Antibacterial, antifungal and anthelmintic activities of root barks of Uvaria hookeri and Uvaria narum

On a pharmacological screening, substantial antibacterial, antifungal and anthelmintic activities were observed for the hexane and ethyl acetate extracts of the root barks of Uvaria narum Wall. and Uvaria hookeri King. Chromatographic fractionation of these extracts led to the isolation of the triterpenes glutinol, glutinone, taraxerol, beta-sitosterol and Annonaceous acetogenins uvariamicins-I, II and III mixture, isodesacetyluvaricin, squamocin-28-one, narumicins-I and II stereoisomeric mixture, squamocin and panalicin. The acetogenins exhibited antimicrobial and anthelmintic activities in their individual screening comparable with standard drugs and hence their presence could be attributed to a great extent for the biocidal properties of U. narum and U. hookeri extracts.

Reactive Maillard intermediates leading to coloured products-5-hydroxymethyl- and 5-(1,2-dihydroxyethyl)-3(2H)-furanone

In the course of the Maillard reaction, labile sugar degradation products are formed that are susceptible to secondary reactions and therefore have a decisive influence on the product spectrum. Such reactive intermediates may be transformed into stable derivatives with trapping reagents, and thus be protected from further reactions. Secondary processes may also be forestalled if the primary products are removed from the reaction mixture by high-vacuum distillation. By this procedure, 5-hydroxymethyl- and 5-(1,2-dihydroxyethyl)-3(2H)-furanone have been identified directly from Maillard reaction mixtures for the first time. The activated methylene group of these 3(2H)-furanones can easily enter into condensation reactions. The coloured condensation products in turn react with primary amines to pyrrolinone derivatives, which may also contribute to the colouring observed in non-enzymatic browning.

Biocompatible hydrogels of controlled hydrophobicity from copolymers of N-vinyl-2-pyrrolidone and furfuryl methacrylate

Biocompatible copolymers of N-vinylpyrrolidone (P) and furfuryl methacrylate (F) were prepared by free radical polymerization in N,N-dimethylformamide solution at 50 degrees C, using 2,2'-azobisisobutyronitrile as initiator, at low and high conversion. The microstructure of copolymers prepared at low conversion was determined from the composition data by the application of statistical relationships, considering the terminal copolymerization model of Mayo-Lewis, whereas for high conversion copolymers the noticeable difference between the reactivity of F and P was taken into consideration. The swelling behaviour of films prepared from solutions of copolymers with different composition was followed gravimetrically and the diffusion of water was analysed on the basis of the stress relaxation model of copolymer chains. The results obtained are in good agreement with second-order diffusion kinetics, showing that the hydrophilic character of the films is controlled mainly by the content of P in the copolymer systems and the distribution of comonomeric units along the copolymer systems.

Structure-activity relationships of trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine antagonists for mu- and kappa-opioid receptors

A series of racemic N-substituted trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidines were evaluated for opioid agonist and antagonist activity at mu and kappa receptors. Several highly potent mu and kappa antagonists were discovered; however, no compounds with high selectivity for either the mu or kappa receptor were identified. Importantly, no derivative was found to have significant opioid agonist activity. Two derivatives were resolved, and the activities of the enantiomers were investigated. Only a limited stereochemical effect on opioid receptor selectivities was observed. The structure-activity relationships described establish the existence of an important lipophilic binding site distal to the nitrogen for both mu and kappa receptors and confirm the pure opioid antagonist pharmacophore nature of the trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine structure.

Azapsoralens-DNA interactions: crystal structure characterization of furan-side monoadduct and computer-aided studies

In this paper a theoretical study, concerning molecular mechanics optimised structures, obtained by quantum mechanics as well as molecular mechanics calculations was carried out with the aim of correlating the theoretical model of the interactions between azapsoralens and DNA with the data experimentally obtained. The theoretical model suggests that both furan-side and pyrone-side double bonds may be involved in the cycloaddition with pyrimidines (although the cycloaddition at the level of furan is preferred), and is in line with the capacity of these compounds to form inter-strand cross-links. Moreover, concerning the theoretical intercalation model calculations on 3,4,4',5'-tetramethylazapsoralen intercalated inside a polynucleotide, they suggest a cis-syn arrangement between furan-side of the intercalated ligand and the above situated thymine, with which, under light activation, a cycloadduct may take place, having a cis-syn steric arrangement. Also this datum is in agreement with the cis-syn regio and stereochemistry of the isolated 4,4',5'-trimethylazapsoralen-thymine cycloadduct. Finally, from theoretical data, the role of nitrogen seems not important: in fact only small differences were found with the corresponding methylpsoralens so that the small differences observed may be mainly attributed to steric rather than to electronic effects. In general a good correlation between the theoretical model and the experimental data was observed.

A quantitative determination of singlet oxygen with horseradish peroxidase

A singlet oxygen determination method based on the formation of dimethyl-(2,5)-2-methoxy-5-hydroperoxydihydrofuran (DMFO2) followed by acid hydrolysis with 0.1 N H2SO4 is described. Hydrogen peroxide is formed thereby as a product of hydrolysis which is then determined by the horseradish peroxidase-catalyzed formation of the homovanillic acid dimer. Since DMFO2 is a crystalline compound with sufficient stability it can be used as a primary standard for the determination. The peroxidase-catalyzed hydrogen peroxide determination allows detection of singlet oxygen concentrations as low as 10(-7) M.

Characterization of the interaction between human alpha-thrombin and methyl 3-(2-methyl-1-oxopropoxy)[1]benzothieno[3,2-b]furan-2-carboxylate (LY806303) using electrospray mass spectrometry and tandem mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) have been used for the first time to study the interaction of human alpha-thrombin with methyl 3-(2-methyl-1-oxopropoxy)[1]benzothieno[3,2-b]furan-2-carbox ylate (LY806303; 1), a potent and selective inhibitor whose mechanism of action was never fully defined. Using ESI-MS, it is shown that inhibitor 1 covalently modifies human alpha-thrombin as evidenced by a shift in the molecular weight of the native protein by 72 Da, which is consistent with isobutyrylation (C4H7O; 71 Da) of the enzyme at a single site. Tryptic digestion of the modified protein and tandem mass spectral analysis of isolated peptide fragments indicate that compound 1 acylates Ser-205 of the heavy chain of alpha-thrombin. Ser-205, along with His-43 and Asp-99 make up the catalytic triad within the active site of thrombin.

Regeneration of motor nerves in bilobalide-treated rats

Bilobalide, a terpene extracted from the leaves of the Ginkgo biloba tree, has been proposed to exert trophic and protective effects on neurons and on Schwann's cells in various neuropathies. The reinnervation of the extensor digitorum longus muscle following traumatic nerve damage was investigated in rats by using electrophysiological and histological techniques. Evaluation parameters included the membrane resting potential of muscle cells, the spontaneous quantal release of acetylcholine, and the percentage of muscle cells receiving multiple innervation. The percentage of muscle cells receiving multiple innervation reached a peak more rapidly in treated animals and declined subsequently to values lower than those found in controls. These data suggest that the rearrangement of regenerated innervation occurs more rapidly in bilobalide-treated animals.

Structural revisions of some non-adjacent bis-tetrahydrofuran annonaceous acetogenins

The relative stereochemistries of bullatalicin [1] and bullatalicinone [2] were partially reassigned based on COSY and relayed COSY spectra. The structures of annonins VIII [3], IV [4], and XVI [5] were revised and concluded as bullatalicin [1], bullatanocin [6], and squamostatin A [7], respectively.

Solid-state NMR studies of 1H spin diffusion in adsorbed organic molecules

1H spin diffusion times of toluene (MB) and tetrahydrofuran (THF) adsorbed on a series of porous solids (charcoal, SiO2 and Al2O3) were measured by a selective inversion technique. The experimental results show that they cover a wide range (from less than one millisecond to several hundreds of milliseconds). For all samples, a tri-exponential behavior was observed in the magnetization recovery processes of the negative peaks. This is attributed to the existence of the two different kinds of spin diffusion processes in addition to the T1 relaxation. One is assigned to the intermolecular spin diffusion between the surface acidic protons of the adsorbent and the organic molecules adsorbed on the solid surface, the other to the intramolecular spin diffusion of adsorbed molecules. Due to hydrogen bonding between the surface hydroxyl groups and the adsorbate, the intermolecular spin diffusion of THF adsorbed on various solids is more effective compared to that of adsorbed MB. In addition, the intermolecular 1H spin diffusion between charcoal and adsorbed THF molecules was confirmed by indirect measurement suggested by Tekely et al.

Glutathione and N-acetylcysteine inactivations of mutagenic 2(5H)-furanones from the chlorination of humics in water

The mutagenic 2(5H)-furanones resulting from the chlorination of lignohumic substances in water disinfection and paper pulp bleaching are known to be inactivated by thiols. The objectives of the present study were to characterize the kinetics of an inactivating reaction, isolate and characterize products, and determine their mutagenicity in relation to the starting, mutagenic 2(5H)-furanones. The Salmonella typhimurium (TA100) mutagenicity of mucochloric acid (MCA) had a mean value of 2800 revertants/mumol from four assays and was twice as potent as the C-5 isopropyl ether of MCA (MCA-IPE), whose mutagenicity was determined in the same four assays. A second-order reaction of MCA with GSH at pH 7 was observed. The major product, making up 70% of the total product mixture, was identified as a 1.5:1 mixture of two diastereomers formed by sulfur displacement of the C-4 Cl atom from MCA. The major diastereomer was isolated from the 1.5:1 mixture. Connectivity of GSH to the MCA moiety in the product was established by 2D long-range coupling NMR and fully coupled 13C NMR. On the basis of circular dichroism, the major diastereomer had the S configuration at the hydroxyl-bearing, C-5 ring carbon. MCA-IPE reacted with GSH and N-acetylcysteine (NAC), giving 1:1 mixtures of two diastereomers, again by displacement of the C-4 Cl atom from MCA. A single diastereomer was isolated from the 1:1 MCA-IPE plus NAC reaction. Its structure, determined by X-ray crystallography, had the 5R,8R configuration and was in agreement with the ross structure deduced from the NMR analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of ethenocarbaldehyde derivatives of adenosine and cytidine in reactions with mucochloric acid

Mucochloric acid, a genotoxic compound formed during chlorine disinfection of drinking water, was reacted with adenosine and cytidine at pH 4.0, 90 degrees C. HPLC analyses with UV detection at 325 nm showed that one previously unidentified product peak was formed in each reaction. The products were separated and isolated by HPLC and characterized by UV absorbance, 1H and 13C NMR spectroscopy, and mass spectrometry. The products were identified as 3-(beta-D-ribofuranosyl)-7-formylimidazo[2,1-i]purine (I) and 6-(beta-D-ribofuranosyl)-3-formylimidazo[1,2-c]pyrimidin-5(6H)-one (II) (ethenocarbaldehyde derivatives of adenosine and cytidine, respectively). The ethenocarbaldehyde derivative of adenosine was also produced in reactions carried out at pH 7.4 and 37 degrees C. The formation of the ethanocarbaldehyde derivatives and the previously identified etheno derivatives from mucochloric acid is explained by an initial conversion of mucochloric acid, through hydrolysis and decarboxylation, to chloromalonaldehyde. Chloromalonaldehyde reacts with the nucleosides and forms an intermediate adduct which either undergoes ring closure by intramolecular displacement of the chlorine atom or breaks down to form chloroacetaldehyde which subsequently produces the etheno derivatives.

Pyrolysis of inulin, glucose, and fructose

The pyrolytic behavior of inulin, a (2-->1)-linked fructofuranan, is described. Parallel investigations of the pyrolysis of glucose and of fructose were conducted to supplement the inulin results and to aid comparison with previous results from glucans. Effects of neutral and basic additives are emphasized. As with glucans, the addition of such additives (especially basic) increases the yields of the one-, two-, and three-carbon products (as well as of hexosaccharinolactones), while generally decreasing the yields of anhydro sugar and furan derivatives. The former products include glycolaldehyde, acetol, dihydroxy-acetone, acetic acid, formic acid, and lactic acid. Mechanistic speculations are made regarding the origins of these compounds, as well as of furan derivatives and saccharinic acid lactones. Parallels with alkaline degradation are considered.

On the mutagenicity of MX compounds

Electronic properties of chlorofuranones including MX, one of the strongest bacterial mutagens, were studied using the semi-empirical AM1 method to elucidate the key features related to the high mutagenic activity of MX. The electronic structures of MX and guanine (the target base of the Salmonella typhimurium TA100 tester strain) are rationalized with the frontier electron theory. Hydrophobic properties of the MX family are examined. Based on these results and our previous QSAR model a possible mechanism for the MX-DNA interaction is proposed.

[Anti-platelet activating factor constituents, 2,5-diaryltetrahydrofuran type lignans, from Piper futokadsura Sied. et Zucc]

Besides the known components kadsurenone, futoquinol and futoxide, three anti-platelet activating factor principles have been found from the stem part of Piper futokadsura (Piperaceae), the Chinese drug haifengteng. They were separated and identified as galgravin, galbelgin and veraguensin on the basis of HPLC and spectral analysis. The natural existence of these three anti-PAF constituents in haifengteng is reported for the first time.

Solubility parameters, fractional polarities, and bond strengths of some intermediary resins used in dentin bonding

An effective bonding of resin composites to dentin is generally preceded by a conditioning of the surface of the dentin. Previous studies have indicated that the intermediary or adhesive resin should have specific wetting characteristics matching those of the conditioned dentin, in order that optimum bonding can be ensured. The wetting characteristics may be expressed in terms of solubility parameter (delta) and polarity (p) of the resin. The aims of the present study were to determine these variables for a number of compounds used in adhesive resins and to investigate the effects of delta and p on the shear bond strength to dentin. Solubility parameters were obtained according to the method of Small. Fractional polarities were calculated on the basis of measurements of refractive index and dielectric constant of the resins. In the measurements of bond strength, Scotchprep, EDTA + Gluma, or Al2Ox3/glycine were used as dentin conditioners in combination with intermediary resins having various delta and p. For each conditioner, the shear bond strength (BS) could be "explained" by an exponential expression of the form BS = e(a + bx), where x = (delta + cp + d)2, and where a-d are constants depending on the conditioned dentin. It may be concluded that solubility parameter and polarity of the intermediary resins are important variables in the process of bonding to dentin.

Structure of 6-(3,3-dimethyl-2-oxo-2,3-dihydro-5-furanyl)-2-pyridone at 145 K

C11H11NO3, M(r) = 205.21, triclinic, P1, a = 5.725 (1), b = 9.038 (1), c = 10.401 (2) A, alpha = 101.37 (1), beta = 102.63 (1), gamma = 102.83 (1) degrees, V = 494.7 (3) A3, Z = 2, Dx = 1.38 g cm-3, lambda (Mo K alpha) = 1.7107 A, mu = 0.62 cm-1, F(000) = 216, T = 145 K, R = 0.049, wR = 0.063 for 2386 unique observed reflections. The molecules, which are self-associating in solution, are arranged in the crystal in centrosymmetric dimers joined by N--H...O bonds between the amide functional groups. Analysis of displacement parameters indicates that the furanyl and pyridone groups are independently quite rigid, with the furanyl group librating with respect to the hydrogen-bonded pyridone.

Selectivity of organic solvents in micellar liquid chromatography of amino acids and peptides

The influence of the type of organic modifiers on retention behavior in micellar liquid chromatography is studied. A group of amino acids and small peptides was used as the test mixture. It is shown that the chromatographic selectivities of 2-propanol, acetonitrile and tetrahydrofuran which belong to three different groups in Snyder's classification, are considerably similar in the presence of micelles for the test mixture. On the other hand, the selectivities of 2-propanol and butanol which belong to the same solvent selectivity group are different for these solutes in the micellar mobile phases.

Isolation and characterization of four polyether antibiotics, X-14889A, B, C, and D, closely related to lysocellin and the ferensimycins

Streptomyces sp. X-14889 (NRRL 15517) has been found to produce a number of novel polyether antibiotics and an orange pigment. One of the antibiotics, X-14889B (3) was identified as ferensimycin A, which in turn is an isomer of the well-studied polyether antibiotic, lysocellin (1). Of the three other antibiotics, X-14889C (4) is a lower homolog of ferensimycin A and antibiotics X-14889A (2) and D (5) which are respectively the descarboxy and anhydro-descarboxy forms of this same molecule. The latter compound, X-14889D is of interest as it contains an ether bridge across the terminal tetrahydrofuranyl ring in an analogous relationship to that reported earlier for antibiotics X-14873A (6) and G.

Tetronothiodin, a novel cholecystokinin type-B receptor antagonist produced by Streptomyces sp. NR0489. II. Isolation, characterization and biological activities

A novel cholecystokinin type-B receptor antagonist named tetronothiodin has been isolated by column chromatography and preparative HPLC from the fermentation broth of Streptomyces sp. NR0489. Tetronothiodin inhibited the binding of CCK8 (C-terminal octapeptide of cholecystokinin) to rat cerebral cortex membranes (CCK type-B receptors) with an IC50 of 3.6 nM, whereas it did not inhibit CCK8 binding to rat pancreatic membranes (CCK type-A receptors). It also inhibited CCK8 induced Ca2+ mobilization in GH3 cells, a rat anterior pituitary cell line, but was without effect on the basal cytosolic Ca2+ concentration. This finding indicated tetronothiodin was an antagonist of CCK type-B receptors.

Free radical production during photo-assisted NADPH reduction of four alpha-nitroarenofurans

Generation of radical anions during NADPH reduction of four mutagenic and genotoxic alpha-nitroarenofurans was examined. ESR showed that free radicals were generated during reduction solely in the presence of light. Computer simulations of ESR spectra were in good agreement with the experimental ones.

Tetronothiodin, a novel cholecystokinin type-B receptor antagonist produced by Streptomyces sp. NR0489. I. Taxonomy, yield improvement and fermentation

Streptomyces sp. NR0489 produces tetronothiodin, a novel brain-type cholecystokinin receptor antagonist. This species was differentiated from its related species S. gelaticus, S. griseolus and S. hydrogenans on the basis of their cultural characteristics, such as the utilization of carbohydrates and the presence or absence of various enzymatic activities. We applied the DNA-DNA hybridization method using photobiotin, which proved the genetic difference between the four species mentioned above. The yield improvement effort including single colony isolation, mutation, and protoplast regeneration together with medium optimization resulted in more than an 81-fold increase of the productivity of tetronothiodin as compared to that of the wild type strain.

Tetronothiodin, a novel cholecystokinin type-B receptor antagonist produced by Streptomyces sp. NR0489. III. Structural elucidation

Tetronothiodin (1) is a potent and selective cholecystokinin type B (CCK-B) receptor antagonist produced by Streptomyces sp. NR0489. Its structure was elucidated to be a macrocyclic compound comprising cyclohexene, alpha-acyltetronic acid and tetrahydrothiophene moieties based on various 2D NMR experiments on 1 and its dihydro derivative. The stereochemistries for the cyclohexene and tetrahydrothiophene rings were elucidated based on the analysis of NOEs obtained by NOESY experiments and NOE difference spectroscopy. The relative configuration of the cyclohexene moiety in 1 was revealed to be the same as that of the corresponding part in kijanimicin and chlorothricin, which can be structurally related to 1 in terms of their containing a cyclohexene ring with a spirotetronic acid in the molecule.

Correlation of frameshift mutagenicity with DNA intercalation by CGS 20928A using an in vitro DNA unwinding assay

A compound's mutagenicity in different Salmonella tester strains can suggest its mechanism of reaction with DNA. Clear confirmation of such a mechanism, however, requires a direct test of the compound's reaction with DNA, often relying on specific in vitro studies. We report the use of a rapid in vitro test designed to measure DNA unwinding, a characteristic of DNA intercalators and many frameshift mutagens. CGS 20928A, an adenosine antagonist, produced a significant (> 2-fold) increase in revertants only for Salmonella tester strain TA1537, and only without metabolic activation. These data indicated that the compound was a direct acting frameshift mutagen and possibly intercalated into DNA. Our DNA unwinding assay indicated that at concentrations of > 0.1 mM CGS 20928A behaved like known intercalating compounds in that it unwound DNA. These concentrations of compound are comparable to those found mutagenic to TA1537. By comparison, the frameshift mutagen and known intercalating compound 9-aminoacridine unwound DNA in this assay in a concentration dependent fashion between 6-12 microM. ICR-191, another acridine frameshift mutagen, also unwound DNA. A compound structurally related to CGS 20928A, which was not mutagenic in Salmonella tester strains, did not produce any DNA unwinding even at 10 mM. Because the assay uses microgram quantities of material, it should be ideal for screening small amounts of congeneric series suspected of frameshift mutagenicity.

Structural analysis of oxidation products of urofuran acid by hypochlorous acid

The oxidation of urofuran acid derivatives (1-2) by hypochlorous acid (HOCl) was investigated with the goal to possibly simplify the detection of their metabolites in biological materials. The oxidation products of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (1) were obtained as an isomeric mixture and confirmed to exist as cis (3a) and trans (3b) isomers, based on their 13C nuclear magnetic resonance (NMR) spectra. Similarly, the products of 5-H substituted acid 2 obtained by oxidation with HOCl were identified as 4a and 4b by 13C and 1H NMR which indicated the presence of cis and trans hemiacetal hydrogens at C-5 in a ratio of 2.11:1. The oxidation was found to proceed in a manner different from that of the F-acid, because of the presence of the electron withdrawing COOCH3 group at C-3 which favored the nucleophilic attack on the carbonyl group to afford cis- and trans-2,5-dihydroxy-2,5-dihydrofurans (3a-b, 4a-b).

Cytofluorometric assay for the determination of thymidine uptake and phosphorylation in living cells

Thymidine kinase is a key enzyme for the application of drugs in chemotherapy and for diagnosis. Although of great interest, its regulation during cell cycle and differentiation is difficult to study, as current techniques for isolation of cells in different phases of growth are unsatisfactory. An assay that allows the determination of enzymatic activity in situ in single cells would be much faster than present methods and would elegantly avoid synchronization procedures. We synthesized different analogues of thymidine with the 5-methyl group substituted by a fluorochrome. At least three of these compounds were phosphorylated by thymidine kinase in cell free extracts and were taken up and phosphorylated by cells in culture. The cytofluorometric signal of the accumulated fluorochrome in any given cell reflected the thymidine kinase activity of this cell. Simultaneous measurement of cell-cycle dependent parameters allowed the correlation of thymidine kinase activity with the phase of growth in mixed cell populations.

Test of chiral recognition in the Salmonella typhimurium (TA100) mutagenicity of mucochloric acid-cysteine adducts

A difference in biological response to enantiomers is not an uncommon observation and is, therefore, to be expected in various manifestations of genotoxicity. The bacterial mutagen mucochloric acid (2,3-dichloro-5-hydroxy-2(5H)-furanone) has one chiral center, at C-5, but this mutagen exists in racemic form because of the facile stereoisomerization occurring by the mechanism of ring-chain tautomerism. Two readily synthesized enantiomeric analogs of mucochloric acid, as well as the racemic form of the two, were prepared from mucochloric acid and (R)-(+)-, (S)-(-)-, and (R,S)-(+/-)-cysteine. Using Salmonella typhimurium (TA100), the enantiomeric compounds were assayed together in four dose/response assays along with mucochloric acid, the reference mutagen. In three of the same four assays, the racemic form was also assayed. Neither statistically significant differences in mutagenicity, as determined in slope responses, nor distinctions from the plotted curves were observed among the two enantiomers and their racemic form. Therefore, no enantiospecific interaction between enantiomers and chiral DNA or enzymes involved in repair or replication could be concluded.

Tetrahydrofuran (co)polymers as potential materials for vascular prostheses

Polyethers were studied as potential materials for vascular prostheses. By crosslinking poly(tetramethylene oxide)(PTMO) with poly(ethylene oxide)(PEO), hydrophilic networks were obtained containing PTMO as well as PEO. Attempts were made to reduce the crystallinity and melting point of PTMO because of the required elastomeric behaviour at body temperature. Compared to non-crosslinked PTMO, crosslinking in the melt resulted in a decrease in the melting point from 43.7 to 38.4 degrees C and a decrease of the crystallinity from 46 to 28%. By copolymerizing tetrahydrofuran with oxetane or dimethyloxetane, melting points below 38 degrees C were obtained, together with crystallinities lower than 20%.

Synthesis and antimuscarinic properties of some N-substituted 5-(aminomethyl)-3,3-diphenyl-2(3H)-furanones

In a study aimed toward developing new, selective antimuscarinic drugs with potential utility in the treatment of urinary incontinence associated with bladder muscle instability, a series of N-substituted 5-(aminomethyl)-3,3-diphenyl-2(3H)-furanones, conformationally-constrained lactone relatives of benactyzine, was prepared. The compounds were examined in several paradigms that measure muscarinic (M1, M2, and M3) receptor antagonist activity. Selected members of the series that displayed potency and/or selectivity in these tests were studied for their effects on urinary bladder contraction, mydriasis, and salivation in guinea pigs. These studies revealed that incorporation of the amino functionality into an imidazole or pyrazole ring resulted in some novel, potent, and selective antimuscarinic agents. Appropriate alkyl substitution of position 2 of the imidazole strikingly affected muscarinic, particularly M3, receptor activity and may reflect a complementary site of interaction. Some of the compounds selectively reduced bladder pressure in a cystometrogram (CMG) model without producing concomitant mydriatic and salivary effects. The separate and distinct action of several compounds of this series in these in vivo protocols suggests the possibility of subtypes of muscarinic receptors that may correspond to previously characterized molecular cloned subpopulations. In this article, structure-activity relationships for the series of substituted lactones are discussed. These studies led to the identification of (R)-[(2-isopropyl-1H-imidazol-1-yl)methyl]-4,5-dihydro-3,3-diphenyl-2(3H )- furanone (23) as a clinical candidate for treating urinary bladder dysfunction.

A new structure-activity model for Ah receptor binding. Polychlorinated dibenzo-p-dioxins and dibenzofurans

A new structure-affinity model for the aromatic hydrocarbon (Ah) receptor is reported. The proposed mathematical model completely eliminates multiple regression analysis in its formulation and overcomes the cross-class comparison inherent to classical quantitative structure-activity relationships. Taking the polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) as model xenobiotics, the binding affinity of a PCDD relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is shown to be analytically related to the electron affinities, entropies, and lipophilicities of PCDD and TCDD. From the calculated dissociation constants of PCDD-Ah receptor complexes, the corresponding equilibrium constants of PCDF-Ah complexes could be computed, in agreement with the experimental observation that the trend in the binding affinities of PCDDs and PCDFs to the Ah receptor are similar. The reported model is capable of quantitatively explaining the quantitatively estimating the in vitro binding affinities of PCDDs, PCDFs, and related xenobiotics to the Ah receptor. Therefore, a halogenated aromatic compound is expected to have a higher affinity for the cytosolic protein than TCDD if it is less lipophilic and has a higher electron affinity and lower entropy. Furthermore, the affinities of structurally related polychlorinated aromatic xenobiotics for the Ah receptor could be computed from their entropies and electron affinities.

Formation of 3,N4-ethenocytidine, 1,N6-ethenoadenosine, and 1,N2-ethenoguanosine in reactions of mucochloric acid with nucleosides

Mucochloric acid, a genotoxic hydroxyfuranone found in chlorinated drinking water, was reacted with cytidine, adenosine, guanosine, and uridine. HPLC analyses with UV detection at 290 nm showed that one major product peak was formed in the reactions of cytidine, adenosine, and guanosine. The products formed in reactions carried out at 90 degrees C for 24 or 45 h were isolated by HPLC and characterized by 1H and 13C NMR spectroscopy, direct inlet chemical ionization mass spectrometry, and UV absorbance spectroscopy. The structures of the products were assigned to 3,N4-ethenocytidine, 1,N6-ethenoadenosine, and 1,N2-ethenoguanosine. In reactions performed at 37 degrees C and pH 7.0 the same compounds were detected after a reaction time of 7 days. No observable reaction took place between mucochloric acid and uridine.

4-substituted thiophene- and furan-2-sulfonamides as topical carbonic anhydrase inhibitors

A series of 4-substituted thiophene- and furan-2-sulfonamides was prepared and was found to possess nanomolar-level potency for inhibition of human carbonic anhydrase II in vitro. Selected examples from this group were further evaluated for their potential to act as topically effective ocular hypotensive agents in the ocular normotensive albino rabbit and the ocular alpha-chymotrypsinized rabbit. Solubility studies in water and pH 7.4 buffer were carried out to estimate the ability of compounds to be formulated in solution. The sensitization potential of key representative structures was determined by in vitro glutathione reactivity studies and guinea pig maximization testing.

(2S-[2 alpha,3 alpha,3a beta,6 beta(R*),7 alpha, 7a alpha])-6-(3-benzyloxy-2-propyl)-2-hydroxy-2,3,7-trimethylhexahydro-4H- furo [3,2-c]pyran-4-one, a rearrangement product of pyranone derivatives in the tirandamycin A series

The six- and five-membered heterocyclic rings are cis-fused and adopt twist-boat and half-chair conformations, respectively. The average bond distances are: Csp3-Csp3 1.520 (6), Csp3-Csp2 1.494 (6), C-Cbenz 1.360 (10) and Csp3-O 1.425 (5) A; the C = O and Csp2-O bond lengths are 1.214 (5) and 1.324 (5) A, respectively.

Sensitive method for the determination of phenytoin in plasma, and phenytoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin in urine by high-performance liquid chromatography

An isocratic high-performance liquid chromatographic method is described for the quantitative analysis of phenytoin (PHT) in plasma and both phenytoin and its main metabolite, 5-(4-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) in urine. Following ethyl acetate (plasma) and Extrelut-1 (urine) extraction, samples are analysed by means of a reversed-phase column (Nova-Pak C18), using a mobile phase consisting of methanol-water-tetrahydrofuran (40:60:4, v/v/v) with UV detection at 230 nm. The chromatography is complete in 10 min and the results show good precision (RSD 1.23-4.49%) and sensitivity for a linear range of 0.4-4.0 micrograms ml-1 for PHT in plasma, 0.1-1.0 microgram ml-1 for PHT in urine and 0.1-1.2 microgram ml-1 for p-HPPH in urine. The results indicate the method to be suitable for pharmacokinetic studies.

Development, synthesis, and biological evaluation of (-)-trans-(2S,5S)-2-[3-[(2-oxopropyl)sulfonyl]-4-n-propoxy-5-(3- hydroxypropoxy)-phenyl]-5-(3,4,5-trimethoxyphenyl)tetrahydrofuran, a potent orally active platelet-activating factor (PAF) antagonist and its water-soluble prodrug phosphate ester

(-)-trans-(2S,5S)-2-[3-[(2-Oxopropyl)sulfonyl]-4-n-propoxy-5-(3- hydroxypropoxy)phenyl]-5-(3,4,5-trimethoxyphenyl)tetrahydrofuran (10) is one of the most potent platelet-activating factor (PAF) antagonists in vitro and in vivo developed to date. This diaryltetrahydrofuran derivative evolved from modifications of MK 0287 which has been evaluated in clinical studies for asthma. Two structural modifications of MK 0287 were made: (1) elaboration of the 3'-[(hydroxyethyl)sulfonyl] group to a beta-keto propylsulfonyl, and (2) replacement of the 5'-methyl ether by a 3-hydroxypropyl ether. Compound 10 potently and specifically inhibits the binding of [3H]-C18-PAF to human platelet membranes (Ki 1.85 nM) and PMN membranes (Ki 2.89 nM). In vivo, 10 inhibits PAF-induced plasma extravasation and elevated N-acetyl-beta-D-glucosaminidase (NAGA) levels in male rats with ED50 values of 60 micrograms/kg, po and 4 micrograms/kg, iv respectively, and inhibits PAF-induced bronchoconstriction in guinea pigs with an ED50 value of 15 micrograms/kg after intraduodenal administration. Compound 15, a water-soluble phosphate ester prodrug derivative of 10 is at least equipotent to 10 in the in vivo models. Compound 19S, the primary and major metabolite of 10 and 15, is equipotent in in vitro and in vivo models.

Biological inactivation by singlet oxygen: distinguishing O2(1 delta g) and O2(1 sigma g+)

Experiments were performed to determine whether bacterial inactivation in the separated-surface-sensitizer system for singlet oxygen generation is due to O2(1 delta g) or O2(1 sigma g+). The rates of inactivation of Gram-negative Salmonella typhimurium LT-2 and a nonpigmented strain of Gram-positive Sarcina lutea were found to increase linearly with the concentration of 1 delta g. The gas phase lifetime of the inactivating agent was found to be within the range of values expected for the gas phase lifetime of 1 delta g rather than 1 sigma g+. These measurements conclusively demonstrate that bacterial inactivation in this system is due predominantly to 1 delta g. Therefore, studies of bacterial inactivation with this singlet oxygen generating system can be used to assess the role of singlet oxygen in various biological and medically relevant situations.

Biosynthesis of methanofuran in Methanobacterium thermoautotrophicum

The 13C NMR signals of methanofuran were assigned by two-dimensional 1H and 13C NMR experiments. On this basis, the incorporation of 13C-labeled acetate and pyruvate into methanofuran by growing cells of Methanobacterium thermoautotrophicum was analyzed by one- and two-dimensional 13C NMR experiments. The data were analyzed by a retrobiosynthetic approach based on a comparison of labeling patterns in a variety of metabolites. The data show that the furan ring is formed by condensation of two molecules from the pyruvate/triose pool. The tetracarbocylic acid moiety is assembled from ketoglutarate, two molecules of acetyl CoA, and one molecule of carbon dioxide.

[The electronic structure and radiorprotective activity of a series of substituted iminodihydrofurans]

Compounds that increase the survival rate of lethally exposed hybrid (CBA x C57B1/6)F1 mice have been revealed within the series of iminodihydrofurans. The quantum-chemical estimates, made by the MNDO method, show that substances which are capable of donor-acceptance interaction with DNA nucleotides and have the energy of donor orbitals, comparable with the electron structure of nucleotides, possess radioprotective efficacy.

A study of inactivation reactions of N-acetylcysteine with mucochloric acid, a mutagenic product of the chlorination of humic substances in water

The Salmonella typhimurium (TA100) mutagenic compound, mucochloric acid [3,4-dichloro-5-hydroxy-2(5H)-furanone (MCA)], was inactivated by in vitro N-acetylcysteine (NAC). The reaction of MCA with NAC at pH7 was second order and gave products 4, 5, and 6a that resulted from the displacement of chlorine from C-3 or C-4 of MCA. The sodium borohydride treatment of product 4 gave the same product (7) as was obtained by treating 3,4-dichloro-2(5H)-furanone with NAC. The treatment of MCA with (R)-(+)-cysteine gave the bicyclic product 9a, in which the two chlorine atoms of MCA were still present. This product was slightly more mutagenic than MCA, whereas product 5 was less mutagenic than MCA and product 4 was nonmutagenic in the Salmonella typhimurium (TA100) assay.

Isolation and identification of ethisolide as an antibiotic product from Penicillium capsulatum

Ethisolide has been isolated from cultures of Penicillium capsulatum, and its structure determined by means of infrared, mass spectrometry, 1H- and 13C nuclear magnetic resonance. Antibiotic activity against a number of microorganisms is reported.

Structure of asperketal B

3,7,11-Trimethyl-13-oxabicyclo[8.3.0]trideca-2,6-diene-12-spiro-2' -(5',5'-dimethyltetrahydrofuran), asperketal B, C20H30O2, M(r) = 302.46, orthorhombic, P2(1)2(1)2(1), a = 10.064(1), b = 22.214(2), c = 8.330 (1) A, V = 1862.3 A3, Z = 4, Dx = 1.08 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 4.55 cm-1, F(000) = 664, T = 294 (1) K, R = 0.031, wR = 0.027 for 953 data. The backbone of the molecule is composed of a cyclodecadiene ring which is cis fused to a bicyclic ketal system. The relative configurations at C(1), C(10), C(11) and C(12) are 1S*, 10R*, 11R* and 12R*.

Geiparvarin analogues. 3. Synthesis and cytostatic activity of 3(2H)-furanone and 4,5-dihydro-3(2H)-furanone congeners of geiparvarin, containing a geraniol-like fragment in the side chain

Continuing our study on the structural features of geiparvarin (1), responsible for cytostatic activity, a series of 4,5-dihydro-3(2H)-furanones 10a-f and of 3(2H)-furanones 11a-f as well as 2",3"-dihydrogeiparvarin (14) have been designed and synthesized. Their cytostatic activity was evaluated against proliferation of murine (L1210, FM3A) and human (Raji, Molt/4F, and MT4) tumor cells. Modifications in the region of the olefinic double bond by introduction of the characteristic alkenyl side chain of ascofuranone (compounds 10a-f and 11a-f) markedly decreased the cytostatic activity as compared to geiparvarin itself, but this effect does not seem to be correlated to the presence of the furanone moiety linked to the alkenyl chain or to the ability to afford Michael type adducts. Replacement of the coumarin portion by other aromatic rings did not alter the cytostatic activity. The essential inactivity of 2",3"-dihydrogeiparvarin (14) points to the importance of the 3(2H)-furanone ring system in the cytostatic activity; consequently, this moiety may be considered as the determinant pharmacophore for antitumor activity, while the side chain plays a rather modulatory role.

Synthesis and evaluation of novel multifunctional oligomers for dentistry

A new type of multifunctional oligomer was synthesized, and its potential as a base monomer in dental composite formulations was evaluated. The oligomer of ethoxylated bis-phenol A diacrylate (OEBPA) was prepared in good yield by a formaldehyde insertion/condensation reaction. Although double bonds along the oligomer backbone are arranged in pairs such that cyclopolymerization is possible, it is not presently known whether this process plays a significant role in the polymerization. Indirect evidence supporting efficient cyclopolymerization involves the reduced polymerization shrinkage observed for polymerized OEBPA relative to polymers of other monomers used as base resins. Photo-cured composites containing either OEBPA, BIS-GMA, or ethoxylated bis-phenol A dimethacrylate (EBPADM) as base resin and TEGDMA as diluent were compared. While the resulting diametral tensile and transverse strengths did not differ significantly, the values for the energy absorbed to failure indicated that the OEBPA- and EBPADM-based formulations yielded composites with somewhat greater toughness than that of the BIS-GMA material. This multifunctional oligomer offers mechanical strength and conversion values that are comparable with those of existing base resin monomers while providing an approximate 30% reduction in polymerization shrinkage.

[A review on the chemical constituents of Annona plants]

The paper reviews the progress in the research on Annona plants, including the structure of chemical constituents, spectroscopic characteristics and physiological activities. A new kind of anticancer constituent is also introduced.

4-substituted 2-alkoxytetrahydrofurans as potent and long-lasting PAF antagonists

A series of 4-substituted 2-alkoxytetrahydrofuran derivatives featuring an acetal group were prepared and evaluated for PAF antagonist activity in the PAF-induced in vitro platelet-aggregation and in vivo hypotension tests. Compound 2-[[N-acetyl-N-[[[2-(octadecyloxy)tetrahydrofuran-4- yl]methoxy]carbonyl]amino]methyl]-1-ethylpyridinium chloride (4e, UR-11353) was selected for further development on the basis of its high activity and long-lasting action. The compound maintained a significant activity even 24 h after administration of a single dose of 1 mg/kg iv in the PAF-induced mortality test in mice and 10 h after administration of the same dose in the PAF-induced hypotension test in rats. Comparison with previously reported carba analogues suggests that the presence of the acetal group is the structural characteristic that confers its long-lasting activity.

Bullatencin, 4-deoxyasimicin, and the uvariamicins: Additional bioactive annonaceous acetogenins fromAnnona bullata rich. (Annonaceae)

Additional bioactive Annonaceous acetogenins have been isolated from the EtOH extract of the bark of Annona bullata Rich. by bioactivity-directed fractionation using lethality to brine shrimp. These acetogenins include bullatencin, a new single tetrahydrofuran acetogenin having a double bond in the hydrocarbon chain; 4-deoxyasimicin, a new adjacent bis-tetrahydrofuran acetogenin; and the uvariamicins, an isomeric mixture of four single tetrahydrofuran acetogenins showed selective cytotoxicities for certain human solid tumor cell lines comparable to or better than adriamycin.