Chemical constituents of roots of Salvia x jamensis J. Compton grown in aeroponic colture.

In the course of our search for allelochemicals from Salvia species we have previously described the phytotoxic activity of compounds extracted from Salvia x jamensis against Papaver rhoeas L. and Avena sativa L.1,2. In the present work we have investigated the production of these bioactive compounds by the root system, because of its ability to exude a vast array of compounds, including diterpenes3, into the rhizosphere with the potential to affect the inter-relationships between plant4. An aeroponic system has been chosen as this soilless colture allows to access roots with minimal disturbance, decreased plant water stress, enhanced plant growth rates, and optimal aeration of the root zone5,6. Rooting of cuttings with three nodes of S. x jamensis was induced in distilled water containing 5.0 μM IBA and then transferred in the aeroponic colture experiment system in order to obtain the growth of the root apparatus. The nutrient solution was supplied as nebulized solution and replaced biweekly. After 4 months of aeroponic colture, the roots were removed from plants, air dried and extracted. From the root methanolic extract, purified by RP SPE, several diterpenes and triterpenes have been determined by means of HPLC-HRMS; 3-β-hydroxy-isopimaric acid (1), hautriwaic acid (2), betulinic acid (3), isopimaric acid (4) and 14-hydroxy-isopimaric acid (5) have been previously isolated from the exudate of the fresh aerial parts of the plant 1. While the phytotoxic activity of 3 against other dicotyledon and monocotyledon species has been described7,8, 1 and 2 have shown significant phytotoxic activity, 4 has shown significant inhibitory activity on germination of both Papaver and Avena, but low effects on the subsequent growth of these species, and 5 has been inactive1