Biomedical subjects

J W Jaroszewski

Publications and source records attributed to J W Jaroszewski.

At least 19 recordsLinked to original sources

PubMed2003

Modification of the philanthotoxin-343 polyamine moiety results in different structure-activity profiles at muscle nicotinic ACh, NMDA and AMPA receptors.

Voltage-dependent, non-competitive inhibition by philanthotoxin-343 (PhTX-343) analogues, with reduced charge or length, of nicotinic acetylcholine receptors (nAChR) of TE671 cells and ionotropic glutamate receptors (N-methyl-D-aspartate receptors (NMDAR) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR)) expressed in Xenopus oocytes from rat brain RNA was investigated. At nAChR, analogues with single amine-to-methylene or amine-to-ether substitutions had similar potencies to PhTX-343 (IC(50)=16.6 microM at -100 mV) whereas PhTX-(12), in which both secondary amino groups of PhTX-343 were replaced by methylenes, was more potent than PhTX-343 (IC(50)=0.93 microM at -100 mV). Truncated analogues of PhTX-343 were less potent. Inhibition by all analogues was voltage-dependent. PhTX-343 (IC(50)=2.01 microM at -80 mV) was the most potent inhibitor of NMDAR. At AMPAR, most analogues were equipotent with PhTX-343 (IC(50)=0.46 microM at -80 mV), apart from PhTX-83, which was more potent (IC(50)=0.032 microM at -80 mV), and PhTX-(12) and 4,9-dioxa-PhTX-(12), which were less potent (IC(50)s>300 microM at -80 mV). These studies show that PhTX-(12) is a selective nAChR inhibitor and PhTX-83 is a selective AMPAR antagonist.

Animals↗

PubMed2001

Natural glycosides containing allopyranose from the passion fruit plant and circular dichroism of benzaldehyde cyanohydrin glycosides.

[structure: see text] Leaves of the edible passion fruit plant, Passiflora edulis, contain benzylic beta-D-allopyranosides 1 and 2, representatives of a rare class of natural glycosides with D-allose as the only sugar constituent. The glycoside 1 is the first known cyanogenic glycoside containing a sugar different from D-glucose attached directly to the cyanohydrin center. Asymmetric perturbation of the (1)L(b) transition of the benzene chromophore was shown to be useful for determination of absolute configuration of the cyanohydrin center of aromatic cyanogenic glycosides.

Benzaldehydes↗

PubMed2001

Conformational analysis of indole alkaloids corynantheine and dihydrocorynantheine by dynamic 1H NMR spectroscopy and computational methods: steric effects of ethyl vs vinyl group.

1H NMR (400 MHz) spectra of the indole alkaloid dihydrocorynantheine recorded at room temperature show the presence of two conformers near coalescence. Low temperature 1H NMR allowed characterization of the conformational equilibrium, which involves rotation of the 3-methoxypropenoate side chain. Line-shape analysis yielded enthalpy of activation DeltaH(double dagger) = 71 +/- 6 kJ/mol, and entropy of activation DeltaS(double dagger) = 33 +/- 6 J/mol.K. The major and minor conformation contains the methyl ether group above and below the plane of the ring, respectively, as determined by low-temperature NOESY spectra, with free energy difference DeltaG degrees = 1.1 kJ/mol at -40 degrees C. In contrast to dihydrocorynantheine, the corresponding rotamers of corynantheine are in the fast exchange limit at room temperature. The activation parameters determined for corynantheine were DeltaH(double dagger) = 60 +/- 6 kJ/mol and DeltaS(double dagger) = 24 +/- 6 J/mol.K, with DeltaG degrees = 1.3 kJ/mol at -45 degrees C. The difference in the exchange rates of the rotamers of corynantheine and dihydrocorynantheine (respectively, 350 s(-1) and 9 s(-1) at 0 degrees C) reflects the difference in the steric bulk of the vinyl and the ethyl group. The conformational equilibria involving the side chain rotation as well as inversion of the bridgehead nitrogen in corynantheine and dihydrocorynantheine was studied by force-field (Amber and MMFF) and ab initio (density-functional theory at the B3LYP/6-31G level) computational methods, the results of which were in good agreement with the 1H NMR data. However, the calculations identified the rotamers as essentially isoenergetic, the experimental energy differences being to small to be reproduced exactly by the theory. Comparison of density-functional and force-field calculations with experimental results identified Amber as giving the most accurate results in the present case.

Alkaloids↗

PubMed2001

An NMR and ab initio quantum chemical study of acid-base equilibria for conformationally constrained acidic alpha-amino acids in aqueous solution.

The protonation states of a series of piperidinedicarboxylic acids (PDAs), which are conformationally constrained acidic alpha-amino acids, have been studied by (13)C NMR titration in water. The resulting data have been correlated with theoretical results obtained by HF/6-31+G calculations using the polarizable continuum model (PCM) for the description of water. The PDAs are highly ionizable and contain one or two possible internal hydrogen bonds. In the present study, we show that the PCM model is able to reproduce the relative stabilities of the different protonation states of the PDAs. Furthermore, our results show that prediction of relative pK(a) values for two different types of ionizable functional groups covering a pK(a) range from 1.6 to 12.1 is possible with a high degree of accuracy.

Acid-Base Equilibrium↗

PubMed2001

Structural determinants for AMPA agonist activity of aryl or heteroaryl substituted AMPA analogues. Synthesis and pharmacology.

We have previously reported the synthesis and pharmacological characterization of analogues of 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA, 1a), in which the methyl group was replaced by a phenyl group (APPA, 1b) or heteroaryl groups. While 2b and its 3-pyridyl analogue 2-amino-3-[3-hydroxy-5-(3-pyridyl)-4-isoxazolyl]propionic acid (3-Py-AMPA, 3) show very low affinity for AMPA receptors, introduction of heteroaryl substituents containing heteroatom in the 2-position provides potent AMPA receptor agonists. We here report the synthesis and pharmacology of 2-amino-3-(3-hydroxy-5-pyrazinyl-4-isoxazolyl)propionic acid (7) (IC50 = 1.2 microM), which is weaker as an AMPA agonist than AMPA (IC50 = 0.040 microM; EC50 = 3.5 microM) but comparable in potency with 2-Py-AMPA (4) (IC50 = 0.57 microM; EC50 = 7.4 microM), as determined in radioligand binding and electrophysiological experiments, respectively. The AMPA analogues 8a-c, containing 2-, 3-, or 4-methoxyphenyl substituents, respectively, and the corresponding hydroxyphenyl analogues, 9a-c, were also synthesized and evaluated pharmacologically. With the exception of 2-amino-3-[3-hydroxy-5-(2-hydroxyphenyl)-4-isoxazolyl]propionic acid (9a), which is a very weak AMPA agonist (IC50 = 45 microM; EC50 = 324 microM), none of these compounds showed detectable effect at AMPA receptors.

Animals↗

PubMed2001

Leishmanicidal, antiplasmodial, and cytotoxic activity of novel diterpenoid 1,2-quinones from Perovskia abrotanoides: new source of tanshinones.

Cryptotanshinone (1), a quinoid diterpene with a nor-abietane skeleton, and three new natural products, 1beta-hydroxycryptotanshinone (2), 1-oxocryptotanshinone (3), and 1-oxomiltirone (4), were isolated from roots of the Iranian medicinal plant Perovskia abrotanoides. Their structures were established using homo- and heteronuclear two-dimensional NMR experiments, supported by HRMS. The total amount of tanshinones isolated from dry roots of Perovskia abrotanoides was about 1.5%. The compounds exhibited leishmanicidal activity in vitro (IC(50) values in the range 18-47 microM). These findings provide a rationale for traditional use of the roots in Iran as a constituent of poultices for treatment of cutaneous leishmaniasis. The isolated tanshinones also inhibited growth of cultured malaria parasites (3D7 strain of Plasmodium falciparum), drug-sensitive KB-3-1 human carcinoma cell line, multidrug-resistant KB-V1 cell line, and human lymphocytes activated with phytohaemagglutinin A (IC(50) values in the range 5-45 microM). The toxicity of tanshinones toward the drug-sensitive KB-3-1 and the multidrug-resistant KB-V1 cells was the same, indicating that the compounds are not substrates for the P-glycoprotein drug efflux pump.

Abietanes↗

PubMed2001

Recent advances in the medicinal chemistry of polyamine toxins.

This review describes the recent developments in the field of polyamine toxins, with focus on structure activity relationship investigations, including studies of importance of the polyamine moiety for biological activity, photolabeling studies using polyamine toxins as templates, as well as use of solid phase methods for the synthesis of polyamine toxins. The review is mainly concerned with effects of polyamine toxins on nicotinic acetylcholine receptors and ionotropic glutamate receptors.

Animals↗

PubMed2000

NMR characterisation and transdermal drug delivery potential of microemulsion systems.

The purpose of this study was to investigate the influence of structure and composition of microemulsions (Labrasol/Plurol Isostearique/isostearylic isostearate/water) on their transdermal delivery potential of a lipophilic (lidocaine) and a hydrophilic model drug (prilocaine hydrochloride), and to compare the drug delivery potential of microemulsions to conventional vehicles. Self-diffusion coefficients determined by pulsed-gradient spin-echo NMR spectroscopy and T(1) relaxation times were used to characterise the microemulsions. Transdermal flux of lidocaine and prilocaine hydrochloride through rat skin was determined in vitro using Franz-type diffusion cells. The formulation constituents enabled a broad variety of microemulsion compositions, which ranged from water-continuous to oil-continuous aggregates over possible bicontinuous structures, with excellent solubility properties for both lipophilic and hydrophilic compounds. The microemulsions increased transdermal flux of lidocaine up to four times compared to a conventional oil-in-water emulsion, and that of prilocaine hydrochloride almost 10 times compared to a hydrogel. A correlation between self-diffusion of the drugs in the vehicles and transdermal flux was indicated. The increased transdermal drug delivery from microemulsion formulations was found to be due mainly to the increased solubility of drugs and appeared to be dependent on the drug mobility in the individual vehicle. The microemulsions did not perturb the skin barrier, indicating a low skin irritancy.

Administration, Cutaneous↗

PubMed2000

Solid-phase synthesis and biological evaluation of a combinatorial library of philanthotoxin analogues.

The modular structure of philanthotoxins was exploited for construction of the first combinatorial library of these compounds using solid-phase parallel synthesis. (S)-Tyrosine and (S)-3-hydroxyphenylalanine were used as amino acid components, spermine, 1,12-dodecanediamine, and 4,9-dioxa-1,12-dodecanediamine as amine components, and butanoyl, phenylacetyl, and cyclohexylacetyl as N-acyl groups. Following automated preparative HPLC, the resulting 18 compounds were isolated as the S-forms in 40-70% yields. The purity of the products was determined by HPLC with evaporative light scattering detection and by (1)H and (13)C NMR. The thus obtained philanthotoxins were tested electrophysiologically for their antagonist properties on human muscle-type nicotinic acetylcholine receptors (nAChR) expressed in TE671 cells and on rat brain non-NMDA glutamate receptors (non-NMDAR) expressed in Xenopus oocytes. 4-Hydroxy analogues lacking the secondary amino groups (PhTX-12 and 4,9-dioxa-PhTX-12 and their analogues) were inactive on non-NMDAR, whereas the potency of the spermine derivatives (PhTX-343 and its analogues) increased with steric bulk of the N-acyl group. The analogue of PhTX-343 in which the N-butanoyl group was replaced by phenylacetyl group had IC(50) of 15 +/- 4 nM on non-NMDAR. Increasing the steric bulk of the N-acyl group was not advantageous for activity at nAChR, and a sharp decrease in potency with increased steric bulk was observed with the derivatives of PhTX-12. 3-Hydroxy analogues generally exhibited lower activity and different response to alterations of the N-acyl groups as compared to the 4-hydroxy analogues. Since the acyl group alterations in PhTX-343 and 4,9-dioxa-PhTX-12 have a similar effect on potency, which is distinctly different from that observed for PhTX-12, the two former compounds may bind to nAChR in a similar fashion but differently from that of PhTX-12. The combinatorial library approach described in this work represents a prototype methodology for future exploration of structure-activity relationships of philanthotoxins.

Animals↗

PubMed2000

Solid phase synthesis and biological evaluation of enantiomerically pure wasp toxin analogues PhTX-343 and PhTX-12.

PhTX-343 and PhTX-12, analogues of the natural polyamine wasp toxin PhTX-433, were synthesised in 40-60% yields as pure enantiomers using solid phase synthesis techniques. Capillary electrophoresis procedures were developed for chiral separation and determination of enantiomeric purity (ee) of the enantiomers of PhTX-343 and PhTX-12. The methods were optimised with respect to chiral selector, buffer pH, and temperature around the capillary. Thus, rac-PhTX-343 was resolved using a separation buffer containing 30 mM heptakis-(2, 6-di-O-methyl)-beta-cyclodextrin in 50 mM 6-aminocarproic acid (pH 4. 0) at 15 degrees C. rac-PhTX-12 was not resolvable in this system, but could be resolved using a separation buffer containing 10% w/v of dextrin 10, a linear maltodextrin, in 50 mM 6-aminocaproic acid (pH 4.0) at 15 degrees C. Using these methods, the optical purity of the synthetic enantiomers was determined to be ee > 99%. The enantiomers were also characterised by chiroptical methods. The antagonist potency of the enantiomers was tested on nicotinic acetylcholine receptors (human muscle-type nAChR) expressed in TE671 cells, ionotropic glutamate receptors in Xenopus laevis oocytes (expressing recombinant GluR1flop receptors), and locust muscle ionotropic glutamate receptors sensitive to quisqualate (qGluR). The potencies of each pair of enantiomers were similar (eudismic ratio close to 1).

Animals↗

PubMed2000

Synthesis of epimers of L-cyclopentenylglycine using enzymatic resolution.

Both epimers of the naturally occurring nonproteinogenic amino acid L-cyclopentenylglycine, (2S,1'S)- and (2S, 1'R)-2-(cyclopent-2'-enyl)glycine, were obtained via a procedure involving condensation of 3-chlorocyclopentene with diethyl acetylaminomalonate, deethoxycarbonylation, chromatographic separation of the resulting two pairs of enantiomers, and enzymatic resolution of the racemates employing enantioselective hydrolysis of the ethyl ester group with alpha-chymotrypsin. The method was used for preparation of (13)C-labeled compounds of interest for biosynthetic tracer experiments. Enantiomeric purity of the products was determined by chiral HPLC on a Crownpak CR(+) column. The biologically active (2S,1'R) isomer was obtained as a pure compound and characterized for the first time. The (2R,1'R) and (2R,1'S) isomers were obtained as N-acetyl ethyl ester derivatives.

Carbon Isotopes↗

PubMed2000

Rational selection of antisense oligonucleotide sequences.

The purpose of this review is to identify rational selection procedures for the identification of optimal antisense oligonucleotide sequences. The review is firstly focused on how to find optimal hybridization sites, and secondly on how to select sequences that bind to structured RNA. The methods reviewed range from the more empirical testing of large numbers of mRNA complementary sequences to the more systematic techniques, i.e. RNase H mapping, use of combinatorial arrays and prediction of secondary structure of mRNA by computational methods. Structures that bind to structured RNA, i.e. aptastrucs and tethered oligonucleotide probes, and foldback triplex-forming oligonucleotides are also discussed. Relating to selection of antisense sequences by aid of computational analysis, valuable www addresses are given along with examples of folded structures of mRNA.

Base Sequence↗

PubMed2000

Cytotoxic activity of some phenanthroindolizidine N-oxide alkaloids from Cynanchum vincetoxicum.

Two previously known phenanthroindolizidine alkaloids, (-)-10beta-antofine N-oxide (1) and (-)-10beta, 13aalpha-14beta-hydroxyantofine N-oxide (2), and a novel alkaloid, (-)-10beta,13aalpha-secoantofine N-oxide (3), were isolated from aerial parts of Cynanchum vincetoxicum. Their structures were established by means of NMR methods, including COSY, NOESY, HSQC, and HMBC experiments, as well as from their CD spectra. Cytotoxic activity of the alkaloids was assessed in vitro using both a drug-sensitive KB-3-1 and a multi-drug-resistant KB-V1 cancer cell line. The antofine derivatives (1 and 2) showed pronounced cytotoxicity against the drug-sensitive cell line (IC(50) values about 100 nM), whereas the secoantofine derivative (3) was considerably less active. The KB-V1 cell line showed a marginal resistance against all alkaloids, demonstrating that these compounds are poor substrates for the P-glycoprotein (P-170) efflux pump.

Alkaloids↗

PubMed2000

Leishmanicidal, antiplasmodial and cytotoxic activity of indole alkaloids from Corynanthe pachyceras.

Five indole alkaloids, corynantheidine, corynantheine, dihydrocorynantheine, alpha-yohimbine and corynanthine were isolated from bark of Corynanthe pachyceras K. Schum. (Rubiaceae). The structures were established by spectroscopic methods, including previously unreported assignment of all 1H-NMR resonances by COSY and NOESY experiments. These and related alkaloids showed pronounced activity against Leishmania major promastigotes (IC50 at the micromolar level) but no significant in vitro antiplasmodial activity (against chloroquine-sensitive Plasmodium falciparum). Cytotoxicity assessed with drug sensitive KB-3-1 and multidrug-resistant KB-V1 cell lines was low; the alkaloids are apparently not substrates for the P-glycoprotein (P-170) efflux pump.

Alkaloids↗

PubMed2000

Age dependent accumulation of N-acyl-ethanolamine phospholipids in ischemic rat brain. A (31)P NMR and enzyme activity study.

N-acyl-ethanolamine phospholipids (NAPE) can be formed as a stress response during neuronal injury, and they are precursors for N-acyl-ethanolamines (NAE), some of which are endocannabinoids. The levels of NAPE accumulated during post-decapitative ischemia (6 h at 37 degrees C) were studied in rat brains of various age (1, 6, 12, 19, 30, and approximately 70 days) by the use of (31)P NMR spectroscopy of lipid extracts. This ability to accumulate NAPE was compared with the activity of N-acyltransferase and of NAPE-hydrolyzing phospholipase D (NAPE-PLD) in brain microsomes. These two enzymes are involved in the formation and degradation of NAPE, respectively. The results showed that 1) the ability to accumulate NAPE during post-decapitative ischemia is especially high in the youngest rats and is markedly reduced in older brains [in 1-day-old rat brains NAPE accumulated to 1.5% of total phospholipids, while in 30-day-old rat brains NAPE accumulation could not be detected (detection limit 0.09%)] and 2) this age pattern of accumulation can be explained by a combination of the decreased activity of N-acyltransferase and the increased activity of NAPE-PLD during development. These results point out that it would be advantageous to investigate a potential cytoprotective role of NAPE in the brains of very young rats.

Acyltransferases↗

PubMed1999

Analogues of neuroactive polyamine wasp toxins that lack inner basic sites exhibit enhanced antagonism toward a muscle-type mammalian nicotinic acetylcholine receptor.

Philanthotoxin-433 (PhTX-433), a natural polyamine wasp toxin, is a noncompetitive antagonist of certain ionotropic receptors. Six analogues of PhTX-343 (a synthetic analogue of the natural product), in which the secondary amino groups are systematically replaced by oxygen or methylene groups, have been synthesized by coupling of N-(1-oxobutyl)tyrosine with 1,12-dodecanediamine, 4,9-dioxa-1, 12-dodecanediamine, or appropriately protected di- and triamines, the latter being obtained by multistep syntheses. The resulting PhTX-343 analogues were purified and characterized, and their protolytic properties (stepwise macroscopic pK(a) values) were determined by (13)C NMR titrations. All analogues are fully protonated at physiological pH. The effects of these compounds on acetylcholine-induced currents in TE671 cells clamped at various holding potentials were determined. All of the analogues noncompetitively antagonized the nicotinic acetylcholine receptor (nAChR) in a concentration-, time-, and voltage-dependent manner. The amplitudes of acetylcholine-induced currents were compared at their peaks and at the end of a 1 s application in the presence or absence of the analogues. Most of the analogues were equipotent with or more potent than PhTX-343. The dideaza analogue PhTX-12 [IC(50) of 0.3 microM (final current value)] was the most potent, representing the highest potency improvement (about 50-fold) yet achieved by modification of the parent compound (PhTX-343). Thus, the presence of multiple positive charges in the PhTX-343 molecule is not necessary for antagonism of nAChR. In contrast, the compounds were much less potent than PhTX-343 at locust muscle ionotropic glutamate receptors sensitive to quisqualate (qGluR). The results demonstrate that the selectivity for different types of ionotropic receptors can be achieved by manipulating the polyamine moiety of PhTX-343.

Animals↗

PubMed1999

Accumulation of N-acyl-ethanolamine phospholipids in rat brains during post-decapitative ischemia: a 31p NMR study.

Phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy has been used to study accumulation of N-acyl-ethanolamine phospholipids in rat brains during post-decapitative ischemia. Lipids were extracted from rat brain homogenates and the extracts were thoroughly washed with aq. potassium ethylenediaminetetraacetic acid (EDTA). The lower organic phases were isolated and evaporated to dryness under a stream of nitrogen and the lipids were redissolved in CDCl3-CH3OH-H2O 100.0:29.9:5.2 (v/v/v) for NMR analysis. Increasing the period of post-decapitative ischemia resulted in an accumulation of two signals in the NMR spectra at 0.18 and 0.22 ppm (relative to the chemical shift of 1,2-diacyl-sn-glycero-3-phosphocholine (PCDIACYL) at -0.84 ppm). These signals were identified as originating from 1,2-diacyl-sn-glycero-3-phospho-(N-acyl)-ethanolamine (NAPEDIACYL) and 1-(1'-alkenyl)-2-acyl-sn -glycero-3-phospho-(N-acyl)-ethanolamine (NAPEPLAS), respectively, by spiking with authentic materials. Additionally, the identification was verified by thin-layer chromatography, which also showed the accumulation of N-acyl-ethanolamine phospholipids. The use of K-EDTA instead of the commonly used Cs-EDTA in the preparation of the NMR samples allowed the separation of the chemical shifts of N-acyl-ethanolamine phospholipids from those of the ethanolamine phospholipids. Moreover, the chemical shift of cardiolipin was moved from 0.15 ppm observed with Cs-EDTA to about 0.31 ppm with K-EDTA. The present study demonstrates that it is possible to detect and quantify post-decapitative accumulation of NAPE subclasses (NAPEDIACYL and NAPEPLAS) in rat brains by the use of 31P NMR spectroscopy.

Acylation↗

PubMed1998

Angiotensin converting enzyme (ACE) inhibitors from Jasminum azoricum and Jasminum grandiflorum.

Bioactivity-guided fractionation of extracts of the aerial parts of Jasminum azoricum var. travancorense, using an in vitro ACE inhibition assay, led to isolation of three oligomeric, iridoid-type compounds, which were named sambacein I-III. Their structures are based on spectroscopic and chemical evidence. Similarly, fractionation of extracts of aerial parts of J. grandiflorum resulted in the isolation of the previously reported ACE inhibitor, oleacein. The IC50 values of purified ACE inhibitors were 26-36 microM. Moreover, 2-(3,4-dihydroxyphenyl)-ethanol, isoquercitrin and ursolic acid were isolated from J. grandiflorum. Sambaceins and oleacein are formed from genuine iridoid glucosides during processing of the plant material. NMR spectroscopy was used to measure the level of the ACE inhibitors in the traditional medicines prepared in Kerala from these Jasminum species.

Angiotensin-Converting Enzyme Inhibitors↗