TRK-530 INHIBITS ACCUMULATION OF SUPEROXIDE ANIONS DERIVED FROM HUMANPOLYMORPHONUCLEAR LEUKOCYTES AND BONE RESECTION INDUCED BY ACTIVATED OSTEOCLASTS

TRK-530, a newly synthesized bisphosphonate, was assessed for its effe cts on the accumulation of superoxide anions derived from human formyl -methionyl-leucyl-phenylalanine-stimulated polymorphonuclear leukocyte s (PMN), and for its effects on bone resorption using a pit formation assay. TRK-530 concentration-dependently inhibited superoxide accumula tion derived from PMN and osteoclast pit formation stimulated by 1,25- dihydroxyvitamin D-3. Incadronate and risedronate had a strong inhibit ory effect on pit formation, but no antioxidative activity. These data suggest that the anti-bone resorption activities of TRK-530 are possi bly unrelated to its antioxidant properties. However, it is difficult to conclude at present which mechanisms play the most important role i n the anti-bone resorption activities of TRK-530.