Chemical characterisation of the terpenoid constituents of the Algerian plant Launaea arborescens.

Chemical investigation of endemic Algerian plant Launaea arborescens resulted in the isolation of a series of triterpenes and sesquiterpenes from both the aerial parts and roots. Five terpenoids have been chemically characterised by means of spectral methods mainly NMR techniques. In addition, the absolute stereochemistry at the chiral carbon in the side chain of 8-deoxy-15-(3'-hydroxy-2'-methyl-propanoyl)-lactucin-3'-sulfate (6) has been determined by comparison of the (1)H NMR spectra of Mosher derivatives of 6 with those of the corresponding MTPA esters of model compounds.