LAUSR

Abstract Croton gratissimus Burch. is widely used in traditional medicine to treat a range of conditions including malaria, hypertension, diabetes, arthritis, urinary tract infections, gonorrhoea and impotence. The young branches and leaves are pleasantly aromatic, and it is recorded that various ethnic groups in South Africa used the leaves as a perfume. The chemistry of the non-volatile constituents has been widely investigated. However, little scientific data on the volatile constituents are available. Essential oils (EOs) were obtained by hydrodistillation from the leaves and twigs (n = 62) collected at different locations in South Africa. The hydrodistilled oils were analysed with gas chromatography coupled simultaneously to a mass spectrometer (MS) and a flame ionisation detector (FID). GC–MS/FID of the EOs showed the presence of mono- and sesquiterpenes as the major class of compounds. The most abundant compounds were β-pinene (nd–13.7%), sabinene (0.2–16.7%), α-phellandrene (0.4–44.3%), Z-β-ocimene (0.2–12.5%), limonene (0.2–38.3%), p-cymene (0.1–25.2%), phytol (nd–24.9%) and oxidohimachalene (nd–54.6%). Untargeted analysis of the GC–MS data was performed using SIMCA-P + 14.0, and different methods were used to explore possible chemical variation in the data set. After principal component analysis (PCA), the hierarchical cluster analysis (HCA) revealed three major chemotypes. Loadings and contribution plots identified oxidohimachalene as the main chemical marker for chemotype 1. Chemotype 2 was dominated by α-phellandrene, α-pinene and p-cymene, while chemotype 3 was characterised by low yields of α-phellandrene and oxidohimachalene. This study revealed mostly quantitative rather than qualitative variation in the EOs constituents of C. gratissimus.