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Biomedical subjects

N R Farnsworth

Publications and source records attributed to N R Farnsworth.

At least 217 records · Page 12Linked to original sources
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Plant anticancer agents. XIX Constituents of Aquilaria malaccensis.

The stem bark of the Thai tree Aquilaria malaccensis (Thymelaeaceae) has afforded 1,3-dibehenyl-2-ferulyl glyceride (3), which is novel, and 12-O-n-deca- 2, 4, 6-trienoylphorbol-13-acetate (4). The structures of these cytotoxic compounds were elucidated by their spectral and chemical parameters.

Animals↗
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Potential sweetening agents of plant origin. III. Organoleptic evaluation of Stevia leaf herbarium samples for sweetness.

A total of 184 Stevia leaf samples taken from herbarium specimens, representing 110 species and 121 taxa, were screened organoleptically for their taste sensation. Fragments of a 62-year-old leaf of S. rebaudiana exhibited a potent and prolonged sensation of sweetness, thereby indicating the stability of its sweet ent-kaurene glycoside constituents to drying, preservation, mounting and storage. No other leaf samples exhibited an intensity of sweetness equivalent to that of S. rebaudiana, though 18 species and varieties were considered to exhibit a sweet taste. These taxa appear to be promising candidates for future phytochemical investigation for new and known ent-kaurene glycosides.

Glycosides↗
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Plant anticancer agents. XXIII. 6 alpha-senecioyloxychaparrin, a new antileukemic quassinoid from Simaba multiflora.

Fractionation of an aqueous ethanol extract of the wood of Simaba multiflora afforded a new antineoplastic quassinoid, 6 alpha-senecioyloxychaparrin (5), and two known quassinoids 6 alpha-senecioyloxychaparrinone (1) and chaparrinone (2). The structure of 5, which displayed activity against the KB and P-388 test systems, was established through the interpretation of spectral data.

Acetylation↗
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Plant anticancer agents. XXIV. Alkaloid constituents of Simaba multiflora.

Two new cytotoxic canthin-6-ones, 10-methoxycanthin-6-one (1) and 10-hydroxycanthin-6-one (2) were isolated from the wood of Simaba multiflora (Simaroubaceae). Three canthin-2,6-dione (3), 3-methoxycanthin-2,6-dione (4) and canthin-2,6-dione (5), as well as scopoletin (7) and the novel coumarino-lignan cleomiscosin A (6) were also obtained.

Acetylation↗
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Plant anticancer agents. XXVI. Constituents of Peddiea fischeri.

The in vitro P-388 lymphocytic leukemia activity of the chloroform-soluble fraction of the roots of Peddiea fischeri (Thymelaceaceae) was found to be due principally to the quinone 2,6-dimethoxybenzoquinone (2,6-DMBQ), and to a lesser extent the two coumarins daphnoretin and umbelliferone. This is the first report of the occurrence of 2,6-DMBQ in the family Thymelaeaceae. The occurrence of 2,6-DMBQ in higher plants is reviewed.

Animals↗
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Plant anticancer agents XXV. Constituents of Soulamea soulameoides.

Three simaroubolides, glaucarubolone (1), holacanthone (2), and isobrucein A (3) were found to be responsible for the cytotoxic and antileukemic activities observed for extracts of the wood stem, stem bark, and twigs of Soulamea soulameoides. Other cytotoxic constituents isolated include a coumarinolignan cleomiscosin A (4) and the hydroxy canthin-6-one derivative 5. Picrasin B (6) was also obtained, but was not active.

Acetylation↗
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High-field 1H-NMR spectral analysis of some cucurbitacins.

1H-nmr spectra of the natural products cucurbitacins A, B, C, D, E, F, I, L, 23, 24-dihydrocucurbitacin F, and hexanorcucurbitacin F, as well as three acetylated derivatives, were measured at 360 MHz in pyridine-d5. Chemical shifts and coupling constants were tabulated. In addition to all of the ring and side-chain protons, it was possible to assign several of the hydroxy group signals of these compounds. These compiled data should be useful for the structure determination of new compounds in this series.

Cucurbitacins↗
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Plant anticancer agents XLIV. Cytotoxic constituents from Stizophyllum riparium.

Bioactivity-guided fractionation of a CHCl3 extract of Stizophyllum riparium has afforded six new compounds, namely, the triterpene esters, 3 beta-hydroxy-24-transferulyloxyurs-12-en-28-oic acid, 3 beta-hydroxy-24-cis-ferulyloxyurs-12-en-28-oic acid, 3 beta, 19-dihydroxy-24-trans-ferulyloxyurs-12-en-28-oic acid, and the pregnane derivatives, 2 alpha, 3 beta, 12 beta-trihydroxypregna-4,7,16-trien-20-one, 2 alpha, 3 beta, 12 beta-trihydroxypregna-4,7-dien-20-one, and 16 alpha-methoxy-2 alpha, 3 beta, 12 beta-trihydroxypregna-4,7-dien-20-one. The structures of these isolates were established by spectroscopic and chemical methods. Compounds 1, 2, and 4 exhibited cytotoxic activity against the P-388 lymphocytic leukemia test system in cell culture.

Animals↗
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Irisones A and B: two new isoflavones from Iris missouriensis.

Two new isoflavones, irisones A and B, together with the known compound, 5,7-dihydroxy-2',6-dimethoxy isoflavone, were isolated from the roots of Iris missouriensis. With the help of 2D-homonuclear-J-correlation and 2D-nOe experiments the structure of irisone A was deduced to be 5-hydroxy-2'-methoxy-6,7-methylenedioxy isoflavone. The structure of irisone B was elucidated by spectral analyses as 2',5-dihydroxy-6,7-methylenedioxy isoflavone and was confirmed by chemical conversion to irisone A.

Animals↗