Rifomycins. XLIX. Influence of the carboxyl group on the antibacterial activity of rifomycins

Antiviral Antibiotics: Inhibition of Focus-Formation in Human or Mouse Cell Cultures by Sarcoma-Inducing Oncornaviruses with Rifamycins

“…Data on the uptake of labeled DNA, RNA, and protein precursors into TCA-precipitable macromolecular products in a final 2-hour pulse during a total 6-hour exposure of uninfected 3T3 cells and virus-transformed but non virus-shedding 3T3-derived cells [(S*L~)-C243-3] to the various rifamycin compounds are shown in table 11. This test aims at detecting possible toxicity produced by the various compounds under conditions analogous to those prevailing in the early stages of the usual focus assay on mouse 3T3 cells.…”

“…The antibiotic specifically binds to the [3-subunit of RNA polymerase [8]. Other rifamycins, and even the structurally different streptovaricin ansa-macrolide antibiotics, have a similar mode of action [9,10], The antibacterial ineffectiveness of rifamycin B apparently arises from its inability to penetrate the bacterial cell, since it potently inhibits bacterial RNA poly merase in vitro [11],…”

Zur Kenntnis von Rifamycin‐S.‐Reaktionen des Ansaringes. Modifikationen von Antibiotica, 8. Mitteilung [1]

“…Uberschussige Phthalmonopersaure in Ather verwandelt 1 in ein Gemisch der Epoxide 12 (C,,H,,NO,,), 13 (C,,H,,NO1,) uber die reversible Reduktion von 1 zu Rifamycin-SV und iiber die katalytische Hydrierung zu Tetra-und Hexa-hydrorifamycin-S ist bereits berichtet worden 191. Die noch nicht beschriebene Reduktion von 1 zum Rifamycin-1 l-carbinol ({( Rifamycinols) gelingt bei der Behandlung von Rifamycin-SV rnit Natriumborhydrid.…”