Comparative phytochemistry of eleven species of Vigna (Fabaceae)

A survey of the biochemical constituents of 11 species of Vigna indicates the absence of the non-protein amino acid canavanine in their seeds, and absence of proanthocyanidin (polyphenol) in their leaves. Proanthocyanidin was found in the seeds of all, except Vigna subterranea. The constitutive leaf flavonoids of four genotypes of the pantropic V. subterranea were also studied and compared with those from three other cultivated species. The flavonoid kaempferol seems to be most prevalent as it was found in all of the four cultivated species and genotypes. The glycoside kaempferol-3-O-rutinoside was found present in the four genotypes of V. subterranea and other cultivated Vigna species. However, the flavonoid kaempferol-3-O-glucoside-7-rhamnoside is restricted to V. subterranea. This study questions the inclusion of V. subterranea in the genus Vigna on account of absence of seed proanthocyanidin and restricted accumulation of kaempferol-3-O-glucoside-7-rhamnoside in the leaves.