Effect of quercitrin gallate on zymosan A-lnduced peroxynitrite production in macrophages

We previously isolated quercetin 3-O-beta-(2"-galloyl)-rhamnopyranoside (QGR), a quercitrin gallate, from aerial parts of Persicaria lapathifolia (Polygonaceae) to prevent superoxide produc tion in monocytes from venous blood of healthy human donors. In this study, effects of QGR and its building moieties (quercitrin, quercetin and gallic acid) on the production of peroxyni trite, a coupling oxidant between superoxide and nitric oxide (NO) radicals, were investigated in zymosan A-stimulated macrophages RAW 264.7. The QGR, quercitrin and quercetin inhib ited peroxynitrite production in dose-dependent manners with IC50 values of 2.1 microM, 24.5 microM and 5.1 microM, respectively, but gallic acid even at 100 microM was inactive. QGR also inhibited both zymosan A- and phorbol 12-myristate 13-acetate-induced superoxide productions with IC50 values of 3.2 microM and 4.7 microM, respectively. However, QGR affected neither zymosan A-induced NO production nor inducible NO synthase synthesis. Taken together, QGR could inhibit peroxynitrite production by blocking superoxide production without affecting NO production. Finally, this study could provide a pharmacological potential of QGR in the oxidative stress-implicated disorders.