Chikaaki Muro

Inhibitory Activity of Podophyllotoxin and Matairesinol-derivative Lignans on the Root Growth of Brassica campestris

All the lignans tested in a bioassay with Brassica campestris L. subsp. rapa Hook. fil. et Anders inhibited the root growth of this plant, except for deoxypicropodophyllin. The effects of functional groups in the molecule on the inhibitory activity of these compounds were studied. It is suggested that the methylenedioxyl group and the stereochemical configuration of the lactone junction of podophyllotoxin derivatives were closely related to the inhibitory activity. The O-methyl derivative of two hydroxyl groups of matairesinol greatly enhanced the inhibition of root growth in this plant.

Relationship between structure and phytogrowth-inhibitory activity of 2,5-dihydroxy-1,4-dithiane-related compounds

Ten derivatives (II-VI and VIII-XII) from 2, 5-dihydroxy-1, 4-dithiane (I) and 2, 5-dihydroxy-2, 5-dimethyl-1, 4-dithiane (VII) showed inhibitory activity against the growth of root of Brassica rapa L. The inhibitory activity of all ten derivatives was higher than that of the original compounds I and VII. In particular, VIII-XII inhibited the germination of this plant at the concentration of 1.0×10-3M. Among the derivatives VIII-XII, IX exhibited the strongest inhibition. Compound III had the most potent inhibitory activity among the derivatives II-VI. The results indicate that acylation of hydroxyl group with propionic acid enhances the activity. The inhibitory effect of VIII-XII was much stronger than that of II-VI. The findings suggest that methyl groups at 2, 5 dipositions play an important role in the inhibitory activity of 2, 5-dihydrosy-1, 4-dithiane-related compounds. In both derivatives II-VI and VIII-XII, the inhibitory effect of the substituent was in the order of propionyl > acetyl > butyryl > valeryl > isobutyryl. All radicles of this plant treated with the compounds I-XII showed negative geotropism.