Antiviral properties of new arylsulfone derivatives with activity against human betaherpesviruses.

Based on our previous experience with arylsulfone derivatives displaying antiherpetic activity, we synthesized several analogues in which the sulfonyl group is part of a bicyclic structure. The benzene-fused derivative 2H-3-(4-chlorophenyl)-3,4-dihydro-1,4-benzo-thiazine-2-carbonitrile 1,1-dioxide and its thiophene-fused analogue were shown to have favorable activity and selectivity against the betaherpesviruses human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6) and 7 (HHV-7). The benzene-fused derivative retained its anti-HCMV activity when evaluated against virus strains resistant to foscarnet, ganciclovir, and/or cidofovir. The compound conferred >or=95% inhibition of viral DNA synthesis in HHV-6-infected cells. RT-PCR analysis of immediate-early, early and late gene products revealed that this arylsulfone compound acts at a step preceding late gene expression, and coinciding with the inhibition exerted by foscarnet. No inhibitory effect was seen in an enzyme assay for DNA elongation catalyzed by the HCMV or HHV-6 DNA polymerase catalytic subunit. The arylsulfone derivatives had no effect on the functional interaction between the catalytic subunit of HCMV DNA polymerase and its accessory protein, nor did they disrupt the physical interaction between the two proteins. We conclude that these arylsulfone derivatives represent new betaherpesvirus inhibitors with a novel mode of action that results in indirect inhibition of viral DNA synthesis.

Synthesis of 7alpha-substituted derivatives of 17beta-estradiol.

Estrogen receptor (ER) pure antagonists such as ICI-182,780 (fulvestrant) are effective alternatives to tamoxifen (an ER antagonist/weak partial agonist) in the treatment of postmenopausal, receptor-positive human breast cancers. Structurally, these pure antagonists contain the basic core structure of 17beta-estradiol (E(2)) with a long side chain attached to its C-7alpha position. We explored and compared in this study various synthetic routes for preparing a number of C-7alpha-substituted derivatives of E(2), which are highly useful for the design and synthesis of high-affinity ER antagonists, ER-based imaging ligands, and other ER-based multi-functional agents. Using E(2) as the starting material and 1-iodo-6-benzyloxyhexane as a precursor for the C-7alpha side chain, a seven-step synthetic procedure afforded 3,17beta-bis(acetoxy)-7alpha-(6-hydroxyhexanyl)-estra-1,3,5(10)-triene (one of the derivatives prepared) in an overall yield of approximately 45% as compared to other known procedures that afforded substantially lower overall yield (8-27%). The synthetic steps for this representative compound include: (1) protection of the C-3 and C-17beta hydroxyls of E(2) using methoxymethyl groups; (2) hydroxylation of the C-6 position of the bismethoxymethyl ether of E(2); (3) Swern oxidation of the C-6 hydroxy to the ketone group; (4) C-7alpha alkylation of the C-6 ketone derivative of E(2); (5) deprotection of the two methoxymethyl groups; (6) reprotection of the C-3 and C-6 free hydroxyls with acetyl groups; (7) removal of the C-6 ketone and the benzyl group on the side chain by catalytic hydrogenation in acetic acid. As predicted, two of the representative C-7alpha-substituted derivatives of E(2) synthesized in the present study retained strong binding affinities (close to those of E(2) and ICI-182,780) for the human ERalpha and ERbeta subtypes as determined using the radioligand-receptor binding assays.

Chemical synthesis of two novel diaryl ether dimers of estradiol-17beta.

We recently detected the formation of estradiol-17beta (estradiol) dimers, linked together through a diaryl ether bond between the C-3 phenolic oxygen of one estradiol molecule and the 2- or 4-position aromatic carbon of another estradiol, following incubations of [3H]estradiol with human liver microsomes or cytochrome p450 enzymes in the presence of NADPH. Using estradiol as the starting material, we designed a four-step method for the chemical synthesis of these two estrogen dimers with the Ullmann condensation reaction as a key step. Step 1: Synthesis of 2- or 4-bromoestradiol from estradiol. Step 2: Protection of the C-3 phenolic hydroxyl group of the 2- or 4-bromoestradiol. Step 3: The Ullmann condensation reaction between the phenol-protected bromoestradiol and the estradiol potassium salt under our modified reaction conditions (with a 41% product yield). Step 4: Removal of the C-3 benzyl group by catalytic hydrogenation. The chromatographic and various spectrometric properties of the two synthesized compounds were identical to those metabolically formed by human cytochrome p450 3A4.