Sulfonamido, azidosulfonyl and N-acetylsulfonamido analogues of rofecoxib: 4-[4-(N-acetylsulfonamido)phenyl]-3-(4-methanesulfonylphenyl)-2(5H)furanone is a potent and selective cyclooxygenase-2 inhibitor

4-[4-(N-Acetylsulfonamido)phenyl]-3-(4-methanesulfonylphenyl)-2(5H)furanone, possessing a N-acetylsulfonamido pharmacophore, has been identified as a potent and selective COX-2 inhibitor that has the potential to acetylate the COX-2 isozyme.     

Synthesis and biological evaluation of a novel class of rofecoxib analogues as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs)

A group of 4-(4-methanesulfonylphenyl)-3-phenyl-2(5H)furanones possessing an acetyl, 3-oxobut-1-ynyl, [hydroxyl(or alkoxy)imino]alkyl, [hydroxyl(or alkoxy)imino]alkynyl, and N-alkoxy(or N-phenoxy)carbonyl-N-hydroxy-N-ethylamino substituents at the para-position of the C-3 phenyl ring of rofecoxib were synthesized. This group of compounds was designed for evaluation as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs) that exhibit in vivo anti-inflammatory and analgesic activities. In vitro COX-1/COX-2, and 5-LOX/15-LOX, isozyme inhibition structure-activity relationships identified 3-[4-(1-hydroxyimino)ethylphenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (17a) having an optimal combination of COX-2 (COX-2 IC50 = 1.4 microM; COX-2 SI > 71), and 5-LOX and 15 LOX (5-LOX IC50 = 0.28 microM; 15-LOX IC50 = 0.32 microM), inhibitory effects. It was also discovered that 3-[4-(3-hydroxyiminobut-1-ynyl)phenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (18a) possesses dual COX-2 (IC50 = 2.7 microM) and 5-LOX (IC50 = 0.30 microM) inhibitor actions. Further in vivo studies employing a rat carrageenan-induced paw edema model showed that the oxime compounds (17a, 18a) were more potent anti-inflammatory agents than the 5-LOX inhibitor caffeic acid, and 15-LOX inhibitor nordihydroguaiaretic acid (NDGA), but less potent than the selective COX-2 inhibitor celecoxib. The results of this investigation showed that incorporation of a para-oxime moiety on the C-3 phenyl ring of rofecoxib provides a suitable template for the design of dual inhibitors of the COX and LOX enzymes.     

Discovery of a potent and selective COX-2 inhibitor in the alkoxy lactone series with optimized metabolic profile

The COX-2 inhibitor DFP [5,5-dimethyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanone] was found to have a long half-life in humans. Analogues have been characterized in order to optimize pharmacokinetics. This has lead to the discovery of 5(S)-(5-ethyl-5-methyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanone analogue 11 a potent and selective COX-2 inhibitor which is metabolized to a greater extent than DFP upon incubation with rat and human hepatocytes, suggesting a shorter half-life in humans.     

Novel (E)-2-(aryl)-3-(4-methanesulfonylphenyl)acrylic ester prodrugs possessing a diazen-1-ium-1,2-diolate moiety: design, synthesis, cyclooxygenase inhibition, and nitric oxide release studies

A novel group of hybrid nitric oxide-releasing anti-inflammatory drugs (11) possessing a 1-(N,N-diethylamino)diazen-1-ium-1,2-diolate, or 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate, nitric oxide (.NO) donor moiety attached via a one-carbon methylene spacer to the carboxylic acid group of (E)-3-(4-methanesulfonylphenyl)-2-(phenyl)acrylic acids were synthesized. These ester prodrugs (11) all exhibited in vitro inhibitory activity against the cyclooxygenase-2 (COX-2) isozyme (IC(50)=0.94-31.6 microM range). All compounds released .NO upon incubation with phosphate buffer (PBS) at pH 7.4 (3.2-11.3% range). In comparison, the percentage of .NO released was significantly higher (48.6-75.3% range) when these hybrid ester prodrugs were incubated in the presence of rat serum. These incubation studies suggest that both .NO and the parent anti-inflammatory (E)-3-(4-methanesulfonylphenyl)-2-(phenyl)acrylic acid would be released upon in vivo cleavage by non-specific serum esterases. O(2)-[(E)-2-(4-Acetylaminophenyl)-3-(4-methanesulfonylphenyl)acryloyloxymethyl]-1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (11f) is a moderately potent (IC(50)=0.94 microM) and selective (SI>104) COX-2 inhibitor that released 73% of the theoretical maximal release of two molecules of .NO/molecule of the parent hybrid ester prodrug upon incubation with rat serum. Hybrid ester .NO-donor prodrugs offer a potential drug design concept for the development of anti-inflammatory drugs that are devoid of adverse ulcerogenic and/or cardiovascular side effects.     

Design, synthesis, and biological evaluation of (E)-3-(4-methanesulfonylphenyl)-2-(aryl)acrylic acids as dual inhibitors of cyclooxygenases and lipoxygenases

A group of (E)-3-(4-methanesulfonylphenyl)acrylic acids possessing a substituted-phenyl ring (4-H, 4-Br, 3-Br, 4-F, 4-OH, 4-OMe, 4-OAc, and 4-NHAc) attached to the acrylic acid C-2 position were prepared using a stereospecific Perkin condensation reaction. A related group of compounds having 4- and 3-(4-isopropyloxyphenyl)phenyl, 4- and 3-(2,4-difluorophenyl)phenyl and 4- and 3-(4-methanesulfonylphenyl)phenyl substituents attached to the acrylic acid C-2 position were also synthesized, using a palladium-catalyzed Suzuki cross-coupling reaction, for evaluation as dual cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) inhibitors. (E)-2-(3-Bromophenyl)-3-(4-methanesulfonylphenyl)acrylic acid (9h), and compounds having 4-(4-isopropyloxyphenyl-, 2,4-difluorophenyl-, or 4-methylsulfonylphenyl)phenyl moieties at the acrylic acid C-2 position (11a,b,d), were particularly potent COX-2 inhibitors with a high COX-2 selectivity index (COX-2 IC50 approximately 0.32 microM, SI > 316) similar to the reference drug rofecoxib (COX-2 IC50 = 0.5 microM, SI > 200). Acrylic acid analogs with a C-2 4-hydoxyphenyl (9d, IC50 = 0.56 microM), or 4-acetamidophenyl (9g, IC50 = 0.11 microM), substituent were particularly potent 5-LOX inhibitors that may participate in an additional specific hydrogen-bonding interaction. A number of compounds possessing a C-2 substituted-phenyl moiety (4-Br, 4-F, and 4-OH), or a 4- or 3-(2,4-difluorophenyl)phenyl moiety, showed potent 15-LOX inhibitory activity (IC50 values in the 0.31-0.49 microM range) relative to the reference drug luteolin (IC50 = 3.2 microM). Compounds having a C-2 4-acetylaminophenyl, or 4-(2,4-difluorophenyl)phenyl, moiety exhibited anti-inflammatory activities that were equipotent to aspirin, but less than that of celecoxib. The structure-activity data acquired indicate the acrylic acid moiety constitutes a suitable scaffold (template) to design novel acyclic dual inhibitors of the COX and LOX isozymes.     

Synthesis and cyclooxygenase inhibitory activities of linear 1-(methanesulfonylphenyl or benzenesulfonamido)-2-(pyridyl)acetylene regioisomers

A group of 1-(aminosulfonylphenyl and methylsulfonylphenyl)-2-(pyridyl)acetylene regioisomers were designed such that a COX-2 SO2NH2 pharmacophore was located at the para-position of the phenyl ring, or a SO2Me pharmacophore was placed at the ortho-, meta- or para-position of the phenyl ring, on an acetylene template (scaffold). The point of attachment of the pyridyl ring to the acetylene linker was simultaneously varied (2-pyridyl, 3-pyridyl, 4-pyridyl, 3-methyl-2-pyridyl) to determine the combined effects of positional, steric, and electronic substituent properties upon COX-1 and COX-2 inhibitory potency and COX isozyme selectivity. These target linear 1-(phenyl)-2-(pyridyl)acetylenes were synthesized via a palladium-catalyzed Sonogashira cross-coupling reaction. Structure-activity relationship (SAR) data (IC50 values) acquired by determination of the in vitro ability of the title compounds to inhibit the COX-1 and COX-2 isozymes showed that the position of the COX-2 SO2NH2 or SO2Me pharmacophore on the phenyl ring, and the point of attachment of the pyridyl ring to the acetylene linker, were either individual, or collective, determinants of COX-2 inhibitory potency and selectivity. A number of compounds discovered in this study, particularly 1-(4-aminosulfonylphenyl)-2-(3-methyl-2-pyridyl)acetylene (22), 1-(3-methanesulfonylphenyl)-2-(2-pyridyl)acetylene (27), 1-(3-methanesulfonylphenyl)-2-(4-pyridyl)acetylene (29), 1-(4-methanesulfonylphenyl)-2-(2-pyridyl)acetylene (30), and 1-(4-methanesulfonylphenyl)-2-(3-pyridyl)acetylene (31), exhibit potent (IC50 = 0.04-0.33 microM range) and selective (SI = 18 to >312 range) COX-2 inhibitory activities, that compare favorably with the reference drug celecoxib (COX-2 IC50 = 0.07 microM; COX-2 SI = 473). The sulfonamide (22), and methylsulfonyl (27 and 31), compounds exhibited anti-inflammatory activities (ID50 = 59.9-76.6 mg/kg range) that were intermediate in potency between the reference drugs aspirin (ID50 = 128.7 mg/kg) and celecoxib (ID50 = 10.8 mg/kg).     

Design, synthesis, and biological evaluation of N-acetyl-2-(or 3-)carboxymethylbenzenesulfonamides as cyclooxygenase isozyme inhibitors

A group of N-acetyl-2-(or 3-)carboxymethylbenzenesulfonamides, possessing either a F or a substituted-phenyl ring substituent (4-F, 2,4-F2, 4-SO2Me, 4-OCHMe2) attached to its C-4 or C-6 position, was prepared using a palladium-catalyzed Suzuki cross-coupling reaction for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. Although N-acetyl-3-carboxymethyl-6-fluorobenzenesulfonamide [14, COX-1 IC50 = 2.26 microM; COX-2 IC50 = 0.012 microM; COX-2 selectivity index (SI) = 188] and N-acetyl-3-carboxymethyl-6-(4-isopropoxyphenyl)benzenesulfonamide (20c, COX-1 IC50 >100 microM; COX-2 IC50 = 0.15 microM; COX-2 SI >667) exhibited potent in vitro COX-2 inhibitory activity and high COX-2 selectivity, both compounds were inactive anti-inflammatory agents in a carrageenan-induced rat paw edema assay. In contrast, the less potent and less selective COX-2 inhibitors N-acetyl-2-carboxymethyl-4-fluorobenzenesulfonamide (12, COX-1 IC50 = 4.25 microM; COX-2 IC50 = 0.978 microM; COX-2 SI = 4.3), N-acetyl-2-carboxymethyl-4-(2,4-difluorophenyl)benzenesulfonamide (17c, COX-1 IC50 = 1.02 microM; COX-2 IC50 = 1.00 microM; COX-2 SI = 1.02), and N-acetyl-3-carboxymethyl-6-(4-methanesulfonylphenyl)benzenesulfonamide (20e, COX-1 IC50 = 0.109 microM; COX-2 IC50 = 1.14 microM; COX-2 SI = 0.095) exhibited moderate anti-inflammatory activity where a 75 mg/kg oral dose reduced inflammation 26%, 14%, and 20%, respectively, at 3 h postdrug administration relative to the reference drug aspirin where a 50 mg/kg oral dose reduced inflammation by 25% at 3 h postdrug administration.     

6-Alkyl,alkoxy, or alkylthio-substituted 3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones: a novel class of diarylheterocyclic selective cyclooxygenase-2 inhibitors

A novel class of 3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones possessing a central six-membered lactone (pyran-2-one) ring system, in conjunction with C-6 alkyl (Me, Et or i-Pr), alkoxy (OMe, OEt or O-i-Pr), and alkylthio (SMe, SEt or S-i-Pr) substituents, were designed for evaluation as selective COX-2 inhibitors.     

Synthesis and biological evaluation of 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-substituted-phenoxy)pyrimidines as dual EGFR/ErbB-2 kinase inhibitors

A series of 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-substituted-phenoxy)pyrimidine derivatives were elaborately designed based on the skeleton of Lapatinib, and evaluated for their potential to inhibit epidermal growth factor receptor (EGFR) and ErbB-2 tyrosine kinase activities and antiproliferative activities against A431 and SKOV-3 cell lines. Among these synthesized pyrimidine derivatives, 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-acrylamidophenoxy)pyrimidine (6), 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-cyanoacetamidophenoxy)pyrimidine (9), 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-{3-[6-(4-amino)pyrimidinyl]amino) phenoxy}pyrimidine (11) and 4-[3-chloro-4-(3-fluorobenzyloxy)anilino]-6-(3-phenoxyacetamidophenoxy)pyrimidine (14) could significantly inhibit dual EGFR/ErbB-2 kinase activities (IC(50)=37/29 nM, 48/38 nM, 61/42 nM, 65/79 nM, respectively). And compounds 6 and 11 also showed the most potent antiproliferative activities in vitro, with the IC(50) value of 6 being 3.25 μM for A431 and 0.89 μM for SKOV-3, as for 11, 4.24 μM for A431 and 0.71 μM for SKOV-3, respectively. Docking study was also performed to determine the possible binding model.     

Synthesis of new 1-(4-methane(amino)sulfonylphenyl)-5-(4-substituted-aminomethylphenyl)-3-trifluoromethyl-1H-pyrazoles: A search for novel nitric oxide donor anti-inflammatory agents

A group of 1-(4-methane(amino)sulfonylphenyl)-5-(4-substituted-aminomethylphenyl)-3-trifluoromethyl-1H-pyrazoles (12a–f) was synthesized and evaluated as anti-inflammatory agents. While all the compounds (20 mg/kg) showed significant anti-inflammatory activity after 3 h of inflammation induction (69–89%) as compared to celecoxib (80%), 1-(4-methanesulfonylphenyl)-5-(4-methylaminomethylphenyl)-3-trifluoromethyl-1H-pyrazole (12a) was found to be the most effective one (89%). The synthesis of model hybrid nitric oxide donor N-diazen-1-ium-1,2-diolate derivatives of 1-(4-methanesulfonylphenyl)-5-(4-substituted-aminomethylphenyl)-3-trifluoromethyl-1H-pyrazoles (10a–f) requires further investigation since the reaction of N-(4-(1-(4-(methylsulfonyl)phenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl)benzyl)ethanamine (12b) or 1-(4-(1-(4-(methylsulfonyl)phenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl)benzyl)piperazine (12c) with nitric oxide furnished N-nitroso derivatives (13 and 14), respectively, rather than the desired N-diazen-1-ium-1,2-diolate derivatives (10b and 10c).     

Diazen-1-ium-1,2-diolated and nitrooxyethyl nitric oxide donor ester prodrugs of anti-inflammatory (E)-2-(aryl)-3-(4-methanesulfonylphenyl)acrylic acids: synthesis, cyclooxygenase inhibition, and nitric oxide release studies

A new group of hybrid nitric oxide-releasing anti-inflammatory drugs wherein an O(2)-acetoxymethyl-1-(N-ethyl-N-methylamino)diazen-1-ium-1,2-diolate (11a-d), or 2-nitrooxyethyl (12a-d), (*)NO-donor moiety is attached directly to the carboxylic acid group of (E)-3-(4-methanesulfonylphenyl)-2-(phenyl)acrylic acids were synthesized. The 2-nitrooxyethyl ester prodrugs (12a-d) all exhibited in vitro inhibitory activity against the cyclooxygenase-2 (COX-2) isozyme (IC(50)=0.07-2.8 microM range). All compounds released a low amount of (*)NO upon incubation with phosphate buffer (PBS) at pH 7.4 (1.0-4.8% range). In comparison, the percentage (*)NO released was significantly higher (76.2-83.0% range) when the diazen-1-ium-1,2-diolate ester prodrugs were incubated in the presence of rat serum, or moderately higher (7.6-10.1% range) when the nitrooxyethyl ester prodrugs were incubated in the presence of L-cysteine. These incubation studies suggest that both (*)NO and the parent anti-inflammatory (E)-3-(4-methanesulfonylphenyl)-2-(phenyl)acrylic acid would be released upon in vivo cleavage by non-specific serum esterases in the case of the diazen-1-ium-1,2-diolate esters (11a-d), or interaction with systemic thiols in the case of the nitrate esters (12a-d). O(2)-Acetoxymethyl-1-(N-ethyl-N-methylamino)diazen-1-ium-1,2-diolate (E)-3-(4-methanesulfonylphenyl)-2-phenylacrylate (11a) released 83% of the theoretical maximal release of 2 molecules of (*)NO/molecule of the parent hybrid ester prodrug upon incubation with rat serum. Hybrid ester anti-inflammatory/(*)NO donor prodrugs offer a potential drug design concept targeted toward the development of anti-inflammatory drugs that are devoid of adverse ulcerogenic and/or cardiovascular effects.     

Diazen-1-ium-1,2-diolated nitric oxide donor ester prodrugs of 1-(4-methanesulfonylphenyl)-5-aryl-1H-pyrazol-3-carboxylic acids: synthesis, nitric oxide release studies and anti-inflammatory activities

A new group of hybrid nitric oxide-releasing anti-inflammatory drugs (NONO-coxibs) wherein an O(2)-acetoxymethyl-1-(N-ethyl-N-methylamino)diazen-1-ium-1,2-diolate (11a-c) NO-donor moiety is attached directly to the carboxylic acid group of 1-(4-methanesulfonylphenyl)-5-aryl-1H-pyrazol-3-carboxylic acids were synthesized. The diazen-1-ium-1,2-diolate compounds 11a-c all released a low amount of NO upon incubation with phosphate buffer (PBS) at pH 7.4 (7.7-9.3% range). In comparison, the percentage of NO released was significantly higher (67.5-73.6% of the theoretical maximal release of two molecules of NO/molecule of the parent hybrid ester prodrug) when the diazen-1-ium-1,2-diolate ester prodrugs were incubated in the presence of rat serum. These incubation studies suggest that both NO and the anti-inflammatory 1-(4-methanesulfonylphenyl)-5-(4-H, 4-F or 4-Me-phenyl)-1H-pyrazol-3-carboxylic acid (9a-c) would be released from the parent NONO-coxib upon in vivo cleavage by non-specific serum esterases. The 1-(4-methanesulfonylphenyl)-5-(4-H, 4-F or 4-Me-phenyl)-1H-pyrazol-3-carboxylic acids (9a-c) exhibited AI activities (ID(50)=85.2-104.4 mg/kg po range) between that exhibited by the reference drugs aspirin (ID(50)=128.7 mg/kg po) and celecoxib (ID(50)=10.8 mg/kg po). Hybrid ester anti-inflammatory/NO-donor prodrugs (NONO-coxibs) offers a potential drug design concept targeted toward the development of anti-inflammatory drugs that are devoid of adverse ulcerogenic and/or cardiovascular effects.     

3-(2-Methoxytetrahydrofuran-2-yl)pyrazoles: a novel class of potent, selective cyclooxygenase-2 (COX-2) inhibitors

A series of 3-(2-methoxytetrahydrofuran-2-yl)pyrazoles (4–10) was synthesized. The compounds were evaluated for their ability to inhibit cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) activity in human whole blood (HWB). The compound, 5-(4-methanesulfonylphenyl)-3-(2-methoxytetrahydrofuran-2-yl)-1-p-tolyl-1H-pyrazole 5 showed potent and selective COX-2 inhibition (IC₅₀ for COX-1: >100 μM and COX-2: 1.2 μM).     

Synthesis of 3-[4'-(p-chlorophenyl)-thiazol-2'-yl]-2-[(substituted azetidinone/thiazolidinone)-aminomethyl]-6-bromoquinazolin-4-ones as anti-inflammatory agent

N-Chloroacetyl-5-bromoanthranilic acid (1), 3-[4'-(p-chlorophenyl)-thiazol-2'-yl]-2-chloromethyl-6-bromoquinazolin-4-one (2), 3-[4'-(p-chlorophenyl)-thiazol-2'-yl]-2-hydrazinomethyl-6-bromoquinazolin-4-one (3), 3-[4'-(p-chlorophenyl)-thiazol-2'-yl]-2-substitutedbenzylidene aminomethyl-6-bromoquinazolin-4-ones (4-11), 2-[(4'-oxo-3'-chloro-2'-phenylazetidin-1'-yl)aminomethyl]-3-[4'-(p-chlorophenyl)thiazol-2'-yl]-6-bromoquinazolin-4-ones (12-19) and 2-(4'-oxo-2'-phenyl-thiazolidin-3'-yl-aminomethyl)- 3-[4'-(p-chlorophenyl)-thiazol-2'-yl]-6-bromoquinazolin-4-ones (20-27) have been synthesized. All the compounds have been screened for their anti-inflammatory and analgesic activities at the dose of 50mg/kg po. Compound 21 showed maximum anti-inflammatory (38.35%) and analgesic (37.36%) activities. Compound 21 was also tested for ulcerogenic activity and the UD(50) value was found to be 195.6mg/kg po. The structure of all compounds has been evaluated by elemental analysis (C, H, N) and spectral analysis (IR, (1)H NMR and mass spectrometry).     

Synthesis and initial PET imaging of new potential dopamine D3 receptor radioligands (E)-4,3,2-[11C]methoxy-N-4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl-cinnamoylamides

D3 receptor radioligands (E)-4,3,2-[11C]methoxy-N-4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl-cinnamoylamides (4-[11C]MMC, [11C]1a; 3-[11C]MMC, [11C]1b; and 2-[11C]MMC, [11C]1c) were synthesized for evaluation as novel potential positron emission tomography (PET) imaging agents for brain D3 receptors. The new tracers 4,3,2-[11C]MMCs were prepared by O-[11C]methylation of corresponding precursors (E)-4,3,2-hydroxy-N-4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl-cinnamoylamides (4,3,2-HMCs) using [11C]methyl triflate and isolated by the solid-phase extraction (SPE) purification procedure with 40-65% radiochemical yields, decay corrected to end of bombardment (EOB), and a synthesis time of 15-20 min. The PET dynamic studies of the tracers [11C]1a-c in rats were performed using an animal PET scanner, IndyPET-II, developed in our laboratory. The results show that the brain uptake sequence was 4-[11C]MMC > 3-[11C]MMC > 2-[11C]MMC, which is consistent with their in vitro biological properties. The initial PET blocking studies of the tracers 4,3,2-[11C]MMCs with corresponding pretreatment drugs (E)-4,3,2-methoxy-N-4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl-cinnamoylamides (4,3,2-MMCs, 1a-c) had no effect on 4,3,2-[11C]MMCs-PET rat brain imaging. These results suggest that the localization of 4,3,2-[11C]MMCs in rat brain is mediated by nonspecific processes, and the visualization of 4,3,2-[11C]MMCs-PET in rat brain is related to nonspecific binding.     

Biosynthesis in vitro of Ii core glycosphingolipids from neolactotetraosylceramide by beta 1-3- and beta 1-6-N-acetylglucosaminyltransferases from mouse T-lymphoma

The N-acetylglucosaminyltransferases probably involved in the biosynthesis in vitro of Ii core glycosphingolipids have been solubilized from a membrane preparation of mouse lymphoma P-1798 and partially characterized. The detergent-extracted membrane supernatant contains both beta 1-3- and beta 1-6-N-acetylglucosaminyltransferase activities that transfer [3H]GlcNAc from UDP-[3H]GlcNAc to the terminal galactose of neolactotetraosylceramide (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-ceramide; nLcOse4ceramide), to form the Ii core structures. The linkage of [3H]N-acetylglucosamine incorporated into the terminal galactose of nLcOse4Cer was determined from identification of 2,4,6-tri-O-methyl[3H]galactose and 2,3,4-tri-O-methyl[3H]galactose after hydrolysis of the permethylated enzymatic products, GlcNAc beta-[3H]Gal-GlcNAc-Gal-Glc-ceramide. In addition to the presence of beta-N-acetylglucosaminyltransferases, we have detected a galactosyltransferase activity in this soluble supernatant fraction that catalyzes the transfer of [14C]galactose from UDP-[14C]galactose to lactotriaosylceramide (GlcNAc beta 1-3Gal beta 1-4Glc-ceramide; LcOse3ceramide) to form nLcOse4ceramide, the acceptor in the N-acetylglucosaminyltransferase-catalyzed reaction.     

Kaempferol-3-O-glucosyl(1-2)rhamnoside from Ginkgo biloba and a reappraisal of other gluco(1-2, 1-3 and 1-4)rhamnoside structures.

A kaempferol-3-O-glucorhamnoside from Ginkgo biloba is defined as the 3-O-alpha-L-[ beta-D-glucopyranosyl(1-2)rhamnopyranoside] on the basis of 2D NMR evidence. Complete assignments of the 1H and 13C NMR spectra of this compound and of its known p-coumaroyl derivative are presented for the first time. The NMR distinctions of 1-2, 1-3 and 1-4 linked glucopyranosylrhamnopyranosides are discussed and indicate (i) that the 13C NMR assignments for one published gluco(1-3)rhamnoside are in need of modification, (ii) that the published structure of hordenine-O-[6-O-t-cinnamoyl-beta-glucosyl(1-4)-alpha-rhamnoside] from Selaginella doederleinii is not distinguished from the 1-3 linked glucorhamnoside structure, and (iii) that the 8-prenylkaempferol-3-O-[glucosyl(1-4)rhamnoside]-7-O-glucoside and the equivalent 4'-O-methylated xylosyl(1-4)rhamnoside from Epimedium pubescens and E. washanense, respectively, are (1-2)-linked.     

Synthesis and biological evaluation of 1,3-diphenylprop-2-yn-1-ones as dual inhibitors of cyclooxygenases and lipoxygenases

A new class of 1,3-diphenylprop-2-yn-1-ones possessing a p-MeSO2 COX-2 phamacophore on the C-3 phenyl ring was designed for evaluation as dual inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX). Among the group of compounds evaluated, 1-(4-fluorophenyl)-3-(4-methanesulfonylphenyl)prop-2-yn-1-one (11j) exhibited excellent COX-2 inhibitory potency (COX-2 IC50 = 0.1 microM) and selectivity (SI = 300), whereas 1-(4-cyanophenyl)-3-(4-methanesulfonylphenyl)prop-2-yn-1-one (11d) exhibited an optimal combination of COX and LOX inhibition (COX-2 IC50 = 1.0 microM; COX-2 SI = 31.5; 5-LOX IC50 = 1.0 microM; 15-LOX IC50 = 3.2 microM).     

Chemopreventive potential of 3-[2,6-bis(4-fluorophenyl)-3-methylpiperidin-4-ylideneamino]-2-thioxoimidazolidin-4-one on 7,12-dimethylbenz[a]anthracene (DMBA) induced hamster buccal pouch carcinogenesis

In the present work, a new bis heterocyclic compound comprising both the piperidone and thiohydantoin nuclei namely 3-[2,6-bis(4-fluorophenyl)-3-methylpiperidin-4-ylideneamino]-2-thioxoimidazolidin-4-one was synthesised and characterised with the help of mp, elemental analysis, FT-IR, MS and one-dimensional NMR (¹H and ¹³C) spectra. The inhibitory effect of 3-[2,6-bis(4-fluorophenyl)-3-methylpiperidin-4-ylideneamino]-2-thioxoimidazolidin-4-one on 7,12-dimethylbenz[a]anthracene (DMBA) induced buccal pouch carcinogenesis was investigated in Syrian male hamsters. All the hamsters that were painted with DMBA on their buccal pouches for 14 weeks developed squamous cell carcinoma. Administration of 3-[2,6-bis(4-fluorophenyl)-3-methylpiperidin-4-ylideneamino]-2-thioxoimidazolidin-4-one effectively suppressed the oral carcinogenesis initiated with the DMBA as revealed by a reduced incidence of neoplasms. Lipid peroxidation, glutathione (GSH) content and the activities of glutathione peroxidase (GPx), glutathione S-transferase (GST) were used to biomonitor the chemopreventive potential of 3-[2,6-bis(4-fluorophenyl)-3-methylpiperidin-4-ylideneamino]-2-thioxoimidazolidin-4-one. Lipid peroxidation was found to be significantly decreased, whereas GSH, GPx, GST and GGT were elevated in the oral mucosa of tumour bearing animals. Our data suggest that 3-[2,6-bis(4-fluorophenyl)-3-methylpiperidin-4-ylideneamino]-2-thioxoimidazolidin-4-one may exert its chemopreventive effects in the oral mucosa by modulation of lipid peroxidation, antioxidants and detoxification systems.     

Loss of tritium from coprostanone derived from [1,2(n)-3H]cholesterol or [7(n)-3H]cholesterol

After oral administration of a mixture of [1,2(n)-3H]cholesterol and [4-14C]cholesterol to a baboon, fecal coprostanone had a 46% lower 3H/14C ratio than the dose administered. Loss of 3H by enolization of the 3-ketone could account for the decrease in 3H/14C. If [7(n)-3H]cholesterol was administered instead of [1,2(n)-3H]cholesterol a 23% loss of 3H from coprostanone was found. Procedures requiring measurement of 3H-coprostanone derived from [1,2(n)-3H]- or [7(n)-3H]cholesterol could be seriously in error unless an appropriate correction for loss of 3H is made.