Determination of the Absolute Configuration of a Monoglyceride Antibolting Compound and Isolation of Related Compounds from Radish Leaves (Raphanus sativus)

A monoglyceride (1) has been reported to possess an antibolting effect in radish (Raphanus sativus), but its absolute configuration at the C-2 position was not determined earlier. In this work, the absolute configuration of 1 was determined to be (2S), and it was also accompanied by one new (2) and two known monoglycerides (3 and 4). The chemical structure of 2 was determined as beta-(7'Z,10'Z,13'Z)-hexadecatrienoic acid monoglyceride monoglyceride (beta-16:3 monoglyceride). Qualitative and quantitative analytical methods for compounds 1-4 were developed, using two deuterium-labeled compounds (8 and 9) as internal standards. The results revealed a broader range of distribution of 1-4 in several annual winter crops. It was also found that these isolated compounds have an inhibitory effect on the root elongation of Arabidopsis thaliana seedlings at concentrations of 25 and 50 /AM in the medium. However, the inhibitory effect of 1 was not dependent on coronatin-insensitive 1 (COD) protein, which may suggest the involvement of an unidentified signaling system other than jasmonic acid signaling.