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N R Farnsworth

Publications and source records attributed to N R Farnsworth.

At least 73 records · Page 4Linked to original sources
PubMed1994

Quinone-methide triterpenes and salaspermic acid from Kokoona ochracea.

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 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. Salaspermic acid [4] was not active in all the cancer cell lines used in this investigation. 13C-nmr spectra assignments for salaspermic acid have been accomplished through the application of 1D and 2D nmr spectral techniques, and 13C-nmr assignments for celastrol [3] have been revised.

Animals↗
PubMed1994

New lignans from Anogeissus acuminata with HIV-1 reverse transcriptase inhibitory activity.

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.

Animals↗
PubMed1994

Indole alkaloids from Peschiera laeta that enhance vinblastine-mediated cytotoxicity with multidrug-resistant cells.

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.

Alkaloids↗
PubMed1993

Ethnopharmacology and future drug development: the North American experience.

The major programs in North America designed to study plants as sources of potential drugs in which ethnomedical information is used to some extent are reviewed. Most of this work is carried out in academic laboratories in the United States; funded primarily from governmental agencies. A few major pharmaceutical companies in the United States are involved in drug development, using plants as sources of starting material, as well as many small start-up firms. These will be identified in the text with their major thrust, where known. Additionally, the NAPRALERT database on natural products will be described with the goal of illustrating how it may be used in the drug development process. Attenders at the Congress were given an opportunity to query the database on-line from Uppsala to Chicago.

Atlantic Islands↗
PubMed1993

A phytochemical investigation of Homalium ceylanicum.

Vacciniin [4] (6-O-benzoyl-D-glucopyranoside) and two new benzenoid glucosides, homaloside A [1] (1''-O-benzyl-3''-O-benzoyl-alpha-L-arabinopyranosyl(1'''-->4'')- beta-D-glucopyranoside) and homaloside D [2] [1-(1'-hydroxy-6'-oxocyclohex-2'-ene-carboxymethyl)- 5-hydroxyphenyl-6''-O-benzoyl-beta-D-glucopyranoside], were isolated from the n-BuOH fraction of Homalium ceylanicum (Flacourtiaceae). A novel cyclohexenone carboxylic acid ester, 1-hydroxy-6-oxocyclohex-2-enoic acid methyl ester [3], was also isolated from this fraction. The structures were elucidated by chemical and nmr (COLOC, FLOCK, and selective INEPT) techniques.

Carbohydrate Sequence↗
PubMed1993

Further lupane lactones from Kokoona ochracea.

Additional new lupane lactones were isolated from the stem bark of Kokoona ochracea (Celastraceae). Their structures have been elucidated, through the application of 1D and 2D nmr spectroscopic methods, as 20,29-dihydroxy-3-oxolupan-30,21 alpha-olide (ochraceolide D) [1] and 28-hydroxy-3-oxolup-20(29)-en-30,21 alpha-olide (ochraceolide E) [2]. These compounds and the mono- and di-acetates of ochraceolide D (4 and 5, respectively) were evaluated for in vitro cytotoxic activity against P-388 murine lymphocytic leukemia cells and a panel of human cancer cell systems. Ochraceolide D [1] was significantly cytotoxic (ED50, 3.9 micrograms/ml) against human glioblastoma (U373) cells. Other compounds (4, 5, and 2) exhibited only a weak cytotoxic response in certain cancer cell lines.

Animals↗
PubMed1993

Isolation of echinocystic acid-3-O-sulfate, a new triterpene, from Tetrapleura tetraptera, and evaluation of the mutagenic potential of molluscicidal extracts and isolates.

A known triterpene glycoside, 3-O-[beta-D-glucopyranosyl-(1"-6')-2'-acetamido-2'-deoxy-beta-D-gluco pyranosyl]olean-12-en-28-oic acid [3], and new sulfated triterpene, echinocystic acid-3-O-sodium sulfate [4], have been isolated from the stem bark of Tetrapleura tetraptera. Compound 3 was 100% lethal to Biomphalaria glabrata at 20 ppm, while 4 was not molluscicidal at the same concentration. In a forward mutation assay utilizing Salmonella typhimurium strain TM677, T. tetraptera stem bark extracts were found to be mutagenic in the absence of a metabolic activating system (S-9). An MeOH extract of the fruit exhibited weak mutagenic activity only in the presence of S-9. The stem bark isolates, which included aridanin [1], 3-O-(2'-acetamido-2'-deoxy-beta-D-glucopyranosyl)echinocystic acid [2], and compounds 3 and 4, were not mutagenic either with or without metabolic activation.

Animals↗
PubMed1993

Novel antimitotic dibenzocyclo-octadiene lignan constituents of the stem bark of Steganotaenia araliacea.

By means of activity-directed chromatographic fractionation using cultured astrocytoma (ASK) cells, six dibenzocyclo-octadiene lignans were isolated from Steganotaenia araliacea stem bark. In addition to the most abundant analogue, steganangin [1], two other known compounds, steganacin [3] and steganolide A [6], and three new compounds, episteganangin [2], steganoate A [4], and steganoate B [5], were obtained. Episteganangin [2] was chemically correlated with the known ketone steganone [7]. All of these compounds demonstrated cytotoxic activity when tested against a panel of eleven human tumor cell lines, with the exception of steganoate A [4]. The magnitude of this activity tended to correlate with antimitotic activity observed with the ASK assay and in vitro inhibition of microtubule assembly. Steganacin [3] was less cytotoxic than colchicine, but more active in these latter two assay systems.

Animals↗
PubMed1992

Plant anticancer agents, L. cytotoxic triterpenes from Sandoricum koetjape stems.

A new ring-A secotriterpene, koetjapic acid [1], and five known compounds, 3-oxo-olean-12-en-29-oic acid [2] (a novel natural product), katonic acid [3], (-)-alloaromadendrene, (-)-caryophyllene oxide, and (+)-spathulenol, have been isolated and characterized from a cytotoxic Et2O-soluble extract of Sandoricum koetjape stems. Of these compounds, 2 and 3 demonstrated significant cytotoxic activity against cultured P-388 cells (ED50 values of 0.61 and 0.11 microgram/ml, respectively). Significant, albeit less intense, cytotoxicity was also observed with a variety of cultured human cancer cells. The 13C-nmr chemical shifts of these triterpenes were assigned unambiguously using selective INEPT nmr experiments. Aside from compounds 2 and 3, these substances were not toxic with cultured cells.

Animals↗
PubMed1992

Cytotoxic activity of cardenolides from Beaumontia brevituba stems.

Five known cardenolides, digitoxigenin (1), oleandrigenin (2), digitoxigenin alpha-L-cymaroside (3), digitoxigenin beta-gentiobiosyl-alpha-L-cymaroside (4), and delta 16-digitoxigenin beta-D-glucosyl-alpha-L-cymaroside (5), were isolated from the stems of Beaumontia brevituba Oliver by cytotoxicity-directed fractionation monitored by a cultured human lung cancer cell line. The cytotoxic activity of these compounds was evaluated with a panel of twelve human and murine cancer cell lines. The lignan glycoside, syringaresinol beta-D-glucoside, was obtained for the first time in the form of its levo-enantiomer.

Animals↗
PubMed1991

Studies on the antifertility components from Marsdenia koi.

By random screening test, Marsdenia koi was found to have antifertility activity on SD rat. From MeOH extracts of this plant two steroidal glycosides, marsdekoiside A and B, were isolated, and their structures were elucidated on the basis of spectral evidence and by comparison of the hydrolysis products with the authentic samples. Both are newly identified compounds, and marsdekoiside A has good antifertility activity.

Animals↗
PubMed1990

The role of ethnopharmacology in drug development.

There are 119 drugs of known structure that are still extracted from higher plants and used globally in allopathic medicine. About 74% of these were discovered by chemists who were attempting to identify the chemical substances in the plants that were responsible for their medical uses by humans. These 119 plant-derived drugs are produced commercially from less than 90 species of higher plants. Since there are at least 250,000 species of higher plants on earth, it is logical to presume that many more useful drugs will be found in the plant kingdom if the search for these entities is carried out in a logical and systematic manner. The first and most important stage in a drug development programme using plants as the starting material should be the collection and analysis of information on the use(s) of the plant(s) by various indigenous cultures. Ethnobotany, ethnomedicine, folk medicine and traditional medicine can provide information that is useful as a 'pre-screen' to select plants for experimental pharmacological studies. Examples are given to illustrate how data from ethnomedicine can be analysed with the aim of selecting a reasonable number of plants to be tested in bioassay systems that are believed to predict the action of these drugs in humans. The ultimate goal of ethnopharmacology should be to identify drugs to alleviate human illness via a thorough analysis of plants alleged to be useful in human cultures throughout the world. Problems and prospects involved in attaining this goal are discussed.

Drug Evaluation, Preclinical↗
PubMed1990

Sesquiterpene lactones and other constituents from a cytotoxic extract of Michelia floribunda.

The pentane and CHCl3 fractions of a crude extract of Michelia floribunda exhibited cytotoxic activity when tested in KB and P388 tumor cell cultures. Repeated chromatography led to the isolation of three cytotoxic sesquiterpene lactones (costunolide, parthenolide, and santamarine) and a cytotoxic isoquinoline alkaloid (liriodenine). Inactive sesquiterpene lactones obtained during the course of this study included dihydroparthenolide and two new glucosides of dihydrotamaulipin A and dihydroreynosin (1 and 2). The structures of these new compounds were determined through interpretation of their spectroscopic data including 2D-NMR spectroscopy. Syringin was also isolated from the extract.

Animals↗
PubMed1989

Kmeriol and other aromatic constituents of Kmeria duperreana.

The CHCl3-soluble fraction of a crude extract of Kmeria duperreana exhibited cytotoxic activity when tested in both KB and P388 tumor-cell cultures. Bioassay-directed fractionation led to the isolation of a cytotoxic alkaloid, liriodenine (1). Other constituents obtained from the extract included scopoletin (2), (-)-3,4,5-trimethoxyphenyl beta-D-glucopyranoside (3), (+)-syringaresinol beta-D-glucopyranoside (4), and a new phenylpropanol, kmeriol (5), whose chemical structure was established through spectroscopic analysis.

Animals↗
PubMed1988

Studies on zoapatle. VIII: Novel cytotoxic sesquiterpene lactones from Montanoa tomentosa ssp. microcephala.

Investigation of the leaves of Montanoa tomentosa Cerv. ssp. microcephala (Sch.-Bip.) Funk (Compositae) resulted in the isolation of three novel guaianolide sesquiterpenes, montacephalin (1), tomencephalin (2), and 5-hydroxytomencephalin (3), which were shown to be cytotoxic (P-388). The structures of these sesquiterpenes were elucidated through analysis of their spectroscopic characteristics, and complete proton and carbon-13 assignments were made for the new compounds. Also isolated were the known terpenes, beta-amyrin, beta-amyrin acetate, stigmasterol, stigmasterol-3 beta-D-glucoside, (-)-kaur-16-en-19-oic acid, and monoginoic acid.

Animals↗