myricetin and cirsimarin

Several plants collected through different approaches were screened on distinct receptors using ligand-binding studies as bioassay. Extracts of Microtea debilis showed high activity on adenosine A1 receptors. Bioassay-guided fractionation using ligand-binding studies resulted in the isolation of an adenosine A1 active ligand, cirsimarin (cirsimaritin 4'-O-glucoside). GTP did not influence the radioligand inhibition curve of cirsimarin, indicating that this compound is acting as an antagonist at the adenosine-A1 receptors. The use of this plant against "proteinuria" in traditional medicine in Suriname (South America) may be explained by the adenosine A1 antagonistic action of cirsimarin. A series of flavonoids was tested in the same assay, but they were less active. No structure-activity relationship could be observed.

Topics: Animals; Flavones; Flavonoids; Glycosides; In Vitro Techniques; Ligands; Magnetic Resonance Spectroscopy; Mass Spectrometry; Membranes; Plant Extracts; Prosencephalon; Purinergic P1 Receptor Antagonists; Radioligand Assay; Rats; Receptors, Purinergic P1; Spectrophotometry, Ultraviolet; Suriname; Xanthines