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Biomedical subjects

G Montenegro

Publications and source records attributed to G Montenegro.

18 recordsLinked to original sources
PubMed2001

Inhibition of Mycobacterium tuberculosis growth by saringosterol from Lessonia nigrescens.

Assay-guided fractionation of an antitubercular extract obtained from Lessonia nigrescens yielded the phytosterol saringosterol as its active component. No appreciable toxicity against Vero cells was observed for this compound. Saringosterol was also synthesized by oxidation of fucosterol. The MIC values for antitubercular activity of saringosterol and its 24S and 24R epimers were determined as 0.25, 1, and 0.125 microg/mL.

Animals↗
PubMed2000

Synthesis and biological studies of glycosyl dopamine derivatives as potential antiparkinsonian agents.

A new approach to deliver dopamine into the central nervous system, based on the use of D-glucose as transportable agent, has been studied. Glycosyl dopamine derivatives bearing the sugar moiety linked to either the amino group or the catechol ring of dopamine through amide, ester or glycosidic bonds were synthesised as potential antiparkinsonian agents. Studies on the binding to dopamine D2 receptor, in vitro stability, and locomotive effect in mice of the synthetic glycoconjugates are reported.

Animals↗
PubMed2000

Two novel flavanones from Greigia sphacelata.

As part of our continuing phytochemical investigations of plants from arid environments in Chile, the aerial parts of Greigia sphacelata were examined. Two novel flavanones, 5,7,3'-trihydroxy-6, 4',5'-trimethoxyflavanone (1) and 5,3'-dihydroxy-6,7,4', 5'-tetramethoxyflavanone (2), as well as eight known compounds-1, 3-O-di-trans-p-coumaroylglycerol (3), 1-O-trans-p-coumaroylglycerol (4), a mixture of 1-(omega-feruloyldocosanoyl)glycerol (5) and 1-(omega-feruloyltetracosanoyl)glycerol (6), trans-ferulic acid 22-hydroxydocosanoic acid ester (7), arborinone (8), arborinol (9), and isoarborinol (10)-were isolated.

Flavanones↗
PubMed1999

Pentacyclic triterpenes from Chuquiraga ulicina.

Four taraxastane triterpenes, 3 beta-acetoxy-6 beta-hydroxytaraxasta-20-ene, 6 beta-hydroxytaraxasta-20-en-3-one, 6 beta-hydroxytaraxasta-20-ene 3 beta-palmitate and 3 beta,6 beta-dihydroxytaraxasta-20-ene were isolated from the dichloromethane-methanol extract of Chuquiraga ulicina ssp. ulicina together with the known triterpenes lupeol, lupenyl acetate, lupenone, friedelinol, 3 beta-acetoxy-30-nor-lupan-20-one, and 30-nor-lupan-3 beta-ol-20-one.

Chile↗
PubMed1999

Antitubercular activity of pentacyclic triterpenoids from plants of Argentina and Chile.

Screening of plants from South America for antitubercular activity and subsequent assay-guided fractionation resulted in the isolation and characterization of several pentacyclic triterpenoids. The MIC values of 22 triterpenoids were determined using the radiorespiratory BACTEC assay and range from 8 microM to above 128 microM. The structure-activity relationships are discussed.

Antitubercular Agents↗
PubMed1999

Diterpenoids from Baccharis pingraea.

From the aerial parts of Baccharis pingraea the known furolabdane, angeloyl-gutierrezianolic acid (1); two novel diterpenoids, furolabda-6,8-dien-17-oic acid (2) and furolabd-7-en-17-oic acid (3); and the known linear diterpenoid, (10E)-centipedic acid (4), were isolated. LC/MS suggested the presence of gutierrezianolic acid (5). The structures of the new compounds were elucidated by 1D and 2D NMR methods.

Asteraceae↗
PubMed1999

Antibacterial diterpenoid acids from Azorella compacta.

The two novel diterpenoid acids mulin-12,14-dien-11-on-20-oic acid (1) and mulin-12-ene-11,14-dion-20-oic acid (2) have been isolated from Azorella compacta. Their structures have been elucidated by 1D and 2D NMR methods. In contrast to the closely related known mulinolic acid (3) and its dehydration product (4) these new natural products have been shown to exhibit antimicrobial activity.

Anti-Bacterial Agents↗
PubMed1999

Flavonoids and terpenoids from Luma gayana (Barn.) Burret.

The flavonoids 5-hydroxy-7-methoxyflavanone, 6,8-dimethyl-5,7-dihydroxyflavanone and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone, a mixture of alkyl esters of p-coumaric acid, the triterpenoids oleanolic acid and maslinic acid, the monoterpenoid 1 alpha,2 beta,4 beta-trihydroxy-p-menthane, the sesquiterpenoid clovandiol and beta-sitosterol were isolated from the aerial parts of Luma gayana (Barn.) Burret. This is the first report on the chemistry of this species.

Chile↗
PubMed1998

Lignans from Chilean propolis.

Three new (1, 3, 4) and two known lignans (2 and 5) were isolated from Chilean propolis. Compound 1 was identified as a trimeric coniferyl alcohol acetate and 3 as the diastereomer of the dimeric coniferyl alcohol acetate 2. Compound 4 was identified as a dihydrobenzofuran lignan aldehyde, which was isolated together with the related known acetate 5.

Chile↗
PubMed1998

A new antitubercular mulinane diterpenoid from Azorella madreporica Clos.

Bioactivity-guided fractionation of the petroleum ether extract of Azorella madreporica Clos has led to the isolation of the novel, antitubercular mulinane diterpenoid 1. The structure has been elucidated on the basis of its 1D and 2D NMR spectra and by comparison with mulinolic acid 2 and a dehydration product 3 obtained from 1. The MIC of 1 for growth inhibition of the H37Rv strain of Mycobacterium tuberculosis was determined as 20 microg/mL. LC-MS and NMR have suggested the presence of this new compound in four other species of Azorella.

Antitubercular Agents↗
PubMed1993

[Bioessay with brine Artemia to predict antibacterial and pharmacologic activity].

The Brine Shrimp Test (BST) is a simple and inexpensive method to test cytotoxity, to biodirect phytochemical fractionation of natural products and as a predictor for antitumor and pesticidal activity. In this work, the BST test, an antibacterial test and the rat hippocratic screening test were used on 25 plant extracts and fractions, to evaluate the correlation, if any, between the BST and the others. Preliminary results show that the BST is not a predictor of antibacterial activity nor the hippocratic screening test.

Animals↗
PubMedDate not supplied

Triterpenoids from Acaena pinnatifida R. et P.

Eight urs-12-ene triterpenoids, beta-sitosterol, (+)-catechin, and apigenin 7-O-glucoside were isolated from the leaves of Acaena pinnatifida R. et P. The triterpenoids were characterized as pomolic acid, pomolic acid-3-acetate, tormentic acid, 2-epi-tormentic acid, euscaphic acid, tormentic acid glucoside, niga-ichigoside F1, and niga-ichigoside F2.

Chile↗
PubMedDate not supplied

Phytochemical, morphological, and biological investigations of propolis from Central Chile.

Propolis from central Chile was investigated for its plant origin by microscopical analysis of pollen grains and leaf fragments found in the sample. The pollen grains that appear with significant higher frequency in the sample corresponded to four native and two introduced species, whereas leaf fragments corresponded to four native species. Seventeen phenolic compounds that belong to the phenylpropane, benzaldehyde, dihydrobenzofuran, or benzopyran classes, were isolated from an organic extract that was found to have a moderate growth inhibitory activity against Mycobacterium avium, M. tuberculosis, and two strains of Staphylococcus aureus. The components responsible for activity were determined.

Animals↗
PubMedDate not supplied

Propolis from Chilean matorral hives.

Viscidone (0.5%), vanillin, 3',4'-(methylendioxy)acetophenone, 3-ethoxy-4-methoxybenzaldehyde, cinnamic acid, 3-methoxy-4-hydroxymethyl ester were isolated from propolis of hives from Cuncumen. This is the first report on propolis composition of an arid and a Mediterranean type climate area.

Animals↗
PubMedDate not supplied

Iridoids from Stachys grandidentata (Labiatae).

Monomelittoside, melittoside, 8-acetyl-harpagide, harpagide, ajugol, 5-desoxy-harpagide, 5-desoxy-8-acetylharpagide and catalpol were isolated from the aerial parts of S. grandidentata.

Bridged Bicyclo Compounds, Heterocyclic↗