S-(+)- and R-(-)-linalool: a comparison of the in vitro anti-Aeromonas hydrophila activity and anesthetic properties in fish.

Linalool is the main compound of many essential oils and occurs in two isomeric forms: S-(+)- and R-(-)-linalool. This study aimed to determine if linalool isomers have different antimicrobial and anesthetic properties in fish. For this purpose, these compounds were previously isolated from Lippia alba (Mill.)N. E. Brown and Ocimum americanum L. essential oils. Antimicrobial effects were evaluated through the microdilution test against Aeromonas hydrophila, an important fish disease etiologic agent. Induction time until sedation, anesthesia and recovery time were determined in silver catfish (Rhamdia quelen) through bath exposure (60, 180, 300 or 500 µL L-1). The results showed different biological properties for the isomers being S-(+)-linalool the only active against A. hydrophila at 3.2 mg mL-1. The sedation was induced without differences between the compounds, however R-(-)-linalool promoted faster anesthesia. There were no differences regarding the recovery time of the animals exposed to the linalool isomers. Although both S-(+)- and R-(-)-linalool can be used for sedative purposes, their use in A. hydrophila infection is inadvisable due to the high effective concentration. Considering anesthesia as the main objective, the R-(-)-linalool demonstrated clear advantages at lower concentration.

Lanostane-type triterpenes from the fungal endophyte Scleroderma UFSMSc1 (Persoon) Fries.

Two lanostane triterpenoids (sclerodols A and B) were isolated from the culture of the Eucalyptus grandis derived from the endophyte Scleroderma UFSM Sc1(Persoon) Fries together with three known compounds: one related triterpenoid lanosta-8,23-dien-3ß,25-diol, the disaccharide α,ß-trehalose, and the sugar alcohol mannitol. Their structures were elucidated on the basis of 2D NMR, HRME, and single-crystal X-ray diffraction data. The methanol crude extract and the isolated lanostane triterpenoids showed promising anticandidal activities.

Cyclopeptide alkaloids: stereochemistry and synthesis of the precursors of discarines C and D and myrianthine A.

The stereochemistry of discarines C (1) and D (2) and myrianthine A (3), three cyclopeptide alkaloids isolated from Discaria febrifuga, was determined by a combination of NMR studies of 1-3, enantioselective gas chromatography, and comparison of NMR data with those of synthetic tripeptides. For the synthesis of peptides, the nonproteinogenic amino acid 3-phenylserine was also obtained in its four diastereoisomeric forms (l and d threo, obtained by recrystallization of the diastereoisomeric tripeptide, and l and d erythro, obtained by a Mitsunobu reaction with the threo-tripeptides). The general synthetic strategy described in this paper allows the tripeptide to be obtained with the free N-terminal extremity protected or dimethylated. This strategy also allows the synthesis of the corresponding peptide with an imidazolidinone ring.

In vitro evaluation of caffeoyl and cinnamoyl derivatives as potential prolyl oligopeptidase inhibitors.

A screening of the natural product chlorogenic acid, isolated from the Brazilian medicinal plant Hypericum brasiliense, caffeic acid, cinnamic acid, and p-methoxycinnamic acid, and derivatives of caffeoylquinic, caffeoyl, and cinnamoyl against the enzymes prolyl oligopeptidase and dipeptidyl peptidase IV was carried out. Caffeoylquinic, caffeoyl, and cinnamoyl derivatives were prepared using simple derivatization procedures and through coupling reactions with the amino acid proline. The dipeptidyl peptidase IV assay showed inhibitory activity of the tested compounds at a high concentration (500 µM) in the range of 81.5-7.2 %. In contrast, the derivatives methyl ester and 1,7-acetonide obtained from chlorogenic acid, and caffeic acid and its methyl ester derivative showed selectivity and activity as prolyl oligopeptidase inhibitors, with IC50 values of 3 to 14 mM.

Chemical profile and antimicrobial activity of Leonotis nepetifolia (L.) R. Br. essential oils.

Leonotis nepetifolia (L.) R. Br. (Lamiaceae) is a naturalised medicinal plant in Brazil known as 'cordão-de-frade', being used in folk medicine for the treatment of a variety of conditions such as infections and inflammations. L. nepetifolia leaf and flower essential oils were isolated by hydrodistillation, and their compounds were identified by GC-MS analysis. The leaf essential oil major constituents were germacrene D (31.5%), and ß-caryophyllene (19.2%), while in flower essential oil the main constituents were ß-elemene (31.2%), and germacrene D (12.1%). The essential oils were investigated against a broad spectrum of bacteria and fungi using the microdilution method, exhibiting MIC50 values of 3.93-250 µg mL-1. Both oils showed excellent antifungal properties, which is a very important finding since most fungi have shown increased resistance to known antifungal agents. According to these results, the essential oils of L. nepetifolia are promising sources of new antimicrobial agents, especially for yeast.

Absolute configuration of franganine.

The absolute configuration of franganine (1), a cyclopeptide alkaloid isolated from the methanol root bark extract of Discaria americana, was established on the basis of detailed NMR spectroscopic data and X-ray diffraction analysis of its salt (2).

Inhibitory effect of verbascoside isolated from Buddleja brasiliensis Jacq. ex Spreng on prolyl oligopeptidase activity.

The phenylpropanoid glycoside verbascoside [2-(3,4-dihydroxyphenylethyl)-1-O-α-L-rhamnopyranosyl-(1→3)-ß-D-(4-O-caffeyl)-glucopyranoside] (1) has been isolated as the main constituent of the crude extract of Buddleja brasiliensis Jacq. ex Spreng from Southern Brazil. The crude extract, main fractions and the compound 1 were evaluated for inhibition of the enzymes acetylcholinesterase (AChE), dipeptidyl peptidase-IV (DPP-IV) and prolyl oligopeptidase (POP). Compound 1 showed weak activity against DPP-IV with an IC(50) >> 150 µM and was inactive against AChE, with a pMIQ determined by bioautography of 9.6. In contrast, 1 displayed significant inhibition of POP in a dose-dependent manner with an IC(50) value of 1.3 ± 0.2 µM, similar to the positive control, baicalin, with a POP IC(50) of 12 ± 3 µM.

Alkaloids from the stem barks of Scutia buxifolia Reissek (Rhamnaceae): Structures and antimicrobial evaluation.

A reinvestigation of the chemical constituents of the stem barks of Scutia buxifolia, a member of the Rhamnaceae, resulted, along with the known alkaloids scutianine C and scutianene L, in the isolation of three undescribed diastereoisomeric alkaloids - scutianine N, 27-epi-scutianine N and 3, 4, 7-tri-epi-scutianine N -, one undescribed non macrocyclic alkaloid - scutianine Q - and a neutral compound -scutianene M. Their structures were determined using extensive NMR techniques and HRMS. The absolute configurations of the stereogenic centers of the three diastereoisomeric alkaloids have been assigned by gas chromatography employing modified cyclodextrins as chiral stationary phases. Scutianine Q had its structure and stereochemistry defined by single crystal X-ray crystallographic analysis. All tested compounds showed good to moderate antibacterial activity (MICs between 1.56 and 100 µg mL-1) when evaluated in vitro against a panel of Gram-positive and Gram-negative bacteria. Some stereochemistry-activity relationships have been identified for the antibacterial activity of diastereoisomeric alkaloids against the Gram-negative bacteria Enterobacter aerogenes. The alkaloid 27-epi-scutianine N was as active as the standard antibiotic chloramphenicol (MIC = 1.56 µg mL-1), while scutianine N and 3,4,27-tris-epi-Scutianine N were inactive (>100 µg mL-1).

New cyclopeptide alkaloid of Condalia buxifolia and the absolute stereochemistry of Condaline A.

During the course of a study of Condalia buxifolia (Rhamnaceae), one new cyclopeptide alkaloid condaline B (1), together with six known cyclopeptide alkaloids, condaline A (2), and the scutianines B (3), - D (4) and -E (5), frangulanine (6), and 3,4,28-tris-epi-scutianene N (7), were isolated from the rind bark of Condalia buxifolia. Their structures have been confirmed through spectroscopic analyses such as 1D and 2D NMR experiments. The absolute stereochemistry of condaline A (2), was elucidated by X-ray crystal structure determination of its HI salt. In addition, condaline B (1) was obtained synthetically through a structural transformation of condaline A. Meanwhile, the crude methanol extract, the basic ether fraction, and alkaloids 1-7 were tested against various strains of Gram-positive and Gram-negative bacteria and fungus, showing promising antimicrobial activity.

Comparative study of quercetin and its two glycoside derivatives quercitrin and rutin against methylmercury (MeHg)-induced ROS production in rat brain slices.

The hypothesis that methylmercury (MeHg) potently induces formation of reactive oxygen species (ROS) in the brain is supported by observations on the neuroprotective effects of various classes of antioxidants. Flavonoids have been reported to possess divalent metal chelating properties, antioxidant activities and to readily permeate the blood-brain barrier. They can also provide neuroprotection in a wide array of cellular and animal models of neurological diseases. Paradoxically, in vivo administration of quercetin displays unexpected synergistic neurotoxic effect with MeHg. Considering this controversy and the limited data on the interaction of MeHg with other flavonoids, the potential protective effect of quercetin and two of its glycoside analogs (i.e., rutin and quercitrin) against MeHg toxicity were evaluated in rat cortical brain slices. MeHg (100 microM) caused lipid peroxidation and ROS generation. Quercitrin (10 microg/mL) and quercetin (10 microg/mL) protected mitochondria from MeHg (5 microM)-induced changes. In contrast, rutin did not afford a significant protective effect against MeHg (100 microM)-induced lipid peroxidation and ROS production in cortical brain slices. MeHg-generated ROS in cortical slices was dependent upon an increase in intracellular Ca(2+) levels, because the over-production of MeHg-induced H(2)O(2) in mitochondria occurred with a concomitant increase in Ca(2+) transient. Here, we have extended the characterization of mechanisms associated with the neuroprotective effects of quercetin against MeHg-induced toxicity in isolated mitochondria, by performing an array of parallel studies in brain slices. We provide novel data establishing that (1) Ca(2+) plays a central role in MeHg toxicity and (2) in brain slices MeHg induces mitochondrial oxidative stress both via direct interaction with mitochondria (as previously reported in in vitro studies) as well as via mitochondria-independent (or indirect) mechanisms.

A phytochemical study of the Cuphea glutinosa from Southern Brazil: Na+,K+-ATPase activity inhibition and antioxidant properties.

This study investigated the antioxidant activity of Cuphea glutinosa (CG) and its effect on Na+, K+-ATPase from cardiac muscle. The ethanolic extract showed higher antioxidant capacity compared to aqueous and ethyl acetate fraction. Ethyl acetate fraction showed ß-sitosterol-3-O-ß-glucoside, kaempferol, quercetin, isoquercetin, gallic acid methyl ester, and gallic acid. The ethanolic extract also reduced the Na+,K+-ATPase activity. CG presented a promising antioxidant activity and inhibitory effect on the Na+, K+-ATPase activity, supporting biochemical evidences the popular use of this plant in the treatment of heart failure.

Quinolone alkaloids from Waltheria douradinha.

A phytochemical investigation of the stems of Waltheria douradinha resulted in isolation of two 4-quinolone alkaloids, waltherione B and vanessine, along with three known alkaloids, waltherione A, antidesmone and O-methyltembamide. Their structures were elucidated on the basis of their 2D NMR spectroscopic analyses, and from X-ray crystallographic analysis of waltherione A and the O-methyl derivative of waltherione B. Additionally, waltherione B and vanessine, and the O- and N-methyl derivatives of waltherione A and waltherione B, were evaluated for their antimicrobial activities; only vanessine displayed any (weak) antimicrobial activity.

Phytochemical and antimicrobial study of Pilocarpus pennatifolius Lemaire.

The investigation of the crude extract of leaves and bark of Pilocarpus pennatifolius Lemaire allowed isolated of a not yet described coumarin, together with three known coumarins (bergapten, xanthotoxin and dimethyl allyl xanthyletin), and a not yet described imidazole alkaloid. All structures were established by means of spectral analysis, including extensive 2D NMR studies. In addition, the alkaloid had its absolute stereochemistry determined by X-ray diffraction. Meanwhile, extracts and pure compounds were tested against various strains of bacteria and fungi, showing promising antimicrobial activities. We highlight the activities of crude bark methanol extract (CBME), of the leaf basic acetate fraction (LBAcF), and of compound 2 against the Gram negative bacteria Shigella flexneri (MICs = 7.8, 7.8 and 3.12 µg·mL-1, respectively), of compound 5 against the Gram positive Enterococcus fecalis (MIC = 1.56 µg·mL-1), and against two Gram negative bacteria Salmonella enteritidis (MIC = 1.56 µg·mL-1), and Pseudomonas aeruginosa (MIC = 6.25 µg·ml-1). On the other hand, CBME and compounds 3-5 showed excellent activity against the fungus Candida krusei with MICs of 15.6, 1.56, and 3.12 µg·mL-1 respectively, as actives or better than the antifungal standard fluconazole (MIC = 3.12 µg·mL-1).

Chemical constituents from Valeriana polystachya Smith and evaluation of their effects on the acetylcholinesterase and prolyl oligopeptidase activities.

Two new iridoids (1-2) and a new decomposition product of valepotriates (3), together with fifteen known compounds (4-18) were isolated from the roots and rhizomes of Valeriana polystachya Smith, a native species from the Pampa Biome. Their structures were elucidated by means of NMR spectroscopy, mass spectrometry and optical rotation. The structures of 3 and 18 were further confirmed by single crystal X-ray diffraction analysis. In the group of the isolated compounds, 6ß-hydroxysitostenone, hydroxymaltol and isovillosol were isolated from the Valeriana genus for the first time. The extracts and isolated compounds were evaluated for their in vitro activities against acetylcholinesterase (AChE) and prolyloligopeptidase (POP). Compounds 7, 9 and 11 showed weak inhibitory activity against AChE, while 3 and 5 displayed exceptional POP inhibitory activity, with IC50 values of 5.3 ±â€¯0.07 and 7.9 ±â€¯0.4 µM, respectively.

Antimicrobial Evaluation of Erythrinan Alkaloids from Erythrina cristagalli L.

BACKGROUND: Several species of the genus Erythrina have been used as sedative, antidepressant, and anticonvulsant. Erythrina crista-galli is native to the Pampa Biome and is widely used for medicinal purposes. Erythrinan alkaloids exhibit a range of pharmacological properties. OBJECTIVE: The aim of this study was to evaluate the basic fractions and the alkaloids isolated from E. crista-galli bark against a collection of bacteria and fungi for the first time. METHODS: Erythrina crista-galli stem bark was extracted with MeOH under reflux. The crude extract was dissolved in water, acidified and extracted with diethyl ether. Basification of the aqueous solution followed by diethyl ether and ethyl acetate extractions gave the basic ether and basic ethyl acetate fractions. Chromatographic purification of these fractions afforded five known alkaloids: erytharbine (1), erysotrine (2), erysotramidine (3), erysotrine N-oxide (4) and erythratidine (5) along with a new alkaloid named here erythratidine N-oxide (6). Alkaloids 1-6 were investigated against a collection of bacteria and fungi using the broth micro dilution method. RESULTS: In this work, a new alkaloid was isolated from E. crista-galli. The most significant bacterial inhibitory effect of alkaloidal fractions was observed against the Gram-negative Pseudomas aeroginosa (MIC values of 31.25 µg.mL-1). Basic ether fraction displayed good antimicrobial activity against Shigella sonnei with MIC= 62.5 µg.mL-1. Isolated alkaloids 1-6 showed inhibitory activity against all bacteria tested (MIC values of 50-100 µg.mL-1). In addition, the crude extract and alkaloids 1, 2, and 5 also showed good antifungal potential against Candida krusei (MICs between 12.5 and 31.25 µg.mL-1). The previously undescribed alkaloid 6 presented MIC values between 50 and 100 µg.mL-1 against all tested microorganisms. CONCLUSION: In general, as with a considerable number of phytochemicals with antimicrobial activity, alkaloids 1-6 may be considered with potential as antibacterial/antifungal agents. The MIC values of the extract, alkaloidal fractions and compounds 1-6 indicate that, at least in part, the isolates were responsible for the antimicrobial activity observed.

Tiger nut and walnut extracts modulate extracellular metabolism of ATP and adenosine through the NOS/cGMP/PKG signalling pathway in kidney slices.

BACKGROUND: Tiger nut (Cyperus esculentus L.) and walnut (Tetracarpidium conophorum Müll. Arg.) have been reportedly used in the treatment of inflammatory diseases such as atherosclerosis, prevent heart attack and improve blood circulation, reduce serum cholesterol level as well as inhibit oxidation reactions. PURPOSE: This study investigated the effect of tiger nut and walnut hydro-alcoholic extracts on extracellular metabolism of ATP through the NOS/cGMP/PKG signaling pathway induced by Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) in kidney slices. METHODS: The plants were extracted for 24 h in 10 ml of 70% ethanol and 30% distilled water per gram milled material on a mechanical shaker and filtered using Whatman filter paper. The effect of the extracts on ecto-nucleotidases (NTPDase and 5' nucleotidase) and adenosine deaminase activities, nitrites and nitrates levels (NO, markers of NO production) as well as lipid and protein oxidation reactions in kidney slices were evaluated. Also, the phenolic components of the nut samples were determined using High Performance Liquid Chromatography (HPLC). RESULTS: The results revealed a protective effect of tiger nut and walnut on co-incubation with L-NAME of the enzyme activities, increased NO significantly (P < 0.05) when compared to the vehicle. L-NAME also increased the thiobabituric reactive substances but co-incubation with the extracts caused a significant reduction while protein oxidation across groups showed no significant difference when compared to the vehicle group. HPLC finger printing revealed the presence of quercetin and kaempferol as the most abundant phenolic compounds in tiger nut and walnut respectively. CONCLUSION: Tiger nut and walnut extracts showed a protective effect on L-NAME induced kidney slices by reducing the activities of NTPDase (ATP as substrate) and adenosine deaminase, increased NO levels as well as prevent oxidative damage. The effect observed may be attributed to the phenolic compounds present in both nuts as depicted by HPLC finger printing.

Phytochemical analysis of bark from Helietta apiculata Benth and antimicrobial activities.

Extraction and characterization of natural products from the bark of the trunk of Helietta apiculata Benth (Rutaceae) afforded nine alkaloids, eight furoquinoline and one quinolone, limonine, three cinnamic acid derivatives, three neolignans, tetracosanoic acid, six coumarins, of which apiculin A and apiculin B (neolignans), and tanizin (coumarin) are previously undescribed compounds. The structures of all compounds were determined by spectroscopic methods, and the crystal structures of two of the newly undescribed compounds, apiculin A and apiculin B, were determined by X-ray analysis. Extracts and pure compounds isolated from Helietta apiculata showed promising antimicrobial activities.

Chemical composition and evaluation of prolyl oligopeptidase and acetylcholinesterase inhibitory activities of Leonurus Sibiricus L. from Brazil.

Chemical investigation of the aerial parts of Leonurus sibiricus L. used in Brazilian folk medicine led to the identification of the following constituents: the labdane-type diterpenoid leojaponin, the phytosterols ß-sitosterol and ß-sitosterol glucoside and the alkaloid leonurine. The crude extracts obtained from methanol and methanol/1% HCl and pure compounds isolated from L. sibirius were investigated as acetylcholinesterase (AChE) and prolyl oligopeptidase (POP) inhibitors. Extracts obtained by maceration were active against POP (53-58%), but showed weak activity against AChE. The isolated leojaponin and leonurine were evaluated as POP inhibitors.

Quercitrin, a glycoside form of quercetin, prevents lipid peroxidation in vitro.

Reactive oxygen species have been demonstrated to be associated with a variety of diseases including neurodegenerative disorders. Flavonoid compounds have been investigated for their protective action against oxidative mechanisms in different in vivo and in vitro models, which seems to be linked to their antioxidant properties. In the present study, we examine the protective mechanism of quercitrin, a glycoside form of quercetin, against the production of TBARS induced by different agents. TBARS production was stimulated by the incubation of rat brain homogenate with Fe2+, Fe2+ plus EDTA, quinolinic acid (QA), sodium nitroprusside (SNP) and potassium ferricyanide ([Fe(CN)6]3-). Quercitrin was able to prevent the formation of TBARS induced by pro-oxidant agents tested; however, it was more effective against potassium ferricyanide ([Fe(CN)6]3-, IC50=2.5), than quinolinic acid (QA, IC50=6 microg/ml) and sodium nitroprusside (SNP, IC50=5.88 microg/ml) than Fe2+ (Fe2+, IC50=14.81 microg/ml), Fe2+ plus EDTA (Fe2+ plus EDTA, IC50=48.15 microg/ml). The effect of quercitrin on the Fenton reaction was also investigated (deoxyribose degradation). Quercitrin caused a significant decrease in deoxyribose degradation that was not dependent on the concentration. Taken together, the data presented here indicate that quercitrin exhibits a scavenger and antioxidant role, and these effects probably are mediated via different mechanisms, which may involve the negative modulation of the Fenton reaction and NMDA receptor.

Cyclopeptide alkaloids from Scutia buxifolia Reiss and their antimicrobial activity.

The present study reports a cyclopeptide alkaloid, scutianine M, isolated from the methanolic root bark extract of Scutia buxifolia Reiss (Rhamnaceae) along with six known compounds, scutianines-B, -C, -D, -E, -F, and scutianene D. Its structure was established on the basis of spectroscopic analyses, including application of 2D NMR spectroscopic techniques. As part of a study of the bioactive compounds of medicinal plants from southern Brazil, we also compared the antimicrobial activity of the isolated compounds towards Gram (+), Gram (-) bacteria, and yeasts.