Isolation of Pieristoxin A, B and C from the Flowers of Pieris japonica

Toxic components were extracted from the flowers of Pieris japonica D. DON., forming colorless silky crystals of m.p. 217-218°, C20H32O7, colorless needles of m.p. 257°, C22H32O8, and colorless rhomboprismatic crystals of m.p. 262°, C24H38O9. These were considered to be new components and were termed pieristoxin-A, -B, and -C. These three components undergo reactions as indicated in Chart 1 but pieristoxin-A does not contain an acetyl group, while pieristoxin-B contains one acetyl and pieristoxin-C, two acetyl groups.