Search PubMed⌕ Search

Biomedical subjects

W Wiegrebe

Publications and source records attributed to W Wiegrebe.

At least 19 recordsLinked to original sources
PubMed2001

Simple isoquinoline and benzylisoquinoline alkaloids as potential antimicrobial, antimalarial, cytotoxic, and anti-HIV agents.

Twenty-six simple isoquinolines and 21 benzylisoquinolines were tested for antimicrobial, antimalarial, cytotoxic, and anti-HIV activities. Some simple isoquinoline alkaloids were significantly active in each assay, and may be useful as lead compounds for developing potential chemotherapeutic agents. These compounds include 13 (antimicrobial), 25, 26, and 42 (antimalarial), 13 and 25 (cytotoxic), and 28 and 29 (anti-HIV). A quaternary nitrogen atom of isoquinolium or dihydroisoquinolinium type may contribute to enhanced potency in the first three types of activities. In contrast, anti-HIV activity was found with tetrahydroisoquinoline and 6,7-dihydroxyisoquinolium salts.

Alkaloids↗
PubMed2001

In vitro cytotoxicity of the protoberberine-type alkaloids.

In vitro cytotoxic activities of 24 quaternary protoberberine alkaloids related to berberine have been evaluated using a human cancer cell line panel coupled with a drug sensitivity database. Extending the alkyl chain at position 8 or 13 strongly influenced the cytotoxic activity, that is, relative lipophilicity as well as the size of the substituent affects cytotoxicity. The highest level of activity was observed in 8- or 13-hexyl-substituted derivatives of berberine. Structure-activity relationships are described.

Animals↗
PubMed2001

Dimethylfumarate inhibits tumor-necrosis-factor-induced CD62E expression in an NF-kappa B-dependent manner.

Fumaric acid esters are thought to improve psoriasis by altering leukocyte, keratinocyte, and/or endothelial functions. To determine specificity, kinetics, and molecular mechanisms of different fumaric acid esters in their ability to inhibit endothelial cell activation, we analyzed CD62E and CD54 expression in endothelial cells in vivo and in vitro. In lesional skin of psoriatic patients, oral fumaric acid ester treatment resulted in a marked reduction of CD62E but not CD54 expression on dermal microvessels. Using human umbilical vein endothelial cells, dimethylfumarate almost completely inhibited tumor-necrosis-factor-induced CD62E, but not CD54 expression at concentrations < or = 70 microM, mimicking the situation in vivo. A 60 min dimethylfumarate preincubation was sufficient to block tumor-necrosis-factor-induced CD62E expression for up to 24 h. In contrast, equimolar concentrations of methylhydrogenfumarate, the hydrolysis product of dimethylfumarate, did not suppress tumor-necrosis-factor-induced CD62E expression. Likewise, all fumaric acid esters other than dimethylfumarate were ineffective. Using CD62E, NF-kappa B, or AP-1-responsive promoter constructs, dimethylfumarate inhibited tumor-necrosis-factor-induced activation of the CD62E and the NF-kappa B but not the AP-1 promoter construct. In summary, at a dose range < or = 70 microM, dimethylfumarate appeared to be a specific inhibitor of CD62E expression in an NF-kappa B-dependent manner.

Capillaries↗
PubMed2000

Medicinal plants from nepal: evaluation as inhibitors of leukotriene biosynthesis.

The methanolic extracts of 25 different Nepalese medicinal plants were tested for their activity to inhibit the biosynthesis of leukotriene B(4) in bovine polymorphonuclear leukocytes. The selected indigenous plants are used in traditional herb remedies to treat inflammatory diseases such as asthma, bronchitis, rheumatism, and skin disorders presumed to be mediated by leukotrienes. The leaves of Zanthoxylum nepalensis were shown to be the most potent inhibitor with an IC(50) value of 11 microgram/ml. The extracts obtained from Astercantha longifolia and Hedychium ellipticum also exhibited potent inhibitory action with IC(50) values of 20 and 22 microgram/ml, respectively.

Humans↗
PubMed2000

A new steroidal alkaloid from the roots of Cynanchum caudatum.

A new steroidal alkaloid, 12-O-nicotinoylsarcostin, gagamine (1), was isolated from the roots of Cynanchum caudatum Max. (Asclepiadaceae), together with a known alkaloid, gagaminine (2). Their structures were established using spectroscopic methods, some 13C-NMR data of 2 have to be revised.

Alkaloids↗
PubMed1999

Synthesis of enantiomerically pure (-)-(S)-brevicolline

(-)-(S)-Brevicolline (1) and related beta-carbolines were synthesized using an enantiomerically pure Michael-acceptor synthon (3). Subsequent Pictet-Spengler reaction afforded the tetrahydro-beta-carboline skeleton, which, in turn, was transformed to the beta-carboline by catalytic dehydrogenation.

Journal Article↗
PubMed1999

Potential antipsoriatic agents: lapacho compounds as potent inhibitors of HaCaT cell growth.

A number of lapacho compounds, representing the most common constituents of the inner bark of Tabebuia impetiginosa, together with some synthetic analogues, were evaluated in vitro against the growth of the human keratinocyte cell line HaCaT. With an IC(50) value of 0.7 microM, beta-lapachone (4) displayed activity comparable to that of the antipsoriatic drug anthralin. 2-Acetyl-8-hydroxynaphtho[2,3-b]furan-4,9-dione (7), which was prepared in a four-step synthesis from 2,8-dihydroxy-1, 4-naphthoquinone, was the most potent inhibitor among the known lapacho-derived compounds and inhibited cell growth with an IC(50) value of 0.35 microM. Furthermore, other active constituents of lapacho inhibited keratinocyte growth, with IC(50) values in the range of 0.5-3.0 microM. However, as already observed with anthralin, treatment of HaCaT cells with these potent lapacho compounds also caused remarkable damage to the plasma membrane. This was documented by leakage of lactate dehydrogenase into the culture medium, which significantly exceeded that of the vehicle control. Because of their potent activity against the growth of human keratinocytes, some lapacho-derived compounds appear to be promising as effective antipsoriatic agents.

Administration, Topical↗
PubMed1998

Antimicrobial activity of 8-alkyl- and 8-phenyl-substituted berberines and their 12-bromo derivatives.

The 8-alkyl- (3-6), 8-phenyl- (7), 12-bromo- (8), 8-alkyl-12-bromo- (9-12), and 12-bromo-8-phenyl- (13) berberine derivatives were prepared and tested for their antimicrobial activity in vitro to evaluate structure-activity relationships. Introduction of the alkyl or phenyl group and the bromine atom into the C-8 and C-12 positions of berberine (1), respectively, led to significant increases of the antimicrobial activity. In both the 8-alkyl- and 8-alkyl-12-bromo-berberines (3-6 and 9-12, respectively), the antibacterial activity increased as the length of the aliphatic chain increased. The exception was the activity against Candida albicans and Escherichia coli, which did not always increase as the alkyl side chain lengthened. Among the compounds tested, 12-bromo-8-n-hexylberberine (12) was 64, 256, 128, 16, and 32 times more active against Staphylococcus aureus, Bacillus subtilis, Salmonella enteritidis, E. coli, and C. albicans, respectively, in comparison to the clinically used berberine. Compound 12 was also found to be 8, 16, and 128 times more active against S. aureus, S. enteritidis, and C.albicans, respectively, than kanamycin sulfate, but was of the same order of activity against B. subtilis, and only one-fourth as active against E. coli.

Anti-Bacterial Agents↗
PubMed1998

Anthranoid free radicals found in pseudomelanosis coli.

Pseudomelanosis coli occurs after prolonged intake a anthranoids. After discontinuation of intake the pigmentation disappears apparently without noxious effects, including carcinogenicity and genotoxicity. We are presenting ESR spectra of pseudomelanosis coli specimen, compared to ESR spectra of pigmented skin scales taken from psoriatic patients treated topically with anthralin, and with ESR spectra of anthralin brown material formed in vitro. The ESR spectra show comparable g values within the accuracy of measurements. The examined specimens reveal remarkable stability: the intensity of the ESR signal remained practically constant over the period of four years. The chemical and physicochemical properties of the brown pigments formed from anthranoids explain the observed bio-inertness of these materials including that of melanosis coli pigment derived from anthranoids.

Administration, Topical↗
PubMed1996

Antipsoriatic anthrones with modulated redox properties. 3. 10-thio-substituted 1,8-dihydroxy-9(10H)-anthracenones as inhibitors of keratinocyte growth, 5-lipoxygenase, and the formation of 12(S)-HETE in mouse epidermis.

The synthesis of a series of 1,8-dihydroxy-9(10H)-anthracenones bearing sulfur-linked substituents in the 10-position is described. These compounds were evaluated for their ability to inhibit the growth of the human keratinocyte cell line HaCaT and the 5- and 12-lipoxygenase enzymes in bovine polymorphonuclear leukocytes and mouse epidermal homogenate, respectively. In addition, the following redox properties of the compounds were determined: reactivity against 2,2-diphenyl-1-picrylhydrazyl, generation of hydroxyl radicals as measured by deoxyribose degradation, and inhibition of lipid peroxidation in model membranes. Compounds 4e and 4h of this series compare favorably in the cellular assays with the antipsoriatic anthralin. They have the combined inhibitory action against leukotriene B4 and 12(S)-HETE formation and are highly potent antiproliferative agents against keratinocyte growth. In contrast to anthralin, 4h, 1,8-dihydroxy-10-[(4-hydroxyphenyl)thio]-9(10H)-anthracenone, is not cytotoxic as documented by the LDH activity released from cytoplasm of keratinocytes and does not enhance lipid peroxidation in model membranes.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1995

Modification of DNA bases by anthralin and related compounds.

Modification of bases in calf thymus DNA by treatment with the antipsoriatic drug anthralin was studied. The products of DNA bases were identified and their yields measured by gas chromatography-mass spectrometry with selected ion monitoring. Treatment of calf thymus DNA with anthralin significantly enhanced the amount of modified bases above control levels. Purine bases were modified to products identical with those known to be typical of DNA damage induced by hydroxyl radicals. The yields of Fapy-adenine, 8-hydroxyadenine, Fapy-guanine, and 8-hydroxyguanine were maximally increased at an anthralin concentration of 75 microM. A variety of structural analogues of anthralin were also tested at 75 microM were either weaker or stronger hydroxylating agents. It is likely that damage to DNA bases induced by anthrones contributes to their antiproliferative activity. The pharmacological implications of these characteristics of the action of anthralin on DNA bases are discussed.

Adenine↗
PubMed1995

1,3-Diphenylpropane-1,3-diamines, VI): DNA-interaction, estrogen receptor affinity, and cytostatic activity of 1,3-diphenylpropane-1,3-diamine-Pt(II) complexes.

The Pt(II) complexes of 1,3-diphenylpropane-1,3-diamines (part IV2)) were tested for DNA interaction (UV-difference spectroscopy, Tables 1 and 2), for affinity to the estrogen receptor (calf uterus cytosol; scarcely any affinity), and for cytostatic activity at estrogen independent MDA-MB 231 cells (Tables 3 and 4) and estrogen dependent MCF-7 cells (Tables 5 and 6). The data are compared with those reported for the analogous 1,2-diphenylethane-1,2-diamine-Pt(II) complexes: most probably, the cytostatic activity is not mediated by the estrogen receptor.

Animals↗
PubMed1995

Reduction of nitroxides by anthralin and some of its derivatives.

In DMSO solution, anthralin and its C-10 monosubstituted derivatives reduce nitroxides to the corresponding hydroxylamine derivatives, which are not further transformed. The reaction rate depends on the solvent used, the nitroxide, and the structure of the reducer. It is faster in DMSO than in DMF, piperidine type of nitroxides are reduced faster than the pyrrolidine type, and the substitution on C-10 of anthralin has a significant influence on the reaction rate. Anthralin derivatives without protons at C-10 are not able to reduce nitroxides.

Administration, Topical↗
PubMed1995

Treatment of psoriasis with anthrones-chemical principles, biochemical aspects, and approaches to the design of novel derivatives.

Antipsoriatic anthrones are probably the most commonly used topical agents in the treatment of psoriasis. There is growing evidence that the biochemical basis for their mechanism of action at the molecular level is related to their redox activity leading to the production of active oxygen species, which include singlet oxygen, superoxide anion radical, and hydroxyl radical. These species are involved in a variety of oxidative effects affecting cellular targets that have been implicated both in the mode of action and the skin-irritating properties of antipsoriatic anthrones: interaction with DNA, inhibition of various enzyme systems associated with cell proliferation and inflammation, such as glucose-6-phosphate dehydrogenase and inflammation, such as glucose-6-phosphate dehydrogenase and 5-lipoxygenase, and destruction of membrane lipids. Furthermore, the application of this information to the design of novel derivatives is discussed. In particular, compounds with diminished oxygen radical-generating properties have been developed, which may permit a separation of antipsoriatic and inflammatory effects. Some of the novel anthrone analogs which produced significantly less amounts of oxygen radicals than dithranol compared favorably in biological tests with this known antipsoriatic drug as an alternative method of treating psoriasis.

Anthracenes↗
PubMed1994

Dibenzo[a,f]quinolizines: syntheses and cytostatic activity in estrogen-sensitive tumor cells.

A number of methoxy-substituted 7,11b,12,13-tetrahydro-6H-dibenzo-[a,f]quinolizines with short alkyl groups in position 6 or 12 were synthesized by the Bischler-Napieralski reaction using the appropriate starting material followed by a second ring closure reaction involving a base-generated benzyne intermediate. The methoxy functions in positions 2 or 3 and 9 were cleaved with BBr3 and the free hydroxy groups converted into the acetates. The enantiomers of two of these derivatives were separated by liquid chromatography on triacetylcellulose. Compounds with alkyl substituents bind strongly to the estrogen receptor except those with a cis-orientation at the central ring connection. The RBA values ranged from 2.2-10.8 (17 beta-estradiol: RBA = 100). There was no major difference in binding between the (+) and (-)-enantiomers. The 3,9-diacetoxy-6-alkyl derivatives also showed binding affinity for the progesterone receptor (RBA: 1.2-3.1). The 2,9-diacetoxydibenzoquinolizines trans-61 and -6m with ethyl and propyl respectively in position 12 strongly inhibited the growth of hormone-sensitive MCF-7 breast cancer cells at concentrations of 10(-6) M and higher but were inactive in hormone-independent MDA-MB 231 breast cancer cells. Preliminary tests with hormone-dependent MXT mouse mammary tumors as model showed that these compounds have also antineoplastic activity in vivo. Derivative trans-61 at a dose of 20 mg/kg body weight, administered 3 times/week, inhibited the growth of these tumors by 78% (tamoxifen: 76% inhibition). Studies on the estrogenic and antiestrogenic properties of these agents in mice revealed that they are mixed agonists/antagonists with strong antiestrogenic activity at low doses but significant estrogenic effects at higher doses.

Animals↗
PubMed1993

Antipsoriatic anthrones with modulated redox properties. 1. Novel 10-substituted 1,8-dihydroxy-9(10H)-anthracenones as inhibitors of 5-lipoxygenase.

The syntheses, the biological evaluation, and the structure-activity relationships of a novel series of 1,8-dihydroxy-9(10H)-anthracenones bearing acyl-, alkyl-, or alkylidene-linked aromatic substituents in the 10-position are described. The phenylacyl and phenylalkylidene analogs were far more potent inhibitors of 5-lipoxygenase (5-LO) from bovine polymorphonuclear leukocytes (IC50 values in the 10(-7) M range) than the antipsoriatic drug anthralin, whereas phenylalkyl analogs were only weak inhibitors. Among the active compounds were both potent generators of hydroxyl radicals, as determined by deoxyribose degradation, and strong reducers of the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). However, several derivatives of this series maintained 5-LO inhibitory activity but did not generate hydroxyl radicals and were not reactive with DPPH. In particular, phenylacyl analogs were also 6 times more efficient in inhibition of lipid peroxidation in model membranes than anthralin. Structure-activity relationships have shown that the presence of free phenolic groups in the attached aromatic ring is beneficial but not required for 5-LO inhibitory potency. The inhibitory potency in the 10-phenylacyl series increased with the length of the acyl chain with three methylene units being the optimum, suggesting a specific enzyme interaction which would not be expected for nonspecific redox inhibitors.

Administration, Topical↗