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Jari Yli-Kauhaluoma

Publications and source records attributed to Jari Yli-Kauhaluoma.

17 recordsLinked to original sources
PubMed2006

Microplate screening assay for binding of ligands to bovine or reindeer beta-lactoglobulins.

Several analytical methods have been used to determine whether ligands bind to bovine beta-lactoglobulin (betaLG). The most common methods are based on fluorescence quenching. We have miniaturised this method from a quartz cell to a 96-well plate. The miniaturisation was evaluated using retinol. The binding constants between the two methods demonstrated a good correlation. The 96-well plate method is much faster and allows many references to be used in the same analysis. The miniaturised method was used to study the binding of three different ligands (4-HPR, arotinoid, warfarinyl palmitate) modelled to bind to betaLG. The binding data showed that all of these ligands bound to betaLG. The method was further used to demonstrate that reindeer betaLG could also bind the four ligands in the same way as bovine betaLG. Because one aim is to use bovine and reindeer betaLG as a binder molecule for aliments in e.g. functional food or for drugs, the influence of pH was also studied and demonstrated that short-term acidic conditions had only a slight effect on the binding properties.

Animals↗
PubMed2006

Pharmacological properties of the ubiquitous natural product betulin.

Betulin (lup-20(29)-ene-3beta,28-diol) is an abundant naturally occurring triterpene and it is found predominantly in bushes and trees forming the principal extractive (up to 30% of dry weight) of the bark of birch trees. Presently, there is no significant use for this easily isolable compound, which makes it a potentially important raw material for polymers and a precursor of biologically active compounds. Betulin can be easily converted to betulinic acid, which possesses a wide spectrum of biological and pharmacological activities. Betulinic acid has antimalarial and anti-inflammatory activities. Betulinic acid and its derivatives have especially shown anti-HIV activity and cytotoxicity against a variety of tumor cell lines comparable to some clinically used drugs. A new mechanism of action has been confirmed for some of the most promising anti-HIV derivatives, which makes them potentially useful additives to the current anti-HIV therapy. Betulinic acid is specifically cytotoxic to several tumor cell lines by inducing apoptosis in cells. Moreover, it is non-toxic up to 500 mg/kg body weight in mice. The literature concerning derivatization of betulin for structure-activity relationship (SAR) studies and its pharmacological properties is reviewed.

Animals↗
PubMed2006

Stereochemical sensitivity of the human UDP-glucuronosyltransferases 2B7 and 2B17.

A set of 28 enantiomers comprising rigid and flexible secondary alcohols was synthesized by the asymmetric Corey-Bakshi-Shibata reduction. The enantiomerically pure alcohols were subjected to enzymatic glucuronidation assays employing the human UDP-glucuronosyltransferases (UGTs) 2B7 and 2B17. Both UGTs displayed high levels of stereoselectivity, favoring the conjugation of the (R)-enantiomers over their respective (S)-stereoisomers at eudismic ratios up to 256. The spatial arrangement of the hydroxy group determined the diastereoselectivity of the UGT2B17-catalyzed reaction in agreement with Pfeiffer's rule (eudismic activity quotient = 0.83 +/- 0.14). Inhibition studies revealed that the enantiomers had similar affinities toward the enzymes. The diastereoselectivity of the UGT-catalyzed conjugation stemmed, therefore, from the arrangement of the substrates in the catalytic site, rather than from distinct affinities toward the enzymes. Taken together, this study showed that metabolic enzymes that are generally conceived to be rather "flexible" in nature are capable of displaying high levels of chiral distinction.

Alcohols↗
PubMed2006

Morphine, oxycodone, methadone and its enantiomers in different models of nociception in the rat.

We studied the effects of the commonly used mu-opioid receptor agonists morphine, oxycodone, methadone and the enantiomers of methadone in thermal and mechanical models of acute pain and in the spinal nerve ligation model of neuropathic pain in rats. Subcutaneous administration of morphine, oxycodone, and methadone produced a dose-dependent antinociceptive effect in the tail flick, hotplate, and paw pressure tests. l-methadone, racemic methadone, and oxycodone had a similar dose-dependent antinociceptive effect, whereas the dose-response curve of morphine was shallower. In the spinal nerve ligation model of neuropathic pain, subcutaneous administration of morphine, oxycodone, methadone and l-methadone had antiallodynic effects in tests of mechanical and cold allodynia. l-methadone showed the strongest antiallodynic effect of the tested drugs. d-methadone was inactive in all tests. Morphine 5.0 mg/kg, oxycodone 2.5 mg/kg, and l-methadone 1.25 mg/kg decreased spontaneous locomotion 30 min after drug administration. In conclusion, in acute nociception all mu-opioid receptor agonists produced antinociception, with morphine showing the weakest effect. In nerve injury pain, l-methadone showed the greatest antiallodynic potency in both mechanical and cold allodynia compared with the other opioids. Opioids seem to have different profiles in different pain models. l-methadone should be studied for neuropathic pain in humans.

Acute Disease↗
PubMed2006

Chiral distinction between the enantiomers of bicyclic alcohols by UDP-glucuronosyltransferases 2B7 and 2B17.

The stereoselective binding and transformation of optically pure bicyclic alcohols by human UDP-glucuronosyltransferases from subfamily 2B were investigated. The enantiomers of 1-indanol, 1-tetralol, and 1-benzosuberol were synthesized by asymmetric Corey-Bakshi-Shibata reduction and subjected to glucuronidation assays. The alcohols studied were primarily glucuronidated by UGT2B7 and UGT2B17. The catalytic transformation by UGT2B17 was highly stereoselective, favoring conjugation of the (R)-enantiomers. UGT2B7, on the other hand, did not exhibit stereoselectivity toward 1-benzosuberol, the best substrate in this series. To assess binding affinities to the enzymes, the six different compounds were tested for their efficiency as inhibitors of either UGT2B7 or UGT2B17. The results of the latter analyses indicated that the affinities of both enantiomers of each pair towards UGT2B7 and UGT2B17 were of the same order of magnitude. Therefore, the findings of this study suggest that the spatial arrangement of the hydroxy group plays an important role in the glucuronic acid transfer reaction, but not necessarily in substrate binding to the UGTs.

Alcohols↗
PubMed2005

Exploring the scope of the 29G12 antibody catalyzed 1,3-dipolar cycloaddition reaction.

[Chemical reaction: See text] 29G12 is a murine monoclonal antibody programmed to catalyze the regio- and enantioselective 1,3-dipolar cycloaddition reaction between 4-acetamidobenzonitrile N-oxide 1a and N,N-dimethylacrylamide 2a (Toker, J. D.; Wentworth, P., Jr.; Hu, Y.; Houk, K. N.; Janda, K. D. J. Am. Chem. Soc. 2000, 122, 3244). Given the unique nature of 29G12 as a protein biocatalyst for this chemical reaction, we have investigated both the substrate specificity and mechanistic parameters of the 29G12-catalyzed process. These studies have shown that while 29G12 is specific for its dipole substrate 1a, the antibody is highly promiscuous with respect to the dipolarophiles it can process. 29G12 accepts a bulky hydrophobic dipolarophile cosubstrate, with rates of product formation up to 70-fold faster than with the original substrate 2a. In all cases, the respective isoxazoline products are produced with exquisite regio- and stereochemical control (78-98% ee). Comparison between the steady-state kinetic parameters from the 29G12-catalyzed reaction of 1a with the most efficient versus the original dipolarophile cosubstrate (2m and 2a, respectively), reveals that while the effective molarities (EM)s are almost identical (EM(2m)) 26 M; EM((2a)) 23 M), the affinity of 29G12 for the larger dipolarophile 2m is more than 1 order of magnitude higher than for 2a [Km(2m) 0.44 +/- 0.04 mM; Km(2a) 5.8 +/- 0.4 mM]. Furthermore, when 2m is the cosubstrate, the affinity of 29G12 for its dipole 1a is also greatly improved [Km(1a) 0.82 +/- 0.1 mM compared to Km(1a) 3.4 +/- 0.4 mM when 2a is the cosubstrate]. An analysis of the temperature dependence of the 29G12-catalyzed reaction between 1a and 2m reveals that catalysis is achieved via a decrease in enthalpy of activation (DeltaDeltaH 4.4 kcal mol(-1)) and involves a large increase in the entropy of activation (DeltaDeltaS 10.4 eu). The improved affinity of 29G12 for the nitrile oxide 1a in the presence of 2m, coupled with the increase in DeltaDeltaS during the 29G12-catalyzed reaction between 1a and 2m supports the notion of a structural reorganization of the active site to facilitate this antibody-catalyzed reaction.

Acrylamides↗
PubMed2005

Microwave-assisted synthesis of imidazoles: reaction of p-toluenesulfonylmethyl isocyanide and polymer-bound imines.

A convenient method for the synthesis of 1,5-disubstituted imidazoles has been developed on a polymeric support using base-promoted 1,3-dipolar cycloaddition reaction of p-toluenesulfonylmethyl isocyanide (TOSMIC) with immobilized imines under microwave irradiation. The immobilized imines were synthesized by the reaction of various primary benzyl amines with 4-formyl-3-methoxyphenoxymethyl polystyrene in the presence of trimethyl orthoformate at room temperature. Cleavage from the polymeric support using trifluoroacetic acid gave the desired 1,5-disubstituted imidazoles with excellent yield and high purity.

Cyclization↗
PubMed2005

Methadone increases intracellular calcium in SH-SY5Y and SH-EP1-halpha7 cells by activating neuronal nicotinic acetylcholine receptors.

(-)-Methadone acts as an agonist at opioid receptors. Both (+)- and (-)-enantiomers of methadone have been suggested to be potent non-competitive antagonists of alpha3beta4 neuronal nicotinic acetylcholine receptors (nAChRs). In the present study, we have examined interactions of methadone with nAChRs by using receptor binding assays, patch-clamp recording and calcium fluorometry imaging with SH-SY5Y cells naturally expressing alpha7 and alpha3* nAChR subtypes and SH-EP1-halpha7 cells heterologously expressing human alpha7 nAChRs. Methadone potently inhibited binding of [3H]methyllycaconitine to alpha7 nAChRs and that of [3H]epibatidine to alpha3* nAChRs. Methadone pretreatment induced up-regulation of epibatidine binding sites in SH-SY5Y cells. Using whole-cell patch-clamp recording, both isomers of methadone activated cation currents via mecamylamine-sensitive nAChRs in SH-SY5Y cells. Nicotine and both (+)- and (-)-methadone evoked increases in [Ca2+]i in both fluo-3AM loaded cell lines, and these effects were blocked by mecamylamine and by the alpha7 selective antagonist methyllycaconitine, suggesting effects of methadone as alpha7-nAChR agonist. Sensitivity of sustained nicotine and methadone effects to blockade by CdCl2, ryanodine and xestospongin-c implicates voltage-operated Ca2+ channels and intracellular Ca2+ stores as downstream modulators of elevated [Ca2+]i. Collectively, our results suggest that methadone engages in complex and potentially pharmacologically significant interactions with nAChRs.

Analgesics, Opioid↗
PubMed2005

Analysis of small molecules by ultra thin-layer chromatography-atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry.

The feasibility of ultra thin-layer chromatography atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry (UTLC-AP-MALDI-MS) has been studied in the analysis of small molecules. Because of a thinner adsorbent layer, the monolithic UTLC plates provide 10-100 times better sensitivity in MALDI analysis than conventional high performance thin-layer chromatography (HPTLC) plates. The limits of detection down to a low picomole range are demonstrated by UTLC-AP-MALDI-MS. Other advantages of UTLC over HPTLC include faster separations and lower solvent consumption. The performances of AP-MALDI-MS and vacuum MALDI-MS have been compared in the analysis of small drug molecules directly from the UTLC plates. The desorption from the irregular surface of UTLC plates with an external AP-MALDI ion source combined with an ion trap instrument provides clearly less variation in measurements of m/z values when compared with a vacuum MALDI-time-of-flight (TOF) instrument. The performance of the UTLC-AP-MALDI-MS method has been applied successfully to the purity analysis of synthesis products produced by solid-phase parallel synthesis method.

Atmospheric Pressure↗
PubMed2005

Recent advances in 1,3-dipolar cycloaddition reactions on solid supports.

Solid-phase methods are of a great significance in organic synthesis. Recent developments of these methods are providing new ways to construct libraries of small organic molecules. Five-membered heterocyclic compounds, which can be utilized in a variety of applications, are formed in the 1,3-dipolar cycloaddition reaction between dipolarophiles and dipoles. This review deals with the solid-phase synthesis of heterocycles via [3+2] cycloaddition reaction. Cycloaddition reactions of polymer-bound dipoles and polymer-bound dipolarophiles and intramolecular solid-phase cycloadditions are discussed in separate sections. Reactions of dipolarophiles such as alkenes, alkynes, and imines with dipoles such as azomethine ylides, azomethine imines, nitrile imines, azides, nitrones, and nitrile oxides are described. The recent literature up to December 2003 is covered.

Chemistry, Organic↗
PubMed2003

On the hydrolytic behavior of tinidazole, metronidazole, and ornidazole.

Using two UV-spectrophotometric methods, the hydrolysis of tinidazole was studied at pH 1.00-8.45 at 80 degrees C. The reaction followed apparent first-order kinetics throughout the studied range. No kinetic salt effect was detected, indicating that at least one of the reacting partners forming the transition state has a charge of 0. The reaction rate macro constants M(1)-M(4) were calculated to be 3.35 x 10(-2) M(-1) h(-1), 1.45 x 10(-2) h(-1), 3.76 x 10(-6) M h(-1), and 2.85 x 10(-11) M(2) h(-1), respectively. At pH >or= 7, the uncharged tinidazole was decomposed by the hydroxide ion; the reaction was found out to involve a proton transfer from the ethylsulfonylethyl side chain. At around pH 4.5, the degradation of the uncharged tinidazole was due to the solvent. In more acidic conditions, the reaction mechanism could not be fully resolved. The alkaline hydrolysis of metronidazole was studied on the basis of literature data. A general reaction mechanism was proposed, but an unequivocal explanation for the inflection point in the pH rate profile at pH 6 could not be found. The implications of the proposed reaction mechanism for the hydrolytic behavior of ornidazole were discussed.

Antitrichomonal Agents↗
PubMed2002

Electrospray ionization mass spectrometry and tandem mass spectrometry of clodronate and related bisphosphonate and phosphonate compounds.

The bisphosphonate family with a P-C-P structure is a broad class of drugs, widely investigated as potential inhibitors in bone diseases and calcium metabolic disorders. In this study, the mass spectrometric (MS) behavior and fragmentation of clodronate and related bisphosphonate and phosphonate compounds was studied by using negative ion electrospray ionization (ESI) with triple quadrupole and ion trap instruments. The effect of pH on the degree of deprotonation of the polyprotic bisphosphonic and phosphonic acids in negative ion ESI-MS was investigated, and the degree of deprotonation in the ESI mass spectra and the dissociation in the liquid phase were compared. The results provide evidence that the measured ESI mass spectra do not correlate with the chemistry in the liquid phase owing to the decrease in the pH of the solvent droplets during the ion evaporation process and the charge state neutralization in the gas phase. Ion trap MS(n) provided useful information on the fragmentation study of clodronate and related bisphosphonate and phosphonate compounds, in which interesting fragmentation pathways including the direct elimination of carbon monoxide from deprotonated bisphosphonates and formation of a P-P bond were observed. Reactions between the product ions with a -PO(2) group and residual water in the ion trap or in the high-pressure region of the triple quadrupole instrument formed other unexpected fragmentation paths for all the bisphosphonates studied.

Antimetabolites↗
PubMedDate not supplied

A modification of the Hammett equation for predicting ionisation constants of p-vinyl phenols.

Currently there are several compounds used as drugs or studied as new chemical entities, which have an electron withdrawing group connected to a vinylic double bond in a phenolic or catecholic core structure. These compounds share a common feature--current computational methods utilizing the Hammett type equation for the prediction of ionisation constants fail to give accurate prediction of pK(a)'s for compounds containing the vinylic moiety. The hypothesis was that the effect of electron-withdrawing substituents on the pK(a) of p-vinyl phenols is due to the delocalized electronic structure of these compounds. Thus, this effect should be additive for multiple substituents attached to the vinylic double bond and quantifiable by LFER-based methods. The aim of this study was to produce an improved equation with a reduced tendency to underestimate the effect of the double bond on the ionisation of the phenolic hydroxyl. To this end a set of 19 para-substituted vinyl phenols was used. The ionisation constants were measured potentiometrically, and a training set of 10 compounds was selected to build a regression model (r2 = 0.987 and S.E. = 0.09). The average error with an external test set of six compounds was 0.19 for our model and 1.27 for the ACD-labs 7.0. Thus, we have been able to significantly improve the existing model for prediction of the ionisation constants of substituted p-vinyl phenols.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition.

The solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition of polymer-bound azides to various alkynes is reported. Polymer-bound azides were synthesized from polymer-bound halides and sodium azide and reacted with alkynes to produce polymer-bound 1,2,3-triazoles. Cleavage of the triazoles was performed with trifluoroacetic acid. A traceless synthesis of 1,2,3-triazoles was developed using 2-methoxy-substituted resin (polymer-bound 4-hydroxy-2-methoxybenzyl alcohol). In addition, a synthesis of 4-hydroxybenzyl-substituted 1,2,3-triazoles from the bromo-Wang resin (4-(bromomethyl)phenoxymethyl polystyrene) was achieved.

Technology, Pharmaceutical↗
PubMedDate not supplied

Polymer-supported 1,3-oxazolium-5-olates: synthesis of 1,2,4-triazoles.

A traceless synthesis of 3,5-disubstituted 1,2,4-triazoles has been developed on polymeric supports. The synthetic process utilizes immobilized mesoionic 1,3-oxazolium-5-olates (munchnones) as key intermediates in the 1,3-dipolar cycloaddition reaction. The initial step in the synthesis involves reductive alkylation of phenylglycine methyl esters with Ameba resin. The resulting immobilized amino acid esters were subsequently acylated with a variety of carboxylic acid chlorides and subjected to hydrolysis with 15% KOH to yield the polymer-bound carboxylic acids. Finally, the cycloaddition between diethyl diazocarboxylate or 4-phenyl-4H-1,2,4-triazoline-3,5-dione and the polymer-bound munchnones generated from the corresponding carboxylic acids afforded the polymer-bound 3,5-disubstituted 1,2,4-triazoles. Cleavage from the polymeric support using trifluoroacetic acid gave the desired 3,5-disubstituted 1,2,4-triazoles with excellent yield and high purity.

Molecular Structure↗