In vitro antioxidant properties of calpain inhibitors: leupeptin and calpain inhibitor-1.
The aim of this study was 1/ to assess the efficacy of calpain inhibitors: leupeptin and calpain inhibitor-1, to inhibit calpain activity in vitro, 2/ to measure the scavenging abilities of these compounds against free radicals. The efficacy of calpain inhibitors to block calpain activity was tested with azocasein as a substrate for calpain. Leupeptin and calpain inhibitor-1 inhibited calpain activity in the same range of concentrations, the IC50 being 0.14 microM and 0.09 microM, respectively. We measured the antioxidant properties of leupeptin and calpain inhibitor-1 using the allophycocyans assay after identification offree radical species produced by the complex H2O2 + Cu(++). Electron paramagnetic resonance (EPR) spin-trapping studies performed by using DMPO showed that a quartet signal (hyperfine couplings aN = aH = 14.9 G) arisen from DMPO-OH was formed. We found a correlation between leupeptin concentration and oxygen radical absorbance capacity (ORAC) values (r2 = 0.975) indicating an in vivo antioxidant capacity. In contrast, calpain inhibitor-1 showed no protection. In conclusion, our findings indicate that leupeptin and calpain inhibitor-1 are equipotent inhibitors on calpain activity but exhibit diffrent antioxidant efficacy.
Perrin
Caroline
C
Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Facultés de Médecine et Pharmacie, Dijon, France. caroline.perrin@u-bourgogne.fr
Vergely
Catherine
C
Zeller
Marianne
M
Rochette
Luc
L
D000975:Antioxidants / Q000494:pharmacology*; D002154:Calpain / Q000037:antagonists & inhibitors*; D004578:Electron Spin Resonance Spectroscopy; D006023:Glycoproteins / Q000494:pharmacology*; D007700:Kinetics; D007976:Leupeptins / Q000494:pharmacology*; D010798:Phycocyanin / Q000494:pharmacology
D000975:Antioxidants; D006023:Glycoproteins; D007976:Leupeptins; C002497:allophycocyanin; C039304:calpain inhibitors; D010798:Phycocyanin; D002154:Calpain; C032854:leupeptin