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Biomedical subjects

N R Farnsworth

Publications and source records attributed to N R Farnsworth.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Plant anticancer agents, XLVI. Cytotoxic casbane-type constituents of Agrostistachys hookeri.

In addition to the previously characterized agrostistachin, three additional cytotoxic macrocyclic casbane-type diterpenes were isolated from a CHCl3 extract of Agrostistachys hookeri, by bioactivity-guided fractionation using the P-388 lymphocytic leukemia cell culture system. These novel compounds, 14-dehydroagrostistachin, 17-hydroxyagrostistachin, and agroskerin, identified by spectral data comparison to agrostistachin and demonstrated ED50 values of 2.8, 0.8, and 1.4 micrograms/ml, respectively, with cultured P-388 cells.

Animals↗
PubMedDate not supplied

Pseudosemiglabrin, a platelet aggregation inhibitor from tephrosia semiglabra.

Following bioassay-directed fractionation procedures, two 7-oxygenated-8-prenylflavones, (-)-pseudosemiglabrin [1] and (-)-semiglabrin [2], were isolated from an MeOH extract of Tephrosia semiglabra. (-)-Pseudosemiglabrin [1] displayed in vitro inhibitory effects on human platelet aggregation.

Flavonoids↗
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Plant anticancer agents, XLVIII. New cytotoxic flavonoids from Muntingia calabura roots.

From a cytotoxic Et2O-soluble extract of Muntingia calabura roots, twelve new flavonoids were isolated, constituting seven flavans 1-7, three flavones 8, 10, and 12, and two biflavans 9 and 11. The structures of compounds 1-12 were established by the interpretation of spectral data, with the nmr assignments of these constituents being based on 1H-1H COSY, 1H-13C HETCOR, and selective INEPT experiments. This is the first report of the occurrence of 7,8-di-O-substituted flavans, biflavans, and flavones. Most of the isolates demonstrated cytotoxic activity when tested against cultured P-388 cells, with the flavans being more active than the flavones. Furthermore, certain of these structurally related flavonoids exhibited somewhat selective activities when evaluated with a number of human cancer cell lines.

Animals↗
PubMedDate not supplied

New cytotoxic lupane lactones from Kokoona ochracea.

Three new compounds, ochraceolides A, B, and C, were isolated from nonpolar extracts derived from Kokoona ochracea stem bark. Based on spectroscopic data, their structures were determined to be the closely related lupane lactones: 3-oxolup-20(29)-en-30,21 alpha-olide, 20,29-epoxy-3-oxolupan-30,21 alpha-olide, and 3,6-dioxolup-20(29)-en-30,21 alpha-olide. Compounds 1 and 3 exhibited significant cytotoxic activity with cultured P-388 cells (ED50 values of 0.26 and 0.53 microgram/ml, respectively) but were at least tenfold less active with a variety of human tumor cell lines. Compound 2 was weakly active with cultured P-388 and KB-3 cells (ED50 values of 7.8 and 5.2 micrograms/ml, respectively), but no significant activity was observed with other human cancer cell types (ED50 values of more than 20 micrograms/ml).

Animals↗
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Potential anticancer agents, XI. X-ray structure determination of acantholide.

The X-ray structure of acantholide, a melampolide sesquiterpene lactone from Acanthospermum glabratum (DC.) Willd. was determined by the aid of direct methods. The compound was cytotoxic but displayed no antitumor activity. Evaluation of the X-ray and NMR data indicated that the same conformation exists in the solid state as in solution.

Antineoplastic Agents, Phytogenic↗
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Alkaloid screening. VI.

One thousand and five plant extracts were screened for the presence of alkaloids. The number of positive tests obtained was 267, or 34.01%. New to the literature are 137 species. In the five previous communications (1-5) in this series we have reported on the screening of 4,990 plant extracts for alkaloids. These 4,990 extracts represented 4,103 species of plants, of which 1,069 gave positive tests.

Alkaloids↗
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Evaluation of Fagara zanthoxyloides root extract in sickle cell anemia blood in vitro.

An aqueous extract was prepared from roots of Fagara zanthoxyloides and examined for evidence of an antisickling effect in vitro. Addition of 25 mg/ml of the extract to fresh blood samples from sickle anemia subjects produced no change in the blood oxygen dissociation curves, and approximately equal percentages of sickled cells were observed at comparable oxygen saturation levels in the presence or absence of the extract. These observations fail to confirm previous reports describing an antisickling effect of root extracts of Fagara zanthoxyloides.

Anemia, Sickle Cell↗
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Akaloid screening. VII.

One thousand and five plant extracts were screened for the presence of alkaloids. The number of positive tests obtained was 190, or 18.91%. There were 153 species found to contain alkaloids that are new to the literature. In the six previous communications (1-6) we have reported on the screening of 5,995 plant extracts for alkaloids. These extracts represented 4,888 species of plants, of which 1,336 gave positive alkaloid tests.

Alkaloids↗
PubMedDate not supplied

Alkaloid screening. VIII.

One thousand plant extracts were screened for the presence of alkaloids. The number of positive tests was 185 (18.5%). There are 107 new alkaloid-containing species.

Alkaloids↗
PubMedDate not supplied

Experimental antitumor agents from plants, 1974-76.

The published literature in the areas of antitumor agents and cocarcinogens, for the years 1974-6 is reviewed. Some of the chemical classes of compounds discussed include tthe sesquiterpene lactones, diterpenes of the phorbol and simaroubolide types, triterpenes of the withanolide and cucurbitacin types, lignans, monomeric and dimeric indole alkaloids, isoquinoline alkaloids, Cephalotaxus alkaloids, camptothecin and the maytansinoids. Emphasis is placed on the isolation, synthesis, biosynthesis and biological activities of the most promising entities.

Alkaloids↗
PubMedDate not supplied

Potential anticancer agents vi. Constituents of Ailanthus excelsa (Simaroubaceae).

Ailanthione (1), glaucarubinone (2) and a mixture of glaucarubol 15-isovalerate (3) and 13,18-dehydroglaucarubol 15-isovalerate (4) were found to be the compounds responsible for the antitumor and cytotoxic activities of extracts of the root bark of Ailanthus excelsa (Simaroubaceae). The latter compound, 4, is new.

Antineoplastic Agents↗