POTENTIAL ALLELOPATHIC LUPANE TRITERPENES FROM BIOACTIVE FRACTIONS OF MELILOTUS-MESSANENSIS

The aerial parts of Melilotus messanenis (sweet clover) afforded, from the medium polar bioactive fractions, in addition to the known lupane triterpenes lupeol, betulin, betulin aldehyde and betulinic acid, the new norlupane messagenin (30-norlupane-3 beta,28-diol-20-one) which have been tested as allelochemicals. Structures and their stereochemistries were elucidated by spectral methods and chemical transformations. Messagenin has been synthesized from betulinic acid. The effect of a series of aqueous solutions at 10(-4)-10(-9) M of eight natural and synthetic lupane derivatives were tested for their effects on the germination and growth of the dicotyledon species Lactuca sativa and Lepidium sativum and the monocotyledon species Hordeum vulgare and Triticum aestivum. All eight lupane triterpenes possess potential allelopathic activity in particular over dicotyledon species and they are likely to be significantly involved in the allelopathic action of Melilotus messanensis.