Abstract:
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 H
2O
2-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.