Seven alkaloids including five undescribed ones(1a/1b,2,3 and 5)were obtained from the leaves of Isatis indigotica Fortune.Their structures were established by extensive spectroscopic analyses.The absolute configurations of compounds 1a,1b,3 and 5 were determined by comparison of the experimental and calculated electronic circular dichroism(ECD)spectra.Subsequently,the neuroprotective effects of all the isolates against H2O2-induced injury in SH-SY5Y cells were evaluated in vitro by MTT assay.Moreover,Annexin V-FITC/PI double staining was performed,while the activities of antioxidant enzymes(SOD,CAT and GSH-Px)for compounds 1a and 1b were measured.