4-Alkoxybenzamidines as new potent phospholipase A2 inhibitors

Chemometric profiling and anti-arthritic activity of aerial parts of Glinus oppositifolius (L.) Aug. DC

ETHNOPHARMACOLOGICAL RELEVANCE

Glinus oppositifolius (L.) Aug. DC. belongs to the family Molluginaceae, an annual prostrate herb traditionally used to treat inflammations, arthritis, malarial, wounds, fevers, diarrhoea, cancer, stomach discomfort, jaundice, and intestinal parasites. However, the anti-arthritic activity of the aerial part has still not been reported.

AIM OF THE STUDY

To investigate the antioxidant and anti-arthritic activity of G. oppositifolius in Complete Freund's Adjuvant (CFA) induced rats.

MATERIALS AND METHODS

The dried aerial parts of this plant material were defatted with n-hexane and extracted by methanol using a soxhlet apparatus. The in vitro anti-arthritic activity of methanolic extract of G. oppositifolius (MEGO) was evaluated in protein denaturation, membrane stabilization, and inhibition of proteinase assay at 25, 50, 100, 200, and 400 μg/ml concentrations. Female Wistar rats were immunized sub-dermally into the right hind paw with 0.1 ml of CFA. Rats were administered with MEGO at doses of 200 and 400 mg/kg once daily for fourteen days after arthritis induction. Assessment of arthritis was performed by measuring paw diameter, arthritic index, arthritic score, body weight, organ weight, and hematological and biochemical parameters, followed by the analysis of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), interleukin-1-beta (IL-1β), cyclooxygenase-2 (COX-2), interleukin 13 (IL-13) and interleukin 10 (IL-10) and histopathological study. In vivo antioxidant effect was investigated in enzymatic assays. The presence of phytoconstituents was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS), respectively. In silico molecular docking study of the compounds was carried out against COX-2, IL-1β, IL-6, and TNF-α using AutoDock 4.2 and BIOVIA-Discovery Studio Visualizer software.

RESULTS

MEGO's in vitro anti-arthritic activity showed dose-dependent inhibition of protein denaturation, membrane stabilization, and proteinase inhibition, followed by significant in vivo anti-arthritic activity. The rats treated with MEGO showed tremendous potential in managing arthritis-like symptoms by restoring hematological, biochemical, and histological changes in CFA-induced rats. MEGO (200 and 400 mg/kg) showed a significant alleviation in the levels of hyper expressed inflammatory mediators (TNF-α, IL-1β, and IL-6) and oxidative stress (SOD, CAT, GSH, and LPO) in CFA-induced rats. Spergulagenin-A as identified by LC-MS analysis, exhibited the highest binding affinity against COX-2 (-8.6), IL-1β (7.2 kcal/mol), IL-6 (-7.4 kcal/mol), and TNF-α (-6.5 kcal/mol).

CONCLUSIONS

Provided with the comprehensive investigation, methanolic extract of G. oppositifolius against arthritic-like condition is a proof of concept that revalidates its ethnic claim. The presence of Spergulagenin-A might be responsible for the anti-arthritic activity.

Ephedra alata Subsp. Alenda as a Novel Source of Bioactive Phytochemicals: Characterization Based on the Mass Spectrometry and Profiling of Antioxidant and Anti-Inflammatory Properties

The aim of the present study was to examine, for the first time, the phytochemical content of Ephedra alata pulp extract (EAP) and explore its antioxidant and anti-inflammatory capacities. High-performance liquid chromatography-electrospray ionization-quadrupole-time-of-flight mass spectrometry (HPLC-ESI-QTOF/MS) was used for phytochemical analysis and three in vitro antioxidant assays together with three in vitro anti-inflammatory tests were used for the assessment of biological activity. The HPLC-ESI-QTOF/MS analysis revealed the presence of 42 metabolites, including flavonoids, sphingolipides, fatty acids, ephedrine derivatives, and amino acid derivatives. In vitro findings revealed that EAP has interesting 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide, and ferrous ion chelating capacities (IC₅₀ values were 0.57 mg/mL, 0.55 mg/mL, and 0.51 mg/mL for DPPH, superoxide radical, and ferrous ion, respectively). Furthermore, EAP showed a noticeable anti-inflammatory ability by inhibiting the two cyclooxygenase isoforms, COX-1 and COX-2 (IC₅₀ of 59.1 and 58.8 µg/mL for COX-1 and COX-2, respectively), preventing protein denaturation (IC50 = 0.51 mg/mL), and protecting membrane stabilization (IC50 = 0.53 mg/mL). The results highlighted the use of Ephedra alata pulp as a potential source of natural compounds with therapeutic effects for the management of inflammatory disorders.

In Vitro Anti-Inflammatory Properties of Selected Green Leafy Vegetables

The study investigated the anti-inflammatory activity of the hydro methanolic extract of six leafy vegetables, namely Cassia auriculata, Passiflora edulis, Sesbania grandiflora, Olax zeylanica, Gymnema lactiferum, and Centella asiatica. The anti-inflammatory activity of methanolic extracts of leafy vegetables was evaluated using four in vitro-based assays: hemolysis inhibition, proteinase inhibition, protein denaturation inhibition, and lipoxygenase inhibition. Results showed that the percent inhibition of hemolysis from these leaf extracts (25–100 µg/mL dry weight basis (DW)) was within the range from 5.4% to 14.9%, and the leaves of P. edulis and O. zeylanica showed a significantly higher (p < 0.05) inhibition levels. Percent inhibition of protein denaturation of these leafy types was within the range of 36.0–61.0%, and the leaf extract of C. auriculata has exhibited a significantly higher (p < 0.05) inhibition level. Proteinase inhibitory activity of these leaf extracts was within the range of 20.2–25.9%. The lipoxygenase inhibition was within the range of 3.7–36.0%, and the leaf extract of G. lactiferum showed an improved ability to inhibit lipoxygenase activity. In conclusion, results revealed that all the studied leaves possess anti-inflammatory properties at different levels, and this could be due to the differences in the composition and concentration of bioactive compounds.

Anti-inflammatory activity of Theobroma cacao L. stem bark ethanol extract and its fractions in experimental models

ETHNOPHARMACOLOGICAL RELEVANCE

The stem bark of Theobroma cacao L. have been used for the treatment of inflammation, toothache, measles and malaria in ethnomedicine. However, the anti-inflammatory activity of Theobroma cacao stem bark has not been fully elucidated.

AIM

The anti-inflammatory activity of Theobroma cacao stem bark ethanol extract and its fractions was investigated in this study.

MATERIALS AND METHODS

The anti-inflammatory effect of ethanol extract of Theobroma cacao stem bark (EETc) and its dichloromethane (DCMF), ethylacetate (EAF) and aqueous (AQF) fractions was investigated in erythrocytes membrane stabilizing assay and carrageenan-induced paw oedema. The anti-inflammatory activity of the EAF and EETc was investigated in carrageenan induced-granuloma air pouch models.

RESULTS

The extract and fractions showed significant membrane stabilizing action on rat erythrocytes cell membrane. The oral administration of DCMF, EAF and AQF (250 mg/kg) significantly inhibited paw oedema induced by carrageenan (41.3%, 55.0% and 45.0%, respectively) compared to control group. The EAF (62.5, 125 and 250 mg/kg) and EETc (250 mg/kg) significantly inhibited exudates formation in carrageenan air pouch by (63.8, 71.5, 74.5, 64.3%) at 24 h and by (69.4%, 75.7%, 77.1% and 68.4%) at 72 h respectively. The EETc and EAF significantly reduced neutrophil counts, protein, nitrite, Tumor necrosis factor (TNF-α) and malondialdehyde (MDA) but increased reduced glutathione (GSH) levels compared to control in pouch exudates. The HPLC fingerprint of EAF revealed presence of caffeic acid, rutin, ferulic acid and morin.

CONCLUSION

Ethanol extract of Theobroma cacao and its ethylacetate fraction demonstrated anti-inflammatory activity partly by reducing neutrophil migration and inflammatory mediator production.

Purification and structural elucidation of three bioactive compounds isolated from Streptomyces coelicoflavus BC 01 and their biological activity

The strain Streptomyces coelicoflavus BC 01 was isolated from mangrove soil and used as inoculum for submerged fermentation. The fermented broth was extracted with ethyl acetate, the crude extract was subjected to silica gel column chromatography and the homogeneity of the isolated fractions was determined by TLC and then subjected to RP-HPLC for their purity. The purification steps led to the isolation of three pure bioactive compounds named as BC 01_C1, BC 01_C2 and BC 01_C3. The chemical structure of these three compounds was established on the basis of their spectroscopic studies like UV, IR, ¹H and ¹³C NMR and GC–MS data by comparison with reference data from literature. The structure of the compound BC 01_C1 was established as 5-amino-2-(6-(2-hydroxyethyl)-3-oxononyl) cyclohex-2-enone. The compound BC 01_C2 was established as8-(aminomethyl)-7-hydroxy-1-(1-hydroxy-4-(hydroxylmethoxy)-2,3-dimethylbutyl)-2-methyl dodecahydro phenanthren-9(1H)-one and the compound BC 01_C3 was established as1-((E)-2-ethylhex-1-en-1-yl)2-((E)-2-ethylidenehexyl)cyclohexane-1,2-dicarboxylate. The MIC values of the three isolated compounds (BC 01_C1, BC 01_C2 and BC 01_C3) were found between 12.5–75 μg/ml for bacteria and 50–125 μg/ml for fungi used in this study. These compounds also possess in vitro antioxidant and anti-inflammatory activities.

In vitro Anti-oxidant Activity and HPLC-DAD System Based Phenolic Content Analysis of Codiaeum variegatum Found in Bangladesh

PURPOSE

This study evaluated the in vitro antioxidant potential of two varieties of Codiaeum variegatum leaves (spiral (CP) and royal like (BP)) extracts.

METHODS

The different antioxidant assays, including DPPH free radical scavenging, nitric oxide scavenging, hydrogen peroxide, reducing power, total antioxidant activity, protection of lipid peroxidation and RBC membrane stabilization activity, were studied. Moreover, high-performance liquid chromatography (HPLC) coupled with diode-array detection was used to identify and quantify the phenolic compounds in the royal like (BP) leaves extract.

RESULTS

Codiaeum variegatum extracts showed effective DPPH free radical scavenging, hydrogen peroxide radical scavenging and nitric oxide scavenging activity. However, reducing power of ferric ion was not significant compared to the standard antioxidant activity. In addition, Codiaeum variegatum extracts exhibited protection against lipid peroxidation. The total antioxidant activity was increased dose dependently when compared with standard drug ascorbic acid. (-)-Epicatechin, p-coumaric acid, rutin hydrate and ellagic acid were identified in the extract. Among the phenolic compounds, ellagic acid was abundantly present in the extract.

CONCLUSION

Our investigation suggests that Codiaeum variegatum leaves contain high amount of phenolic compounds which may responsible for its biological activities in folkloric medicine.

Bioassay-guided isolation, identification and molecular ligand-target insight of lipoxygenase inhibitors from leaves of Anisomeles malabarica R.Br

Background:

Anisomeles malabarica R. Br. (Lamiaceae) is extensively used in traditional medicine in major parts of India for several medicinal purposes, including their use in rheumatism.

Materials and Methods:

The air-dried leaves of A. malabarica were extracted with ethanol, defatted with n-hexane and then successively partitioned into chloroform and n-butanol fractions. Bioassay-guided fractionation and purification of chloroform fraction from A. malabarica lead to the isolation of lipoxygenase (LOX) inhibitors. The structures of isolated compounds were elucidated by ultraviolet, infrared, ¹H nuclear magnetic resonance (NMR), ¹³C NMR and mass spectrometry spectroscopic techniques and assessed further by in vitro soybean lipoxygenase (sLOX) assay. In addition, the enzyme type inhibition was evaluated through molecular docking technique as a part of computational study.

Results:

The bioactive compounds 3, 4 dihydroxy benzoic acid (1) and 4’, 5, 7-trihydroxyflavone (2) were isolated from chloroform fraction of A. malabarica, whose bioactivity was observed to be dose-dependent compared to n-butanol fraction. Among the compounds, 3, 4 dihydroxy benzoic acid showed significant sLOX inhibitory activity with 74.04% ±2.6% followed by 4’, 5, 7-trihydroxyflavone (34.68% ±1.9%). The computational analysis of compounds showed their molecular interaction with important amino acid residues and nonheme iron atom in the catalytic site of LOX by enlightening their potential binding mode at molecular level.

Conclusions:

The LOX inhibitory constituents were identified from A. malabarica by means of bioassay-guided fractionation process. The results derived from in vitro and computational experiments confirm the potential of the isolated compounds and provide additional evidence for its traditional use in inflammatory disorders.

Studies of synthetic chalcone derivatives as potential inhibitors of secretory phospholipase A2, cyclooxygenases, lipoxygenase and pro-inflammatory cytokines

Arachidonic acid metabolism leads to the generation of key lipid mediators which play a fundamental role during inflammation. The inhibition of enzymes involved in arachidonic acid metabolism has been considered as a synergistic anti-inflammatory effect with enhanced spectrum of activity. A series of 1,3-diphenyl-2-propen-1-one derivatives were investigated for anti-inflammatory related activities involving inhibition of secretory phospholipase A2, cyclooxygenases, soybean lipoxygenase, and lipopolysaccharides-induced secretion of interleukin-6 and tumor necrosis factor-alpha in mouse RAW264.7 macrophages. The results from the above mentioned assays exhibited that the synthesized compounds were effective inhibitors of pro-inflammatory enzymes and cytokines. The results also revealed that the chalcone derivatives with 4-methlyamino ethanol substitution seem to be significant for inhibition of enzymes and cytokines. Molecular docking experiments were carried out to elucidate the molecular aspects of the observed inhibitory activities of the investigated compounds. Present findings increase the possibility that these chalcone derivatives might serve as a beneficial starting point for the design and development of improved anti-inflammatory agents.

Pharmacological evaluation and docking studies of α,β-unsaturated carbonyl based synthetic compounds as inhibitors of secretory phospholipase A₂, cyclooxygenases, lipoxygenase and proinflammatory cytokines

Arachidonic acid and its metabolites have generated high level of interest among researchers due to their vital role in inflammation. The inhibition of enzymes involved in arachidonic acid metabolism has been considered as synergistic anti-inflammatory effect. A series of novel α,β-unsaturated carbonyl based compounds were synthesized and evaluated for their inhibitory activity on secretory phospholipase A₂ (sPLA₂), cyclooxygenases (COX), soybean lipoxygenase (LOX) in addition to proinflammatory cytokines comprising IL-6 and TNF-α. Six α,β-unsaturated carbonyl based compounds (2, 3, 4, 12, 13 and 14) exhibited strong inhibition of sPLA₂ activity, with IC₅₀ values in the range of 2.19-8.76 μM. Nine compounds 1-4 and 10-14 displayed inhibition of COX-1 with IC₅₀ values ranging from 0.37 to 1.77 μM (lower than that of reference compound), whereas compounds 2, 10, 13 and 14 strongly inhibited the COX-2. The compounds 10-14 exhibited strong inhibitory activity against LOX enzyme. All compounds were evaluated for the inhibitory activities against LPS-induced TNF-α and IL-6 release in the macrophages. On the basis of screening results, five active compounds 3, 4, 12, 13 and 14 were found strong inhibitors of TNF-α and IL-6 release in a dose-dependent manner. Molecular docking experiments were performed to clarify the molecular aspects of the observed COX and LOX inhibitory activities of the investigated compounds. Present findings increases the possibility that these α,β-unsaturated carbonyl based compounds might serve as beneficial starting point for the design and development of improved anti-inflammatory agents.

Evaluation of an ethnomedicinal combination containing Semecarpus kurzii and Hernandia peltata used for the management of inflammation

CONTEXT

Scientific validation of an ethnomedicinal combination consisting of Semecarpus kurzii Engler (Anacardeaceae) leaves (SKL) and Hernandia peltata Meisn (Hernandeaceae) stem-bark (HPB), traditionally used in ailments related to inflammation, pain and fever.

OBJECTIVE

To validate in vivo and in vitro analgesic and antiinflammatory activities of methanol extract of SKL, HPB and their combination.

MATERIALS AND METHODS

Analgesic activity was tested by acetic acid induced writhing reflex and tail flick in Swiss albino mice, while the anti-inflammatory activity was studied in acute, subacute and chronic model on Wistar rats. The vascular permeability, membrane stabilization and protein denaturation were examined to know the possible mode of action.

RESULTS

Significant (p < 0.01) analgesic (78.04% inhibition of writhing) and antiinflammatory (72.54% inhibition of paw edema) activity was observed in combination of SKL and HPB extracts at 250 mg/kg each. The SKL extract alone inhibits acetic acid-induced vascular permeability (64.4%) at 500 mg/kg, while in combination at 250 mg/kg each, the inhibition was 69.49% (p < 0.01). Furthermore, SKL in combination with HPB (0.25 mg/mL each) prevent RBC hemolysis (61.91%) and inhibition of protein denaturation (76.52%)-like indomethacin.

DISCUSSION AND CONCLUSION

The SKL and HPB extract, alone (500 mg/kg) and in combination, (250 mg/kg each) had significant analgesic and antiinflammatory activity, probably by inhibiting the release of certain inflammatory mediators and membrane stabilization, due to the presence of triterpenes, tannins and related phytochemicals in the extracts. Thus, our results demonstrated that this combination provide the scientific rationale of its folk use.

Inhibition of NO(2), PGE(2), TNF-α, and iNOS EXpression by Shorea robusta L.: An Ethnomedicine Used for Anti-Inflammatory and Analgesic Activity

This paper is an attempt to evaluate the anti-inflammatory and analgesic activities and the possible mechanism of action of tender leaf extracts of Shorea robusta, traditionally used in ailments related to inflammation. The acetic-acid-induced writhing and tail flick tests were carried out for analgesic activity, while the anti-inflammatory activity was evaluated in carrageenan-and dextran- induced paw edema and cotton-pellet-induced granuloma model. The acetic-acid-induced vascular permeability, erythrocyte membrane stabilization, release of proinflammatory mediators (nitric oxide and prostaglandin E₂), and cytokines (tumor necrosis factor-α, and interleukins-1β and -6) from lipopolysaccharide-stimulated human monocytic cell lines were assessed to understand the mechanism of action. The results revealed that both aqueous and methanol extract (400 mg/kg) caused significant reduction of writhing and tail flick, paw edema, granuloma tissue formation (P < 0.01), vascular permeability, and membrane stabilization. Interestingly, the aqueous extract at 40 μg/mL significantly inhibited the production of NO and release of PGE₂, TNF-α, IL-1β, and IL-6. Chemically the extract contains flavonoids and triterpenes and toxicity study showed that the extract is safe. Thus, our study validated the scientific rationale of ethnomedicinal use of S. robusta and unveils its mechanism of action. However, chronic toxicological studies with active constituents are needed before its use.

Crocetin from the tubular calyx of Nyctanthes arbor-tristis

A carotenoid aglycone Ag-NY1 was isolated from the orange coloured tubular calyx of flowers of Nyctanthes arbor-tristis. The elucidation of the structure through a detailed spectroscopic study revealed that the carotenoid molecule is crocetin, which is the major aglycone present in the stigma of Crocus sativus. The compound exhibited a good membrane stabilising activity as compared to the corresponding glycoside crocin.

Exploring the potential of Nelumbo nucifera rhizome on membrane stabilization, mast cell protection, nitric oxide synthesis, and expression of costimulatory molecules

Immunomodulatory activity of Nelumbo nucifera rhizome was evaluated for its standardized extract (NNRE) with respect to betulinic acid. Various key parameters including erythrocyte membrane stabilization, inhibition of histamine release, reduction in nitric oxide production and depletion of expression of costimulatory molecules of macrophages were estimated. The result displayed that NNRE stabilized erythrocyte membrane significantly at 10 (42.05%) and 100 microg/mL (44.31%). Although considering the protection of mast cells from degranulation, NNRE showed 38.66% (100 microg/mL) and 69.66% (10 microg/mL) degranulation against compound 48/80 (C 48/80). NNRE at 1 and 5 microg/mL inhibited lipopolysaccharide (LPS)-induced activation of macrophages by decreasing the expression of costimulatory molecules. Expression of CD40, CD80, and CD86 by NNRE was seen significantly at 5 microg/mL compared to LPS-treated group. The extracts also inhibited the nitrite concentration at 1 and 5 microg/mL compared to LPS-treated group.

Anti-inflammatory activity of Trichosanthes cucumerina Linn. in rats

AIM OF THE STUDY

Trichosanthes cucumerina Linn. (Family: Cucurbitaceae) is one of the medicinal plants that is often used in Sri Lankan traditional systems of medicine. One of its uses is the treatment of inflammatory conditions. However, validity of the anti-inflammatory activity has not been scientifically investigated so far. Therefore, the aim of this study was to investigate the anti-inflammatory potential of Trichosanthes cucumerina hot water extract (HWE) and its fractions.

MATERIALS AND METHODS

The anti-inflammatory activity of Trichosanthes cucumerina was evaluated by use of the carrageenan-induced paw oedema model in Wistar rats. In addition, the mechanism/s by which Trichosanthes cucumerina is mediated the anti-inflammatory activity was assessed by determining its effects on (a) membrane stabilizing activity and (b) nitric oxide inhibitory activity.

RESULTS

Apart from the lowest dose of the HWE, other tested doses (500, 750, 1000 mg/kg) produced a significant (P ≤ 0.05) inhibition of the inflammation, most pronounced at 5h after the injection of carrageenan. The anti-inflammatory effect induced by 750 mg/kg, was comparable to that of the reference drug, indomethacin at 4 and 5h. Inhibition of nitric oxide (NO) production and membrane stabilization activities are probable mechanisms by which Trichosanthes cucumerina mediates its anti-inflammatory actions. Among the tested fractions, methanol fraction (MEF) and aqueous fraction (AQF) at a dose of 75 mg/kg exhibited marked inhibition against carrageenan-induced hind paw oedema. The anti-inflammatory effect induced by MEF, was comparable to that of the reference drug, indomethacin and as well as to the 750 mg/kg of HWE at 4 and 5h.

CONCLUSIONS

(a) These findings rationalize the traditional usage of this plant as an anti-inflammatory agent and (b) membrane stabilizing properties and NO inhibitory activity are possible mechanisms through which Trichosanthes cucumerina mediates its anti-inflammatory action.

Inhibition of Secreted Phospholipase A2. 4-Glycerol Derivatives of 4,5-Dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one with Broad Activities

Secreted phospholipases A2 (sPLA2s) have been reported to play an important role in various inflammatory conditions and thus represent an attractive therapeutic target. Previous SAR studies from our laboratory have revealed certain important features of our recently discovered specific hGIIA sPLA2 inhibitors, and we report here the synthesis and biological activities of glycerol-containing derivatives of our lead compound III (Figure 1). Efficient and selective synthesis methods have been developed to make glycerol trisubstituted by different groups on desired positions. In terms of biological activities, the best compounds (A3, A6, and A15) are more active than III (Figure 1), as potent as Me-Indoxam, an sPLA2s inhibitor of reference, against hGIIA, hGV, and hGX sPLA2s and at least 10 times less active toward the GIB enzymes in two in vitro assay systems. By synthesis of enantiopure (S)-A6, we demonstrated that no important improvement of the inhibitory potency could be achieved by this approach. Furthermore, the results show that the global lipophilicity is likely responsible for the anti-PLA2 activity and two oxadiazolone moieties seem too big to be accommodated by the active site of the hGIIA enzyme.

Inhibitors of brain phospholipase A2 activity: their neuropharmacological effects and therapeutic importance for the treatment of neurologic disorders

The phospholipase A(2) family includes secretory phospholipase A(2), cytosolic phospholipase A(2), plasmalogen-selective phospholipase A(2), and calcium-independent phospholipase A(2). It is generally thought that the release of arachidonic acid by cytosolic phospholipase A(2) is the rate-limiting step in the generation of eicosanoids and platelet activating factor. These lipid mediators play critical roles in the initiation and modulation of inflammation and oxidative stress. Neurological disorders, such as ischemia, spinal cord injury, Alzheimer's disease, multiple sclerosis, prion diseases, and epilepsy are characterized by inflammatory reactions, oxidative stress, altered phospholipid metabolism, accumulation of lipid peroxides, and increased phospholipase A(2) activity. Increased activities of phospholipases A(2) and generation of lipid mediators may be involved in oxidative stress and neuroinflammation associated with the above neurological disorders. Several phospholipase A(2) inhibitors have been recently discovered and used for the treatment of ischemia and other neurological diseases in cell culture and animal models. At this time very little is known about in vivo neurochemical effects, mechanism of action, or toxicity of phospholipase A(2) inhibitors in human or animal models of neurological disorders. In kainic acid-mediated neurotoxicity, the activities of phospholipase A(2) isoforms and their immunoreactivities are markedly increased and phospholipase A(2) inhibitors, quinacrine and chloroquine, arachidonyl trifluoromethyl ketone, bromoenol lactone, cytidine 5-diphosphoamines, and vitamin E, not only inhibit phospholipase A(2) activity and immunoreactivity but also prevent neurodegeneration, suggesting that phospholipase A(2) is involved in the neurodegenerative process. This also suggests that phospholipase A(2) inhibitors can be used as neuroprotectants and anti-inflammatory agents against neurodegenerative processes in neurodegenerative diseases.

Inhibition of secretory phospholipase A2. 2-Synthesis and structure–activity relationship studies of 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one (PMS1062) derivatives specific for group II enzyme

We have recently reported the discovery of a series of specific inhibitors of human group IIA phospholipase A(2) (hGIIA PLA(2)) to display promising in vitro and in vivo properties. Here we describe the influence of different structural modifications on the specificity and potency against hGIIA PLA(2) versus porcine group IB PLA(2). The SAR results, as well as the logP and pK(a) values of oxadiazolone determined in this work, provide important information towards the comprehension of the mode of action of this kind of compounds.

Functional characteristics of a phospholipase A(2) inhibitor from Notechis ater serum

A phospholipase A(2) inhibitor has been purified p6om the serum of Notechis ater using DEAE-Sephacel chromatography. The inhibitor was found to be composed of two protein subunits (alpha and beta) that form the intact complex of approximately 110 kDa. The alpha-chain is a 30-kDa glycoprotein and the beta-chain a nonglycosylated, 25-kDa protein. N-terminal sequence analysis reveals a high level of homology to other snake phospholipase A(2) inhibitors. The inhibitor was shown to be extremely pH and temperature stable. The inhibitor was tested against a wide variety of phospholipase A(2) enzymes and inhibited the enzymatic activity of all phospholipase A(2) enzymes tested, binding with micromole to nanomole affinity. Furthermore, the inhibitor was compared with the Eli-Lilly compound LY311727 and found to have a higher affinity for human secretory nonpancreatic phospholipase A(2) than this chemical inhibitor. The role of the carbohydrate moiety was investigated and found not to affect the in vitro function of the inhibitor.

Morelloflavone, a novel biflavonoid inhibitor of human secretory phospholipase A2 with anti-inflammatory activity

The flavanonylflavone morelloflavone inhibited secretory phospholipase A2 (PLA2) in vitro, with a high potency on the human recombinant synovial and bee venom enzymes (IC50 = 0.9 and 0.6 microM, respectively). The inhibition was apparently irreversible. In contrast, the compound was inactive on cytosolic PLA2 activity from human monocytes. Morelloflavone scavenged reactive oxygen species generated by human neutrophils (IC50 = 2.7 and 1.8 microM for luminol and lucigenin, respectively) but did not modify cellular responses such as degranulation or eicosanoid release. This biflavonoid exerted anti-inflammatory effects in animal models, with a potent inhibition of 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced ear inflammation in mice after topical administration. In this test, morelloflavone was found to decrease oedema and myeloperoxidase levels in ear homogenates ID50 = 58.5 and 74.3 micrograms/ear, respectively). In contrast, this biflavonoid failed to modify arachidonic acid-induced ear inflammation or eicosanoid levels in ear homogenates. A significant anti-inflammatory effect was also observed in the mouse paw carrageenan edema after oral administration, with the highest inhibition at 3 hr after induction of inflammation. Morelloflavone is an inhibitor of secretory PLA2 with selectivity for groups II and III enzymes and may be a pharmacological tool. In addition, it shows anti-inflammatory activity apparently not related to the synthesis of eicosanoids, but likely dependent on other mechanisms such as scavenging of reactive oxygen species.

Activation of the transcription factor NF-kappaB in lipopolysaccharide-stimulated U937 cells

During the course of serious bacterial infections, lipopolysaccharide (LPS) interacts with monocyte/macrophage receptors, resulting in the generation of inflammatory cytokines. Transcription factor NF-kappaB is crucial in activating the transcription of genes encoding proinflammatory cytokines. In this paper, we demonstrate that the activation of NF-kappaB by LPS in a promonocytic cell line (U937) followed a rather slow kinetics, depending on the rate of IkappaB-alpha inhibitor hydrolysis. No degradation of p105 and p100 inhibitors was observed under these conditions. The transduction pathway leading to NF-kappaB activation in U937 cells involved the intracellular generation of reactive oxygen species (ROS), as demonstrated by the concomitant inhibitory effects of antioxidants on NF-kappaB activation and the emission of a fluorescent probe reacting intracellularly with hydrogen peroxide. This ROS pathway was also characterized by the use of other inhibitors. This finding indicates that phospholipase A2 and 5-lipoxygenase are also involved. However, the NF-kappaB activation pathway involving the acidic sphingomyelinase of the endolysosomial membrane did not seem to participate in the LPS-induced NF-kappaB activation in U937 cells.