F. Rodriguez Luis

Guaianolides from Centaurea canariensis

Abstract The reinvestigation of Centaurea canariensis var. subexpinnata provided, along with three known compounds, three new sesquiterpene lactones of the guaiane series.

An acidic xyloglucan from grape skins

Abstract The structure of one hemicellulose A fraction (A-1) isolated from grape skins ( Vitis vinifera ) of the Palomino variety has been studied by methylation analysis, NMR spectroscopy and partial acid hydrolysis. Hemicellulose A-1 appeared to be homogeneous with a weight-average M r of 35 544. It was shown to be a linear acidic xyloglucan constituted by a linear chain of xylopyranosyl and glucopyranosyl residues linked by β-(1 → 4) glycosidic bonds containing 4- O -methylglucuronopyranosy acid, l -arabinofuranosyl and xylopyranosyl residues attached at position 2, in a ratio of one residue for every 10 units of xylose in the main chain, and l -arabinofuranosyl and glucopyranosyl residues attached at position 6 of the units of glucose, in a ratio of one residue for every four glucoses in the main chain.

Flavonoids from Artemisia lanata

Abstract A new flavonoid, gossypetin-7,8,3′,4′-tetramethyl ether (3,5-dihydroxy-7,8,3′,4′-tetramethoxyflavone) was isolated and its structure elucidated by chemical and spectroscopic methods. The known flavonoids 5-hydroxy-6,7,3′,4′-tetramethoxyflavone and artemetin were also isolated. Chemical transformations led to the conclusion that the structure previously reported as ‘8,3′,4′-trimethoxyizalpinin’ (3,5-dihydroxy-7,8,3′,4′-tetramethoxyflavone) must be the isomer quercetagetin 6,7,3′,4′-tetramethyl ether (3,5-dihydroxy-6,7,3′,4′-tetramethoxyflavone).

Integrifolin, a guaianolide from Andryala integrifolia

Abstract Integrifolin, the major constituent of Andryala integrifolia , has been isolated and characterized as 3β,8β-dihydroxy-4(15),10(14),11(13)-trien-(1αH), (5αH) guaian-6,12-olide (8-epi-desacylcynaropicrin).

Structure, chemistry and stereochemistry of clementeins, sesquiterpene lactones from centaurea clementei

The stereochemistry of clementein (1) (the first oxetane-containing sesquiterpene lactone) is determined to be 16(S) on the basis of chemical and spectroscopic data. Clementeins B (2) and C (3), isolated from the same source (Centaurea clementei D.C.) were shown to be closely related guaianolides,with an 11,13-oxetane ring. A number of chemical transformations on the oxetane in 2 and 3 have been accomplished.

Four aromatic derivatives from Ruta angustifolia

Abstract A new group of four shikimate metabolites have been isolated from aerial parts of Ruta angustifolia and their structures deduced from IR, 1 H NMR, 13 C NMR and MS data. They have been named moskachans.

Mariolin, a germacranolide from Anacyclus radiatus☆

Abstract A new sesquiterpene lactone, the germacranolide mariolin, was isolated from the aerial part of Anacyclus radiatus along with several known compounds. The structure of mariolin was determined by spectroscopic methods.