Alfonso Romo de Vivar

Mode of action of Buddleja cordata verbascoside against Staphylococcus aureus.

We evaluate the mode of action of verbascoside obtained from Buddleja cordata against Staphylococcus aureus by killing kinetics and incorporation of precursors methods. Verbascoside induced lethal effect on S. aureus, by affecting protein synthesis and inhibiting leucine incorporation.

The germacranolides of Viguiera buddleiaeformis structures of budlein-A and -B

Abstract The structure of budlein-A, the main sesquiterpene lactone of Viguiera buddleiaeformis was established as the 8 angeloyl ester of 1 keto, 8-β, 14-dihydroxy germacra-2,4,11 (13)-trien-3, (10 β) oxido-6 α, 12-olide. Its structure and stereochemistry was determined by chemical and spectroscopic means. Budlein-B, found in the same plant as a minor constituent, is 8 α, 15-dihydroxygermacra-1 (10), 4, 11 (13)-trien-6 α, 12-olide.

Sesquiterpene lactones from Viguiera species

Abstract Viguiera eriophora yielded the sesquiterpene lactones erioflorin, acetylerioflorin and 17,18-dehydroviguiepinin, which was correlated with tetrahyd

Sesquiterpene lactones of Artemisia mexicana var. Angustifolia

Abstract Seven eudesmanolides were isolated and characterized from Artemisia mexicana var. angustifolia . These included arglanin, artemexifolin, ludalbin, santamarine and three new compounds named 8α-acetoxyarmexifolin, α-epoxyludalbin and armefolin. The structure of armexifolin is revised.

Terpenoids and a flavan-3-ol from viguiera quinqueradiata

Abstract The isolation is reported of the new natural products from Viguiera quinqueradiata, acetylleptocarpin and (2R,3S-4′-hydroxy-3′,5,7-tri-O-methyl-flavan-3-ol. The diterpenes 15α-angeloyloxy-ent-kaur-16-en-19-oic acid, 15α-tigloyloxy-ent-kaur-16-en-19-oic acid and the sesquiterpene lactones leptocarpin and budlein A were also found.

Viguilenin, a germacranolide from Viguiera linearis

Abstract The new germacranolide, viguilenin, was isolated from Viguiera linearis and its structure was established by chemical and spectroscopic means.

Eremophilanolides from Senecio toluccanus var. modestus.

Abstract Senecio toluccanus var. modestus afforded four new eremophilanolides whose structures and absolute stereochemistry were determined by spectroscopic methods and chemical transformations. An X-ray analysis of toluccanolide C was performed.

13C-N.M.R. characterizations of the sarsasapogenin disaccharides, the filiferins a and b: 2-O-(β-d-xylopyranosyl)- and 2-O(β-d-glucopyranosyl)-β-d-galactopyranosides

Abstract Filiferin B is identical to timosaponin A-III, which had previously been shown to be 3- O -[2- O -(β- d -glucopyranosyl)-β- d -galactopyranosyl]sarsasapogenin. A larger-scale isolation of filiferin B from the seeds of Yucca filifera led to the isolation of filiferin A, now shown to be 3- O -[2- O -β- d -xylopyranosyl)-β- d -galactopyranosyl]-sarsasapogenin. The presence of the xylose residue was established by way of hydrolysis. 8-Methoxycarbonyloctyl 2- O -(β- d -glucopyranosyl)-β- d -galactopyranoside was synthesized to serve as a model for interpretation of the 13 C-n.m.r. spectrum of filiferin B. The information thus gained, together with the 13 C-n.m.r. spectra of other, simple model-compounds, permitted assignment of the structure for filiferin A. 8-Methoxycarbonyloctyl 2- O -(α- d -glucopyranosyl)-β- d -galactopyranoside was also synthesized.

Diterpenoids from Viguiera insignis

Abstract The isolation of several known diterpenoids and one new diterpene diol from aerial parts of Viguiera insignis is reported.

Sesquiterpene lactones of artemisia klotzchiana

Abstract Six sesquiterpene lactones and two flavones were isolated and characterized from Artemisia klotzchiana. These included chrysartemin A, matricarin, desacetyl matricarin, ridentin, hanphyllin, jaceosidin, sudatichin and the new guaianolide chloroklotzchin, which is a halogenated lactone. The X-ray structure of hanphyllin is reported.