Eduardo Navarro

Lignans from Justicia hyssopifolia

Abstract Two new lignans named J 1 and J 2 have been isolated from leaves of Justicia hyssopifolia , the latter as a β- d -glucoside, together with the known lignans helioxanthin, justicidin E, gadain, cubebin and sesamin. The structures of the novel compounds have been elucidated by spectroscopical methods and chemical transformations.

Diuretic action of an aqueous extract of Lepidium latifolium L.

An aqueous extract of Lepidium latifolium L. given orally and intraperitoneally considerably enhanced urinary excretion (UV) in rats with respect to control groups. A slight increase in ion excretion was also observed. Other parameters such as specific gravity, nitrite, pH, glucose, ketone bodies, urobilinogen, and blood were also studied. A good correlation for the dosage rat/man for the aqueous extract was achieved.

Opposite effects of low and high doses of arginine on glutamate-induced nitric oxide formation in rat substantia nigra

L-arginine is a very versatile amino acid that is involved in many important physiological processes such as protein, nitric oxide (NO), agmatine, putrescine, urea, L-ornithine or creatine synthesis and is essential for posttranslational arginylation of protein. The present study was designed to evaluate in vivo the effect of L-arginine on NO production in substantia nigra. In vivo spectroscopic and voltammetric studies were addressed in rats to record modifications in methemoglobin and NO levels under glutamate stimulation. Results showed that, under physiological L-arginine extracellular concentration, the intranigral infusion of glutamate produced an increase in NO levels. When a low dose of L-arginine was co-infused with glutamate, a persistent and higher increase in NO levels was observed. The co-infusion of glutamate with a moderate dose of L-arginine induced drastic and persistent NO production. It was also observed that high doses of either L-arginine or D-arginine inhibit NO production. Subsequently, these data show that L-arginine and D-arginine are involved in a mechanism that inhibits NO production.

Photochemical synthesis of halleridone, hallerone, rengyol and derivatives

Abstract Oxidation of the p-hydroxyphenethyl alcohol with singlet oxygen led to the synthesis of halleridone ( 4 ), hallerone ( 8 ) and their monoepoxide ( 9 ). The cyclohexanols rengyol ( 5a ), isorengyol ( 5b ) and the hydroxyketone form of rengyoxide 6b were also obtained by known procedures.

Cardiovascular activity of a methanolic extract of Digitalis purpurea spp. heywoodii

The paper deals with the effects of a glycosidal extract of Digitalis heywoodii, ssp. of Digitalis purpurea L., (Schrophulariaceae) grown in Badajoz (Spain), on isolated cardiac auricle of rabbits, urinary excretion of rats, as well as its emetic effect in pigeons. These effects using vehicle (propylene glycol-ethanol-water, 40:10:50) and digoxin as standards are presented. The extract at concentrations of 20 and 40 microg/ml produced an increase in the contraction force of auricles in a dose-dependent way. At doses of 15 and 30 mg/kg a slight diuretic and natriuretic effect was observed. The active dose range for emesis was 0.5-4 mg/kg and a decrease of the emesis time within 10 min of injection in dose-dependent manner was obtained. The pharmacological activity of the extract is related to gitoxin derivatives (digitalinum verum and strospeside), the most abundant compounds obtained from the leaves of Digitalis purpurea spp. heywoodii.

Lignans from Apollonias barbujana

Abstract Two new lignans, 2,3- bis [(4-hydroxy-3,5-dimethoxyphenyl)-methyl]-1,4-butanediol and demethylpiperitol, together with three already-known ones, have been isolated from the leaves of Apollonias barbujana (Lauraceae). The structures were fully characterized by spectroscopical methods. The known lignans were identified as sesamin, syringaresinol and the neolignan, dihydro-dehydrodiconiferyl alcohol.

Cyclohexyl-ethanol derivatives from Isoplexis chalcantha

Abstract Two new cyclohexyl-ethanol derivatives were obtained as minor components from a chloroform extract of the leaves of Isoplexis chalcantha . Their structures were elucidated by spectroscopic methods.

PHARMACOLOGICAL STUDY OF THE MUSCLE PARALYZING ACTIVITY OF THE JUICE OF THE BANANA TRUNK

Extracts of the juice of the banana trunk were assayed in the isolated phrenic nerve-diaphragm muscle preparation of the rat. The chemical composition of those producing muscular paralysis was then studied. As active extracts mainly consisted of monopotassium oxalate, the effect of this compound on the muscle preparation was investigated and compared with that of the active extracts. The pattern of muscular paralysis induced by monopotassium oxalate was the same as that seen with the juice extracts. Likewise inhibition of contractions of the tibialis muscle was observed in vivo after intra-arterial administration of both the crude concentration of the juice and monopotassium oxalate. These findings suggest that monopotassium oxalate could be responsible for the muscular paralysis caused by the juice of banana trunk.

Toxicity and Neuropharmacological Effects of Elenine

Elenine is the aglycone of elenoside, a cytotoxic arylnaphthalene lignan (NSC 644013-W/1) derived from Justicia hyssopifolia. (Family: Acanthaceae). Elenoside is a β-D-glucoside, with a similar chemical structure to etoposide, exhibiting central depressant activity. In the present study, elenine was given to mice and rats at doses of 10, 20, and 40 mg/kg. Acute toxicity (24 h) and general behaviour in mice was studied as well as its effects on muscular relaxant activity, locomotor activity (Varimex test), and the open-field test and were compared with 10 mg/kg of chlorpromazine. Elenine produced a reduction in the permanence time in muscular relaxant activity (traction test). Spontaneous activity was lower in the Varimex test. The ambulation and rearing were lower compared with the control group, and an increase in boluses was observed in the open-field test. Thus, it can be concluded that elenine has central sedative effects at lower doses than those used with elenoside and has a possible application in conditions of anxiety.

New C13-Norisoprenoids from Apollonias barbujana

Abstract Two new C13-norisoprenoids, (3S,4S,5R,6R)*−3,4,6-tri-hydroxy-5,6-dihydro-β-ionol (1) and (3S,5R,6R)*-3,5,6-trihydroxy-5,6-dihydro-β-ionol (2), were isolated from the leaves of Apollonias barbujana (Lauraceae). Their structures were determined on the basis of spectroscopic analysis.