This invention features a method for enhancing bone growth or inhibiting bone resportion. The method includes administering to a subject in need thereof a compound of the following formula: ##STR00001## A is H, R, or ##STR00002## each of Ar.sub.1, Ar.sub.2, and Ar.sub.3, independently, is phenyl, thienyl, furyl, or pyrrolyl; each of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6, independently, is H, halogen, R, C(O)OH, C(O)OR, C(O)SH, C(O)SR, C(O)NH.sub.2, C(O)NHR, C(O)NRR', ROH, ROR', RSH, RSR', NHR, NRR', RNHR', or RNR'R''; or R.sub.1 and R.sub.2 together, R.sub.3 and R.sub.4 together, or R.sub.5 and R.sub.6 together are ORO; wherein each of R, R', and R'', independently is C.sub.1.about.C.sub.6 alkyl; and n is 1, 2, or 3.