Synthesis and biochemical characterization of naphthoquinone derivatives targeting bacterial histidine kinases.

Waldiomycin is an inhibitor of histidine kinases (HKs). Although most HK inhibitors target the ATP-binding region, waldiomycin binds to the intracellular dimerization domain (DHp domain) with its naphthoquinone moiety presumed to interact with the conserved H-box region. To further develop inhibitors targeting the H-box, various 2-aminonaphthoquinones with cyclic, aliphatic, or aromatic amino groups and naphtho [2,3-d] isoxazole-4,9-diones were synthesized. These compounds were tested for their inhibitory activity (IC50) against WalK, an essential HK for Bacillus subtilis growth, and their minimum inhibitory concentrations (MIC) against B. subtilis. As a result, 11 novel HK inhibitors were obtained as naphthoquinone derivatives (IC50: 12.6-305 µM, MIC: 0.5-128 µg ml-1). The effect of representative compounds on the expression of WalK/WalR regulated genes in B. subtilis was investigated. Four naphthoquinone derivatives induced the expression of iseA (formerly yoeB), whose expression is negatively regulated by the WalK/WalR system. This suggests that these compounds inhibit WalK in B. subtilis cells, resulting in antibacterial activity. Affinity selection/mass spectrometry analysis was performed to identify whether these naphthoquinone derivatives interact with WalK in a manner similar to waldiomycin. Three compounds were found to competitively inhibit the binding of waldiomycin to WalK, suggesting that they bind to the H-box region conserved in HKs and inhibit HK activity.

Effect of OS-0544, a selective estrogen receptor modulator, on endothelial function and increased sympathetic activity in ovariectomized rats.

Estrogens are known to contribute to endothelial function and sympathetic activity, both of which are strongly associated with the pathogenesis of ischemic heart disease. In addition, estrogens improve impaired lipid profile, a risk factor of endothelial dysfunction. In this study, we investigated the effects of OS-0544, a structurally new selective estrogen receptor modulator (SERM), on endothelial function, sympathetic activity, and plasma cholesterol level in ovariectomized (OVX) rats. Female Sprague-Dawley rats were ovariectomized and orally treated with OS-0544 (or OS-0689, the (R)-enantiomer of OS-0544), or 17beta-estradiol (E2) for 4 weeks, starting the next days after ovariectomy or for 1 week, starting 6 weeks after ovariectomy. Ovariectomy significantly increased vasopressin-induced mean blood pressure (AVP-MBP) (57+/-3.3 mm Hg vs. 46+/-3.5 mm Hg, P<0.05) and decreased acetylcholine (Ach)-induced maximum vasorelaxation response (69+/-5.6% vs. 81+/-4.0%, P<0.05). OS-0544 significantly inhibited AVP-MBP elevation (46+/-3.5 mm Hg vs. 57+/-3.3 mm Hg, P<0.05) and decreased Ach-induced maximum vasorelaxation response (90+/-3.3% vs. 69+/-5.6%, P<0.05) in OVX rats. In addition, OS-0689 as well as E2 significantly reduced (up to 67%) the increase in sympathetic activity in OVX rats. Moreover, like E2, OS-0544 significantly decreased plasma cholesterol level in OVX rats. These results demonstrate that OS-0544 has vascular protective effect on vascular function after ovariectomy. It is therefore believed that OS-0544 has vascular protective effect in postmenopausal woman.

Discovery and preclinical characterization of (+)-3-[4-(1- piperidinoethoxy)phenyl]spiro[indene- 1,1'-indane]-5,5'-diol hydrochloride: a promising nonsteroidal estrogen receptor agonist for hot flush.

In our studies of the development of a novel class of selective estrogen receptor modulators, (+)-3-[4-(1-piperidinoethoxy)phenyl]spiro[indene-1,1'-indane]-5,5'-diol hydrochloride (1) was found to be an estrogen receptor ligand with beneficial effects in rat models for human hot flush. Moreover, 1 was found to have beneficial effects on lipid and bone metabolism while maintaining marginal effects on the uterus and breasts. These findings suggest that 1 would provide a new treatment for hot flush.

4-(4-alkylpiperazin-1-yl)phenyl group: a novel class of basic side chains for selective estrogen receptor modulators.

In the structure-activity relationships of spiro[indene-1,1'-indane] series, the 4-(4-alkylpiperazin-1-yl)phenyl group was found to be functionally equipotent to the 4-(1-piperidinoethoxy)phenyl group, the most widely used basic side chain in selective estrogen receptor modulators.