Putrescine has hypothermic and antipyretic activity, in rats

Intraperitoneal injection of putrescine induced dose-related hypothermia in rats. The effect was more pronounced at room temperature (22 degrees C) than in a warm environment (30 degrees C), the maximum hypothermia (-2.64 +/- 0.29 degrees C, 30 min. after treatment) being obtained with the dose of 300 mg/Kg and remaining significant throughout 3 hr of observation. Putrescine also had antipyretic activity, as it significantly reduced pyrogen-induced fever at a dose level (100 mg/Kg i.p.) ineffective in causing hypothermia in normal rats. The hypothermic and antipyretic effects of putrescine were not associated with any obvious sign of toxicity.     

A fusion protein of conotoxin MVIIA and thioredoxin expressed in Escherichia coli has significant analgesic activity

omega-Conotoxin MVIIA (CTX MVIIA) is a potent and selective blocker of the N-type voltage-sensitive calcium channel in neurons. Its analgesic and neuroprotective effects may prove useful in treatment of severe pains and ischemia. In this paper, we report that a fusion form of CTX MVIIA with thioredoxin (Trx) has analgesic function. The DNA fragments were chemically synthesized and ligated to form the DNA sequence encoding CTX MVIIA. The synthetic gene was then cloned into the expression vector pET-32a(+) and the fusion protein Trx-CTX MVIIA containing 6x His-tag was purified by one-step metal chelated affinity chromatography (MCAC). The purity of final product was over 95% determined by HPLC and the yield of the fusion protein was approximately 40 mg/L. The analgesic function was detected by using mouse hot-plate assay. After intracranially administering fusion protein with the dose of 0.6 mg/kg, marked analgesia was observed. The analgesic effects (elevated pain thresholds) were dose-dependent and the biological half-life of the fusion toxin was approximately 1.6 h.     

A rapid method for evaluation of analgesic and anti-inflammatory activity in rats

Carrageenin (2%) was used to produce edema and hyperalgesia; indomethacin, phenylbutazone, aspirin, ibuprofen, analgin, paracetamol and phenacetin were tested at different doses for anti-inflammatory and analgesic activity in the same rats as the peak for the edema reached at the end of 3rd hr and for the hyperalgesia at the end of 4th hr. Indomethacin, phenylbutazone and ibuprofen reduced edema and increased the pain threshold. Analgin and aspirin increased the pain threshold relatively at a low dose. Paracetamol and phenacetin were inactive in the doses tested. Carrageenin (2%) was observed to possess both phlogistic and allogenic properties.     

Synthetic muO-conotoxin MrVIB blocks TTX-resistant sodium channel NaV1.8 and has a long-lasting analgesic activity

MuO-conotoxin MrVIB is a blocker of voltage-gated sodium channels, including TTX-sensitive and -resistant subtypes. A comprehensive characterization of this peptide has been hampered by the lack of sufficient synthetic material. Here, we describe the successful chemical synthesis and oxidative folding of MrVIB that has made an investigation of the pharmacological properties and therapeutic potential of the peptide feasible. We show for the first time that synthetic MrVIB blocks rat NaV1.8 sodium channels and has potent and long-lasting local anesthetic effects when tested in two pain assays in rats. Furthermore, MrVIB can block propagation of action potentials in A- and C-fibers in sciatic nerve as well as skeletal muscle in isolated preparations from rat. Our work provides the first example of analgesia produced by a conotoxin that blocks sodium channels. The emerging diversity of antinociceptive mechanisms targeted by different classes of conotoxins is discussed.     

Synthesis and analgesic activity of N,N'-dicarbonyltryptamines

5-Methoxytryptamine and L-tryptophan methyl ester were acylated with malonic acid, dimethyl malonate, or succinic anhydride to produce the corresponding N,N'-dicarbonyltryptamine derivatives. The analgesic activity was evaluated by the tail flick test. All of the compounds exhibited desirable analgesic potency. This result is consistent with that of N-(N-acetyl-L-tryptophanyl)-5-methoxytryptamine and confirmed that introducing substituted tryptamine into the amide chain of melatonin does enhance analgesic potency.     

Plants with central analgesic activity

The present communication constitutes a global review on plant analgesic activity with special emphasis on those found in different parts of the world, including Brazil, which act on the central nervous system. One hundred and sixty six plants belonging to 79 families are reported.     

Retro-nociceptin methylester, a peptide with analgesic and memory-enhancing activity

Retro-nociceptin methylester (retro-Noc-ME), which has an oppositely directed structure to that of nociceptin, showed weak affinity for nociceptin receptor and antagonized nociceptin-induced inhibition of contraction in a guinea pig ileum (GPI) assay. The peptide induced analgesia after intracerebroventricular (i.c.v.) administration at a dose of 100 nmol per mouse. Analgesia was not blocked by the opioid antagonist naloxone, which suggests that the analgesia is not mediated by opioid receptor. Furthermore, analgesia caused by retro-Noc-ME was not attenuated after repeated administration, that is, there was an absence of tolerance. The peptide improved learning ability after i.c.v. administration in a step-through experiment in mice.     

Fibrinogen has chaperone-like activity

Partially or completely unfolded polypeptides are highly prone to aggregation due to nonspecific interactions between their exposed hydrophobic surfaces. Extracellular proteins are continuously subjected to stresses conditions, but the existence of extracellular chaperones remains largely unexplored. The results presented here demonstrate that one of the most abundant extracellular proteins, fibrinogen has chaperone-like activity. Fibrinogen can specifically bind to nonnative form of citrate synthase and inhibit its thermal aggregation and inactivation in an ATP-independent manner. Interestingly, fibrinogen maintains thermal-denatured luciferase in a refolding competent state allowing luciferase to be refolded in cooperation with rabbit reticulocyte lysate. Fibrinogen also inhibits fibril formation of yeast prion protein Sup35 (NM). Furthermore, fibrinogen rescues thermal-induced protein aggregation in the plasma of fibrinogen-deficient mice. Our studies demonstrate the chaperone-like activity of fibrinogen, which not only provides new insights into the extracellular chaperone protein system, but also suggests potential diagnostic and therapeutic approaches to fibrinogen-related pathological conditions.     

Putrescine uptake in saintpaulia petals

Putrescine uptake and the kinetics of this uptake were studied in petals of Saintpaulia ionantha Wendl. Uptake experiments of [³H] or [¹⁴C] putrescine were done on single petals at room temperature at various pH values. The results show that putrescine uptake occurs against a concentration gradient at low external putrescine concentration (0.5-100 micromolar) and follows a concentration gradient at higher external putrescine concentrations (100 micromolar to 100 millimolar). 2,4-Dinitrophenol and carbonylcyanide-m-chlorophenylhydrazone, two uncouplers, had no effect on putrescine uptake. Uptake rates were constant for 2 hours, reaching a maximum after 3 to 4 hours. Putrescine uptake depended markedly on the external pH and two maxima were observed: at low external concentrations of putrescine, the optimum was at pH 5 to 5.5; at higher concentrations the optimum was at pH 8.     

Putrescine catabolism in mammalian brain

In contrast with putrescine (1,4-diaminobutane), which is a substrate of diamine oxidase, monoacetylputrescine is oxidatively deaminated both in vitro and in vivo by monoamine oxidase. The product of this reaction is N-acetyl-gamma-aminobutyrate. The existence of a degradative pathway in mammalian brain for putrescine is shown, which comprises acetylation of putrescine, oxidative deamination of monoacetylputrescine to N-acetyl-gamma-aminobutyrate, transformation of N-acetyl-gamma-aminobutyrate to gamma-aminobutyrate and degradation of gamma-aminobutyrate to CO(2) via the tricarboxylic acid cycle.     

Putrescine transport in human platelets

Putrescine transport has been studied in human platelets. The uptake of putrescine is saturable and appears to be an energy-dependent process, since it is inhibited by the uncoupler 2,4-dinitrophenol and low temperature. The evidence presented suggests that the uptake process is complex and may be dependent upon pH gradient, membrane potential, and other unidentified factors. Putrescine transport is not inhibited by amino acids and is only slightly inhibited by spermidine and spermine. A membrane protein involved in putrescine transport has been identified and partially purified. Differential labeling with N-ethylmaleimide identified proteins with apparent molecular weights of 65000 and 23000 as determined by SDS-polyacrylamide gel electrophoresis. Column chromatographic purification on a putrescine affinity column revealed a Mr 55000 protein which copurified with the Mr 65000 protein. Additional evidence supporting the involvement of these proteins in putrescine transport was seen in putrescine protection against N-ethylmaleimide inhibition of putrescine uptake. Putrescine uptake may occur via the serotonin transport system, since imipramine inhibits transport and because of the similarities in the molecular weights of the proteins implicated in transport.     

Synthesis and bradykinin inhibitory activity of novel non-peptide compounds,and evaluation of in vivo analgesic activity

A series of novel non-peptide diamide compounds was synthesized and evaluated as antibradykinin agents by utilizing guinea-pig ileum smooth muscle. Among the final compounds, (Z)-4-(4-(bis(4-fluorophenyl)methyl)piperazin-1-yl)-4-oxo-N-(4-phenylbutan-2-yl)but-2-enamide showed most favorable bradykinin inhibitory activity and demonstrated analgesic efficacies in the rat models of inflammatory and neuropathic pain.     

Metacytofilin has potent anti-malarial activity

Metacytofilin (MCF) was isolated from the fungus Metarhizium sp. TA2759. Although MCF possesses anti-Toxoplasma activity, the effects of this compound against other parasites are unknown. Here, we evaluated the in vitro anti-malarial activity of MCF against the 3D7 strain and the chloroquine-resistant K1 strain of Plasmodium falciparum. The half maximal inhibitory concentrations (IC₅₀) of MCF against the 3D7 and K-1 strains following culture for 48 h were 666 nM and 605 nM, respectively. Artemisinin was more potent than MCF against both strains (3D7 IC₅₀: 17.4 nM; K-1 IC₅₀: 18.3 nM), while chloroquine was ineffective against the chloroquine-resistant strain (3D7 IC₅₀: 39.1 nM; K-1 IC₅₀: 1.62 μM). MCF affected the ring stage of the parasites, resulting in their death as shown by spots within red blood cells. MCF also inhibited parasite growth following culture for 72 h (3D7 IC₅₀, 285 nM). Four optical isomers of cyclo[Leu-Phe]-diketopiperazine derivatives with modified methoxy and/or hydroxyl groups lost anti-malarial activity, suggesting that the spatial positions of the methoxy and hydroxyl groups in MCF play an important role in its anti-malarial effects. Together, these data suggest that MCF may represent a promising lead compound for treatment of drug-resistant malarial parasites.     

Putrescine biosynthesis in Tetrahymena thermophila.

The putrescine-biosynthesis pathway in Tetrahymena thermophila was delineated by studying crude extracts prepared from exponentially growing cultures. A pyridoxal phosphate-stimulated ornithine decarboxylase activity competitively inhibited by putrescine was detected. CO2 was also liberated from L-arginine, but analyses by t.l.c. and enzyme studies suggested that the activity was not due to arginine decarboxylase, nor could enzyme activities converting agmatine into putrescine be detected. We conclude that the decarboxylation of L-ornithine is probably the only major route for putrescine biosynthesis in this organism during exponential growth.     

Opioid activity of C8813, a novel and potent opioid analgesic

Compound trans-4-(p-bromophenyl)-4-(dimethylamino)-1-(2-thiophen-2-yl-ethyl)-cyclohexanol (C8813), structurally unrelated to morphine, is a novel analgesic. The present study examined the antinociception, opioid receptor selectivity and in vitro activity of C8813. The antinociceptive activity was evaluated using mouse hot plate and acetic acid writhing tests. In mouse hot plate test, the antinociceptive ED(50) of C8813 was 11.5 microg/kg, being 591 times and 3.4 times more potent than morphine and fentanyl respectively. In mouse writhing test, the antinociceptive ED(50) of C8813 was 16.9 microg/kg, being 55 times and 2.3 times more active than morphine and fentanyl respectively. In the opioid receptor binding assay, C8813 showed high affinity for mu-opioid receptor (K(i) = 1.37 nM) and delta-opioid receptor (K(i) = 3.24 nM) but almost no affinity for kappa-opioid receptor (at 1 microM). In the bioassay, the inhibitory effect of C8813 in the guinea-pig ileum (GPI) was 16.5 times more potent than in the mouse vas deferens (MVD). The inhibitory effects of C8813 in the GPI and MVD could be antagonized by mu-opioid receptor antagonist naloxone and delta-opioid receptor antagonist ICI174,864 respectively. However, the inhibitory effect of C8813 in the rabbit vas deferens was very weak. These results indicated that C8813 was a potent analgesic and a high affinity agonist for the mu- and delta-opioid receptors.