Objective: To investigate the effects of Periploca forrestii against osteoclast differentiation and determine its active fraction. Method: The three indicators-morphological observation

hematoxylin and eosin(HE)staining

tartrate-resisstant acid phosphatase(TRAP) staining were used to identify osteoclasts which was obtained by vitamin D3(VD3) inducing rabbit bone marrow cells. The active fraction was determined

the inhibitory effects of each polarity of P. forrestii with different doses-low

medium and high dose groups (1

10

100 mg·L-1) on the TRAP enzyme activity of osteoclasts

TRAP+ cells and bone resorption whirlpool area were measured. Result: In addition to the high-dose of water-saturated n-butanol layer

high-dose group as well as middle-dose of ethyl acetate layer also had significant inhibition on marrow cells differentiating into osteoclasts with dose-dependent manner(P<0.01).The measuring result of the bone resorption ability of osteoclast

showed that ethyl acetate layer inhibited bone resorption whirlpool area dose-dependently (P<0.01)

while the high-dose group of n-butanol layer also had apparent effects (P<0.01). Conclusion: Ethyl acetate fraction is the most active part of P. forrestii to suppress differentiation of bone marrow cells into osteoclast and bone resorption capacity.