()-Brunneusine, a new phenolic compound with antibacterial properties in aqueous medium from the leaves of (Engl.) Tiegh (LORANTHACEAE).

(Loranthaceae) is a hemiparasitic plant growing on (Fabaceae). The chemical investigation of its leaves and flowers led to the isolation of one new phenolic compound namely (-)-brunneusine (), together with 13 known compounds. The crude leaves and flowers extracts (CLE and CFLE) with their ethyl acetate fractions (EAFL and EAFFL) and some isolated compounds (; and ) have been tested on four bacterial species of sanitary importance isolated in an aquatic environment.

In vitro leishmanicidal activity of some Cameroonian medicinal plants.

Eleven plants used in the Cameroonian traditional medicine for the treatment of some parasitic infections were tested for their activity on the promastigote form of Leishmania donovani. After incubation with different plant extracts at doses of 1600, 800, 400 and 200 microgram/mL, the evaluation of the cell viability was done by the trypan blue exclusion technique and by flow cytometry. This study shows that 48 h after incubation of promastigotes with plant extract, Solanocia mannii and Solanum torvum significantly inhibited the proliferation of promastigotes in culture with IC50 of 60.

Chemical constituents of Stereospermum acuminatissimum and their urease and α-chymotrypsin inhibitions.

Phytochemical investigation of the stem bark of Stereospermum acuminatissimum K. Schum. resulted in the isolation of 21 compounds, including two new guanine derivatives, 1,3,7-trimethylguanin-1/3-ium (1) and 3,7-dimethylguanin-1/3-ium (2), and one new phenolic long chain ester, 2-(4-hydroxyphenyl)ethyl hentriacontanoate (3).

In vitro hepatoprotective and antioxidant activities of crude extract and isolated compounds from Ficus gnaphalocarpa.

The in vitro hepatoprotective effect of the methanolic extract from Ficus gnaphalocarpa (Miq.) Steud. ex A.

The EpiSkin phototoxicity assay (EPA): development of an in vitro tiered strategy using 17 reference chemicals to predict phototoxic potency.

The aim of the study was to investigate the ability of human reconstructed epidermis EpiSkin(LM) to identify the phototoxic potency of topically or systemically applied chemicals (EPA: EpiSkin phototoxicity assay). Three classes, according to their available human phototoxic potential, were evaluated: systemic phototoxic compounds, topical phototoxic chemicals and non-phototoxic compounds. Non-cytotoxic concentrations of chemicals were applied topically or directly added to the underlying culture medium in order to mimic a systemic-like administration.

Involvement of NMDA in a plasticity phenomenon observed in the adult frog monocular optokinetic nystagmus.

The frog horizontal monocular optokinetic nystagmus (H-OKN) is asymmetrical, the reflex being evoked by a temporal-nasal (T-N) component, but not by a nasal-temporal (N-T) component. Coil recordings showed that, in adult animals, 8 days of monocular deprivation (by unilateral eyelid suture) provoked the appearance of a N-T component, the H-OKN becoming symmetrical, reacting for both directions of stimulation. This delay was shortened to 2 days following two successive unilateral pretectal administrations of NMDA or of LY 285 265, an NMDA agonist, the first 2 days of eyelid suture.

Different effects of dopamine and piribedil (a dopamine D2 agonist) on frog monocular optokinetic nystagmus asymmetry.

Frog monocular optokinetic nystagmus (OKN) displays a directional asymmetry, reacting only to stimulations in the temporal-nasal (T-N) direction. The nasal-temporal (N-T) component is almost absent. The systemic or intrapretectal injection of Piribedil, a D2 dopamine agonist, provokes the appearance of a N-T component suppressing the monocular OKN asymmetry.

Protective role of excitatory amino acid antagonists in experimental retinal ischemia.

Background: Excitatory amino acids and their analogues (NMDA, kainate and AMPA) are implicated in the pathogenesis of ischemic brain injury. In order to fully understand their involvement in the pathogenesis of retinal ischemic injury, we studied the electrophysiological and histopathological effects of two excitatory amino acid antagonists, cis-PDA and MK 801, in an experimental retinal ischemia model.

Methods: The two antagonists were injected intravitreously 15 min before ischemia was induced by elevatory intraocular pressure caused by external compression.

Are retinal or mesencephalic dopaminergic systems involved in monocular optokinetic nystagmus asymmetry in frog?

In monocular vision, frogs display a unidirectional optokinetic horizontal nystagmus (H-OKN) reacting only to temporal-nasal (T-N) stimulation. The N-T component is almost absent. The analysis of search coil recordings after administration of dopamine into the viewing eye, the occluded eye or directly into the pretectum, hardly modifies the H-OKN triggered by the viewing eye irrespective of the concentration used.

Some biochemical and pathophysiological aspects of long-term elevation of brain ornithine concentrations.

Mice and chicken were given 5-fluoromethylornithine (5FMOrn), a selective inactivator of ornithine aminotransferase (OAT) over extended periods of time. This treatment allowed us to maintain elevated concentrations of ornithine in all tissues. Since gyrate atrophy, an autosomal recessive human disease, is characterized by the absence of OAT, special emphasis was put on the study of the visual system.

N-methyl-D-aspartate antagonists suppress the development of frog symmetric monocular optokynetic nystagmus observed after unilateral visual deprivation.

In monocular vision, frogs display a unidirectional optokinetic nystagmus (OKN), reacting only to temporal-nasal (T-N) stimulation. The OKN N-T component is almost absent. However, prolonged monocular visual deprivation by unilateral eyelid suture provoked the appearance of the N-T component.

Pharmacological study of the chicken's monocular optokinetic nystagmus: involvement of the ON retinal channel evidenced by the glutamatergic separation of ON and OFF pathways.

The chicken's monocular optokinetic nystagmus (OKN), recorded by the magnetic search coil technique, displays a directional asymmetry, the temporal-nasal (T-N) stimulation being more efficient than the nasal-temporal (N-T) one to evoke the reflex. The intravitreal administration of APB, a glutamate agonist which selectively blocks the ON retinal channel strongly reduced the eye monocular OKN; it also induced spontaneous eye movements in the T-N direction. The intravitreal injection of PDA another glutamate analog, which reduces the OFF channel, while increasing the activity of the ON channel, induced a large increase in OKN velocity gain, especially for a N-T stimulation at the lowest drum speeds.

Pharmacological study of the chicken's monocular optokinetic nystagmus: effects of GABAergic agonist and antagonists.

When injected into the chicken open eye, the GABA-agonist THIP and the GABA-antagonists bicuculline and picrotoxin induced spontaneous eye movements in nasal-temporal (N-T) and in temporal-nasal (T-N) direction, respectively. These spontaneous movements were scarcely modulated by optokinetic stimulation, irrespective of the direction of stimulation. It is suggested that they are due to the suppression of directional selectivity of retinal ganglion cells.

Plasticity of the frog monocular OKN: involvement of pretectal GABAergic and cholinergic systems.

The frog horizontal monocular optokinetic nystagmus (OKN) is asymmetrical, the temporal-nasal (T-N) stimulation being the sole stimulation efficient to evoke the reflex, the nasal-temporal (N-T) component being almost absent. Coil recordings showed that, in adult animals, prolonged monocular visual deprivation by unilateral eyelid suture provoked the appearance of the N-T component. The OKN became symmetrical, reacting for both directions of stimulation.

Directional asymmetry of the frog monocular optokinetic nystagmus: cholinergic modulation.

The frog monocular optokinetic gaze nystagmus (OKN) was studied by coil recordings after intravitreal administration of cholinergic drugs into the closed eye. Before injection, the frog displayed OKN for stimulations in the temporo-nasal (T-N) direction only. The injection of muscarinic agonists, as well as that of nicotinic antagonists, provoked the appearance of a naso-temporal (N-T) component, the slow phase velocity gain then being strongly and significantly increased.

Possible involvement of cholinergic and glycinergic amacrine cells in the inhibition exerted by the ON retinal channel on the OFF retinal channel.

In the frog retina, the inhibition exerted by the ON channel on the OFF channel was evidenced by the increase in transient ganglion cell OFF responses, when the ON channel was blocked by 2-amino-4-phosphonobutyrate (APB). Intraocular administration of the neurotoxic choline analog ethylcholine mustard arizidinium ion (ECMA) also provoked an increase in the number of spikes of transient ganglion cell OFF responses, without suppressing the ON responses. APB, when administrated after ECMA, abolished the ON responses, but did not modify the OFF responses already increased by ECMA.

The pretectal cholinergic system is involved through two opposite ways in frog monocular OKN asymmetry.

Frog monocular horizontal optokinetic nystagmus (OKN) has been studied by coil recordings, before and after unilateral microinjection of cholinergic drugs into the pretectum. The recorded eye was either contralateral or ipsilateral to the injected structure. Before injection, monocular OKN displayed a directional asymmetry, reacting only to stimulations in the temporonasal (T-N) direction.

[Interactions between GABAergic and cholinergic mechanisms involved in monocular optokinetic nystagmus in frogs].

The systemic administration of atropine, a muscarinic cholinergic antagonist, was found to suppress the Nasal-Temporal (N-T) component of the frog monocular optokinetic nystagmus (OKN), which had appeared following a prior injection of bicuculline and which does not exist in the normal animal. On the contrary, the administration of a nicotinic cholinergic antagonist (D-TC, alpha-BGT, Hexamethonium) following that of bicuculline has prolonged the duration of the induced N-T component. Thus, ACh was shown to attenuate or to reinforce the GABAergic inhibition of the N-T component through muscarinic receptors or nicotinic receptors respectively.

Effects on the chicken monocular OKN of unilateral microinjections of GABAA antagonist into the mesencephalic structures responsible for OKN.

The SR 95531, a GABAA antagonist was microinjected into either the pretectum nuclei, (nucleus Superficialis Synencephali nSS) or the nBOR (nucleus Ectomammillaris nEM) of chickens. Monocular optokinetic nystamus (OKN) of each eye was recorded by the search coil technique before and after unilateral intracerebral drug administration. Before injection, monocular horizontal OKN in chickens, as in other lower vertebrates, displays a directional asymmetry: the stimulation in the Temporo-Nasal (T-N) direction is more efficient in evoking OKN than is stimulation in the Naso-Temporal (N-T) direction.

Unilateral pretectal microinjections of SR 95,531, a GABA A antagonist: effects on directional asymmetry of frog monocular OKN.

Monocular eye movements have been studied in frogs using the search coil technique before and after unilateral microinjection of SR 95,531, a GABA A antagonist, into the pretectal nuclei contralateral to the open eye. Before injection, monocular, horizontal optokinetic nystagmus (OKN) in frogs, as in other lower vertebrates, displays a directional asymmetry: the stimulation in the T-N (temporo-nasal) direction is more efficient in evoking OKN than is stimulation in the N-T (naso-temporal) direction. The N-T component is almost absent and displays only slow phases of very low speed.

EOG and ERG modifications induced in the chicken eye after blockade of catecholamine and 5-hydroxytryptamine biosynthesis.

The involvement of catecholaminergic and indoleaminergic systems in the modulation of the standing potential of the eye was tested in chickens by means of an indirect electrooculography method and direct current electroretinogram recordings. D,L alpha-monofluoromethyl dopa (MFMD), 50 and 100 nmol), a highly specific inactivator of aromatic L-amino acid decarboxylase, was injected intravitreally. This treatment is known to induce a selective and irreversible blockade of dopamine and 5-hydroxytryptamine biosynthesis.

Electrooculographic and electroretinographic study in the chicken after dopamine and haloperidol.

The implication of dopamine in the modulation of the standing potential of the eye was tested in the chicken through an indirect electrooculographic method and direct current electroretinogram (ERG) recording after haloperidol, a mixed D1-D2 antagonist. The standing potential of the eye was reduced within 15 min after intravitreal injection of the antagonist (150 micrograms). This effect is rapidly reversed by an application of dopamine.

Abolition of monocular optokinetic nystagmus directional asymmetry after unilateral visual deprivation in adult vertebrates: involvement of the GABAergic mechanism.

In lower vertebrates such as frogs and chickens, monocular optokinetic nystagmus (OKN) displays directional asymmetry, temporal-nasal (T-N) stimulation being more efficient in evoking this visuomotor reflex than N-T stimulation. The N-T component of monocular OKN is significantly weaker in chickens, while it is almost absent in frogs. Coil recordings showed that in adult frogs and chickens, prolonged monocular visual deprivation by unilateral eyelid suture provoked the appearance of the N-T component in frogs as well as its significant and progressive increase in both species.

Directional asymmetry of the horizontal monocular head and eye optokinetic nystagmus: effects of picrotoxin.

Frog monocular eye and head optokinetic nystagmus (OKN) were studied by coil recordings after intravitreal administration of picrotoxin into the closed eye. Before injection, the frog displayed an OKN only for stimulations in the temporo-nasal (T-N) direction. The injection of picrotoxin provoked the appearance of a N-T component of the head and eye OKN: the slow phase velocity gain and the resetting fast phase frequency were strongly and significantly increased.

Neurotransmission in the frog retina: possible physiological and histological correlations.

In the frog retina, extracellular recordings of transient ganglion cells have shown that the inhibitory surround of the receptive field of these cells was mediated by gamma-aminobutyric acid and acetylcholine (through the nicotinic receptors). Histoautoradiographic and immunocytochemical studies for the two respectively have shown that these neurotransmitters can act through horizontal and amacrine cells. The separation of the ON and OFF channels mediated by glutamate at the bipolar cell level may also be obtained by glycine and/or acetylcholine (through muscarinic receptors).