Labdanum from mediterranean Cistus species: GC-MS fingerprints and relative quantification of antispirochaetal manoyloxides

Abstract

The oleoresin labdanum from Cistus creticus was used in ancient Greece as incense, anti-infective, and wound treatment [1]. On Crete, the main production center since antiquity, it is brushed off the leaves with long textile strings. After the Ottoman conquest of Crete 1645, Western Europe imported Spanish labdanum prepared by hot water extraction of aerial parts of Cistus ladanifer. Shortly there- after, labdanum fell out of pharmaceutical use [2]. Presently, C. creticus leaf extracts from Turkey are applied by German self-help groups for borreliosis therapy [3]. Our results indicate that this anti- spirochaetal activity is mainly due to manoyloxides in the essential oil [3,4]. Here, 8 labdanum sam- ples were analyzed by GC-MS for these active constituents, revealing exceptionally high contents of 13-epi-manoyloxide, 2-keto-manoyloxide, ent-3β-hydroxy-13-epi-manoyloxide, manoyloxide, sclareol, and acetoxy-manoyloxide in the Cretan ones. In other eastern Mediterranean samples, the concentration of these compounds was several orders of magnitude lower, whereas Spanish labda- num is dominated by simple alkanes with only trace amounts of manoyloxide and 13-epi-man- oyloxide. Thus, discontinuation of medicinal use of labdanum in Western Europe is understandable as “labdanum” from C. ladanifer is clearly not equivalent to the traditionally harvested C. creticus drug. Rumors that C. creticus contains psychotropic THC were refuted.