Kaurane Diterpenes from the Fruits of Zanthoxylum leprieurii (Rutaceae)

The fruits of Zanthoxylum leprieurii Guill. & Perr. (Rutaceae) are traditionally used in Africa, particularly in Cameroon, as a spice and in the treatment of sickle cell anaemia. Phytochemical investigation on the fruits of this plant afforded five kaurane diterpenes, i.e., kaurenoic acid (1), xylopic acid (2), ent-kauran-16β-ol (3), ent-16β-hydroxykauran-19-al (4) and ent-16β-hydroxykauran-19-oic acid (5). The structures of these diterpenes were determined comprehensively by spectroscopic means (1D and 2D NMR spectroscopy and MS analyses) and also by comparison with respective literature data. Among the isolated compounds, only kaurenoic acid (1) exhibited cytotoxicity against the PC3 cell line with an IC 50 value of 33.28 ± 9.14 µg/mL. To the best of our knowledge, this is the first report on the isolation of these kaurane diterpenes (1-5) from the genus Zanthoxylum.