Most axons in the adult mammalian central nervous system (CNS) have little ability for regeneration after damage.Failure of successful axonal regeneration in the CNS is attributed not only to the intrinsic regenerative incompetence of adult neurons,but also to the local environment encountered by these axons.Ample evidence suggests that the main inhibitory activity in the local CNS environment is associated with components of CNS myelin at the lesion site.Immobilized CNS myelin proteins have been shown to inhibit axon outgrowth of a variety of neurons.To identify small molecules could promote axonal regeneration,we screened a compound library purified from traditional Chinese herbs (TCM) with neurite outgrowth-assay in PC 12 cells model.Pj38,a small compound isolated from Polygala japonica,was found to promote neurite outgrowth of PC12 cells.This compound could also enhance the axon elongation of rat cerebellar granule neurons cultured on immobilized CNS myelin proteins.Moreover,Pj38 was demonstrated to potently inhibit the activity of RhoA.Thus,it may provide a therapeutic approach to stimulating axon regeneration after CNS damage and degeneration.