Epoxomicin (BU-4061T,Aids010837) is a selective proteasome inhibitor with anti-inflammatory activity, inhibits primarily the CH-L activity of the 20S proteasome, while T-L and PGPH catalytic activities are also inhibited at 100- and 1000-fold reduced rate.

Epoxomicin covalently binds to the LMP7, X, MECL1, and Z catalytic subunits of the proteasome. Epoxomicin (100 nM) results in a 30-fold increase in the levels of p53 protein, a known target of the proteasome, in HUVECs. Epoxomicin (10 μM) results in the accumulation of ubiquitinated proteins in HeLa cells. Epoxomicin (10 μM) inhibits IκBα degradation by 10-fold in HeLa cells. Epoxomicin (10 μM) produces a significant dose-dependent reduction in TNF-α-stimulated NF-κB DNA-binding activity in HeLa cells. [1] Epoxomicin inhibits proliferating of EL4 lymphoma cells with biotinylated chimerae with IC50 of 4 nM. [2] Epoxomicin (1 μM) leads to a reduction of LCMV GP33 presentation and an enhancement of GP276 presentation. [3] Epoxomicin inhibits growth of Babesia bigemina with IC50 of 4 nM. Epoxomicin (0.5 mg/kg and 0.05 mg/kg) results in peak parasitemia levels of 34.8% and 42.3% in B. microti. [4] Epoxomicin (100 nM) decreases the total parasitemia by 78%, 86% and 77% in Plasmodium falciparum. Epoxomicin (10 μM) inhibits gametogenesis and exflagellation as well as development into oocysts of anopheles mosquitoes. [5]

Epoxomicin (0.58 mg/kg per day) reduces the CS response by 44% relative to the control group of mice treated with vehicle alone. Epoxomicin (2.9 mg/kg) potently inhibits the irritant-associated inflammatory response by 95% when ear edema measurements are made 24 hours postchallenge in mice. [1]