Kaurane and trachylobane diterpenes from Xylopia aethiopica

Phytochemical investigation of Xylopia aethiopica (Annonaceae) has resulted in the isolation of two novel diterpenes, 15-oxo-(-)-trachyloban-19-oic acid and (-)-kaur-15-en-17-al-19-oic acid. Also encountered were the known compounds 15-hydroxy-(-)-trachyloban-19-oic acid, 15β-hydroxy-(-)-kaur-16-en-19-oic acid (as an inseperable mixture), 15-oxo-(-)-kaur-16-en-19-oic acid and sitosterol glucoside. 13C NMR assignments of 15-hydroxy-(-)- trachyloban-19-oic acid and the assignment of the configuration of its hydroxyl group at C-15 have been carried out for the first time.