Chroman amide and nicotinyl amide derivatives: Inhibition of lipid peroxidation and protection against head trauma

A series of chroman amide and nicotinyl amide derivatives was designed and synthesized for the treatment of traumatic and ischemic CNS injury. Five compounds were significantly more potent inhibitors of lipid peroxidation in vitro than the reference antioxidant, trolox (p < 0.01). Quantitative structure activity studies demonstrated that the inhibitory action was related to the ability to donate electrons, charge on hydroxy group and E_LUMO, to scavenging radicals and to the lipophilicity log P, which determines penetration of membrane lipids. ESR study indicated the ability of 12 to scavenge the hydroxyl radicals. The most promising compound, [(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2yl)carbonyl]-3′-(aminoethyl) indole (12), inhibited ex vivo lipid peroxidation in a head injury model and showed potent in vivo neuroprotective efficacy. Improvement of neurological recovery within 1 h of injury (grip test score) by as much as 200% was observed together with significant anti-anoxia activity. Compound 12 was a potent antagonist of methamphetamine-induced hypermotility resulting from dopamine release in the mouse brain. These results support the importance of cerebroprotective radical-scavenging agents for the treatment of traumatic injury and anoxia as well as provide additional evidence for the role of oxygen radicals and dopamine in brain damage.     

Chroman amide 12P inhibition of lipid peroxidation and protection against learning and memory impairment

Structure modification of the cerebroprotective chroman amide 12 to improve the drug delivery to the target organ by protecting the active hydroxy functional group was carried out in this study. Chroman amide 12P, which the O-acetyl group was served to protect the active group to be delivered to the target organ, was synthesized. Ex vivo antilipid peroxidation activity of 12P was significantly greater than the activity of 12 while the in vitro inhibition of 12P was found to be lower. These indicated that 12P with protected active group effectively reached the brain, the target site, but in vitro, 12P was unable to release its parent or released slowly. Neuropharmacological effect of 12P was investigated in mice. 12 and 12P (50-100 mg/kg, i.p.) showed significant suppression on the hypermotility induced by methamphetamine. 12P (100 mg/kg, i.p.) was more potent than 12, 54.36% and 38.73% suppression, respectively. The result suggested the enhancement of brain delivery and the antagonism against aberrant dopamine release. In the water maze test, 12P (200 mg/kg) as well as tacrine (3 mg/kg) significantly reduced the learning and memory impairment induced by scopolamine (0.5 mg/kg). The results support the enhanced brain delivery and the additional role of radical scavengers in the modulation of brain neurotransmitters in the aberrant condition.     

Synthesis and anticancer activity of novel amide derivatives of non-acetal deoxoartemisinin

Novel amide derivatives of C-12 non-acetal deoxoartemisinin were synthesized. Some of the derivatives had potent in vitro anticancer activity against major human cancer cell lines. The deoxoartemisinin amide trimer had potent in vivo antiangiogenic activity, according to the mouse matrigel plug assay.     

The antioxidative property of green tea against iron-induced oxidative stress in rat brain

The antioxidative property of green tea against iron-induced oxidative stress was investigated in the rat brain both in vivo and in vivo. Incubation of brain homogenates at 37 degrees C for 4 hours in vitro increased the formation of Schiff base fluorescent products of malonaldehyde, an indicator of lipid peroxidation. Auto-oxidation (without exogenous iron) of brain homogenates was inhibited by green tea extract in a concentration-dependent manner. Moreover, incubation with iron (1 microM) elevated lipid peroxidation of brain homogenates after 4-hour incubation at 37 degrees C. Co-incubation with green tea extract dose-dependently inhibited the iron-induced elevation in lipid peroxidation. For the in vivo studies: ferrous citrate (iron, 4.2 nmoles) was infused intranigrally and induced degeneration of the nigrostriatal dopaminergic system of rat brain. An increase in lipid peroxidation in substantia nigra as well as a decrease in dopamine content in striatum was observed seven days after the iron infusion. Intranigral infusion of green tea extract alone did not increase, and in some cases, even decreased lipid peroxidation in substantia nigra. Co-infusion of green tea extract prevented oxidative injury induced by iron. Both iron-induced elevation in lipid peroxidation in substantia nigra and iron-induced decrease in dopamine content in striatum were suppressed. Oral administration of green tea extract for two weeks did not prevent the iron-induced oxidative injury in nigrostriatal dopaminergic system. Our results suggest that intranigral infusion of green tea extract appears to be nontoxic to the nigrostriatal dopaminergic system. Furthermore, the potent antioxidative action of green tea extract protects the nigrostriatal dopaminergic system from the iron-induced oxidative injury.     

Antioxidant properties of EPC-K1: a study on mechanisms.

Scavenging effects of L-ascorbic acid 2-[3,4-dihydro-2,5,7,8- tetramethyl-2-(4,8,12-trimethytridecyl)-2H-1-benzopyran- 6-yl-hydrogen phosphate] potassium salt (EPC-K1) on hydroxyl radicals, alkyl radicals and lipid radicals were studied with ESR spin trapping techniques. The inhibition effects of EPC-K1 on lipid peroxidation were assessed by TBA assay. The kinetics of EPC-K1 reacting with hydroxyl radicals and linoleic acid radicals were studied by pulse radiolysis. The active site of EPC-K1 and the structure-antioxidative activity relationships were discussed. The superoxide radicals scavenging capacity of the brain homogenate of EPC-K1-treated rats was measured. The results revealed that in comparison with Trolox and vitamin C, EPC-K1 showed better overall antioxidative capacity in vitro and in vivo. EPC-K1 was a moderate scavenger on hydroxyl radicals and alkyl radicals, a potent scavenger on lipid radicals, and an effective inhibitor on lipid peroxidation. EPC-K1 could react with hydroxyl radicals with a rate constant of 7.1 x 10(8) dm3 mol-1 s-1 and react with linoleic acid radicals with a rate constant of 2.8 x 10(6) dm3 mol-1 s-1. The active site of EPC-K1 was the enolic hydroxyl group. After administration of EPC-K1, the ability of rat brain to scavenge superoxide radicals was significantly increased. The potent scavenging effects of EPC-K1 on both hydrophilic and hydrophobic radicals were relevant with its molecular structure, which consisted of both hydrophilic and hydrophobic groups.     

Oxidative stress following traumatic brain injury in rats: quantitation of biomarkers and detection of free radical intermediates

Oxidative stress may contribute to many pathophysiologic changes that occur after traumatic brain injury. In the current study, contemporary methods of detecting oxidative stress were used in a rodent model of traumatic brain injury. The level of the stable product derived from peroxidation of arachidonyl residues in phospholipids, 8-epi-prostaglandin F(2alpha), was increased at 6 and 24 h after traumatic brain injury. Furthermore, relative amounts of fluorescent end products of lipid peroxidation in brain extracts were increased at 6 and 24 h after trauma compared with sham-operated controls. The total antioxidant reserves of brain homogenates and water-soluble antioxidant reserves as well as tissue concentrations of ascorbate, GSH, and protein sulfhydryls were reduced after traumatic brain injury. A selective inhibitor of cyclooxygenase-2, SC 58125, prevented depletion of ascorbate and thiols, the two major water-soluble antioxidants in traumatized brain. Electron paramagnetic resonance (EPR) spectroscopy of rat cortex homogenates failed to detect any radical adducts with a spin trap, 5,5-dimethyl-1-pyrroline N:-oxide, but did detect ascorbate radical signals. The ascorbate radical EPR signals increased in brain homogenates derived from traumatized brain samples compared with sham-operated controls. These results along with detailed model experiments in vitro indicate that ascorbate is a major antioxidant in brain and that the EPR assay of ascorbate radicals may be used to monitor production of free radicals in brain tissue after traumatic brain injury.     

Lipopolysaccharide-induced pulmonary inflammation is not accompanied by a release of anandamide into the lavage fluid or a down-regulation of the activity of fatty acid amide hydrolase

The effect of lipopolysaccharide inhalation upon lung anandamide levels, anandamide synthetic enzymes and fatty acid amide hydrolase has been investigated. Lipopolysaccharide exposure produced a dramatic extravasation of neutrophils and release of tumour necrosis factor alpha into the bronchoalveolar lavage (BAL) fluid, which was not accompanied by epithelial cell injury. The treatment, however, did not change significantly the levels of anandamide and the related compound palmitoylethanolamide in the cell-free fraction of the BAL fluid. The activities of the anandamide synthetic enzymes N-acyltransferase and N-acylphosphatidylethanolamine phospholipase D and the activity of fatty acid amide hydrolase in lung membrane fractions did not change significantly following the exposure to lipopolysaccharide. The non-selective fatty acid amide hydrolase inhibitor phenylmethylsulfonyl fluoride was a less potent inhibitor of lung fatty acid amide hydrolase than expected from the literature, and a dose of 30 mg/kg i.p. of this compound, which produced a complete inhibition of brain anandamide metabolism, only partially inhibited the lung metabolic activity.     

Synthesis and structure activity relationships of glycine amide derivatives as novel Vascular Adhesion Protein-1 inhibitors

Vascular Adhesion Protein-1 (VAP-1) is a promising therapeutic target for the treatment of several inflammatory-related diseases including diabetic microvascular complication. We identified glycine amide derivative 3 as a novel structure with moderate VAP-1 inhibitory activity. Structure-activity relationship studies of glycine amide derivatives revealed that the tertiary amide moiety is important for stability in rat blood and that the position of substituents on the left phenyl ring plays an important role in VAP-1 inhibitory activity. We also found that low TPSA values and weak basicity are both important for high PAMPA values for glycine amide derivatives. These findings led to the identification of a series of orally active compounds with enhanced VAP-1 inhibitory activity. Of these compounds, 4g exhibited the most potent ex vivo efficacy, with plasma VAP-1 inhibitory activity of 60% after oral administration at 1 mg/kg.     

Hepatoprotective amide constituents from the fruit of Piper chaba: Structural requirements,mode of action,and new amides

The 80% aqueous acetone extract from the fruit of Piper chaba (Piperaceae) was found to have hepatoprotective effects on d-galactosamine (d-GalN)/lipopolysaccharide-induced liver injury in mice. From the ethyl acetate-soluble fraction, three new amides, piperchabamides E, G, and H, 33 amides, and four aromatic constituents were isolated. Among the isolates, several amide constituents inhibited d-GalN/tumor necrosis factor-α (TNF-α)-induced death of hepatocytes, and the following structural requirements were suggested: (i) the amide moiety is essential for potent activity; and (ii) the 1,9-decadiene structure between the benzene ring and the amide moiety tended to enhance the activity. Moreover, a principal constituent, piperine, exhibited strong in vivo hepatoprotective effects at doses of 5 and 10 mg/kg, po and its mode of action was suggested to depend on the reduced sensitivity of hepatocytes to TNF-α.     

Suppressive effects of Active Hexose Correlated Compound on the increased activity of hepatic and renal ornithine decarboxylase induced by oxidative stress

Active Hexose Correlated Compound (AHCC), an extract derived from fungi of Basidiomycetes family has been shown to act as a biological response modifier in various disorders. In our present study, ferric nitrilotriacetate (Fe-NTA), which generates hydroxyl radicals in vivo, was given intraperitoneally to rats and AHCC was tested for its ability to suppress oxidative stress and the activity of ornithine decarboxylase (ODC) in the liver and kidney. Substantial increments in glutathione-related enzymes including glutathione reductase, glutathione peroxidase activity as well as oxidized glutathione contents were shown in the liver at 12 h after treatment with Fe-NTA (7.5 mg Fe/kg body weight). Effects of oxidative stress induced by Fe-NTA were also demonstrated by the increase in serum lipid peroxidation, aminotransferases and urinary 8-hydroxy-2'-deoxyguanosine. However, the increases in these parameters were restored to normal in AHCC-pretreated rats. The ODC activity in the liver and kidney was significantly increased by Fe-NTA, while the increased ODC activity induced by Fe-NTA was normalized in AHCC-pretreated rats. These results suggest AHCC acts as a potent antioxidant and protects against disorders induced by oxidative stresses.     

The enzymatic inactivation of the fatty acid amide class of signaling lipids

The fatty acid amide (FAA) class of signaling lipids modulates a number of neurobehavioral processes in mammals, including pain, sleep, feeding, and locomotor activity. Representative FAAs include the endogenous cannabinoid anandamide and the sleep-inducing lipid oleamide. Despite activating several neuroreceptor systems in vitro, most FAAs produce only weak and transient behavioral effects in vivo, presumably due to their expeditious catabolism. This review focuses on one enzyme, fatty acid amide hydrolase (FAAH) that appears to play a major role in regulating the amplitude and duration of FAA signals in vivo. In particular, we will highlight a series of recent papers that have investigated the physiological functions of the mouse and human FAAH enzymes. Collectively, these studies promote FAAH as a central component of FAA signaling pathways, especially those mediated by the endocannabinoid anandamide, and suggest that this enzyme may represent an attractive pharmaceutical target for the treatment of pain and related neurophysiological disorders.     

A structure-activity relationship study on N-arachidonoyl-amino acids as possible endogenous inhibitors of fatty acid amide hydrolase

N-arachidonoyl-glycine (NAGly) has been recently identified in rodent tissues and found to exhibit analgesic activity in vivo. NAGly is a potent inhibitor of the fatty acid amide hydrolase (FAAH), the enzyme primarily responsible for the degradation of the endocannabinoid N-arachidonoyl-ethanolamine (anandamide), and was shown recently to elevate the blood levels of the this analgesic compound. We have synthesized several N-arachidonoyl-amino acids of potential natural occurrence, as well as the D- and L-isomers of N-arachidonoyl-alanine, and have tested their activity on FAAH preparations from mouse, rat, and human cell lines, and from mouse or rat brain. The results indicate that the relative potency and enantioselectivity of N-arachidonoyl-amino acids as FAAH inhibitors depend on the animal species. Thus, whilst NAGly is the most potent compound on the rat and mouse enzymes, N-arachidonoyl-isoleucine is active only on human FAAH and N-arachidonoyl-alanine enantiomers show a varying degree of potency. Taken together, these data support the view that an enhancement of endogenous anandamide levels underlies in part the analgesic effects of NAGly in rodents.     

Manganese-based complexes of radical scavengers as neuroprotective agents

Manganese was incorporated in the structure of the selected antioxidants to mimic the superoxide dismutase (SOD) and to increase radical scavenging ability. Five manganese complexes (1-5) showed potent SOD activity in vitro with IC(50) of 1.18-1.84 microM and action against lipid peroxidation in vitro with IC(50) of 1.97-8.00 microM greater than their ligands and trolox. The manganese complexes were initially tested in vivo at 50 mg/kg for antagonistic activity on methamphetamine (MAP)-induced hypermotility resulting from dopamine release in the mice brain. Only manganese complexes of kojic acid (1) and 7-hydroxyflavone (3) exhibited the significant suppressions on MAP-induced hypermotility and did not significantly decrease the locomotor activity in normal condition. Manganese complex 3 also showed protective effects against learning and memory impairment in transient cerebral ischemic mice. These results supported the brain delivery and the role of manganese in SOD activity as well as in the modulation of brain neurotransmitters in the aberrant condition. Manganese complex 3 from 7-hydroxyflavone was the promising candidate for radical implicated neurodegenerative diseases.     

Arachidonylsulfonyl derivatives as cannabinoid CB1 receptor and fatty acid amide hydrolase inhibitors

Arachidonylsulfonyl fluoride (3), reported here for the first time, is similar in potency to its known methyl arachidonylfluorophosphonate (2) analogue as an inhibitor of mouse brain fatty acid amide hydrolase activity (IC(50) 0.1 nM) and cannabinoid CB1 agonist [3H]CP 55,940 binding (IC(50) 304-530 nM). Interestingly, 3 is much more selective than 2 as an inhibitor for fatty acid amide hydrolase relative to acetylcholinesterase, butyrylcholinesterase and neuropathy target esterase. N-(2-Hydroxyethyl)arachidonylsulfonamide (4) is at least 2500-fold less potent than N-(2-hydroxyethyl)arachidonamide (anandamide) (1) at the CB1 agonist site.     

Radical Trapping and Inhibition of Iron-Dependent CNS Damage by Cyclic Nitrone Spin Traps

Abstract: Oxidative damage in the CNS is proposed to play a role in many acute and chronic neurodegenerative disorders. Accordingly, the nitrone spin trap α-phenyl- N - tert -butylnitrone (PBN), which reacts covalently with free radicals, has shown efficacy in a variety of animal models of CNS injury. We have synthesized a number of cyclic variants of PBN and examined their activity as radical traps and protectants against oxidative damage in CNS tissue. By using electron spin resonance spectroscopy, the cyclic nitrones MDL 101,002 and MDL 102,832 were shown to trap radicals in a manner similar to that of PBN. All cyclic nitrones tested prevented hydroxyl radical-dependent degradation of 2-deoxyribose and peroxyl radical-dependent oxidation of synaptosomes more potently than PBN. The radical scavenging properties of the cyclic nitrones contributed to a three- to 25-fold increase in potency relative to PBN against oxidative damage and cytotoxicity in cerebellar granule cell cultures. Similar to the phenolic antioxidant MDL 74,722, the nitrones minimized seizures and delayed the time to death in mice following central injection of ferrous iron. Although iron-induced lipid peroxidation was inhibited by MDL 74,722, the nitrones had no effect on this biochemical end point, indicating that iron-induced mortality does not result solely from lipid peroxidation and suggesting additional neuroprotective properties for the nitrones. These results indicate that cyclic nitrones are more potent radical traps and inhibitors of lipid peroxidation in vitro than PBN, and their ability to delay significantly iron-induced mortality in vivo suggests they may be useful in the treatment of acute and chronic neurodegeneration. Furthermore, the stability of the spin trap adducts of the cyclic nitrones provides a new tool for the study of oxidative tissue injury.     

Enhancement of endocannabinoid signaling by fatty acid amide hydrolase inhibition: A neuroprotective therapeutic modality

AimsThis review posits that fatty acid amide hydrolase (FAAH) inhibition has therapeutic potential against neuropathological states including traumatic brain injury; Alzheimer's, Huntington's, and Parkinson's diseases; and stroke.Main methodsThis proposition is supported by data from numerous in vitro and in vivo experiments establishing metabolic and pharmacological contexts for the neuroprotective role of the endogenous cannabinoid (“endocannabinoid”) system and selective FAAH inhibitors.Key findingsThe systems biology of endocannabinoid signaling involves two main cannabinoid receptors, the principal endocannabinoid lipid mediators N-arachidonoylethanolamine (“anandamide”) (AEA) and 2-arachidonoyl glycerol (2-AG), related metabolites, and the proteins involved in endocannabinoid biosynthesis, biotransformation, and transit. The endocannabinoid system is capable of activating distinct signaling pathways on-demand in response to pathogenic events or stimuli, thereby enhancing cell survival and promoting tissue repair. Accumulating data suggest that endocannabinoid system modulation at discrete targets is a promising pharmacotherapeutic strategy for treating various medical conditions. In particular, neuronal injury activates cannabinoid signaling in the central nervous system as an intrinsic neuroprotective response. Indirect potentiation of this salutary response through pharmacological inhibition of FAAH, an endocannabinoid-deactivating enzyme, and consequent activation of signaling pathways downstream from cannabinoid receptors have been shown to promote neuronal maintenance and function.SignificanceThis therapeutic modality has the potential to offer site- and event-specific neuroprotection under conditions where endocannabinoids are being produced as part of a physiological protective mechanism. In contrast, direct application of cannabinoid receptor agonists to the central nervous system may activate CB receptors indiscriminately and invite unwanted psychotrophic effects.     

Lipase-catalyzed production of a bioactive fatty amide derivative of 7,10-dihydroxy-8(E)-octadecenoic acid

Enzymatic syntheses of fatty amides are of considerable interest due to their wide ranging industrial applications in detergents, shampoo, cosmetics and surfactant formulations. Amidation reaction of Candida antarctica lipase B (CALB) was investigated for direct amidation of carboxylic acid in organic solvent. CALB-mediated production of a novel secondary amide was carried out by reacting the hydroxy oleic acid derivative, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), with N-methylethanol amine in organic solvent medium. A single, new product peak corresponding to the secondary amide of DOD (D2AM) was detected by high-performance liquid chromatography and thin-layer chromatography. The production of D2AM was achieved in high yields (95%) after 72 h at 50 degrees C in a CALB-catalyzed reaction that contained 100 IU enzyme activity, 50 mM DOD, and 100 mM N-methylethanol amine in isoamyl alcohol. The new fatty amide D2AM displayed potent antimicrobial activity towards Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Proteus vulgaris and Klebsiella pneumonae). D2AM also exhibited antioxidative activity by its alpha,alpha-diphenyl-beta-picryl-hydrazyl (DPPH) radicals scavenging effects.     

Neuroprotective effects of alpha-lipoic acid and its positively charged amide analogue.

Elevated levels of extracellular glutamate have been linked to reactive oxygen species mediated neuronal damage and brain disorders. Lipoic acid is a potent antioxidant that has previously been shown to exhibit neuroprotection in clinical studies. A new positively charged water soluble lipoic acid amide analog, 2-(N,N-dimethylamine) ethylamido lipoate HCl (LA-plus), with a better cellular reduction and retention of the reduced form was developed. This novel antioxidant was tested for protection against glutamate induced cytotoxicity in a HT4 neuronal cell line. Glutamate treatment for 12 h resulted in significant release of LDH from cells to the medium suggesting cytotoxicity. Measurement of intracellular peroxides showed marked (up to 200%) increase after 6 h of glutamate treatment. Compared to lipoic acid, LA-plus was more effective in (1) protecting cells against glutamate induced cytotoxicity, (2) preventing glutamate induced loss of intracellular GSH, and (3) disallowing increase of intracellular peroxide level following the glutamate challenge. The protective effect of LA-plus was found to be independent of its stereochemistry. The protective function of this antioxidant was synergistically enhanced by selenium. These results demonstrate that LA-plus is a potent protector of neuronal cells against glutamate-induced cytotoxicity and associated oxidative stress.     

Design,synthesis, and biological evaluation of a series of piperazine ureas as fatty acid amide hydrolase inhibitors

A series of piperazine ureas were designed, synthesized, and evaluated for their potential as novel orally efficacious fatty acid amide hydrolase (FAAH) inhibitors for the treatment of neuropathic and inflammatory pain. We carried out an optimization study of compound 5 to improve its in vitro FAAH inhibitory activity, and identified the 2-pyrimidinylpiperazine derivative 21d with potent inhibitory activity, favorable DMPK profile and brain permeability. Compound 21d showed robust and dose-dependent analgesic efficacy in animal models of both neuropathic and inflammatory pain.     

Iso-lactam and reduced amide analogues of the peptidomimetic dopamine receptor modulator 3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide

An analogue of the highly potent gamma-lactam Pro-Leu-Gly-NH(2) peptidomimetic, 3(R)-[(2(S)-pyrrolidinylcarbonyl) amino]-2-oxo-1-pyrrolidineacetamide (2), 4(R)-[[2(S)-pyrrolidinylcarbonyl]amino]-2-oxo-1-pyrrolidineacetamide (3), in which the lactam carbonyl moiety has been placed in a different position with respect to the 3-amino group was synthesized. Also, a series of analogues of 2, compounds 4-6, were synthesized in which each of the amide bonds of 2 were systematically replaced with a reduced amide bond surrogate. The analogues were tested for their ability to enhance the binding of [3H]N-propylnorapomorphine to dopamine receptors in a functional in vitro assay utilizing bovine striatal membranes. Peptidomimetic 3 was shown to be more potent than 2, while 4 and 5 were significantly less effective than 2. Peptidomimetic 6 had a pharmacological profile similar to that of 2.