-sulfate potassium salt (2) was isolated from a Mexican herb "Sinfito" (Potentilla candicans) as a potent AR inhibitory active constituent. 2 was more potent (IC50 = 8.0 x 10(-8)M) than ellagic acid, which is one of the natural inhibitors of AR. So we examined the synthesis of ellagic acid derivatives and found that the sulfate group is one of the important function.     

Synthesis of phenoxyacetic acid derivatives as highly potent antagonists of gastrin/cholecystokinin-B receptors. III.

In order to improve the biological characteristics of DA-3934 (5), a novel gastrin/cholecystokinin (CCK)-B receptor antagonist, phenoxyacetic acid derivatives replacing the N-methyl-N-phenylcarbamoylmethyl moiety of 5 with various alkyl chains have been synthesized and their biological activity evaluated. The relationship between the structure of these compounds and their human gastrin receptor binding affinity showed that there should be the optimal size among the various N-alkyl chains. Also a significant increase in the receptor binding affinity was achieved by several compounds. Among those compounds, 2-[3-[3- [N-cyclohexylmethyl-N-[2-(N-methyl- N-phenylcarbamoylmethoxy)phenyl]carbamoylmethyl]ureido]pheny l]acetic acid (22c) and (+/-)-2-[3-[3-[N-[2-(N-methyl-N- phenylcarbamoylmethoxy)phenyl]-N-(3-methylpentyl)carbamoy lmethyl]ureido] phenyl]acetic acid (22h) exhibited high affinity for human gastrin receptors and were also more potent inhibitors in a pentagastrin-induced gastric acid secretion model than the parent compound, 5. The ED50 values of these compounds when administered intraduodenally to rats were 0.12 and 0.63 mg/kg, respectively.     

Synthesis and anti-influenza evaluation of polyvalent sialidase inhibitors bearing 4-guanidino-Neu5Ac2en derivatives

Polyvalent sialidase inhibitors bearing 4-guanidino-Neu5Ac2en derivatives on a poly-L-glutamine backbone are described. Aiming for a longer retention time of 4-guanidino-Neu5Ac2en (zanamivir) in bronchi and lungs, we focused on supermolecules bearing 4-guanidino-Neu5Ac2en derivatives bound at their C-7 position through noncleavable alkyl ether linkages. We first found that alkylation of the 7-hydroxyl group of sialic acid derivative 8 proceeded smoothly, and produced 7-O-alkyl-4-guanidino-Neu5Ac2en derivatives 13, which exhibited equipotent inhibitory activity against not only influenza A virus sialidase but also influenza A virus in the cell culture. Next, we synthesized poly-L-glutamine bearing 7-O-alkyl-4-guanidino-Neu5Ac2en derivatives linked by amide bonds, 26, which showed enhanced antiviral activity against influenza A virus and more potent efficacy in vivo relative to a monomeric sialidase inhibitor.     

Molecular interactions of new pregnenedione derivatives

The in vitro inhibitory activity of five new progesterone derivatives: 17alpha-hydroxy-16beta-methylpregna-1,4,6-triene-3,20-dione 1; 16beta-methyl-17alpha-toluoyloxypregna-1,4,6-triene-3,20-dione 2; 17alpha-hydroxy-6-methylenepregn-4-ene-3,20-dione 3; 6-methylene-17alpha-toluoyloxypregn-4ene-3,20-dione 4 and 17alpha-(p-bromobenzoyloxy)-6-methylenepregn-4-ene-3,20-dione 5 was determined. These compounds were evaluated as 5alpha-reductase inhibitors as well as antagonists for the androgen receptor. Compounds 1, 2, 3, 4 and 5 showed the following inhibitory activity for the 5alpha-reductase enzyme with IC(50) values of: 1 (1.65 microM), 2 (10 microM), 3 (19 nM), 4 (100 nM) and 5 (100 nM). The results of this study also showed the effect of increasing concentrations of the novel steroids upon [(3)H]dihydrotestosterone binding to androgen receptors from male hamster prostate. The K(i) values for compounds 1, 2, 3, 4, 5 and dihydrotestosterone showed the following order of affinity for the androgen receptor: 4>5>dihydrotestosterone>2>3>1. The overall data indicated that all synthesized compounds 1, 2, 3, 4 and 5 are inhibitors of the 5alpha-reductase enzyme present in the hamster prostate. In addition compounds 1, 2, 3, 4 and 5 also presented an affinity for the androgen receptor.     

Discovery of a more potent anticancer agent than C4-benzazole 1,8-naphthalimide derivatives against murine melanoma

Three novel naphthalimide-based derivatives were synthesized and tested in vitro as anticancer agents. Our previous report of the C4-benzazole 1,8-naphthalimide derivatives showed good inhibition against murine melanoma. We aimed to synthesize more potent agents and found that compound 5 reported in this article behaved 5- to 10-fold potency than our previous best results. The unique structure of compound 5 consisted of a naphthalimide framework in which C4 position was linked with an ethylenediamine group where the amino group was coupled with a 2-piconic acid moiety. Compound 5 exhibited the most potent inhibitory activity toward human DNA topoisomerase II proteins with IC₅₀ value (2.6 ± 0.1 μM) against murine B16F10 melanoma cells among the three target compounds synthesized in this study. In accordance with this finding, the results of molecular docking also revealed that compound 5 has the highest affinity with human DNA topoisomerase II among the selected compounds. Compound 5 , therefore, has high potential for becoming a lead compound.     

Novel 17 substituted pregnadiene derivatives as 5 alpha-reductase inhibitors and their binding affinity for the androgen receptor

The in vitro antiandrogenic activity of four new progesterone derivatives: 4, 5, 6 and 7 (8 is a known compound) was determined. These compounds were evaluated as 5alpha-reductase inhibitors as well as by their capacity to bind to the androgen receptor in gonadectomized hamster prostate. The IC(50) value was determined using increasing concentrations of 4, 5, 6, 7 and 8 in the presence of [(3)H]T and the microsomal fraction of the hamster prostate containing the 5alpha-reductase enzyme. In this paper we also demonstrated the effect of increasing concentrations of the novel steroids upon [(3)H]DHT binding to the androgen receptors from hamster prostate which produces competition for the androgen receptor sites. The in vitro studies showed that steroids 4, 5, 6, 7 and 8 had an inhibitory activity for the 5alpha-reductase with IC(50) of: 4 (0.17 microM), 5 (0.19 microM), 6 (1 microM), 7 (4.2 microM), and 8 (2.7 microM). On the other hand, the IC(50) value for compounds 4, 5, 6, 7, 8 and DHT showed the following order of affinity for the androgen receptor: 6>7>5>DHT. Surprisingly compounds 4 and 8 did not bind to the androgen receptor. The overall data indicate that all synthesized compounds are inhibitors for the enzyme 5alpha-reductase present in the hamster prostate. In contrast, compounds 5, 6 and 7, which have a cyclohexyl group in the side chain showed a high affinity for the androgen receptor.     

Studies on the syntheses of analgesics. Part 50. Synthesis of optically active 2-[4-(1-oxo-2-isoindolinyl)phenyl]propanoic acid. [Studies on the syntheses of heterocyclic compounds. Part 742]

2-[4-(1-Oxo-2-isoindolinyl)phenyl]propanoic acid ( 1 ) having a potent analgesic and anti-inflammatory activity could be obtained by three methods, which were found to provide extremely useful ways for the synthesis of 1 from the industrial point of view. (E)- and (Z)-Isomers of 2-butenoic acid and oxiranecarboxylic acid derivatives as the intermedaites in the synthesis of 1 were separated and characterized. Furthermore, the optical resolution of (±)-2-[4-(1-oxo-2-isoindolinyl)phenyl]propanoic acid was successfully achieved using cinchonidine as a resolution reagent.     

Structure-activity relationships of estrogen derivatives as aromatase inhibitors. Effects of heterocyclic substituents

Aromatase, which is responsible for the conversion of androgens to estrogens, is a potential therapeutic target for the selective lowering estrogen level in patients with estrogen-dependent breast cancer. We prepared and tested series of the pyridine- and other heterocyclic ring-containing derivatives of 2- and 4-aminoestrones, estrone, and estradiol, compounds 5, 10, 12 and 15. The isonicotinyl derivatives of 2- and 4-aminoestrone, compounds 5c and 10c, were fairly potent competitive inhibitors of aromatase (K(i), 2.1+/-0.14 and 1.53+/-0.08 microM for 5c and 10c, respectively) and other compounds did not show, to a significant extent, the aromatase inhibitory activity. This result suggests that the isonicotinyl-substituted derivatives 5c and 10c would be accessible to the active site of aromatase.