Inhibition of Polymorphic Human Carbonyl Reductase 1 (CBR1) by the Cardioprotectant Flavonoid 7-monohydroxyethyl Rutoside (monoHER)

Abstract

Purpose-Carbonyl reductase 1 (CBR1) reduces the anticancer anthracyclines doxorubicin and daunorubicin into the cardiotoxic metabolites doxorubicinol and daunorubicinol. We evaluated whether the cardioprotectant monoHER inhibits the activity of polymorphic CBR1.Methods-We performed enzyme kinetic studies with monoHER, CBR1 (CBR1 V88 and CBR1 I88) and anthracycline substrates. We also characterized CBR1 inhibition by the related flavonoids triHER and quercetin.Results-MonoHER inhibited the activity of CBR1 V88 and CBR1 I88 in a concentrationdependent manner. The IC 50 values of monoHER were lower for CBR1 I88 compared to CBR1 V88 for the substrates daunorubicin and doxorubicin (daunorubicin, IC 50-CBR1 I88: 164 μM vs. IC 50 -CBR1 V88: 219 μM; doxorubicin, IC 50 -CBR1 I88: 37 μM vs. IC 50 -CBR1 V88: 59 μM; p < 0.001). Similarly, the flavonoids triHER and quercetin exhibited lower IC 50 values for CBR1 I88 compared to CBR1 V88 (p < 0.001). MonoHER acted as a competitive CBR1 inhibitor when using daunorubicin as a substrate (Ki = 45 ± 18 μM). MonoHER acted as an uncompetitive CBR1 inhibitor for the small quinone substrate menadione (Ki = 33 ± 17 μM). Conclusions-The cardioprotectant monoHER inhibits CBR1 activity. CBR1 V88I genotype status and the type of anthracycline substrate dictate the inhibition of CBR1 activity.

Structure–activity relationship of flavonoids as potent inhibitors of carbonyl reductase 1 (CBR1)

“…Representative synthetic inhibitors are ethacrynic acid, indomethacin [13], 3-(1-tert-butyl-4-amino-1H-pyrazolo [3,4-d]pyrimidin-3-yl)phenol (hydroxy-PP) [14], triclosan and zearalenone analogues [15], of which a zearalenone analogue shows the most potent inhibition (IC 50 0.21 μM). The natural inhibitors are resveratrol [16] and flavonoids [15,[17][18][19][20], of which some flavonoids were reported to act as protectors against in vitro and in vivo cardiotoxicity [21,22]. However, the IC 50 values of the inhibitory flavonoids range from 68 to 0.67 μM [15,[17][18][19][20], and a molecular docking study of four flavonoids in CBR1 suggested their different orientations in its active site [18].…”

Pharmacogenetics of Human Carbonyl Reductase 1 (CBR1) in Livers from Black and White Donors

“…CBR1 V88I results in CBR1 protein variants (CBR1 V88 and CBR1 I88) with distinctive catalytic and thermodynamic properties . Further studies demonstrated that the anthracycline reductase activities of CBR1 V88 and CBR1 I88 are differentially inhibited by the cardioprotectant flavonoid monoHER (Gonzalez-Covarrubias et al, 2008). A second nonsynonymous SNP on CBR1 (CBR1 S131P, rs41557318) has been recently reported by the dbSNP database (build 129).…”

Characterization of the Canine Anthracycline-Metabolizing Enzyme Carbonyl Reductase 1 (cbr1) and the Functional Isoform cbr1 V218

“…Kinetic analyses were performed in an identical manner as described for the substrate menadione. The inhibitory effects of the naturally occurring flavonoid rutin on canine cbr1 activity was assessed essentially as previously described (Gonzalez-Covarrubias et al, 2008). Reaction mixtures (200 ml) contained 0.1 M potassium phosphate buffer (pH 7.4), recombinant protein (6 mg), rutin (2-25 mM), daunorubicin (5-300 mM), and NADPH (250 mM).…”