Bioactive phenolics and polar compounds from Melilotus messanensis

The methanolic extract from sweetclover, Melilotus messanensis, afforded the new coumestan melimessanol A, the 3-arylcoumarin melimessanol B and the 2-arylbenzofuran melimessanol C, which where identified on the basis of spectroscopic methods. The known isoflavones formononetin and cyclosin; the isoflavanone vestitone; the flavanone liquiritigenin; the pterocarpans (3R,4R)-medicarpin, 3-hydroxymedicarpin and melilotocarpane B; the coumestans coumestrol, 4'-O-methylcoumestrol and 7-hydroxy-4',5'-dimethoxycoumestan; the 3-arylcoumarin 3-(4'-methoxy-2'-hydroxyphenyl)-7-hydroxycoumarin; the lignan pinoresinol; 3-hydroxycoumarin and the simple phenolics p-coumaric acid, vanillic acid, p-hydroxybenzoic acid, a diterpene, two loliolides, a cyclitol and two saponins have been also isolated and spectroscopically identified. Cyclosin, vestitone, 4'-O-methylcoumestrol, 7-hydroxy-4',5'-dimethoxycoumestan, 3-(4'-methoxy-2'-hydroxyphenyl)-7-hydroxycoumarin and 3-hydroxycoumarin are first reported in the genus Melilotus. The effects of a series of aqueous solutions from 10(-4)-10(-9) M of twelve phenolics, two loliolides, a diterpene and a cyclitol on germination and growth of the dicotyledons Lactuca sativa cvs. Roman and Nigra and Lycopersicum esculentum and the monocotyledons Allium cepa and Hordeum vulgare, have been studied. The isoflavones formononetin and cyclosin and the pterocarpan medicarpin have been found to inhibit principally A. cepa germination. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.