ZEOLITE A INHIBITS OSTEOCLAST-MEDIATED BONE-RESORPTION IN-VITRO

The effects of Zeolite A on bone resorbing activity of highly purified avian osteoclasts were analyzed. The present study demonstrates that when 100 mu g/ml of acid-treated Zeolite A is added to the media the n umber of pits per osteoclast is reduced 3-fold at 24 h after treatment . Secreted cathepsin B enzyme activity was also reduced 3-fold. A simi lar reduction in pit number per osteoclast was measured following 48 h of treatment with Zeolite A but there appeared to be less reduction o f cathepsin B enzyme activity. The effects on pit number and cathepsin B protein activity were Zeolite dose dependent. The structure of the compound seemed to be responsible for the effects measured since compo unds used to represent constituents of Zeolite A (silicon dioxide and aluminum chloride) failed to inhibit bone resorption or reduce the lev el of secreted cathepsin B enzyme activity. Thus the molecular archite cture of Zeolite A or a derivative thereof appears to be important. In conclusion, the data indicate that Zeolite A can inhibit bone resorpt ion. Together with previous data on osteoblasts, this might suggest a potential positive activity of intact Zeolite A or a partial substruct ure of Zeolite A on bone turnover. (C) 1995 Wiley-Liss, Inc.