Aryl ketones from Acronychia pedunculata with cyclooxygenase-2 inhibitory effects

1-[2,4-Dihydroxy-6-methoxy-3,5-bis(3-methylbut-2-en-1-yl)phenyl]ethanone (1), and a new aryl ketone, named acrovestenol (2), were isolated as cyclooxygenase-2 (COX-2) inhibitory principles from a CH2Cl2 extract of the bark of Acronychia pedunculata by a bioassay-guided fractionation procedure. Compound 2 inhibited COX-2 with an IC50 value of 142.0+/-2.15 microM, compared to the COX-2 inhibitory reference compound NS-398 with an IC50 value of 11.3+/-1.12 microM. Compound 1 inhibited COX-2-catalyzed PG biosynthesis with 68% at a concentration of 500 microM. The structures were determined by UV, IR, and 1D- and 2D-NMR, including TOCSY, HSQC-DEPT, and HMBC, and MS investigations.     

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.     

Design, synthesis, and biological evaluation of N-acetyl-2-carboxybenzenesulfonamides: a novel class of cyclooxygenase-2 (COX-2) inhibitors

N-Acetyl-2-carboxybenzenesulfonamide (11), and a group of analogues possessing an appropriately substituted-phenyl substituent (4-F, 2,4-F(2), 4-SO(2)Me, 4-OCHMe(2)) attached to its C-4, or C-5 position, were synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1/COX-2 inhibition studies showed that 11 is a more potent inhibitor (COX-1 IC(50)=0.06microM; COX-2 IC(50)=0.25microM) than aspirin (COX-1 IC(50)=0.35microM; COX-2 IC(50)=2.4microM), and like aspirin [COX-2 selectivity index (S.I.)=0.14], 11 is a nonselective COX-2 inhibitor (COX-2 S.I.=0.23). Regioisomers having a 2,4-difluorophenyl substituent attached to the C-4 (COX-2 IC(50)=0.087microM; COX-2 S.I. >1149), or C-5 (COX-2 IC(50)=0.77microM, SI>130), position of 11 exhibited the most potent and selective COX-2 inhibitory activity relative to the reference drug celecoxib (COX-1 IC(50)=33.1microM; COX-2 IC(50)=0.07microM; COX-2 S.I.=472). N-Acetyl-2-carboxybenzenesulfonamide (11, ED(50)=49 mg/kg), and its C-4 2,4-difluorophenyl derivative (ED(50)=91 mg/kg), exhibited superior antiinflammatory activity (oral dosing) in a carrageenan-induced rat paw edema assay compared to aspirin (ED(50)=129 mg/kg). These latter compounds exhibited comparable analgesic activity to the reference drug diflunisal, and superior analgesic activity compared to aspirin, in a 4% NaCl-induced abdominal constriction assay. A molecular modeling (docking) study indicated that the SO(2)NHCOCH(3) substituent present in N-acetyl-2-carboxy-4-(2,4-fluorophenyl)benzenesulfonamide, like the acetoxy substituent in aspirin, is suitably positioned to acetylate the Ser(530) hydroxyl group in the COX-2 primary binding site. The results of this study indicate that the SO(2)NHCOCH(3) pharmacophore present in N-acetyl-2-carboxybenzenesulfonamides is a suitable bioisostere for the acetoxy (OCOMe) group in aspirin.     

Design, synthesis, and biological evaluation of linear 1-(4-, 3- or 2-methylsulfonylphenyl)-2-phenylacetylenes: a novel class of cyclooxygenase-2 inhibitors

A group of regioisomeric 1-(methylsulfonylphenyl)-2-phenylacetylenes possessing a COX-2 SO(2)Me pharmacophore at the para-, meta- or ortho-position of the C-1 phenyl ring, in conjunction with a C-2 phenyl or substituted-phenyl ring substituent (3-F, 3-OMe, 3-OH, 3-OAc, 4-Me), were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. These target linear 1,2-diarylacetylenes were synthesized via a palladium-catalyzed Sonogashira cross-coupling reaction followed by oxidation of the respective 1-(methylthiophenyl)-2-phenylacetylene intermediate. In vitro COX-1/COX-2 isozyme inhibition structure-activity studies identified 1-(3-methylsulfonylphenyl)-2-(4-methylphenyl)acetylene (12d) as a potent COX-2 inhibitor (IC(50) = 0.32 microM) with a high COX-2 selectivity index (SI > 320) comparable to the reference compound rofecoxib (COX-2 IC(50) = 0.50 microM; COX-2 SI > 200). A molecular modeling study where (12d) was docked in the binding site of COX-2 showed that the MeSO(2) COX-2 pharmacophore was positioned in the vicinity of the secondary COX-2 binding site near Val(523). The 1-(4-methylsulfonylphenyl)-2-(3-acetoxyphenyl)acetylene (11f, COX-1 IC(50) = 1.00 microM; COX-2 IC(50) = 0.06 microM; COX-2 SI = 16.7) and 1-(3-methylsulfonylphenyl)-2-(3-acetoxyphenyl)acetylene (12f, COX-1 IC(50) = 6.5 microM; COX-2 IC(50) = 0.05 microM; COX-2 SI = 130) regioisomers exhibited comparable COX-2 inhibition, and moderately lower selective COX-2 selectivity, relative to the reference drug celecoxib (COX-1 IC(50) = 33.1 microM; COX-2 IC(50) = 0.07 microM; COX-2 SI = 472). The most potent anti-inflammatory agent 1-(3-methylsulfonylphenyl)-2-(4-methylphenyl)acetylene (12d) exhibited moderate oral anti-inflammatory activity (ED(50)= 129 mg/kg) at 3 h postdrug administration relative to the reference drug celecoxib (ED(50) = 10.8 mg/kg) in a carrageenan-induced rat paw edema assay. The structure-activity data acquired indicate that the acetylene moiety constitutes a suitable scaffold (template) to design novel acyclic 1,2-diarylacetylenes with selective COX-2, or dual COX-1/COX-2, inhibitory activities.     

Design and synthesis of 1,3-diarylurea derivatives as selective cyclooxygenase (COX-2) inhibitors

A group of 1,3-diarylurea derivatives, possessing a methylsulfonyl pharmacophore at the para-position of the N-1 phenyl ring, in conjunction with a N-3 substituted-phenyl ring (4-F, 4-Cl, 4-Me, 4-OMe), were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1/COX-2 isozyme inhibition structure-activity studies identified 1-(4-methylsulfonylphenyl)-3-(4-methoxyphenyl) urea (4e) as a potent COX-2 inhibitor (IC(50)=0.11 microM) with a high COX-2 selectivity index (SI=203.6) comparable to the reference drug celecoxib (COX-2 IC(50)=0.06 microM; COX-2 SI=405). The structure-activity data acquired indicate that the urea moiety constitutes a suitable scaffold to design new acyclic 1,3-diarylurea derivatives with selective COX-2 inhibitory activity.     

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).     

Structure-activity relationship of aza-steroids as PI-PLC inhibitors

A number of aza-steroids were synthesized as potent phosphatidylinositol phospholipase C (PI-PLC) inhibitors. The epimeric mixtures 22,25-diazacholesterol (8a) and 3beta-hydroxy-22,25-diazacholestane (8b) were among the most active of these inhibitors, with IC(50) values of 7.4 and 7.5 microM, respectively. The 20alpha epimer, 8a2 (IC(50)=0.64 microM), whose stereochemistry at C-20 coincides with that of cholesterol, was found 50 times more potent than the 20beta epimer, 8a1 (IC(50)=32.2 microM). In diaza-estrone derivatives, the 3-methoxy group on the aromatic A-ring of 23 exhibited moderate PI-PLC inhibitory activity (IC(50)=19.7 microM), while compound with a free hydroxyl group (21) was inactive. However, in diaza-pregnane derivatives, epimers with a 3-hydroxyl group (8a, IC(50)=7.4 microM) exhibited more potent PI-PLC inhibitory activity than their counterparts with 3-methoxyl group on the non-aromatic A-ring (26, IC(50)=17.4 microM). We have illustrated in our previous publication that 3-hydroxyl-6-aza steroids are potent PI-PLC inhibitors.(3) However, simultaneous presence of the 6-aza and 22,25-diaza moieties in one molecule as in 13, led to loss of activity. Epimeric mixture 8a showed selective growth inhibition effects in the NCI in vitro tumor cell screen with a mean GI(50) value (MG-MID) of 5.75 microM for 54 tumors.     

Synthesis and biological evaluation of acyclic triaryl (Z)-olefins possessing a 3,5-di-tert-butyl-4-hydroxyphenyl pharmacophore: dual inhibitors of cyclooxygenases and lipoxygenases

A new class of regioisomeric acyclic triaryl (Z)-olefins possessing a 3,5-di-tert-butyl-4-hydroxyphenyl (DTBHP) 5-lipoxygenase (5-LOX) pharmacophore that is vicinal to a para-methanesulfonylphenyl cyclooxygenase-2 (COX-2) pharmacophore were designed for evaluation as selective COX-2 and/or 5-LOX inhibitors. The target compounds were synthesized via a highly stereoselective McMurry olefination cross-coupling reaction. This key synthetic step afforded a (Z):(E) olefinic mixture with a predominance for the (Z)-olefin stereoisomer. Structure-activity studies for the (Z)-1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-(4-methanesulfonylphenyl)-1-phenylalk-1-ene regioisomers showed that COX-1 inhibition decreased, COX-2 inhibition increased, and the COX-2 selectivity index (SI) increased as the chain length of the alkyl substituent attached to the olefinic double bond was increased (Et-->n-butyl-->n-heptyl). In this group of compounds, inhibition of both 5-LOX and 15-LOX was dependent upon the length of the alkyl substituent with the hex-1-ene compound 9c having a n-butyl substituent exhibiting potent inhibition of both 5-LOX (IC50=0.3 microM) and 15-LOX (IC50=0.8 microM) relative to the inactive (IC50>10 microM) Et and n-heptyl analogs. Compound 9c is of particular interest since it also exhibits a dual inhibitory activity against the COX (COX-1 IC50=3.0 microM, and COX-2 IC50=0.36 microM, COX-2 SI=8.3) isozymes. A comparison of the relative inhibitory activities of the two groups of regioisomers investigated shows that the regioisomers in which the alkyl substituent is attached to the same olefinic carbon atom (C-2) as the para-methanesulfonylphenyl moiety generally exhibit a greater potency with respect to COX-2 inhibition. The 4-hydroxy substituent in the 3,5-di-tert-butyl-4-hydroxyphenyl moiety is essential for COX and LOX inhibition since 3,5-di-tert-butyl-4-acetoxyphenyl derivatives were inactive inhibitors. These structure-activity data indicate acyclic triaryl (Z)-olefins constitute a suitable template for the design of dual COX-2/LOX inhibitors.     

Synthesis and biological evaluation of novel T-type Ca2+ channel blockers

A small molecule library of piperazinylalkylisoxazole derivatives containing about 600 compounds was designed, synthesized and evaluated for blocking effects on T-type Ca(2+) channel. Several ligands were identified to possess high inhibitory activity against the T-type Ca(2+) channel. The compound 21 with trifluoromethyl substituents at C(3)-position of phenyl group (R(1)) and C(2)-position of phenyl group (R(2)) showed the highest inhibitory activity with IC(50) value of 1.02 microM, which is comparable to that of mibefradil.     

Inhibition of rat liver cyclic AMP-dependent protein kinase by flavonoids.

Rat liver cyclic AMP-dependent protein kinase catalytic subunit (cAK), assayed using the synthetic peptide substrate, LRRASLG, is inhibited by a range of plant-derived flavonoids. In general, maximal inhibitory effectiveness (IC50 values 1 to 2 microM) requires 2,3-unsaturation and polyhydroxylation involving at least two of the three flavonoid rings. 3-Hydroxyflavone (IC50 value 4 microM), 3,5,7,2',4'-pentahydroxyflavone (IC50 = 10 microM) and 5,7,4'-trihydroxyflavone (IC50 = 7 microM) represent somewhat less active variations from this pattern. Flavonoid O-methylation or O-glycosylation greatly decreases inhibitory effectiveness, as does 2,3-saturation. Various flavonoid-related compounds, notably gossypol (IC50 = 10 microM), also inhibit cAK. Flavonoids and related compounds are in general much better inhibitors of cAK than of avian Ca(2+)-calmodulin-dependent myosin light chain kinase or of plant Ca(2+)-dependent protein kinase. Tricetin (IC50 = 1 microM) inhibits cAK in a fashion that is non-competitive with respect to both peptide substrate and ATP (Ki value 0.7 microM). When histone III-S is used as a substrate, inhibition of cAK requires much higher flavonoid concentrations.     

Development of inhibitors against lipase and alpha-glucosidase from derivatives of monascus pigment

New derivatives of monascus pigment were produced during Monascus fermentation by the addition of unnatural amino acids, and the inhibitory activities of the derivatives against diet-related lipase and alpha-glucosidase were tested. Derivatives with penicillamine (H-Pen), cyclohexylalanine (H-Cha), butylglycine (L-t-Bg), and norleucine (H-Nle) showed relatively high inhibitory activities against lipase. The H-Pen derivative exhibited the highest inhibitory activity, with an IC(50) (50% inhibition) value of 24.0 microM. The four derivatives all showed noncompetitive inhibition patterns against lipase. The inhibition constant (K(i)) of the H-Pen derivative was estimated to be 20.7 microM. The H-Pen derivative also exhibited a relatively high inhibitory activity against alpha-glucosidase, with an IC(50) value of 50.9 microM. The inhibition pattern of the H-Pen derivative against alpha-glucosidase appeared to be of a mixed type. The inhibition constants K(i) and were estimated to be 25.9, and 98.9 microM, respectively.     

Design and synthesis of 2,6-diprenyl-4-iodophenol TX-1952 with a novel and potent anti-peroxidative activity

The structure-based elucidation of 2,4,6-tri-substituted phenols for their antioxidative and anti-peroxidative effects has been investigated using TX-1952 (2,6-diprenyl-4-iodophenol), TX-1961, TX-1980, BTBP and BHT. In the inhibition of mitochondrial lipid peroxidation, the inhibitory activity of 2,6-di-tert-butyl-4-bromophenol (BTBP) (IC(50)=0.17 microM) was twice as high as that of 2,6-di-tert-butyl-4-methylphenol (BHT) (IC(50)=0.31 microM). This result shows that the 4-halogen group increases inhibitory activity for mitochondrial lipid peroxidation. Besides, TX-1952 (IC(50)=0.60 microM) was the highest inhibitor among 2,6-diprenyl-4-halophenols, followed by TX-1961 (IC(50)=0.93 microM) and TX-1980 (IC(50)=1.2 microM). In 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging experiments, the activity of TX-1952 (IC(0.200)=53.1 microM) was lower than that of BHT (IC(0.200)=33.7 microM) and BTBP (IC(0.200)=16.0 microM), but TX-1952 and BHT showed the same HOMO energy (-8.991 eV). These results suggest that the two prenyl groups at ortho position hinder the phenolic hydrogen abstraction by DPPH radical. These findings demonstrated that TX-1952 was a novel and potent inhibitor for lipid peroxidation.     

Synthesis and biological evaluation of 1,3-diphenylprop-2-en-1-ones possessing a methanesulfonamido or an azido pharmacophore as cyclooxygenase-1/-2 inhibitors

A group of (E)-1,3-diphenylprop-2-en-1-one derivatives (chalcones) possessing a MeSO(2)NH, or N(3), COX-2 pharmacophore at the para-position of the C-1 phenyl ring were synthesized using a facile stereoselective Claisen-Schmidt condensation reaction. In vitro COX-1/COX-2 structure-activity relationships were determined by varying the substituents on the C-3 phenyl ring (4-H, 4-Me, 4-F, and 4-OMe). Among the 1,3-diphenylprop-2-en-1-ones possessing a C-1 para-MeSO(2)NH COX-2 pharmacophore, (E)-1-(4-methanesulfonamidophenyl)-3-(4-methylphenyl)prop-2-en-1-one (7b) was identified as a selective COX-2 inhibitor (COX-2 IC(50)=1.0 microM; selectivity index >100) that was less potent than the reference drug rofecoxib (COX-2 IC(50)=0.50 microM; SI>200). The corresponding 1,3-diphenylprop-2-en-1-one analogue possessing a C-1 para-N(3) COX-2 pharmacophore, (E)-1-(4-azidophenyl)-3-(4-methylphenyl)prop-2-en-1-one (7f), exhibited potent and selective COX-2 inhibition (COX-1 IC(50)=22.2 microM; COX-2 IC(50)=0.3 microM; SI=60). A molecular modeling study where 7b and 7f were docked in the binding site of COX-2 showed that the p-MeSO(2)NH and N(3) substituents on the C-1 phenyl ring are oriented in the vicinity of the COX-2 secondary pocket (His90, Arg513, Phe518, and Val523). The structure-activity data acquired indicate that the propenone moiety constitutes a suitable scaffold to design new acyclic 1,3-diphenylprop-2-en-1-ones with selective COX-1 or COX-2 inhibitory activity.     

Phenylsulphonyl urenyl chalcone derivatives as dual inhibitors of cyclo-oxygenase-2 and 5-lipoxygenase

Two series of phenylsulphonyl urenyl chalcone derivatives (UCH) with various patterns of substitution were tested for their effects on nitric oxide (NO) and prostaglandin E2 (PGE2) overproduction in RAW 264.7 macrophages. None of the tested compounds reduced NO production more than 50% at 10 microM but most of them inhibited the generation of PGE2 with IC50 values under the micromolar range. Me-UCH 1, Me-UCH 5, Me-UCH 9, Cl-UCH 1, and Cl-UCH 9 were selected to evaluate their influence on human leukocyte functions and eicosanoids generation. These derivatives selectively inhibited cyclo-oxygenase-2 (COX-2) activity in human monocytes being Me-UCH 5 the most potent (IC50 0.06 microM). Selected compounds also reduced leukotriene B4 synthesis in human neutrophils by a direct inhibition of 5-lipoxygenase (5-LO) activity, with IC50 values from 0.5 to 0.8 microM. In addition, lysosomal enzyme secretion, such as elastase or myeloperoxidase as well as superoxide generation in human neutrophils were also reduced in a similar range. Our findings indicate that UCH derivatives exert a dual inhibitory effect on COX-2/5-LO activity. The profile and potency of these compounds may have relevance for the modulation of the inflammatory and nociceptive responses with reduction of undesirable side-effects associated with NSAIDs.     

Design, synthesis, and biological evaluation of substituted 2-alkylthio-1,5-diarylimidazoles as selective COX-2 inhibitors

A new type of 1-aryl-5-(4-methylsulfonylphenyl)imidazoles, possessing C-2 alkylthio (SMe or SEt) substituents, were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo anti-inflammatory activity. The compound, 1-(4-bromophenyl)-5-(4-methylsulfonylphenyl)-2-methylthioimidazole (11g), was the most potent and selective COX-2 inhibitor (COX-2 IC50=0.43 microM with no inhibition of COX-1 up to 25 microM) relative to the reference drug celecoxib (COX-2 IC50=0.21 microM with no inhibition of COX-1 up to 25 microM) and also showed very good anti-inflammatory activity compared to celecoxib in carrageenan-induced rat paw edema assay.     

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.     

Aldose reductase inhibitory effect by tectorigenin derivatives from Viola hondoensis

Aldose reductase (AR), the key enzyme of the polyol pathway, is known to play important roles in the diabetic complication. The inhibitors of AR, therefore, would be potential agents for the prevention of diabetic complication. The AR inhibition activity of several isoflavonoids was evaluated in vitro against rat lens. Tectoridin-4'-O-beta-D-glucoside exhibited strong AR inhibition activity on rat lens with an IC50 of 0.54 microM. Similar activities were recorded for the natural tectorigenin and tectoridin. In contrast, tectoridin-4'-O-beta-D-glucoside showed a stronger inhibitory activity than tectorigenin and tectoridin. Our results indicate that glucose conjugation position in this type of isoflavonoids may be required for the activity.     

Design, synthesis, and biological evaluation of 1,3-diarylprop-2-en-1-ones : a novel class of cyclooxygenase-2 inhibitors

A group of regioisomeric (E)-1,3-diarylprop-2-en-1-one derivatives possessing a COX-2 SO2Me pharmacophore at the para position of the C-1 or C-3 phenyl ring, in conjunction with a C-3 or C-1 phenyl (4-H) or substituted-phenyl ring (4-F, 4-OMe and 4-Me), were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. These target (E)-1,3-diarylprop-2-en-1-ones were synthesized via a Claisen-Schmidt condensation reaction. In vitro COX-1/COX-2 isozyme inhibition structure-activity studies identified (E)-1-(4-methanesulfonylphenyl)-3-(4-methylphenyl)prop-2-en-1-one (9f) as a potent COX-2 inhibitor (IC50=0.3 microM) with a high COX-2 selectivity index (SI=106) comparable to that of the reference drug rofecoxib (COX-2 IC50=0.5 microM; COX-2 SI>200). A molecular modeling study where 9f was docked in the binding site of COX-2 showed that the para-SO2Me substituent on the C-1 phenyl ring is oriented in the vicinity of the secondary COX-2 binding site near Val523. The structure-activity data acquired indicate that the propenone moiety constitutes a suitable scaffold to design novel acyclic 1,3-diarylprop-2-en-1-ones with selective COX-2 inhibitory activity.     

Resveratrol analogues as selective cyclooxygenase-2 inhibitors: synthesis and structure-activity relationship

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is found in grapes and various medical plants. Among cytotoxic, antifungal, antibacterial cardioprotective activity resveratrol also demonstrates non-selective cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibition. In order to find more selective COX-2 inhibitors a series of methoxylated and hydroxylated resveratrol derivatives were synthesized and evaluated for their ability to inhibit both enzymes using in vitro inhibition assays for COX-1 and COX-2 by measuring PGE(2) production. Hydroxylated but not methoxylated resveratrol derivatives showed a high rate of inhibition. The most potent resveratrol compounds were 3,3',4',5-tetra-trans-hydroxystilbene (COX-1: IC(50)=4.713, COX-2: IC(50)=0.0113 microM, selectivity index=417.08) and 3,3',4,4',5,5'-hexa-hydroxy-trans-stilbene (COX-1: IC(50)=0.748, COX-2: IC(50)=0.00104 microM, selectivity index=719.23). Their selectivity index was in part higher than celecoxib, a selective COX-2 inhibitor already established on the market (COX-1: IC(50)=19.026, COX-2: IC(50)=0.03482 microM, selectivity index=546.41). Effect of structural parameters on COX-2 inhibition was evaluated by quantitative structure-activity relationship (QSAR) analysis and a high correlation was found with the topological surface area TPSA (r=0.93). Docking studies on both COX-1 and COX-2 protein structures also revealed that hydroxylated but not methoxylated resveratrol analogues are able to bind to the previously identified binding sites of the enzymes. Hydroxylated resveratrol analogues therefore represent a novel class of highly selective COX-2 inhibitors and promising candidates for in vivo studies.     

Inhibition of gamma-endorphin generating endopeptidase activity of rat brain by peptides: structure activity relationship

gamma-Endorphin generating endopeptidase (gamma EGE) activity is an enzyme activity which converts beta-endorphin into gamma-endorphin and beta-endorphin-(18-31). The inhibitory potency on gamma EGE activity of neuropeptides and analogues or fragments of neuropeptides was tested. Dynorphin-(1-13) (IC50: 0.14 microM), human beta-endorphin-(1-31) (IC50: 15.5 microM), porcine ACTH-(1-39) (IC50: 6.3 microM), and substance P (IC50: 26 microM) had an inhibitory activity on gamma EGE activity. beta-Endorphin-(18-31) (IC50: 0.35 microM) but not gamma-endorphin potently inhibited gamma EGE activity. The IC50 of poly (Lys)40-60 was 0.8 microM. It is concluded that 1) gamma EGE activity is strongly inhibited by its product beta-endorphin-(18-31), 2) the enzyme is strongly inhibited by peptides with an aromatic amino acid at the NH2-terminal and/or basic amino acids in the COOH-terminal of the peptide chain.