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Biomedical subjects

Olov Sterner

Publications and source records attributed to Olov Sterner.

At least 37 records · Page 2Linked to original sources
PubMed2004

Synthesis and biological evaluation of paclitaxel-thiocolchicine hybrids.

The bifunctional taxoid-colchicinoid hybrids 6-8 were synthesized and evaluated in assays of cytotoxicity and tubulin assembly/disassembly. All compounds showed a high degree of cytotoxicity, but, while 6 and 7 behaved as bifunctional tubulin binders not unlike an equimolecular mixture of taxol and thiocolchicine, 8 was surprisingly devoid of tubulin activity, acting on a distinct and yet to identify molecular target.

Animals↗
PubMed2004

The use of a pharmacophore model for identification of novel ligands for the benzodiazepine binding site of the GABAA receptor.

A Catalyst pharmacophore model has been developed for the benzodiazepine site within the GABA(A) receptor complex. The model is based on a pharmacophore model originally proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) and further developed by Kahnberg et al. (J. Med. Chem. 2002, 45, 4188-4201). The Catalyst pharmacophore model has been validated by using a series of flavonoids with varying affinities for the benzodiazepine receptor and has then been used as a search query in database searching with the aim of finding novel structures which have the possibility to be modified into novel lead compounds. Five of the hits from the database searching were purchased and their affinities for the benzodiazepine site of the GABA(A) receptor were determined. Two of the compounds displayed K(i) values below 10 microM. The substance showing highest potency in-vitro displayed an affinity of 121 nM making it an interesting compound for optimization. The false positive compounds (K(i) values >10 microM affinities) have been analysed in terms of conformational energy penalties and possibilities for hydrogen bond interactions. The analysis clearly demonstrates the need for post processing of Catalyst hits.

Animals↗
PubMed2004

3-hydroxypropionic acid as a nematicidal principle in endophytic fungi.

3- Hydroxypropionic acid was isolated by bioactivity-guided fractionation of extracts obtained from submerged cultures of several endophytic fungi isolated from above-ground plant organs. This compound showed selective nematicidal activity against the plant-parasitic nematode Meloidogyne incognita with LD50 values of 12.5-15 microg/ml. Activity against the saprophytic Caenorhabditis elegans was fivefold lower. No antimicrobial, cytotoxic or phytotoxic effects were observed. Propionic acid and D- and L-lactic acids were not active against either nematode species. Based on morphological features and ITS, 18S and 28S rDNA analyses, the producing strains were identified as Phomopsis phaseoli isolated from the leaf of a tropical tree, and four strains of Melanconium betulinum isolated from twigs of Betula pendula and B. pubescens in Germany. This is the first report of 3-hydroxypropionic acid in fungi, and of the nematicidal activity of this metabolite.

Animals↗
PubMed2004

Two labdane diterpenoids and a seco-tetranortriterpenoid from Turreanthus africanus.

Examination of the methylene chloride soluble portion of the acetone extract of the seeds of Turreanthus africanus yielded two labdane diterpenoids 12,15-epoxylabda-8(17),12,14-trien-16-al (1) and 16-acetoxy-12(R),15-epoxy-15beta-hydroxylabda-8(17),13(16)-diene (2) and a limonoid, 17-epi 12-dehydroxyheudebolin (3). Structures elucidation was based on the analysis of spectroscopic data.

Diterpenes↗
PubMed2004

New peptaibols from Mycogone cervina.

From cultures of Mycogone cervina, a mycophilic fungus growing on the fruit bodies of ascomycete Paxina acetabulum, two new peptaibols (cervinin, N-Ac-Leu-Aib-Pro-Aib-Leu-Aib-Pro-Ala-Aib-Pro-Val-red-Leu (1) and the red-Leu O-acetylated derivative 2) were isolated. The structures of 1 and 2 were elucidated by spectroscopic techniques. They exhibited weak antibacterial as well as cytotoxic activities. They are the first secondary metabolites described from M. cervina.

Animals↗
PubMed2004

Structure-activity relationships of ring C-secotaxoids. 1. Acylative modifications.

The acylative modification of IDN 5390 (3a), a 7,8-secotaxoid under preclinical development, was investigated. A modest decrease of potency was observed upon acylation of the primary and the enolic hydroxyls, suggesting that, just like in paclitaxel, the hydroxyl groups in the upper right-hand sector are not critical for cytotoxicity. The activity of these analogues, and especially of the chemically robust carbonates 3c and 3d, makes it unlikely that the activity of IDN 5390 is due to in vivo oxidation to a fledgling 7-aldehyde and re-aldolization to the corresponding taxane derivative.

Acylation↗
PubMed2004

Structure--activity relationships of the estrogenic sesquiterpene ester ferutinin. Modification of the terpenoid core.

Esterification of p-hydroxybenzoic acid, a very weak estrogenic compound, with the daucane alcohol jaeschkeanadiol (1b) leads to a spectacular magnification of the estrogenic activity. To identify the structural elements responsible for this effect, the terpenoid core of jaeschkeanadiol p-hydroxybenzoate (ferutinin, 1a) was modified, capitalizing on the presence of two functionalities, the monoacylated, hydrogen-bonded 1,3-diol system and the double bond. The hydrogen bonding, while possibly useful, was not critical for activity, while hydrogenation and cyclopropanation of the double bond were tolerated. Conversely, oxidative modifications of the double bond that placed a hydroxyl on the alpha-face of the molecule proved detrimental. Taken together, these observations identified the substitution at C-8/C-9 as critical for activity.

Benzoates↗
PubMed2004

Inhibition of inducible TNF-alpha expression by oxaspirodion, a novel spiro-compound from the ascomycete Chaetomium subspirale.

In a search for compounds inhibiting the inducible TNF-alpha promoter activity in T cells, a new spiro-compound, designated oxaspirodion, was isolated from fermentations of the ascomycete Chaetomium subspirale. Oxaspirodion inhibited TNF-alpha promoter-driven luciferase reporter gene expression with an IC50 value of 2.5 microg/ml (10 microM) in TPA/ionomycin-stimulated Jurkat T cells. Studies on the mode of action of the compound revealed that the inhibition of the TNF-alpha promoter activity is caused by an inhibition of the phosphorylation of the ERK1/2 kinases. In addition, oxaspirodion inhibited the activation of the transcription factor NF-kappaB, which is involved in the inducible expression of many proinflammatory genes.

Animals↗
PubMed2004

Two new biologically active cyclopentenones from Dasyscyphus sp. A47-98.

Two new biological active cyclopentenones VM 4798-1a (1a) and VM 4798-1b (1b) were obtained as a 3:1 inseparable mixture from fermentations of Dasyscyphus sp. A47-98. The mixture of the two isomers showed cytotoxic and weak antibacterial and antifungal properties. VM 4898-1 (2-hydroxy-3,4-dimethyl-2-cyclopenten-1-one, 4), produced by another Dasyscyphus sp. showed no significant biological activity. The structures were elucidated by NMR techniques.

Anti-Bacterial Agents↗
PubMed2004

Phomol, a new antiinflammatory metabolite from an endophyte of the medicinal plant Erythrina crista-galli.

Phomol (1), a novel antibiotic, was isolated from fermentations of a Phomopsis species in the course of a screening of endophytic fungi from the medicinal plant Erythrina crista-galli. For this Argentinean leguminosa antiinflammatory and neuroleptic activities have been described. The compound exhibits antifungal, antibacterial and weak cytotoxic acticity. The antiinflammatory activity was tested in different reporter gene assays (TNF-alpha, STAT1/STAT2 and NF-kappaB) and in an ear edema model in mice. In the reporter gene assays 1 exhibited no activity, whereas 1 showed interesting antiinflammatory activity in the mouse ear assay. The compound is a polyketide lactone and its structure was elucidated by spectroscopic methods.

Animals↗
PubMed2003

Pterocarpans from Bituminaria morisiana and Bituminaria bituminosa.

The aerial parts of Mediterranean papilionaceous plants Bituminaria morisiana and B. bituminosa afforded, along with known phenolics, the prenylated pterocarpans bitucarpin A and B, whose structure was elucidated by spectroscopic techniques. A known isoflavonoid (8-prenyldaidzein) was also obtained for the first time as a genuine plant constituent. The accumulation of pterocarpans at the expense of biogenetically more primitive shikimate metabolites like furanocoumarins or isoflavonoids supports the inclusion of this plant, once part of the genus Psoralea, into the distinct genus Bituminaria.

Fabaceae↗
PubMed2003

A new P-glycoprotein inhibitor from the caper spurge (Euphorbia lathyris).

The macrocyclic lathyrane polyester Euphorbia factor L10 (1a) has been obtained from the seeds of the caper spurge (E. lathyris). The interaction of L10 (1a) and its acetyl derivative (1b) with P-glycoprotein, a multidrug transporter overexpressed in cancer cells and responsible for resistance to chemotherapy, was investigated. The results established lathyrane diterpenoids as a novel chemotype for P-glycoprotein inhibitors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Trypanocidal diarylheptanoids from Aframomum letestuianum.

Three new diarylheptanoids, (4Z,6E)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-4,6-dien-3-one, letestuianin A (1), (4Z,6E)-5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-4,6-dien-3-one, letestuianin B (2), and 1,7-bis(4-hydroxyphenyl)heptan-3,5-dione, letestuianin C (3), as well as the known (4Z,6E)-5-hydroxy-1,7-bis(4-hydroxyphenyl)hepta-4,6-dien-3-one (5) were isolated from Aframomum letestuianum. The known flavonoids 3-acetoxy-5,7,4'-trihydroxyflavanone, 3-acetoxy-7-methoxy-5,4'-dihydroxyflavanone, 7-methoxy-3,5,4'-trihydroxyflavone, and 3,3',4',5,7-pentahydroxyflavan were also obtained from this plant. Their structures were determined using a combination of 1D and 2D NMR techniques. The four diarylheptanoids were tested for growth inhibitory activity in vitro versus bloodstream forms of African trypanosomes. IC(50) values in the range of 1-3 microg/mL were found for compounds 3 and 5.

Animals↗
PubMed2003

S14-95, a novel inhibitor of the JAK/STAT pathway from a Penicillium species.

In a search for new inhibitors of the IFN-gamma mediated signal transduction in HeLa S3 cells using secreted alkaline phosphatase (SEAP) as reporter gene, a novel compound, designated as S14-95 was isolated from fermentations of the imperfect fungus Penicillium sp. 14-95. The compound inhibits the IFN-gamma mediated expression of the reporter gene with IC50 values of 2.5 to approximately 5 microg/ml (5.4 to approximately 10.8 microM). Furthermore the compound inhibited the expression of the proinflammatory enzymes COX-2 and NOS II at 5 microg/ml (10.8 microM) in LPS/IFN-gamma stimulated J774 mouse macrophages. Studies on the mode of action of the compound revealed that the inhibition of the IFN-gamma dependent signaling pathway is caused by an inhibition of the phosphorylation of the STAT1alpha transcription factor. In addition, S14-95 inhibited the activation of the p38 MAP kinase, which is involved in the inducible expression of many proinflammatory genes.

Animals↗
PubMed2002

Refinement and evaluation of a pharmacophore model for flavone derivatives binding to the benzodiazepine site of the GABA(A) receptor.

To further develop and evaluate a pharmacophore model previously proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) for ligands binding to the benzodiazepine site of the GABA(A) receptor, 40 new flavone derivatives have been synthesized and their affinities for the benzodiazepine site have been determined. Two new regions of steric repulsive interactions between ligand and receptor have been characterized, and the receptor region in the vicinity of 6- and 3'-substituents has been mapped out. 2'-Hydroxy substitution is shown to give a significant increase in affinity, which is interpreted in terms of a novel hydrogen bond interaction with the previously proposed hydrogen bond-accepting site A2. On the basis of the results of these studies and the refined pharmacophore model, 5'-bromo-2'-hydroxy-6-methylflavone, the highest affinity flavone derivative reported so far (K(i) = 0.9 nM), was successfully designed. A comparison of the pharmacophore model with a recently proposed alternative model (Marder; et al. Bioorg. Med. Chem., 2001, 9, 323-335) has been made.

Animals↗
PubMed2002

Gerronemins A-F, cytotoxic biscatechols from a Gerronema species.

The gerronemins A-F (1-6) were isolated as the cytotoxic components of an extract of a Gerronema species detected in a screening for new cytotoxic metabolites from basidiomycetes. Their structures were elucidated by spectroscopic techniques, and they are composed of a C12-C16 alkane or alkene substituted at both ends by 2,3-dihydroxyphenyl groups. The gerronemins blocked the inducible expression of a hCOX-2 and iNOS promoter driven reporter gene with IC50-values of 1-5 microg/ml. In addition, cytotoxic activities were observed which were due the inhibition of cellular macromolecular syntheses.

Agaricales↗