Cultivation of rue (Ruta graveolens L., Rutaceae) for the production of furanocoumarins of therapeutic value

Common rue (Ruta graveolens L.) synthesizes furanocoumarins, which are used in dermatology. The production of these molecules requires the improvement of cultural techniques so as to provide plant material with a high content and (or) yield of furanocoumarins for the pharmaceutical extraction indust ry. Two experiments were set up, firstly, to improve our understanding of t he production of these secondary metabolites by the plant and, secondly, to study the influence of successive cuts on their synthesis. The furanocouma rin content was dependent on the proportion of leaves and fruits on the pla nt. Conversely, it was independent of the biomass at a given age. The shoot s harvested 3 months after sowing had a high furanocoumarin content, as did the fruits in the 2nd year (in both cases about 0.9% of the dry matter). H owever, the dry matter yield produced was low (0.2 and 1.6 tonnes ha(1), re spectively). The harvest of the shoots in the 2nd year gave a high yield (a bout 5 tonnes ha(1)) but had a lower furanocoumarin content (0.4%). A syste m of successive cuts (three cuts in the 2nd year) enabled harvesting to be spread out. The plant material then contained 0.5% furanocoumarins, for 3.3 tonnes of dry matter harvested. The proportion of different furanocoumarin s varied according to year and plant parts.