Showing papers by "Norman R. Farnsworth published in 1994"
TL;DR: Two new dibenzylbutadiene lignans isolated from Anogeissus acuminata were identified as the active HIV-1 reverse transcriptase (RT) inhibitory constituents of this plant obtained by bioassay-guided fractionation.
Abstract: Anolignan A [1] and anolignan B [3] are new dibenzylbutadiene lignans isolated from Anogeissus acuminata. Compounds 1 and 3 were identified as the active HIV-1 reverse transcriptase (RT) inhibitory constituents of this plant obtained by bioassay-guided fractionation. Compound 3, which was very weakly active when tested alone, showed high activity when combined with 1. The activity of 1 was likewise enhanced in the presence of 3. A concave isobole obtained from a plot of data derived from assays with 1 and 3 in combination indicated their synergistic effects. Another new lignan, anolignan C [5], and a known lignan, (-)-secoisolariciresinol [10], were also isolated from this plant. Compounds 5 and 10 did not have activity against HIV-1 RT. Compounds 1, 3 and 5 were either weakly cytotoxic or noncytotoxic when tested in various cancer cell lines. The structures of 1-5 and 10 were established by spectroscopic methods, especially by 1D and 2D nmr experiments.
73 citations
TL;DR: The quinone-methide triterpenes 1-3 exhibited strong but non-specific in vitro cytotoxicity against P-388 murine lymphocytic leukemia cells and a panel of human cancer cell lines.
Abstract: Tingenone [1], 20-hydroxy-20-epi-tingenone [2], celastrol [3], and salaspermic acid [4] have been isolated from Kokoona ochracea stem bark. The quinone-methide trirerpenes 1-3exhibited strong but non-specific in vitro cytotoxicity against P-388 murine lymphocytic leukemia cells and a panel of human cancer cell lines. Salaspermic acid [4] was nor active in all the cancer cell lines used in this investigation. 13 C-nmr spectra assignments for salaspermic acid have been accomplished through the application of 1D and 2D nmr spectral techniques, and 13 C-nmr assignments for celastrol [3] have been revised
56 citations
TL;DR: Three indole alkaloids isolated from Peschiera laeta have been found to enhance the cytotoxic response mediated by vinblastine with multidrug-resistant KB cells, and appear to function by binding with P-glycoprotein.
Abstract: Coronaridine [1], conoduramine [2], and voacamine [3], three indole alkaloids isolated from Peschiera laeta, have been found to enhance the cytotoxic response mediated by vinblastine [4] with multidrug-resistant KB cells Inhibition of vinblastine binding with membrane vesicles isolated from this cell line was also assessed, and the bisindole alkaloids conoduramine [2] and voacamine [3] were found to be more potent inhibitory agents than the monomeric alkaloid, coronaridine [1] Thus, these compounds appear to function by binding with P-glycoprotein
42 citations
TL;DR: Three cytotoxic clerodane diterpenes were purified from an ethyl acetate-soluble extract of the stem bark of Polyalthia barnesii and were found to exhibit broad cytotoxicity against a panel of human cancer cell lines.
36 citations
TL;DR: Three new biflavonoids were isolated as cytotoxic constituents from the flowers of Calycopteris floribunda Lamk.
Abstract: Three new biflavonoids to which we have accorded the trivial names caly- copterone (1), isocalycopterone (2), and 4-demethylcalycopterone (3) and the known flavone 4',5-dihydroxy-3,3',6,7-tetramethoxyflavone (4) were isolated as cytotoxic constituent from the flowers of Calycopteris floribunda Lamk. (Combretaceae). Compounds (1-3) showed a wide range of activity against a panel of solid tumor cell lines. Among the biflavo- noids, calycopterone (1) is the major constituent
27 citations
TL;DR: In this paper, the structure of conocarpan and pterostilbene from Anogeissus acuminata var. lanceolata (Combretaceae) was determined by spectroscopic means, mainly through 1D and 2D NMR experiments.
Abstract: Further phytochemical work on Anogeissus acuminata var. lanceolata (Combretaceae) led to the isolation of pterostilbene (1), dihydrodehydrodiconiferyl alcohol (2), and conocarpan (3). The structure of these compounds were determined by spectroscopic means, mainly through 1D and 2D NMR experiments. A revision of some of the 13C NMR chemical shifts of 1 and 2 were made possible by HETCOR, FLOCK, and selective INEPT experiments. Homonuclear spin-decoupling and 1H-1H COSY experiments also enabled the precise assignment of the 1H NMR chemical shifts of 2. Compounds 1–3 exhibited in vitro cytotoxicity in various cancer cell lines. This is the first isolation of 1–3 from Anogeissus.
25 citations
16 citations