Showing papers by "Norman R. Farnsworth published in 2002"

Novel Bioactive Clerodane Diterpenoids from the Leaves and Twigs of Casearia sylvestris

Abstract: Fractionation of a methanol extract of the leaves and twigs of Casearia sylvestris, as directed by activity against KB cell cytotoxicity, led to the isolation of three novel clerodane diterpenoids, casearvestrins A-C (1-3). The structures of 1-3 were deduced from one- and two-dimensional NMR experiments, including relative stereochemical assignments based on ROESY correlations and COSY coupling constants. All three compounds displayed promising bioactivity, both in cytotoxicity assays against a panel of tumor cell lines and in antifungal assays via the growth inhibition of Aspergillus niger in a disk diffusion assay.

Black Cohosh (Cimicifuga racemosa L.) Protects against Menadione-Induced DNA Damage through Scavenging of Reactive Oxygen Species: Bioassay-Directed Isolation and Characterization of Active Principles

Abstract: The roots/rhizomes of Cimicifuga racemosa L. (Nutt.) (black cohosh) have traditionally been used to treat menopausal symptoms through an unknown mechanism of action. In an effort to determine if black cohosh had additional health benefits, methanol extracts were investigated for their potential to scavenge reactive oxygen species and to protect against menadione-induced DNA damage. These extracts effectively scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. In addition, the extracts showed dose-dependent decreases in DNA single-strand breaks and oxidized bases induced by the quinone menadione using the comet (single-cell gel electrophoresis assay) and fragment length associated repair enzyme assays, respectively. Bioassay-directed fractionation of the methanolic extracts using the DPPH assay as a monitor led to the isolation of nine antioxidant active compounds: caffeic acid (1), methyl caffeate (2), ferulic acid (3), isoferulic acid (4), fukinolic acid (5), cimicifugic acid A (6), cimicifugic acid B (7), cimicifugic acid F (8), cimiracemate A (9), and cimiracemate B (10). Six of these antioxidants were found to reduce menadione-induced DNA damage in cultured S30 breast cancer cells with the following order of potency: methyl caffeate (2) > caffeic acid (1) > ferulic acid (3) > cimiracemate A (9) > cimiracemate B (10) > fukinolic acid (5). These data suggest that black cohosh can protect against cellular DNA damage caused by reactive oxygen species by acting as antioxidants.

Trifolium pratense (Red Clover) Exhibits Estrogenic Effects In Vivo in Ovariectomized Sprague-Dawley Rats

Abstract: Studies were conducted using an ovariectomized rat model to determine the estrogenic and antiestrogenic activity of Trifolium pratense L. (red clover) extracts. A red clover extract, standardized to contain 15% isoflavones was administered by gavage [250, 500 and 750 mg/(kg x d)] to virgin, ovariectomized 50-d-old Sprague-Dawley rats, for 21 d in the presence and absence of 17beta-estradiol [50 microg/(kg x d)]. Estrogenic effects included an increase in uterine weight, vaginal cell cornification and mammary gland duct branching. Red clover produced a dose-dependent increase in uterine weight and differentiated vaginal cells at the two higher doses, but it did not stimulate cell proliferation in the mammary glands. Neither antiestrogenic nor additive estrogenic properties were observed in any of the tissues studied. These data suggest that red clover extract is weakly estrogenic in the ovariectomized rat model.

Evaluation of the potential cancer chemotherapeutic efficacy of natural product isolates employing in vivo hollow fiber tests.

Abstract: The hollow fiber test has been developed for the preliminary in vivo assessment of cancer chemotherapeutic efficacy of selected natural products. Using this model, we have established growth conditions for HL-60, HUVEC, Ishikawa, KB, KB-V1, LNCaP, Lu1, MCF-7, Mel2, P-388, and SW626 cells implanted at the intraperitoneal (i.p.) and subcutaneous (s.c.) compartments of athymic mice. Five cytotoxic natural product isolates (2−6) were tested in this model, along with paclitaxel (taxol) (1). Among the compounds tested, dioscin (2) and 13-methoxy-15-oxozoapatlin (3) were found to be active, indicating their potential to function as cancer chemotherapeutic agents. On the other hand, ochraceolide A (4), α-lapachone (5), and 2-(1-hydroxyethyl)naphtha[2,3-b]furan-4,9-quinone (6), all of which were significantly cytotoxic to cultured mammalian cells, did not mediate significant responses with the hollow fiber model. In further xenograft studies using KB cells implanted at the subcutaneous site, compound 3 mediated a ...

Constituents of the leaves and twigs of Ficus hispida.

Abstract: A new norisoprenoid, ficustriol (1), and the known phenanthroindolizidine alkaloid O-methyltylophorinidine (2), were isolated from a CHCl3 extract of the leaves and twigs of Ficus hispida. O-Methyltylophorinidine showed potent cytotoxic activity when tested against a small panel of human cancer cells, while ficustriol was inactive. The structure and stereochemistry of 1 were determined using chemical and spectral methods.

Activity-guided fractionation of the seeds of Ziziphus jujuba using a cyclooxygenase-2 inhibitory assay

Abstract: Bioactivity-guided fractionation of petroleum ether- and EtOAc-soluble extracts of the seeds of Ziziphus jujuba using a cyclooxygenase-2 assay as a monitor indicated that the triglyceride, 1,3-di-O-[9(Z)-octadecenoyl]-2-O-[9(Z),12(Z)-octadecadienoyl]glycerol (3), and a fatty acid mixture of linoleic, oleic and stearic acids, were the major active components. A new pentacyclic lupane-type triterpene derivative, 3-O-[9(Z)-octadecenoyl]betulinic acid (1), and betulinic acid (2) were also isolated and identified. All isolates as well as pure linoleic, oleic and stearic acids were evaluated for their inhibitory effects against both cyclooxygenases-1 (COX-1) and -2 (COX-2).

Cytotoxic prenylated xanthones and the unusual compounds anthraquinobenzophenones from Cratoxylum sumatranum.

Abstract: Six new xanthones, cratoxyarborenones A−F (1−6), were isolated from the leaves, twigs, and/or stem bark of Cratoxylum sumatranum along with the known compound, vismione B (9), as active constituents by bioassay-directed fractionation using the KB human cancer cell line cytotoxicity assay. In addition, two novel anthraquinobenzophenones, cratoxyarborequinones A (7) and B (8), and two known compounds, 2,4,6-trihydroxybenzophenone 4-O-geranyl ether and δ-tocotrienol, were obtained as inactive constituents.

Cytotoxic flavonoids from the stem bark of Lonchocarpus aff. fluvialis.

Abstract: Activity-guided fractionation of a chloroform-soluble extract of Lonchocarpus aff. fluvialis stem bark using a human epidermoid (KB) tumour cell line as a monitor afforded five rotenoids, one pterocarpan, one chalcone, three flavanones, one flavone and one triterpenoid. All of the compounds isolated proved to be of previously known structure. Among them, the rotenoids (-)-sumatrol and (+/-)-villosinol, the dibenzoylmethane derivative (+)-3,4-methylenedioxy-2'-methoxy-[2",3":4',3']-furanodibenzoylmethane, and the flavanones (-)-isoglabrachromene and (-)-candidone have been shown to exhibit significant cytotoxic activity against human cancer cells for the first time. This is the first report of the chemical constituents of this species, and the profile of compounds obtained was in accordance with the established chemosystematic patterns of species in the tribe Tephrosieae (Leguminosae, Papilionoideae).

Reversal of multidrug resistance by tropane alkaloids from the stems of Erythroxylum rotundifolium.

Abstract: Six tropane alkaloid esters were isolated from the stems of Erythroxylum rotundifolium. The structures of three new tropane esters, 7β-hydroxy-6β-(3,4,5-trimethoxybenzoyloxy)-3α-(E)-(3,4,5-trimethoxycinnamoyloxy)tropane (1), 6β-benzoyloxy-3α-(Z)-(3,4,5-trimethoxycinnamoyloxy)tropane (2), and (−)-6β-benzoyloxy-3α-hydroxytropane (3), were established by spectroscopic techniques. When alkaloids 1−6 were evaluated against a panel of human cancer cell lines, the new compound 6β-benzoyloxy-3α-(Z)-(3,4,5-trimethoxycinnamoyloxy)tropane (2) and three known compounds, 6β-benzoyloxy-3α-(3,4,5-trimethoxycinnamoyloxy)tropane (4), 6β-benzoyloxy-3α-(E)-(3,4,5-trimethoxycinnamoyloxy)tropane-7β-ol (5), and 7β-acetoxy-6β-benzoyloxy-3α-(E)-(3,4,5-trimethoxycinnamoyloxy)tropane (6), demonstrated greatest activity with multidrug-resistant oral epidermoid carcinoma (KB-V1) cells incubated in the presence of vinblastine. Thus, tropane esters of this type can reverse the multidrug-resistance phenotype, presumably by interacting ...