Trigoxazonane, a monosubstituted trioxazonane from Trigonella foenum-graecum root exudate, inhibits Orobanche crenata seed germination.

O. crenata is a major threat to grain legume prodn. Fenugreek is an annual legume that has been shown to effectively reduce O. crenata infection when intercropped with grain legumes. This can be attributed to allelopathy, through inhibition of the germination of O. crenata by fenugreek root exudates. The main inhibitory metabolite was isolated and characterized. Allelopathy was demonstrated in different bioassays, by inhibition of O. crenata seeds germination both by growing fenugreek and pea plants together (intercropped), and by application of fenugreek root exudates. Fenugreek root exudates were extd. with org. solvent and fractionated giving several fractions, two of which showed moderate (27%) and strong (54%) inhibition of O. crenata seed germination, resp. The most active metabolite is a new monosubstituted trioxazonane, characterized by spectroscopic methods as the 2-butyl-[1,4,7,2]trioxazonane and named trigoxazonane.