| synthesis of a fluorine-18 labeled derivative of epibatidine for in vivo nicotinic acetylcholine receptor pet imaging. | epibatidine (exo-2-(2'-chloro-5'-pyridyl)-7-azabicyclo[2.2.1]heptane), a natural compound isolated from the skin of the ecuadorian poison frog epipedobates tricolor, is the most potent nicotinic acetylcholine receptor (nachr) agonist reported to date. in order to visualize and quantify in vivo these receptors in human brain using positron emission tomography (pet), [18f]norchlorofluoroepibatidine (exo-2-(2'-[18f]fluoro-5'-pyridyl)-7-azabicyclo[2.2.1]heptane), a fluorine-18 (t(1/2): 110 min) radi ... | 1999 | 10220033 |
| a new subclass of alkaloids from a dendrobatid poison frog: a structure for deoxypumiliotoxin 251h. | deoxypumiliotoxin 251h [4], representing a new subclass of the pumiliotoxin-a class of alkaloids, has been isolated from a dendrobatid frog, epipedobates tricolor. the structure, elucidated by nmr, gc-ftir, and mass spectral analyses, is proposed to be an 8-methyl-6-(5-hydroxy-2-methylhexylidene)-1-azabicyclo[4.3.0]nonan e. the absolute stereochemistry and the relative configuration of the hydroxyl group are unknown. | 1995 | 7760066 |
| development of muscarinic analgesics derived from epibatidine: role of the m4 receptor subtype. | epibatidine, a neurotoxin isolated from the skin of epipedobates tricolor, is an efficacious antinociceptive agent with a potency 200 times that of morphine. the toxicity of epibatidine, because of its nonspecificity for both peripheral and central nicotinic receptors, precludes its development as an analgesic. during the synthesis of epibatidine analogs we developed potent antinociceptive agents, typified by cmi-936 and cmi-1145, whose antinociception, unlike that of epibatidine, is mediated vi ... | 1999 | 10027852 |
| bioassay-guided isolation of epiquinamide, a novel quinolizidine alkaloid and nicotinic agonist from an ecuadoran poison frog, epipedobates tricolor. | analytical hplc fractionation, combined with an off-line 96-well fluorescent bioassay screen, has been developed and used for the separation and screening of a natural product extract. this method was used to guide the isolation of a novel quinolizidine alkaloid from the methanolic skin extracts of an ecuadoran frog, epipedobates tricolor. the structure was determined on the basis of ms, ir, and nmr analysis as (1r,10r)-1-acetamidoquinolizidine (alkaloid 196). we have named this compound epiquin ... | 2003 | 14575435 |
| epibatidine and its analogues as nicotinic acetylcholine receptor agonist: an update. | epibatidine (epb) (1), an alkaloid isolated from the skin of the ecuadorian poison frog, epipedobates tricolor has attracted attention because of its exceptionally powerful analgesic properties: several hundred times greater than those of morphine, and the fact that it acts at nicotine rather than opiate receptors. although the substance is toxic, it does serve as a lead compound in the development of drugs for pain relief as well as treatment of disorders whose pathogenesis involves nicotinic r ... | 2006 | 16644549 |
| epiquinamide: a poison that wasn't from a frog that was. | in 2003, we reported the isolation, structure elucidation, and pharmacology of epiquinamide (1), a novel alkaloid isolated from an ecuadoran poison frog, epipedobates tricolor. since then, several groups, including ours, have undertaken synthetic efforts to produce this compound, which appeared initially to be a novel, beta2-selective nicotinic acetylcholine receptor agonist. based on prior chiral gc analysis of synthetic and natural samples, the absolute structure of this alkaloid was establish ... | 2009 | 19245264 |
| the 7-aza-norbornane nucleus of epibatidine: 7-aza-bicyclo-[2.2.1]heptan-7-ium chloride. | 7-aza-bicyclo-[2.2.1]heptane (7-aza-norbornane) is a bridged heterocyclic nucleus found in epibatidine, the alkaloid isolated from the skin of the tropical poison frog epipedobates tricolor. since epibatidine is known as one of the most potent acetyl-choline nicotinic receptor agonists, a plethora of literature has been devoted to this alkaloid. however, there are no structural data on the unsubstituted 7-aza-norbornane, the parent bicyclic ring of epibatidine and its derivatives. we herein pres ... | 2017 | 28932481 |
| variation in the schedules of somite and neural development in frogs. | the timing of notochord, somite, and neural development was analyzed in the embryos of six different frog species, which have been divided into two groups, according to their developmental speed. rapid developing species investigated were xenopus laevis (pipidae), engystomops coloradorum, and engystomops randi (leiuperidae). the slow developers were epipedobates machalilla and epipedobates tricolor (dendrobatidae) and gastrotheca riobambae (hemiphractidae). blastopore closure, notochord formatio ... | 2012 | 23184997 |
| calling is an honest indicator of paternal genetic quality in poison frogs. | several competing hypotheses have been put forward to explain why females of many species mate preferentially with males possessing the most conspicuous signals (e.g., ornaments, displays, or songs). we performed a laboratory experiment using two species of poison frogs, dendrobates leucomelas and epipedobates tricolor, to test the hypothesis that male calling performance is an honest indicator of parental quality. our analyses are based on data from behavioral observations of mating activities ... | 2006 | 17133871 |
| analysis of cell size in the gastrula of ten frog species reveals a correlation of egg with cell sizes, and a conserved pattern of small cells in the marginal zone. | we investigated the relationship between egg and cell sizes in the early gastrula of ten species of frogs with eggs of 1,100-3,500 μm diameters. we asked whether differences in cell size of the vegetal region, blastocoel roof, and marginal zone of the early gastrula were associated with egg size. alternatively, we proposed that cell size differences may associate with gastrulation characteristics. the analyzed species were as follows: xenopus laevis, engystomops randi, engystomops coloradorum, e ... | 2017 | 27381278 |
| the extraordinary biology and development of marsupial frogs (hemiphractidae) in comparison with fish, mammals, birds, amphibians and other animals. | the study of oogenesis and early development of frogs belonging to the family hemiphractidae provide important comparison to the aquatic development of other frogs, such as xenopus laevis, because reproduction on land characterizes the hemiphractidae. in this review, the multinucleated oogenesis of the marsupial frog flectonotus pygmaeus (hemiphractidae) is analyzed and interpreted. in addition, the adaptations associated with the incubation of embryos in the pouch of the female marsupial frog g ... | 0 | 29305906 |
| epibatidine is a nicotinic analgesic. | epibatidine, an alkaloid isolated from skin of the poison frog, epipedobates tricolor, has been shown to be a very potent analgesic with a non-opioid mechanism of action. we found that epibatidine was about 120 times more potent and has longer duration than nicotine in analgesia, which could be antagonized by pretreatment with mecamylamine. furthermore, epibatidine competed with high affinity (ic50 = 70 pm, ki = 43 pm) for [3h]cytisine binding in rat brain preparations. these results indicated t ... | 1993 | 8112391 |
| epibatidine, an alkaloid from the poison frog epipedobates tricolor, is a powerful ganglionic depolarizing agent. | epibatidine, a newly discovered alkaloid from the skin of dendrobatidae frogs, has structural similarities to nicotine. we examined the effects of epibatidine on cardiorespiratory function and ganglionic synaptic transmission. superior cervical or splanchnic sympathetic nerve discharge (ssnd) and phrenic nerve discharge (pnd) were recorded along with arterial pressure (ap) in urethane-anesthetized, paralyzed and artificially ventilated rats. epibatidine administered i.v. at low doses (0.5-2 micr ... | 1994 | 8071862 |
| the lung-eardrum pathway in three treefrog and four dendrobatid frog species: some properties of sound transmission. | frequency-response curves of the tympanum and lateral body wall (lung area) were measured by laser doppler vibrometry in three treefrog (smilisca baudini, hyla cinerea, osteopilus septentrionalis) and four dendrobatid frog (dendrobates tinctorius, d. histrionicus, epipedobates tricolor, e. azureiventris) species. the high-frequency cut-off of the body wall response was always lower than that of the tympanum. the best response frequencies of the lateral body wall were lower than those of the tymp ... | 1994 | 7964416 |
| antinociceptive and toxic effects of (+)-epibatidine oxalate attributable to nicotinic agonist activity. | 1. epibatidine is an analgesic substance, isolated from the skin of the poisonous frog epipedobates tricolor, for which the mechanism of action was previously unknown. 2. the ic50 of synthetic (+)-epibatidine oxalate (the naturally occurring isomer) for [3h]-nicotine binding to rat whole-brain membranes was 0.1 nm. the (-)-isomer also exhibited high affinity (ic50 = 0.2 nm). 3. (+)- and (-)-epibatidine exhibited much lower affinity for displacement of the muscarinic ligand [3h]-n-methylscopolami ... | 1994 | 7889306 |
| characterization of (+/-)(-)[3h]epibatidine binding to nicotinic cholinergic receptors in rat and human brain. | epibatidine is an alkaloid that was first isolated from the skin of the ecuadoran frog epipedobates tricolor by daly et al. [j. am. chem. soc. 102:803-836 (1980)] and was found to have very high affinity for neuronal nicotinic receptors, where it acts as a potent agonist. here we have measured and characterized the binding of (+/-)(-)[3h]epibatidine to nicotinic receptors in rat brain. in rat forebrain homogenates, (+/-)(-)[3h]epibatidine binds to two sites, with apparent affinities of 15 pm and ... | 1995 | 7651361 |
| diversity of nicotinic acetylcholine receptors in rat hippocampal neurons. iii. agonist actions of the novel alkaloid epibatidine and analysis of type ii current. | the nicotinic-agonist properties of epibatidine, an alkaloid originally isolated from the ecuadorian frog epipedobates tricolor, was investigated in rat hippocampal neurons grown in culture. the ability of epibatidine enantiomers to evoke nicotinic whole-cell currents of type ia, sensitive to blockade by alpha-bungaro-toxin and methyllycaconitine and presumably subserved by an alpha-7-based nachr, and of type ii, sensitive to blockade by dihydro-beta-erythroidine and presumably subserved by an a ... | 1995 | 7543571 |