Lespedeza cyrtobotrya

Isol. from heartwood of Lespedeza cyrtobotrya. Brownish needles. Mp 207-208°. 

Isol. from Dolichos biflorus, Lablab niger, Lespedeza cyrtobotrya, Macrotyloma axillare, Ougeinia dalbergiodes, Phaseolus vulgaris and Stizolobium deeringianum (all Leguminosae, Papilionoideae). 

Bowdichione (42) is colored, unlike most isoflavonoids, which are colorless. It is also unique in that it remains the only quinonoid derivative in this series. More numerous are the isoflavanones, of which 39 structures are known. Only some of these occur in woody tissues, such as dihydrodaidzein (43) in Pericopsis montana and dalbergioidin (44) in Lespedeza cyrtobotrya. Isoflavanones have an optically active center at C-3, as do the pterocarpens (e.g. 45-48). Racemization may occur during isolation so that optically inactive forms are sometimes described in the literature. In fact, the absolute configurations of most isoflavanones and pterocarpans have still to be determined. 

Leguminosae they are also commonly formed in leaf tissue as phytoalexins, in response to microbial infection (21). TWo structural types closely related to the isoflavans are the isoflavan quinones and the isoflavenes. Examples are mucro-quinone (51) from woods of Machaerium mucronulatum and Cyclolobium claus-seni, and haginins B and D (52a, 52b) from wood of Lespedeza cyrtobotrya. 

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