Andrés Navarrete

α-Glucosidase Inhibitors from Brickellia cavanillesii

An aqueous extract from the aerial parts of Brickellia cavanillesii attenuated postprandial hyperglycemia in diabetic mice during oral glucose and sucrose tolerance tests. Experimental type-II DM was achieved by treating mice with streptozotocin (100 mg/kg) and β-nicotinamide adenine dinucleotide (40 mg/kg). These pharmacological results demonstrated that B. cavanillesii is effective for controlling fasting and postprandial blood glucose levels in animal models. The same aqueous extract also showed potent inhibitory activity (IC(50) = 0.169 vs 1.12 mg/mL for acarbose) against yeast α-glucosidase. Bioassay-guided fractionation of the active extract using the α-glucosidase inhibitory assay led to the isolation of several compounds including two chromenes [6-acetyl-5-hydroxy-2,2-dimethyl-2H-chromene (1) and 6-hydroxyacetyl-5-hydroxy-2,2-dimethyl-2H-chromene (2)], two sesquiterpene lactones [caleins B (3) and C (4)], several flavonoids [acacetin (5), genkwanin (6), isorhamnetin (7), kaempferol (8), and quercetin (9)], and 3,5-di-O-caffeoylquinic acid (10). Chromene 2 is a new chemical entity. Compounds 2, 4, 7, and 9 inhibited the activity of yeast α-glucosidase with IC(50) 0.42, 0.28, 0.16, and 0.53 mM, respectively, vs 1.7 mM for acarbose. Kinetic analysis revealed that compounds 4 and 7 behaved as mixed-type inhibitors with K(i) values of 1.91 and 0.41 mM, respectively, while 2 was noncompetititive, with a K(i) of 0.13 mM. Docking analysis predicted that these compounds, except 2, bind to the enzyme at the catalytic site.

Antinociceptive effect and GC/MS analysis of Rosmarinus officinalis L. essential oil from its aerial parts

The rationale of this investigation was to examine the antinociceptive properties of the essential oil obtained from Rosmarinus officinalis aerial parts, using a rat model of arthritic pain. The essential oil (100, 300 and 600 mg/kg, I. P.) produced a dose-dependent antinociceptive effect, manifested as a significant reduction in the dysfunction in the pain-induced functional impairment model in the rat (PIFIR model), mainly at high doses. Chemical constituents of the essential oil were further analyzed by gas chromatography-mass spectrometry (GC/MS). The major compounds in the essential oil were alpha-pinene (14.10 %), camphene (11.47 %), beta-pinene (12.02 %), myrcene (3.31 %), alpha-phellandrene (7.87 %), eucalyptol (8.58 %), 2-bornanone (3.42 %), camphor (8.75 %), isoborneol (3.48 %), borneol (4.85 %) and borneol acetate (6.49 %). The antinociceptive effects of R. officinalis essential oil were tested in combination with 0.12 mg/kg WAY100635, s. c. (an antagonist of 5-HT(1A) receptors) or 1 mg/kg naloxone, i. p. (an antagonist of endogenous opioids receptors), demonstrating in both cases an inhibition of the antinociceptive response. This study suggests an involvement, at least in part, of the serotonergic system via 5-HT(1A) receptors and endogenous opioids in the antinociceptive effect of R. officinalis essential oil in the PIFIR model.

Some pharmacological effects of the ethanol extract of leaves of Annona diversifolia on the central nervous system in mice

In the present study we investigated some neuropharmacological effects of the ethanol extract of the leaves of Annona diversifolia (Annonaceae). Intraperitoneal administration of the extract delayed the onset of clonic seizures induced by pentylenetetrazole and delayed the time in the ‘rota‐rod’ and ‘swimming’ test. In addition, the extract augmented the duration of sleeping time induced by sodium pentobarbital. These results indicate that the ethanol extract of the leaves of A. diversifolia has depressant activity on the central nervous system. Copyright

Pharmacological exploration of the sedative mechanism of hesperidin identified as the active principle of Citrus sinensis flowers.

The infusion of flowers of several species of Citrus genera is used as a sedative to treat insomnia in Mexican traditional medicine. The aims of this study were to investigate the sedative effect of different extracts of flowers of Citrus sinensis (L.) Osbeck (Rutaceae) and describe the pharmacological action mechanism of the sedative active compounds of this plant. The methanol and dichloromethane extracts, obtained from the flowers of Citrus sinensis (L.) Osbeck (Rutaceae), showed a dose-dependent sedative effect in the exploratory cylinder model in mice, with ED50 (ip) values of 47.04+/-12.03 mg/kg and 129.15+/-21.25 mg/kg, respectively. Hesperidin (ED50=11.34+/-2.48 mg/kg) was identified in the methanol extract as the sedative active principle of this plant. The pre-treatment with atropine (1 mg/kg I. P.), flumazenil (2 mg/kg I. P.), clonidine (0.01 mg/kg I. P.), isoproterenol (0.3 mg/kg I. P.), haloperidol (0.3 mg/kg I. P.), WAY 100 635 (3 mg/kg I. P.), P-chlorophenylalanine (250 mg/kg I. P., twice per day for 2 days), forskolin (3 mg/kg I. P.) and rolipram (0.173 mg/kg I. P.) did not modify the sedative effect of 30 mg/kg hesperidin. However, the sedative effect of this compound was potentiated by yohimbine (1.25 mg/kg I. P.) and buspirone (1 mg/kg I. P.), and reverted by pretreatment with aminophylline (30 mg/kg I. P.), caffeine (30 mg/kg I. P.) and several doses of 1,3-dimethyl-8-phenylxanthine (10, 30 and 54.7 mg/kg I. P.). These results suggest that adenosine receptors might be involved in the sedative action of hesperidin, identified as the active principle of the flowers of Citrus sinensis.

Amoebicidal and giardicidal compounds from the leaves of Zanthoxylum liebmannianun

The crude ethanol extract from the leaves of Zanthoxylum liebmannianum exhibited inhibitory effect on the reproduction of trophozoites of Entamoeba histolytica (IC(50)=3.48 microg/ml) and Giardia lamblia (IC(50)=58.00 microg/ml). From this extract, asarinin, hyperin, beta-sitosterol, and beta-sitosterol glucoside were isolated. Among them, asarinin was the most active with IC(50) values of 19.86 microg/ml for E. histolytica and 35.45 microg/ml for G. lamblia. The remaining compounds showed moderate activity against both parasites.

Chemical Composition and Antimicrobial and Spasmolytic Properties of Poliomintha longiflora and Lippia graveolens Essential Oils

UNLABELLED In the present study, we reported a comparative analysis of the chemical composition and pharmacological properties of the essential oils obtained from 2 Mexican oreganos, Poliomintha longiflora and Lippia graveolens. The gas chromatography-mass spectrometry (GC-MS) profiles of the oils showed high amounts of oxygenated monoterpenes, mainly carvacrol (%[mg/100 g dry matter]) (18.36 [459.0] in P. longiflora and 13.48 [164.7] in L. graveolens). In addition, these oils contained marked quantities of p-cymene (14.09 [352.2] and 7.46 [37.3], respectively), β-caryophyllene oxide, β-caryophyllene, and carvacrol acetate. Headspace analyses of the leaves of both species using different coated fibers revealed that γ-terpinene, eucalyptol, and p-cymene were the principal light volatile components. Chromatographic fingerprints and a suitable analytical method for quantifying the main components of both essences were established using high-performance liquid chromatography (HPLC) as analytical tool. The essential oils of both species were not toxic in the acute toxicity studies in mice performed according to the Lorke procedure (DL(50) > 5000 mg/kg). The oils and the major constituents, carvacrol and p-cymene, displayed a moderate in vitro antibacterial activity, with minimum inhibitory concentration values ranging from 128 to 512 μg/mL. In addition, these samples demonstrated a marginal antispasmodic activity in vivo and provoked a concentration-dependent inhibition of the carbachol- and histamine-induced contractions using the isolated guinea-pig ileum preparation. In particular, p-cymene exerts good selective inhibitory activity on the carbachol-induced contractions (IC(50) = 9.85 μg/mL). PRACTICAL APPLICATION The analytical methods using GC-MS and HPLC techniques will be useful for establishing quality control as well as preclinical pharmacological and toxicological parameters of the crude drug P. longiflora, which is widely used as substitute of L. graveolens for medicinal and flavorings purposes. This overall information will be also useful for elaborating scientific and pharmacopoeic monographs of this very Mexican medicinal plant.

Flavonoids and terpenoids of Chenopodium graveolens

Abstract Three flavonoids, four terpenoids and three steroids were isolated from Chenopodium graveolens. These included pinostrobin, stigmasterol, stigmast-22-en-3-ol, 3α-sitosteryl-glucoside, geranyl acetate, pinocembrin, chrysin, cryptomeridiol, and two new sesquiterpenes which were characterized by spectral means as (+)-8α-hydroxyelemol and (+)-8α-acetoxycryptomeridiol.

Isobolographic analysis of the sedative interaction between six central nervous system depressant drugs and Valeriana edulis hydroalcoholic extract in mice

It has been declared frequently that valerian may potentiate the effect of other central nervous system (CNS) depressant drugs, however there has been a lack of experimental data. We have evaluated the profile of the interactions between the ethanol extract of Valeriana edulis spp procera and six CNS depressant drugs using an exploratory model to test the sedative effect in mice. All the compounds tested showed a dose‐dependent sedative effect with the following ED50 values: valerian 181.62, diazepam 1.21, ethanol 1938, pentobarbital 11.86, buspirone 1.04, haloperidol 0.41 and diphenhydramine 17.06 mg kg−1. An isobolographic analysis was used to evaluate the sedative interaction of the intraperitoneal co‐administration of 1:1 fixed‐ratio combination of equi‐effective doses of valerian extract with each CNS depressant drug. The ED50 theoretical (Zadd) and experimental (Zexp) for each combination were: valerian + diazepam, Zadd = 91.41 mg kg−1, Zexp = 81.64 mg kg−1; valerian + ethanol, Zadd = 1060.22 mg kg−1, Zexp = 687.89 mg kg−1; valerian + pentobarbital, Zadd = 96.74 mg kg−1, Zexp = 151.83 mg kg−1; valerian + buspirone, Zadd = 91.33 mg kg−1, Zexp = 112.73 mg kg−1; valerian + haloperidol, Zadd = 91.01 mg kg−1, Zexp = 91.52 mg kg−1; valerian + diphenhydramine, Zadd = 99.34 mg kg−1, Zexp = 123.52 mg kg−1. Neither synergistic nor attenuate effects were found in any of the combinations evaluated. We concluded that the valerian extract did not potentiate the sedative effect of commonly prescribed CNS depressant drugs as was expected. The additive effect found through the isobolographic analysis suggested that the sedative effect of V. edulis resulted from the activation of common mechanisms of haloperidol, diazepam, buspirone, pentobarbital, diphenhydramine and ethanol.

Gastroprotective effect of Astragaloside IV: role of prostaglandins, sulfhydryls and nitric oxide

This investigation evaluated the gastroprotective activity of Astragaloside IV, a cycloartane‐type triterpene glycoside isolated from Astragalus zahlbruckneri. Gastric mucosal damage was induced in rats by intragastric ethanol (1 mL/rat). Rats treated orally with Astragaloside IV suspended in Tween 80 at 3, 10 and 30 mg kg−1, showed 15, 37 and 52% gastroprotection, respectively. The gastroprotection observed at 30 mg kg−1 for this compound was attenuated in rats pretreated with NG‐nitro‐l‐arginine methyl ester (70 mg kg−1, i.p), a nitric oxide (NO)‐synthase inhibitor, suggesting that the gastroprotective mechanism of this glycoside involves, at least in part, the participation of NO. The gastroprotective effect of Astragaloside IV was not affected by the inhibition of prostaglandin synthesis with indometacin (10 mg kg−1, s.c.) nor by the block of endogenous sulfhydryls with N‐ethylmaleimide (NEM, 10 mg kg−1, s.c.). Carbenoxolone was used as a gastroprotective model drug and showed a dose‐dependent gastroprotective effect (25, 43 and 88% of gastroprotection, at 3, 10 and 30 mg kg−1, respectively). The partial participation of prostaglandins, sulfhydryls and NO was observed in the gastroprotective mechanism of carbenoxolone.

Anticonvulsant Effect of Annona diversifolia Saff. and Palmitone on Penicillin‐induced Convulsive Activity. A Behavioral and EEG Study in Rats

Summary:  Purpose: To evaluate hypnotic and anticonvulsant activities of Annona diversifolia Saff. and palmitone by using behavior and electroencephalographic (EEG) analysis in an experimental model of focal seizures in rats.