5-LOX Inhibitory Activity Research Articles

Synthesis of Celecoxib Analogues Possessing a N-Difluoromethyl-1,2-dihydropyrid-2-one 5-Lipoxygenase Pharmacophore: Biological Evaluation as Dual Inhibitors of Cyclooxygenases and 5-Lipoxygenase with Anti-Inflammatory Activity

A novel class of 1-(4-methanesulfonylphenyl and 4-aminosulfonylphenyl)-5-[4-(1-difluoromethyl-1,2-dihydropyrid-2-one)]-3-trifluoromethyl-1H-pyrazole hybrid cyclooxygenase-2 (COX-2)/5-lipoxygenase (5-LOX) inhibitory anti-inflammatory agents was designed. Replacement of the tolyl ring present in celecoxib by the N-difluoromethyl-1,2-dihydropyrid-2-one moiety provided compounds showing dual selective COX-2/5-LOX inhibitory activities. 1-(4-Aminosulfonylphenyl)-5-[4-(1-difluoromethyl-1,2-dihydropyrid-2-one)]-3-trifluoromethyl-1H-pyrazole exhibited good anti-inflammatory (AI) activity (ED(50) = 27.7 mg/kg po) that compares favorably with the reference drugs celecoxib (ED(50) = 10.8 mg/kg po) and ibuprofen (ED(50) = 67.4 mg/kg po). The N-difluoromethyl-1,2-dihydropyridin-2-one moiety provides a novel 5-LOX pharmacophore for the design of cyclic hydroxamic mimetics for exploitation in the development of COX-2/5-LOX inhibitory AI drugs.

Antiinflammatory and antinociceptive activities of gossypin and procumbentin – cyclooxygenase‐2 (COX‐2) inhibition studies

In the present study the antiinflammatory and antinociceptive activities of a few selected flavonoids were investigated. Procumbentin, gossypin, chrysin and methylhespiridin were studied for antiinflammatory and antinociceptive activities using in vitro enzymatic assays and in animal models utilizing acetic acid-induced writhing in mice and hind paw edema in rats. In vitro studies were performed using TMPD (NNN'N'-tetramethyl-p-phenylene diamine) and oxygraphic methods for COX-1 (cyclooxygenase-1), COX-2, 5-LOX (5-lipoxygenase) and 15-LOX. Gossypin and procumbentin showed COX-2 inhibitory activity and exhibited IC(50) (COX-2/COX-1) ratios of 0.14 and 0.11, respectively. None of the flavonoids tested in this study showed LOX inhibitory activity. Four groups were studied for each test compound following intraperitoneal (i.p.) administration of doses of 10, 30 and 100 mg/kg. Antiinflammatory activity was measured by the carrageenin-induced rat hind paw edema model and antinociceptive activity by acetic acid-induced writhing. Procumbentin and gossypin showed antinociceptive activity at the 100 mg/kg dose. Gossypin showed antiinflammatory activity at doses of 10, 30, 100 mg/kg. Procumbentin and gossypin exhibited COX-2 inhibitory activity when tested by in vitro methods. Procumbentin and gossypin showed antinociceptive, and gossypin showed antiinflammatory, activities.

The in vitro biological activity of selected South African Commiphora species

Ten South African Commiphora (Burseraceae) species were investigated to validate their use in traditional healing rites. The leaf and stem extracts of each species were analysed for the anti-oxidant (ABTS and DPPH assays), antimicrobial (MIC and death kinetic assays), anti-inflammatory (5-LOX assay), anticancer (SRB assay) properties, as well as the cytotoxic effects (tetrazolium-based assay). The best anti-oxidant activity (ABTS assay) was observed for the stem extracts of Commiphora tenuipetiolata IC 50 = 5.10 μg/ml), Commiphora neglecta (IC 50 = 7.28 μg/ml) and Commiphora mollis (IC 50 = 8.82 μg/ml). Extracts generally exhibited poor anti-oxidant activity in the DPPH assay, with the exception of Commiphora schimperi (stem), Commiphora neglecta (stem), Commiphora tenuipetiolata (stem and leaf), and Commiphora edulis (stem), with IC 50 values ranging between 7.31 and 10.81 μg/ml. The stem extracts exhibited moderate to good 5-LOX inhibitory activity with Commiphora pyracanthoides (stem) displaying the greatest inhibitory effect (IC 50 = 27.86 ± 4.45 μg/ml). For the antimicrobial (MIC) assay, a greater selectivity was exhibited by the extracts against the Gram-positive bacteria (0.01–8.00 mg/ml) and the yeasts (0.25–8.00 mg/ml) than against the Gram-negative bacteria (1.00–8.00 mg/ml). Using death kinetic studies (time–kill studies), the rate at which Commiphora marlothii (stem) kills Staphylococcus aureus over a 24 h period was determined. Mostly, a concentration-dependent antibacterial activity was observed beginning after ca. 30 min. All concentrations exhibited antibacterial activity, with complete bactericidal effect achieved by the 24 th hour. The most active Commiphora species against the HT-29 cells (SRB anticancer assay) were Commiphora glandulosa (leaf and stem) and Commiphora marlothii (leaf). The MCF-7 cells (SRB anticancer assay) exhibited the highest sensitivity to indigenous Commiphora species, with Commiphora edulis (leaf and stem), Commiphora glandulosa (leaf and stem), Commiphora marlothii (leaf), Commiphora pyracanthoides (leaf and stem), Commiphora schimperi (stem), and Commiphora viminea (stem) all possessing a percentage inhibition greater than 80% at 100 μg/ml. Commiphora glandulosa (leaf and stem) and Commiphora pyracanthoides (leaf and stem) were the two most active species against the SF-268 cells (SRB anticancer assay), with IC 50 values ranging between 68.55 ± 2.01 and 71.45 ± 1.24 μg/ml. The majority of the Commiphora extracts were largely non-cytotoxic against Graham human kidney epithelial cells when investigated in the MTT assay.

Assessing 12( S)-lipoxygenase inhibitory activity using colorectal cancer cells overexpressing the enzyme

12( S)-Lipoxygenase (LOX) is regarded as a pro-tumorigenic enzyme and as a potential target for therapy and prevention of cancer so that the search for specific 12( S)-LOX inhibitors is part of drug development strategies. To facilitate the identification of specific 12( S)-LOX inhibitors we have created an assay cell line by introducing a12( S)-LOX expression vector into SW480 colorectal cancer cells. When arachidonic acid was supplied in the medium both transiently and stably overexpressing cells produced 12( S)-hydroxytetraenic acid (HETE) originating from the transfected gene at 4–5-fold the amount obtained from control transfectants. 12( S)-HETE production was 1913.7 ± 17.2 pg/ml and reached a steady state level 24 h after addition of arachidonic acid. To demonstrate the models suitability of 12( S)-LOX overexpressing SW480 cells they were used to measure the inhibitory activity of the plant phenols baicalein, kaempferol, quercetin, nordihydroguaretic acid and resveratrol which are known for their chemopreventive as well as LOX-inhibitory activity in different tumour models. All 5 compounds inhibited 12( S)-HETE production at concentrations below those necessary for growth inhibition.

Synthesis, stereochemical assignments, and biological activities of homoisoflavonoids

A series of four naturally occurring homoisoflavonoids and eight analogs have been synthesized starting from an appropriately substituted phenol through chroman-4-one, in four steps. The products were assigned as E-isomers based on NMR spectroscopic data. The E-isomers were converted into Z-isomers by photoisomerization. The E- and Z-isomers showed distinct chemical shifts and the differences between ( E) and ( Z)-homoisoflavonoids in the proton NMR spectra afford a useful method for ascertaining the stereochemistry. The antioxidant activity of homoisoflavonoids was determined by superoxide (NBT) and DPPH free radical scavenging methods. The analog 7-hydroxy-3-[(3,4,5-trihydroxyphenyl)methylene]chroman-4-one displayed excellent activity followed by sappanone A in both the methods and were several times potent than the commercial antioxidants like BHA, BHT, etc. These compounds were evaluated in vitro for their inhibitory activities against 5-lipoxygenase (5-LOX) enzyme. The analog 7-hydroxy-3-[( N, N-dimethylaminophenyl)methylene]chroman-4-one was found to possess potent inhibitory activity and was comparable to that of the standard, nordihydroguiaretic acid. These results suggest that these homoisoflavonoids, with their potent antioxidant and 5-LOX inhibitory activities, may have useful applications as antioxidants and lead compounds for asthma and inflammatory diseases.

HPLC based activity profiling for 5-lipoxygenase inhibitory activity in Isatis tinctoria leaf extracts

In the pursuit of the anti-inflammatory constituents in lipophilic woad extracts, the 5-lipoxygenase (5-LOX) inhibitory activity was investigated by HPLC-based activity profiling. In a low-resolution profiling, two time windows with peaks of activity were found. The first coincided with tryptanthrin, a known dual inhibitor of cyclooxygenase-2 (COX-2) and 5-LOX, whereas the major inhibitory fraction was towards the end of the HPLC run. The active fractions were profiled in a peak-resolved manner, and the compounds analyzed by LC-MS, GC and TLC. The activity in the lipophilic fractions of the Isatis extract could be linked to an unsaturated fatty acid, α-linolenic acid.

Synthesis, cytotoxicity, cellular uptake and influence on eicosanoid metabolism of cobalt–alkyne modified fructoses in comparison to auranofin and the cytotoxic COX inhibitor Co-ASS

Propargylhexacarbonyldicobalt complexes with fructopyranose ligands were prepared and investigated for cytotoxicity in the MCF-7 human breast cancer cell line. The antiproliferative effects depended on the presence of isopropylidene protecting groups in the carbohydrate ligand and correlated with the cellular concentration of the complexes. IC(50) values of > 20 microM demonstrated that the fructose derivatives were only moderately active compared to the references auranofin and the aspirin (ASS) derivative [2-acetoxy(2-propynyl)benzoate]hexacarbonyldicobalt (Co-ASS). In continuation of our studies on the mode of action of cobalt-alkyne complexes we studied the influence of the compounds on the formation of 12-HHT (COX-1 product) and 12-HETE (12-LOX product) by human platelets as an indication of the interference in the eicosanoid metabolism, which is discussed as a target system of cytostatics. Co-ASS was an efficient COX-1 inhibitor without LOX inhibitory activity and auranofin inhibited both COX-1 and 12-LOX eicosanoid production. The missing activity of the fructopyranose complexes at the 12-LOX and the only moderate effects at COX-1 indicate that COX/LOX inhibition may be in part responsible for the pharmacological effects of auranofin and Co-ASS but not for those of the fructopyranose complexes.

Anti-Proliferative Effects of Lichen-Derived Lipoxygenase Inhibitors on Twelve Human Cancer Cell Lines of Different Tissue Originin vitro

Lipoxygenases (LOXs) have been implicated in carcinogenesis in various cancer types. In the current study, three structurally different lichen metabolites, protolichesterinic acid (1), lobaric acid (2) and baeomycesic acid (3) were tested for anti-proliferative effects against 12 different human cancer cell lines. All compounds have known in vitro 5-LOX inhibitory activity, and 1 and 2 also inhibit 12-LOX. The activity of the lichen metabolites was compared to that of a specific 5-LOX inhibitor, zileuton (4). The following cancer cell lines were tested: Capan-1, Capan-2 and PANC-1 (all from pancreas), T47-D (breast), PC-3 (prostate), NCI-H1417 (small cell lung), NIH:OVCAR-3 (ovary), AGS (stomach), WiDr (colorectal), HL-60, K-562 and JURKAT (acute promyelocytic, erythro- and T-cell leukemia, respectively). Compound 1 showed the greatest inhibitory effect against all cell lines, with EC50 ranging from 2.4-18.1 microg mL(-1) (7.4-55.8 microM), followed by 2, with EC50 of 15.2 - 65.5 microg mL(-1) (33.2-143.6 microM). The effects of 3 and 4 were of similar orders of magnitude, with EC50 of 28.7 - >80 microg mL(-1) (76.8 - > 213.9 microM) and 12.9 - > 80 microg mL(-1) (50.4 - > 313.7 microM). The dual 5- and 12-LOX inhibitors 1 and to some extent 2 thus exert significant anti-proliferative effects against a variety of human cancer cell lines, while the selective 5-LOX inhibitors 3 and 4 are considerably less active.

Acetyl-11-keto-beta-boswellic acid (AKBA): structure requirements for binding and 5-lipoxygenase inhibitory activity.

1. 5-Lipoxygenase (5-LOX) products from endogenous arachidonic acid in ionophore-stimulated peritoneal polymorphonuclear leukocytes (PMNL) and from exogenous substrate (20 microM) in 105,000 g supernatants were measured. 2. The effects of natural pentacyclic triterpenes and their derivatives on 5-LOX activity were compared with the inhibitory action of acetyl-11-keto-beta-boswellic acid (AKBA), which has been previously shown to inhibit the 5-LOX by a selective, enzyme-directed, non-redox and non-competitive mechanism. 3. The 5-LOX inhibitory potency of AKBA was only slightly diminished by deacetylation of the acetoxy group or reduction of the carboxyl function to alcohol in intact cells (IC50 = 1.5 vs. 3 and 4.5 microM, respectively) and in the cell-free system (8 vs. 20 and 45 microM). 4. beta-Boswellic acid (beta-BA), lacking the 11-keto function, inhibited 5-LOX only partially and incompletely, whereas the corresponding alcohol from beta-BA, as well as amyrin, acetyl-11-keto-amyrin, 11-keto-beta-boswellic acid methyl ester had no 5-LOX inhibitory activity up to 50 microM in either system. 5. beta-BA only partially prevented the AKBA-induced 5-LOX inhibition, whereas the non-inhibitory compounds, amyrin and acetyl-11-keto-amyrin, almost totally antagonized the AKBA effect and shifted the concentration-inhibition curve for the incomplete inhibitor beta-BA to the right. In contrast, the non-inhibitory 11-keto-beta-BA methyl ester exerted no antagonizing effect. 6. The results demonstrate that the pentacyclic triterpene ring system is crucial for binding to the highly selective effector site, whereas functional groups (especially the 11-keto function in addition to a hydrophilic group on C4 of ring A) are essential for 5-LOX inhibitory activity.