Abstract

Hirsutanines H−O ( 1 − 8 ), eight previously undescribed monoterpene indole alkaloids, along with five known analogues ( 9 − 13 ), were isolated from the stems and leaves of Uncaria hirsuta . Compounds 1 − 4 represent a rare subclass of 3-oxo-3,7- seco -oxindole alkaloids. The structures of 1 − 13 were elucidated by spectroscopic, computational, and chemical means. All the isolates were evaluated for their neuroprotective effects against sodium nitroprusside-induced damage in PC-12 cells. Among them, compounds 1 , 4 , and 9 exhibited pronounced activity, being comparable to that of the positive control, edaravone. Mechanistic studies revealed that 1 , the most active compound, exerted its neuroprotective effect via attenuating oxidative stress.