Submitted to: Plant Physiology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2001
Publication Date: N/A
Interpretive Summary: There are two species and four varieties of coca cultivated in the Andes and Amazonian regions of South America for cocaine and traditional medicines. Flavonoids in their leaves have been determined useful markers for their identification. Leaves harvested from coca fields in the Colombian Amazon contained a different flavonoid which is not present in the other three varieties of coca. Research was conducted to determine if the flavonoids in Colombian Amazon coca were the same as those in leaves of coca in our collection from the Amazon region. To do this, leaves were harvested from Colombian fields and our collection in a secured greenhouse in 1998 - 1999, and extracted overnight with 72 percent methanol for flavonoids. Leaf flavonoid profiles were determined by high performance liquid chromatography and identified by gas chromatography mass spectrometry, liquid chromatography-mass spectrometry and nuclear magnetic resonance. Colombian field-grown coca had flavonoids which differed from those in our collection, with one completely unique flavonol. The flavonol of Colombian field-grown coca that was unique was a kaempferol and a distinct marker. Other flavonoids indicated that it is a mixture of those found in E.c. var.coca, E. c. var. ipadu and E. n. var. truxillense. These findings are valuable to researchers, private industry, and government action agencies that are interested in species identification and traditional medicines.
Technical Abstract: Erythroxylum coca var. ipadu Plowman (E. c. var. ipadu; Amazonian coca) leaves were harvested from fields in Colombia, South America to determine: (a) their leaf flavonoid profile, (b) their similarity or difference to those present in our living collection of the taxon and, (c) the usefulness of the discovered flavonoids as chemotaxonomic markers for the taxon. High performance liquid chromatography was used to separate the flavonoids while spectral analyses with gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and nuclear magnetic resonance spectrometry were used for their identification. A new flavonol was found and isolated from leaf tissue of Amazonian field-grown coca (Erythroxylum coca var. ipadu Plowman) that has not been reported. The structure of the flavonol was determined to be kaempferol 4'-O-rhamnoglucoside. The array of flavonoids present in E. c. var. ipadu is indicative and consistent with ancestralship to E. c. var. coca. However, because of its array of flavonoids, our finding strongly suggests that it is a genetic hybrid of a cross between E. c. var. coca and E. n. var. truxillense. The new flavonol is useful as a chemotaxonomic marker for the taxon.