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Biomedical subjects

J L McLaughlin

Publications and source records attributed to J L McLaughlin.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

3,3',5'-Tri-O-methylpiceatannol and 4,3',5'-tri-O-methylpiceatannol: improvements over piceatannol in bioactivity.

Piceatannol (3,4,3',5'-tetrahydroxy-trans-stilbene) (NSC 365798) has recently been isolated and was subsequently synthesized for NCI tumor panel testing as a new antileukemic natural product from the seeds of Euphorbia lagascae. During the synthesis, a bioactive reaction mixture of several partially O-methylated piceatannol analogues was obtained. This mixture has now been maximized and subjected to bioactivity-directed fractionation, using brine shrimp lethality, to yield 3,3',5'-tri-O-methylpiceatannol (NSC 381281); this new compound has improved stability and better bioactivity in several systems than piceatannol itself. To confirm the structure, 5 was synthesized from vanillin. In addition, the isovanillin analogue, 4,3',5'-tri-O-methylpiceatannol (NSC 381864), another new compound, was synthesized and found to be bioactive.

Animals↗
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3 beta-O-palmityl longispinogenin from Trichocereus chilensis.

From the aerial parts of Trichocereus chilensis a new triterpenetriol fatty acid ester was isolated. Its structure was shown to be 3 beta-O-palmityl longispinogenin (olean-12-ene-3 beta,16 beta,28-triol-3-palmitate) [1] by chemical and spectroscopic methods. Compound 1 is inactive in brine shrimp lethality and cytotoxicity bioassays.

Acetylation↗
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Bullatacin and bullatacinone: two highly potent bioactive acetogenins from Annona bullata.

Screening of crude extracts of the bark of Annona bullata showed cytotoxic and pesticidal activities. By monitoring with brine-shrimp lethality, two novel, extremely potent acetogenins, bullatacin [1] and bullatacinone [2], were isolated. Spectral and chemical methods identified bullatacin as a diastereomer of asimicin. Bullatacinone represents bullatacin with the lactone cleaved and reformed at the 4-OH. Compounds 1 and 2 show selective cytotoxicities in human tumor cell lines, and certain susceptible cells give ED50 values as low as 10(-12)-10(-15) micrograms/ml. Bullatacin was pesticidal at concentrations as low as 1 ppm, but bullatacinone lacked pesticidal activities. The known compounds liriodenine and (-)-kaur-16-en-19-oic acid were also isolated and were lethal to brine shrimp but were not significantly cytotoxic.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Bioactive compounds from the root of Myrsine africana.

Bioactivity-directed fractionation of the EtOH extract of the roots of Myrsine africana, using lethality to brine shrimp, led to the isolation and identification of emodin and 2-hydroxychrysophanol as cytotoxic components, the latter being a new natural product. Nepodin and 5-methoxy-7-hydroxyphthalide were also isolated but were not significantly cytotoxic.

Anthraquinones↗
PubMedDate not supplied

Inhibition of protein-tyrosine kinase activity by flavanoids and related compounds.

A series of 22 flavanoids and related compounds were tested for their ability to inhibit the activity of a protein-tyrosine kinase purified from bovine thymocytes (p40). Flavones or flavanols with hydroxyl groups at C-5 and C-7 or with three hydroxyl groups on the phenyl ring were potent inhibitors of p40. The replacement of hydroxyl groups with methoxyl groups led to a substantial loss of inhibitory activity. The presence of methoxyl or rhamnosyl substituents at C-3 also abolished inhibitory activity. Kinetic analyses indicated that the flavone apigenin [2] was a competitive inhibitor of p40 with respect to ATP. Flavanones and isoflavones were relatively inactive as protein-tyrosine kinase inhibitors. The isoflavone genistein [17], which has been reported as a potent inhibitor of both pp60(v=src) and the epidermal growth factor receptor, was not an inhibitor of p40.

Animals↗
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Additional toxic, bitter saponins from the seeds of Chenopodium quinoa.

Quinoa (Chenopodium quinoa) is an important Native American food grain. Prior to consumption, the seeds must be washed with H2O to remove bitterness and improve nutritive value. From the warm-H2O extract of quinoa seeds from Mexico, saponins 1-4 were isolated by monitoring the fractionation with brine shrimp lethality and a taste test for bitterness. By chemical, spectral, and enzymatic methods, 1-4 were identified as glycosides of oleanolic acid. Saponin 4, 3-O-[(beta-D-xylopyranosyl)(1----3)]-beta-D-glucuronopyranosyl-6-O -methyl ester]-oleanolic acid, is a new natural compound.

Animals↗
PubMedDate not supplied

Majorenolide and majorynolide: a new pair of cytotoxic and pesticidal alkene-alkyne delta-lactones from Persea major.

From the EtOH extract of the bark of Persea major, two bioactive compounds, majorynolide [1] and majorenolide [2], were isolated by activity-directed fractionation using brine shrimp. Their structures have been elucidated on the basis of spectral data as a pair of new alkene-alkyne delta-lactones, each with an exocyclic alkylidene methine carbon. Both 1 and 2 are moderately cytotoxic, and 2 is selectively pesticidal.

Animals↗
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Goniotriol from Goniothalamus giganteus.

The known styrylpyrone, goniotriol, has been isolated from Goniothalamus giganteus. Its bioactivities are reported, and its structure and relative stereochemistry have been determined by X-ray crystallography as 6R-(7R,8R-dihydro-7,8-dihydroxystyryl)-5S,6R-dihydro-5-hydroxy-2-p yrone.

Animals↗
PubMedDate not supplied

Bullatacin, bullatacinone, and squamone, a new bioactive acetogenin, from the bark of Annona squamosa.

Activity-directed fractionation of the stem bark of Annona squamosa, monitoring with brine shrimp lethality, led to the isolation of the highly bioactive acetogenins bullatacin [1] and bullatacinone [2], thus demonstrating a new abundant plant source for these potent compounds. A new keto-monotetrahydrofuran acetogenin with a ketolactone terminus, as first seen in bullatacinone [2], was also isolated, characterized by spectral analyses, and named squamone [3]. The cytotoxicities of 3 were increased significantly by reduction of the two keto groups to hydroxyls, and the tetrahydrosquamone [7] and bullatacinone [2] both showed selective cytotoxicities to MCF-7 human breast carcinoma. Liriodenine and (-)-kaur-16-en-19-oic acid were also isolated.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Annonaceous acetogenins: a review.

The Annonaceous acetogenins are a series of apparently polyketide-derived fatty acid derivatives that possess tetrahydrofuran rings and a methylated gamma-lactone (sometimes rearranged to a methyl ketolactone) with various hydroxyl, acetoxyl, and/or ketoxyl groups along the hydrocarbon chain. They exhibit a broad range of potent biological activities (cytotoxicity, antitumor, antimalarial, antimicrobial, immunosuppressant, antifeedant, and pesticidal). The sources, isolation, chemistry, biogenesis, and biological actions of these compounds, published to date, are tabulated and discussed. Strategies for structural elucidation are reviewed, and structural revisions and refinements are suggested for some of the previously published compounds.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Tubulosine: an antitumor constituent of Pogonopus speciosus.

From the antitumor-bioactive sap of Pogonopus speciosus, tubulosine [1] was isolated, by activity-directed fractionation using the brine shrimp lethality test, as the major antitumor constituent. 1H-nmr assignments, obtained from HETCOR and COSY, and X-ray crystallographic results are reported for the first time. Psychotrine [2] was also isolated, and its spectral data are also reported.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Additional bioactive heptenes from Melodorum fruticosum.

Four additional new bioactive heptenes, melodorinol [2], homomelodienone [4], 7-hydroxy-6-hydromelodienone [5], and homoisomelodienone [7] have been isolated from Melodorum fruticosum. These compounds were slightly to significantly cytotoxic to human tumor cell lines. Their structures have been determined by comparison of their 1H-nmr, 13C-nmr, and mass spectral data with those of prototype compounds (acetylmelodorinol [1], melodienone 3, and isomelodienone [6]).

Alkenes↗
PubMedDate not supplied

Two new styryl lactones, 9-deoxygoniopypyrone and 7-epi-goniofufurone, from Goniothalamus giganteus.

Two new styryl lactones, 9-deoxygoniopypyrone [1] and 7-epi-goniofufurone [3], and a known styryl lactone, goniodiol [5], were isolated from the stem bark of Goniothalamus giganteus. The structures were elucidated by ir, ms, 1H-nmr, 13C-nmr, and 1H-1H COSY spectra; the relative configurations were determined by X-ray crystallographic analysis. Unlike goniopypyrone [2] and goniofufurone [4], neither of the new styryl lactones 1 and 3 showed significant bioactivities to human tumor cells. However, goniodiol [5] showed significant and selective cytotoxicity against human lung tumor cells (A-549).

Animals↗
PubMedDate not supplied

Bioactive neolignans from Endlicheria dysodantha.

From bioactivity-directed fractionation of the EtOH extract of Endlicheria dysodantha, dysodanthin A and dysodanthin B, which are new hexahydrobenzofuranoid neolignans, have been isolated. In addition, the known neolignans, compound 4, which is a burchellin analogue, and megaphone acetate [1] were isolated. All four neolignans showed activities in the brine shrimp lethality test; compounds 1-3 also inhibited the growth of crown gall tumors on potato discs and were cytotoxic to human tumor cells in culture. This is the first report of these neolignans isolated from the genus Endlicheria and of their completely assigned 1H-and 13C-nmr data.

Animals↗