Flavonoids as chemotaxonomic markers for cultivated Amazonian coca

Purported ‘Amazonian coca,’ Erythroxylum coca var. ipadu Plowman (E. coca var. ipadu) was harvested from cultivated fields in Colombia, South America to determine: (a) its identity; (b) if its leaf flavonoids were complimentary to those present in leaf tissue of E. c. var. ipadu in our collection derived from Colombia; and (c) if complimentary, indicative of kinship to E. coca var. ipadu obtained from Colombia, or a related Erythroxylum taxon. Leaf extracts from Amazonian field-grown coca afforded eight O-conjugated flavonoids: two O-conjugates of taxifolin, one O-conjugate of quercetin, two O-conjugates of eriodictyol and three O-conjugates of kaempferol. Present also in leaf tissue of Amazonian field-grown coca, but lacking in leaf tissue from our collection of E. c. var. ipadu was an O-ethyl ester typically found in E. coca var. coca, kaempferols and a 7-O-rutinoside commonly encountered in the E. novogranatense taxons. Flavonoids found in our collection of E. coca var. ipadu were five O-conjugated derivatives of taxifolin and an O-conjugated quercetin. Leaf flavonoids of currently cultivated Amazonian coca are a mixture of those present in E. coca var. coca, E. coca var. ipadu and E. novogranatense var. truxillense, whereas those present in our authenticated living collection are derivatives of E. coca var. coca. Our data suggest that the Amazonian coca under cultivation in Colombia is a genetic hybrid cross between E. coca var. coca and E. novogranatense var. truxillense, occurring after 1972.