Isoquinolines from Corydalis tomentella from Tibet, China, possess hepatoprotective activities

The phytochemical study on Corydalis tomentella Franch, a traditional Chinese medicinal plant in Tibet, China, led to the isolation of six previously undescribed isoquinolines, including two rarely reported N-benzyl ones, and twenty-one known ones firstly obtained from this plant. Their planar structures were elucidated by 1D, 2D NMR experiments and high resolution mass spectrometry, and the absolute configurations were determined by NOE experiments, electronic circular dichroism, and specific rotation. Seven isoquinolines exhibited stronger hepatoprotective activities than that of positive control in D-galactosamine induced L02 cells damage model, which could be served as the leading compounds for further investigations. The primary structure-activity relationship was also summarized accordingly.