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At least 1,801 records · Page 100Linked to original sources
PubMed1990

Response of murine small intestine to combined treatment with fostriecin and X rays.

This radiobiological investigation was based on the measurements of crypt cell survival in mouse small intestine when the animals were injected with a single dose of fostriecin or streptomycin, and subsequently irradiated to the whole body with graded doses of X rays. The experimental data obtained indicated that fostriecin decreased the isoeffect dose to murine intestine by a factor of 2.3, whereas streptomycin did not influence the radiation response. The biological effects of fostriecin on various tumour cell systems in vitro and in vivo are briefly reviewed. The possible basic mechanisms involved in the radiosensitizing action of fostriecin and the implications of these results in the radiation protection of normal tissues are discussed.

Alkenes↗
PubMed1996

Syntheses and biological activities of dihydro-5,6-dehydrokawain derivatives.

The syntheses and biological activities of dihydro-5,6-dehydrokawain derivatives against plant pathogenic fungi and termites were investigated. Dihydro-5,6-dehydrokawain was isolated by a simple method without chromatography from the leaves of Alpinia speciosa K. SCHUM. The white crystalline compound obtained was identified as dihydro-5,6-dehydrokawain (1) by instrumental analyses. 4-Hydroxy-6-(2-phenylethyl)-2H-pyran-2-one (3) was prepared by hydrolyzing dihydro-5,6-dehydrokawain. Three dihydro-5,6-dehydrokawain derivatives were synthesized by reacting 3 with phosphoric agents. Among the synthesized compounds, dimethyl [6-(2-phenylethyl)-2-oxo-2H-pyran-4-yl]phosphorothionate (4) had the strongest antifungal activity of 91% at 100 ppm against Corticium rolfsii.

Animals↗
PubMed1997

Neoagarobiose as a novel moisturizer with whitening effect.

Neoagarobiose, a disaccharide, showed a higher hygroscopic ability than glycerol or hyaluronic acid, typical moisturizing reagents. Beside, neoagarobiose whitened B16 murine melanoma cells, and showed low cytotoxicity. Therefore neoagarobiose was a rare reagent showing both moisturizing and whitening effects.

Animals↗
PubMed1998

Relationship between chemical structures and biological activities of triterpenoid saponins from soybean.

Saponins can be found in more than one hundred plant families and in some marine animals. However, chemical investigation of soybean (Glycine max L. Merrill) saponins has begun only as recently as the 1970s. Here we focus on the chemical structure, the content, and biological activity of soybean saponins in current studies. Especially, we focus on 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) conjugated saponins and define the chemical structure of this as a natural precursor of group B and E saponins.

Animals↗
PubMed2001

Pentalenolactone I and hygromycin A, immunosuppressants produced by Streptomyces filipinensis and Streptomyces hygroscopicus.

Immunosuppressants isolated from Streptomyces filipinensis and S. hygroscopicus were identified with pentalenolactone I and hygromycin A, respectively. The compounds as well as cyclosporin A showed immunosuppressant activity in the mixed lymphocyte reaction, and pentalenolactone I and cyclosporin A suppressed IL-2 production, however, hygromycin A did not. Hygromycin A may have immunosuppressant activity by a different mechanism from pentalenolactone I, cyclosporin A and tacrolimus.

Cinnamates↗
PubMed2001

(-)-Semivioxanthin, a new abscisic active compound against Hinoki cypress leaves isolated from Cryptosporiopsis abietina.

The new naphthopyrone, (-)-semivioxanthin (1) was isolated from Cryptosporiopsis abietina. The structure of 1 was determined as the reversed optical isomer of semivioxanthin by comparing its spectroscopic data with those of semivioxanthin. Compound 1 exhibited abscisic activity against Hinoki cypress leaves and antifungal activity against Cladosporium herbarum.

Abscisic Acid↗
PubMed2003

Inhibitory effects of resveratrol derivatives from dipterocarpaceae plants on tyrosinase activity.

Stilbene derivatives, which are resveratrol (3,4',5-trihydroxy-trans-stilbene) oligomers ranging from monomer to tetramer, isolated from Dipterocarpaceae plants were tested for their inhibitory effects against murine tyrosinase activity. The structure-activity relationships obtained in this study suggest that the double bond in the stilbene skeleton is critical for the inhibition, and also that molecular size is important for inhibitory potency.

Animals↗
PubMed2003

Stimulation by caffeic acid, coumalic acid, and corilagin of the germination of resting spores of the clubroot pathogen Plasmodiophora brassicae.

Some chemicals were examined for their effects on the germination of resting spores of the clubroot pathogen Plasmodiophora brassicae, and on the control of clubroots in Chinese cabbage. Caffeic acid, coumalic acid, and corilagin stimulated the germination of Plasmodiophora spores and prevented the formation of clubroots in Chinese cabbage. Clubroot might be controlled by agents with germination-stimulating effects.

Brassica↗
PubMed2003

Mushroom tyrosinase inhibitory activity of esculetin isolated from seeds of Euphorbia lathyris L.

A tyrosinase inhibitor was isolated from the seeds of Euphorbia lathyris L. by bioassay-guided fractionation and purification, using silica gel column chromatography. It was identified as esculetin by comparing its physical properties and spectral data with those of an authentic sample. The IC50 value of esculetin in the mushroom tyrosinase activity test was 43 microM. The kinetic study indicates that esculetin exhibited competitive inhibition against the oxidation of 3-(3,4-dihydroxyphenyl)-alanine by mushroom tyrosinase. The structure-activity relationships among five esculetin analogs suggest that hydroxyl groups at the C6 and C7 positions of the coumarin skeleton played an important role in the expression of tyrosinase inhibitory activity.

Agaricales↗
PubMed2003

Gnetol as a potent tyrosinase inhibitor from genus Gnetum.

Gnetol (2,3',5',6-tetrahydroxy-trans-stilbene), a naturally occurring compound particularly found in the genus Gnetum, had a strong inhibitory effect on murine tyrosinase activity. Gnetol (IC50, 4.5 microM) was stronger than kojic acid (IC50, 139 microM) as a standard inhibitor for murine tyrosinase activity. Moreover, gnetol significantly suppressed, melanin biosynthesis in murine B16 melanoma cells.

Animals↗
PubMed2004

Tetrapetalone A, a novel lipoxygenase inhibitor from Streptomyces sp.

A simple new assay was designed for lipoxygenase inhibitors. This assay was used to find the novel lipoxygenase inhibitor, tetrapetalone A (1). Tetrapetalone A (1), C26H33NO7, was isolated from Streptomyces sp. USF-4727 strain. Its planar structure was determined by spectroscopic evidence and by methylating with diazomethane to show the presence of a novel tetracyclic skeleton and a beta-D-rhodinosyl moiety. The stereochemistry of 1 was investigated by the coupling constant in the 1H-NMR spectrum, NOE correlations, modified Mosher's method and derivation. We have reported the structural elucidation of 1 in our previous paper. However, further investigation gave another structure for 1, which is described in this paper. Tetrapetalone A showed similar inhibitory activity against soybean lipoxygenase to the two well-known lipoxygenase inhibitors, kojic acid and NDGA, while methylated tetrapetalone A (2) showed little inhibitory activity, even at a concentration of 1 mM.

Drug Evaluation, Preclinical↗
PubMedDate not supplied

Initial therapy for human immunodeficiency virus: broadening the options.

The goal of investigation into new therapeutic options for HIV/AIDS is to further the achievements of highly active antiretroviral therapy by developing new drugs with improved efficacy. Although several therapies are currently available for initial therapy in HIV-infected patients, ongoing research focuses on additions to existing and novel drug classes that might have improved pharmacokinetic and tolerability profiles, as well as on new therapeutic combinations that might result in synergistic activity. To retain activity against resistant strains, novel drugs need to target the numerous critical points in the life cycle of HIV, inhibiting different enzyme subsites than those affected by antiretroviral agents currently in use. An improvement in patient adherence to therapy is another key objective of efforts in HIV treatment, as suboptimal drug levels are a main determinant of antiretroviral regimen failure. This article reviews the current classes of antiretroviral agents in development, describing the clinical data obtained to date. These agents may have potential use as initial therapy in HIV patients.

AIDS Vaccines↗
PubMedDate not supplied

Concomitant use of an active boosted protease inhibitor with enfuvirtide in treatment-experienced, HIV-infected individuals: recent data and consensus recommendations.

Recent data from clinical trials investigating the efficacy of enfuvirtide, a fusion inhibitor, in treatment-experienced patients have revealed that the addition of enfuvirtide (ENF) to an active boosted protease inhibitor regimen doubles the rate of virological response. At week 48 of the TORO studies, 55% of patients previously naive to and receiving lopinavir/ritonavir (LPV/r) with ENF achieved a viral load of <400 copies/mL compared with 24% of patients treated with LPV/r alone. At week 24 of the RESIST studies, 70% of previously ENF-naive patients who took both ENF and tipranavir/ritonavir (TPV/r) achieved a >or=1 log10 reduction in viral load compared with 37% of such patients treated with TPV/r alone. Similarly, concomitant use of TMC114/ritonavir (TMC114/r) with ENF, compared with TMC114/r alone, increased the number of patients with <50 copies/mL from 46% to 64% in a combined 24-week analysis from the POWER trials. Data from these trials suggest that combining one agent from a new class with a new agent from a previously exposed class offers a greater chance of achieving full virological control than either type of agent alone. Undetectable viraemia should be the primary objective for treatment-experienced patients requiring a switch in therapy, and the present data support the combination of an active boosted protease inhibitor with an agent from a new class (e.g., ENF) for triple-class-experienced patients.

Antiretroviral Therapy, Highly Active↗
PubMedDate not supplied

Pharmacokinetic characterization of different dose combinations of coadministered tipranavir and ritonavir in healthy volunteers.

PURPOSE: To characterize the steady-state pharmacokinetic combination of the nonpeptidic protease inhibitor tipranavir (TPV) with ritonavir (RTV) in 95 healthy adult volunteers, a phase 1, single-center, open-label, randomized, parallel-group trial was conducted. METHOD: Participants received 250-mg self-emulsifying drug delivery system (SEDDS) capsules of TPV at doses between 250 mg and 1250 mg twice daily for 11 days, then received one or two RTV 100-mg SEDDS capsules, in addition to the TPV capsules, for the next 21 days. RESULTS: Coadministration of TPV and RTV (TPV/r) resulted in a greater than 20-fold increase in steady-state TPV trough concentrations (Cssmin) as compared with TPV at steady state alone. Mean TPV Cssmin was above a preliminary target threshold of 20 microM with all but one of the RTV-boosted doses; without boosting, none of the TPV-alone doses exceeded the threshold. The average steady-state Cssmin for TPV 500 mg and 750 mg with RTV 100 mg or 200 mg were 20 to 57 times the protein-adjusted TPV IC90R49\CCR418569) for protease inhibitor-resistant HIV-1. An erythromycin breath test, a surrogate marker for cytochrome P450 isoenzyme 3A4 activity, indicated that all TPV/r combinations given provided net inhibition of this isoenzyme. The most frequent treatment-related adverse events were mild gastrointestinal symptoms. CONCLUSION: This phase 1 study demonstrated that RTV-boosted TPV achieves concentrations that are expected to be effective in treating drug-experienced patients.

Administration, Oral↗
PubMed2006

Tipranavir: a protease inhibitor for HIV salvage therapy.

OBJECTIVE: To review the efficacy, safety, pharmacology, virology, pharmacokinetics, and resistance of the nonpeptidic protease inhibitor (PI) tipranavir. DATA SOURCES AND STUDY SELECTION: A PubMed search (1966-February 2006) was conducted using the key words tipranavir or PNU-140690, with the limitation of English-language reports. Pharmacokinetic and randomized clinical trials originating from major HIV conferences, such as the Conference on Retroviruses and Opportunistic Infections, International AIDS Society, European AIDS Conference, and Interscience Conference on Antimicrobial Agents and Chemotherapy, published only in abstract form, from 2000 to February 2006, were reviewed for relevance and included in this review. DATA SYNTHESIS: Phase III studies have shown that tipranavir is effective in the treatment of PI-resistant HIV compared with other PI-containing regimens. Adverse effects associated with tipranavir/ritonavir therapy include gastrointestinal reactions, hepatotoxicity, and elevations in cholesterol and triglyceride levels. Resistance data suggest that tipranavir/ritonavir should be reserved for salvage therapy in antiretroviral-experienced patients who have previously failed standard PI therapies. The potential for hepatotoxicity and drug interactions and the expense of tipranavir due to required ritonavir boosting may limit its widespread use. CONCLUSIONS: Tipranavir/ritonavir is an essential addition to the antiretroviral armamentarium for HIV-infected patients with limited treatment options.

Clinical Trials as Topic↗

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