Isolation and Characterization of an Actinophage (Phage A) active against a Strain of Streptomyces producing Novobiocin

Synthesis and antiproliferative and c-Src kinase inhibitory activities of cinnamoyl- and pyranochromen-2-one derivatives

A series of 6- and 8-cinnamoylchromen-2-one and dihydropyranochromen-2-one derivatives were synthesized and their antiproliferative activities were evaluated against three human cancer cell lines, i.e., ovarian adenocarcinoma (SK-OV-3), leukemia (CCRF-CEM), and breast carcinoma (MCF-7). In general, 8-cinnamoylchromen-2-one derivatives were found to have higher antiproliferative activity against the cancer cells when compared with 6-cinnamoyl analogues. Among all of the hybrid chromen-2-one − chalcone/flavanone compounds, a 7-hydroxy-8-cinnamoylchromen-2-one derivative 35 was found to be consistently active against all the cancer cell lines and inhibited the cell proliferation of SK-OV-3, CCRF-CEM, and MCF-7 by 63%, 50%, and 43%, respectively, at a concentration of 50 μmol/L after 72 h of incubation. This compound also exhibited the highest Src kinase inhibition (IC50= 14.5 μmol/L). Structure−activity relationship studies provided insights for designing the next generation of chromen-2-one − chalcone hybrid prototypes and the development of new leads as anticancer agents and (or) Src kinase inhibitors.

Development of novobiocin analogues that manifest anti-proliferative activity against several cancer cell lines

Recent studies have shown that the DNA gyrase inhibitor, novobiocin, binds to a previously unrecognized ATP-binding site located at the C-terminus of Hsp90 and induces degradation of Hsp90-dependent client proteins at approximately 700 microM. As a result of these studies, several analogues of the coumarin family of antibiotics have been reported and shown to exhibit increased Hsp90 inhibitory activity; however, the monomeric species lacked the ability to manifest anti-proliferative activity against cancer cell lines at concentrations tested. In an effort to develop more efficacious compounds that produce growth inhibitory activity against cancer cell lines, structure-activity relationships were investigated surrounding the prenylated benzamide side chain of the natural product. Results obtained from these studies have produced the first novobiocin analogues that manifest anti-proliferative activity against several cancer cell lines.

A library of noviosylated coumarin analogues

The DNA gyrase inhibitor, novobiocin, was recently shown to inhibit Hsp90 via a previously unrecognized C-terminal ATP-binding site. Previous structure-activity relationship studies identified key moieties that appear important for Hsp90 inhibitory activity. In an effort to provide a more efficacious lead compound, a parallel library of noviosylated coumarin analogues was prepared.

Coumarin-derived discodermolide analogues possessing equivalent antiproliferative activity to the natural product—a further simplification of the lactone region

Analogues of discodermolide in which the complete C-1 to C-7 fragment is replaced with a coumarin moiety display equivalent potency to that of the natural product.