Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 18, 1999
Publication Date: N/A
Interpretive Summary: The current research determined whether flavonoids in the methanolic (polar) extracts from dried leaves of Erythroxylum ulei O. E. Schulz (E. ulei), a native tropical South American species, could be used as chemotaxonomic markers for the species. Leaves of the E. ulei were soaked overnight in a 72% methanol solution and flavonoids identified by HPLC, EI-MS and H NMR. HPLC separation of the methanol extract from E. ulei yielded six flavonoids. Three of the flavonoids were isoflavones, two were isoflavanones and the remainder a flavonol (quercetin). The primary differences in flavonoid HPLC retention times among E. ulei was due to the chemical composition of structures on the parent molecule and the site(s) of location thereon. The six E. ulei O-conjugated flavonoids maybe used as chemotaxonomic markers for the taxa. Results of the current study are invaluable to plant scientists, the pharmaceutical industry, bio-technology, medicinal plant researchers, DEA, CNC, NIH and forensic researchers for identifying the taxa and assaying the flavonoids as bioactive compounds.
Technical Abstract: In the current study, leaves of Erythroxylum ulei O. E. Schulz (E. ulei), a feral Neo-tropical South American species were harvested from greenhouse grown plants at BARC, Beltsville, MD (late summer and fall 1997). Polar leaf extracts from dried leaves of the taxon were assayed for flavonoids to determine if they could be used as chemotaxonomic markers. The dried leaves were extracted overnight in 72% methanol, filtered and separated the following day by HPLC. HPLC separation of the polar leaf extracts of E. ulei afforded six O-conjugated flavonoid aglycones. Three of the flavonoid aglycones were isoflavones, two were isoflavanones and the remainder a flavonol (quercetin). The major glycosides of these flavones included mono-and- dirhamnosides, mono-glucosides and galactosides with either 3', 4', 7 linkage or a combination thereof. Two of the isoflavanones, in addition to being glycosylated, possessed a methyl group at position 2 of the C-ring. Leaf flavonoid structures were confirmed by their 1H NMR spectra and differed from flavonoids of the four cultivated taxa of Erythroxylum. Therefore, the six E. ulei O-conjugated flavonoids may be used as chemotaxonomic markers for the taxon.