Osalmid (Oxaphenamide)

Osalmid is a ribonucleotide reductase small subunit M2 (RRM2) targeting compound; suppresses ribonucleotide reductase activity with an IC50 of 8.23 μM.

Osalmid is identified as a potential ribonucleotide reductase small subunit M2 (RRM2) compound. Osalmid is 10-fold more active in inhibiting ribonucleotide reductase (RR) activity than hydroxyurea, and significantly inhibits HBV DNA and cccDNA synthesis in HepG2.2.15 cells in a time- and dose-dependent manner. After treatment for 8 days with Osalmid, the EC50 for HBV DNA inhibition are 11.1 μM for culture supernatant and 16.5 μM for cells. Osalmid suppresses RR activity in a concentration-dependent manner, with an IC50 of 8.23 μM. Osalmid is shown to possess potent activity against a 3TC-resistant HBV strain, suggesting utility in treating drug-resistant HBV infections[1].

Osalmid reduces RR activity and HBV replication in HBV-transgenic mice and shows a synergistic efficacy with 3TC without significant toxicity. Oral dosing of osalmid at 400 mg/kg/d results in a time-dependent inhibition of HBV DNA replication. After treatment for 4 weeks, osalmid suppresses HBV DNA replication by about 40-45% as compared to the control in mouse sera and liver tissues[1].

[1]. Liu X, et al. Inhibition of hepatitis B virus replication by targeting ribonucleotide reductase M2 protein. Biochem Pharmacol. 2016 Mar 1;103:118-28.