Glycoside primers of Psittacanthus cucullaris.

Bioassay-directed chromatographic separation of the ethyl acetate extract of the whole plant of Psittacanthus cucullaris afforded a new phenolic xyloside, ellagic acid-4-O-beta-xyloside-3,3', 4'-trimethyl ether (1) together with four known compounds, ellagic acid-4-O-beta-xyloside-3,3'-dimethyl ether (2), gallic acid, beta-sitosterol, and beta-sitosterol beta-D-glucoside. The structure of the new compound was determined by spectroscopic methods. Like other beta-D-xylosides, compounds 1 and 2 stimulated the formation of glycosaminoglycan chains when fed to the cultured Chinese hamster ovary cells.

Primers of glycosaminoglycan biosynthesis from Peruvian rain forest plants.

We have developed a rapid, high throughput screening assay for compounds that alter the assembly of glycosaminoglycan chains in Chinese hamster ovary cells. The assay uses autoradiography to measure the binding of newly synthesized [35S]proteoglycans and [35S]glycosaminoglycans to a positively charged membrane. Screening over 1000 extracts from a random plant collection obtained from the Amazon rain forest yielded five plants that stimulated glycosaminoglycan assembly in both wild-type cells and a mutant cell line defective in xylosyltransferase (the first committed enzyme involved in glycosaminoglycan biosynthesis). Fractionation of an extract of Maieta guianensis by silica gel and reverse-phase chromatography yielded two pure compounds with stimulatory activity. Spectroscopic analysis by NMR and mass spectrometry revealed that the active principles were xylosides of dimethylated ellagic acid. One of the compounds also contained a galloyl group at C-3 of the xylose moiety. These findings suggest that plants and other natural products may be a source of agents that can potentially alter glycosaminoglycan and proteoglycan formation in animal cells.