Flavonoids isolating from leguminous plants

Flavonoids are ubiquitous in all terrestrial plants (except the Anthoceropsidae) but the distribution of isoflavonoids among plants is relatively sparse, probably owing to the sporadic occurrence of the enzyme isoflavone synthasa that stabilises, by an aryl migration, the isoflavonoid skeleton. Accordingly, most of the isoflavonoids have been isolated from leguminous plants [3]. 

Iwamura (1984) designed a process for isolating saponins and flavonoids from leguminous plants, including seed, leaf, root, stem, stalk, flower or the entire plant. Alkaline extract, which was clarified by acid precipitation to get rid of proteins, followed by filtration or centrifugation, was applied to a nonpolar resin (styrene-vinyl benzene) or a slightly polar resin (such as acrylic ester resin). Water was used to elute soluble sugars, then the column was eluted with methanol to obtain a mixture of saponins and flavonoids. These two compounds were separated by acetone extraction to yield isoflavones in the soluble fraction. 

Iwamura, J. 1984. Process for isolating saponins and flavonoids from leguminous plants. US patent 4,428,876. January 31, 1984. 

Triterpenoids (including triterpenoid glycosides) are also widely distributed in plants kingdom as well as flavonoids. For searching new anti-tumor-promoters from natural resources, we have also been researching on triterpenoids rich plants which have been used for medicinal purpose in several countries. For a start, from Leguminous plants, many kinds of oleanene type triterpenoid saponins had been isolated and their anti-tumor-promoting activities were examined. 

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