Submitted to: Biochemical Systematics and Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/22/2001
Publication Date: N/A
Citation: Interpretive Summary: There are four species of coca (for example Erythroxylum coca var. ipadu Plowman) cultivated in South America to produce cocaine and traditional medicines. The flavonoids found in their leaves have been determined useful markers for their identification. Leaves harvested from coca fields currently under cultivation in Colombia were distinctly different from leaves of plants previously obtained from Colombia (1978) in our collection. Research was conducted to determine if leaf flavonoids in our collection differed from those in fields under cultivation in Colombia. To do this, leaves were harvested from plants in a secured greenhouse and field site, and fields in Colombia during the fall of 1996 and 1997, and extracted overnight with 70% methanol for flavonoids. Leaf flavonoid profiles were determined by high-pressure liquid chromatography and the flavonoids identified by gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry and nuclear magnetic resonance. Flavonoids in leaves of coca growing in fields of Colombia differed from those in our collection and appear to result from a cross occurring since 1978. The flavonoids of Colombian field grown coca were mixtures of E. coca, E, ipadu and E. novo. truxillense, whereas those in our living collection were derivates of E. coca. These findings are invaluable to researchers, private industry, and government action agencies interested in species identification.
Technical Abstract: Erythroxylum coca var. ipadu Plowman (E. c. var. ipadu; Amazonian coca) leaves were harvested from fields in Colombia, South America (S. A.), 1997 to: (i) determine if their flavonoid profiles were complementary to those of our collection and (ii) determine if the leaf flavonoids could be indicative of kinship to a specific taxon(s) of cultivated Erythroxylum. Polar methanolic extracts from leaf tissue of Amazonian coca harvested from fields in Colombia S. A., were assayed by HPLC, GC-MS, LC-MS and 1H NMR to determine the flavonoid profile and O-conjugation of aglycones. The leaf extracts 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 field grown E. c. var. ipadu, but lacking in leaf tissue from our collection, was an O-ethyl ester (typically found in E. c. var. coca), kaempferols and a O-7-rutinoside commonly encountered in the E. novogranatense taxons. Flavonoids in our collection of Amazonian coca, obtained from Colombia, S. A., contained five O-conjugated derivatives of taxifolin and an O-conjugated quercetin. The flavonoids of E. c. var. ipadu currently under cultivation fields in Colombia are a mixture of those present in E. c. var. coca, E. c. var. ipadu and E. n. var. truxillense, whereas the flavonoids present in our living collection of E. c. var. ipadu are derivates of E. c. var. coca. Our data strongly suggest that E. c. var. ipadu currently under cultivation in Colombian fields is a genetic hybrid between E. c. var. coca and E. n. var truxillense. We propose that this hybridization occurred after the late 1970's.