Development of Androgen-Antagonistic Coumarinamides with a Unique Aromatic Folded Pharmacophore.

First-generation nonsteroidal androgen receptor (AR) antagonists, such as flutamide (2a) and bicalutamide (3), are effective for most prostate cancer patients, but resistance often appears after several years due to the mutation of AR. Second-generation AR antagonists are effective against some of these castration-resistant prostate cancers, but their structural variety is still limited. In this study, we designed and synthesized 4-methyl-7-(N-alkyl-arylcarboxamido)coumarins as AR antagonist candidates and evaluated their growth-inhibitory activity toward androgen-dependent SC-3 cells. Coumarinamides with a secondary amide bond did not show inhibitory activity, but their N-methylated derivatives exhibited AR-antagonistic activity. Especially, 19b and 31b were more potent than the lead compound 7b, which was comparable to hydroxyflutamide (2b). Conformational analysis showed that the inactive coumarinamides with a secondary amide bond have an extended structure with a trans-amide bond, while the active N-methylated coumarinamides have a folded structure with a cis-amide bond, in which the two aromatic rings are placed face-to-face. Docking study suggested that this folded structure is important for binding to AR. Selected coumarinamide derivatives showed AR-antagonistic activity toward LNCaP cells with T877A AR, and they had weak progesterone receptor (PR)-antagonistic activity. The folded coumarinamide structure appears to be a unique pharmacophore, different from those of conventional AR antagonists.

Development of 6-arylcoumarins as nonsteroidal progesterone antagonists. Structure-activity relationships and fluorescence properties.

Progesterone is involved in multiple physiological processes, including female reproduction, via binding to the progesterone receptor (PR). We have developed 6-arylcoumarins such as 5 and 6 as non-steroidal PR antagonists with receptor-binding-dependent fluorescence. In this study, we investigated the structure-activity relationships and fluorescence properties of coumarin derivatives bearing a heterocyclic aromatic moiety. Among these derivatives, 7c (IC50: 34nM) and 10b (IC50: 24nM) showed more potent PR-antagonistic activity than lead compounds 5 (IC50: 500nM) and 6 (IC50: 65nM) in alkaline phosphatase (AP) assay. Compound 9b showed solvent-dependent fluorescence intensity, exhibiting strong fluorescence in the presence of PR LBD only in buffer solution. On the other hand, 10b showed a solvent-dependent shift of the fluorescence maximum wavelength in the presence of PR LBD. These results indicate that 6-arylcoumarin will be a useful scaffold for PR antagonists and fluorescent probes targeting PR.

6-arylcoumarins as novel nonsteroidal type progesterone antagonists: an example with receptor-binding-dependent fluorescence.

Various 6-arylcoumarin derivatives were designed and synthesized as candidate nonsteroidal type progesterone antagonists. 6-Bromocoumarin derivatives were prepared from the corresponding 4-substituted 2-acetoxy-5-bromobenzaldehyde by employing the Still-Gennari modification of the Horner-Wadsworth-Emmons olefination reaction and were converted to 6-arylcoumarins by means of Suzuki-Miyaura cross-coupling reactions. The biological activities of these coumarin derivatives were evaluated by means of alkaline phosphatase assay in the T47D human breast carcinoma cell line. Among the synthesized compounds, 36 (IC(50) = 0.12 µM) and 38 (IC(50) = 0.065 µM), bearing a five-membered heterocycle, showed potent PR antagonist activity. Competitive binding assay showed that compounds 8 and 34 have potent PR binding affinity. The fluorescence of compound 8 was dependent on the solvent properties and was increased in the presence of PR ligand binding domain. This property might be applicable to the development of fluorescence probes for studies on PR.

Diversity of staphylocoagulase and identification of novel variants of staphylocoagulase gene in Staphylococcus aureus.

Staphylocoagulase (SC) is a major phenotypic determinant of Staphylococcus aureus. Serotype of SC (coagulase type) is used as an epidemiological marker and 10 types (I-X) have been discriminated so far. To clarify genetic diversity of SC within a single and among different serotype(s), we determined approximately 1500 bp-nucleotide sequences of SC gene encoding D1, D2, and central regions (N-terminal half and central regions of SC; SC(NC)) for a total of 33 S. aureus strains comprising two to three strains from individual coagulase types (I-VIII, X) and 10 strains which were not determined as previously known SC serotypes (ND-strains). Amino acid sequence identities of SC(NC) among strains with a single coagulase type of II, III, IV, V, VI and X were extremely high (more than 99%), whereas lower identity (56-87%) was observed among different types. In contrast, within a single coagulase type of I, VII, or VIII, sequence divergence was found (lowest identity; 82%). SC(NC) sequences from the ND-strains were discriminated into two genetic groups with an identity of 71% to each other (tentatively assigned to genotypes [XI] and [XII]), and exhibited less than 86% sequence identities to those of most known coagulase types. All the types [XI] and [XII] strains were methicillin susceptible and belonged to different sequence types from those of coagulase types I-X strains reported so far by multilocus sequence typing. These findings indicated genetic heterogeneity of SC in coagulase types I, VII, and VIII strains, and the presence of two novel SC genotypes related to antigenicity of SC serotypes.