A new 1,6-benzoxazocine-5-one alkaloid isolated from the aerial parts of Peristrophe lanceolaria.

A new 1,6-benzoxazocine-5-one alkaloid has been isolated as its butyl acetal derivative (1) along with peristrophine from the n-BuOH and EtOAc fractions of the crude MeOH extract of the aerial parts of Peristrophe lanceolaria growing in Thailand. The structures of these compounds were elucidated on the basis of their spectroscopic data. These compounds were isolated for the first time from P. lanceolaria. The EtOAc and n-BuOH fractions also possessed significant antioxidant activity with IC50 values of 57 and 50 μg/mL, respectively (DPPH method), whereas 1 had an IC50 value of 23 μg/mL.