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.

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.

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).

Evaluation of prolyl oligopeptidase and acetylcholinesterase inhibition by Phyllanthus tenellus Roxb. from Brazil.

Phyllanthus tenellus Roxb. (Phyllanthaceae) is a plant used in Brazilian folk medicine for the treatment of intestinal infections and diabetes. Despite its use in traditional medicine, it was reported that P. tenellus extract may cause several effects in the central nervous system (CNS) of animals, such as agitation and signs of depression. The aim of this study was to determine the main constituents of P. tenellus methanol extract and to investigate whether the extract is able to inhibit the enzymes prolyl oligopeptidase (POP), acetylcholinesterase (AChE) and dipeptidyl peptidase-IV (DPP-IV). Corilagin (1) was isolated as the main constituent of the P. tenellus extract, along with rutin (2) and vitexin-2″-O-rhamnoside (3). The extract presented the ability to inhibit mainly POP. Dichloromethane and ethyl acetate fractions showed the highest inhibitory potency against POP (IC50 values of 1.7 ± 0.4 and 11.7 ± 2 µg/mL, respectively). All fractions were inactive against AChE. Corilagin displayed selective POP inhibition in a dose-dependent manner, with IC50= 19.7 ± 2.6 µg/mL. Corilagin exhibited moderate capacity to pass through the phospholipid membrane by passive diffusion, presenting effective permeability (Pe) of 1.26 × 10-7 cm/s.

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.

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.

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).

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.

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.

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.

Chemical Composition and Inhibitory Effects of Hypericum brasiliense and H. connatum on Prolyl Oligopeptidase and Acetylcholinesterase Activities.

BACKGROUND: The genus Hypericum (family Clusiaceae) comprises various species that are used in traditional medicine, such as wound healing, antidepressant, and anticancer agents. OBJECTIVE: The aim of this study was to evaluate the inhibitory capacity of extracts and fractions from two Hypericum species used in the Brazilian folk medicine (H. brasiliense and H. connatum) against the enzymes prolyl oligopeptidase (POP), dipeptidyl peptidase-IV (DPP-IV), and acetylcholinesterase (AChE), as well as to identify their main active constituents. METHODS: Dried aerial parts of H. connatum and H. brasiliense were subjected to extraction with 8:2 methanol-H2O. Each hydroalcoholic extract was fractioned resulting in ethyl acetate and aqueous fractions. The activity of POP, DPP-IV and AChE was determined in vitro in 96-well microplates. RESULTS: The main components identified in the plant extracts were chlorogenic acid (1), quercitrin (2), rutin (3), quercetin (4), and isoquercitrin (5). Hydroalcoholic extracts, ethyl acetate and aqueous fractions showed high POP inhibitory activity with IC50 values of 2.6 to 3.7 µg/mL. AChE and DPP-IV inhibitory effects were very low for all extracts and substances. CONCLUSION: Chlorogenic acid (1) and quercetin (4) were the main constituent responsible for the activity observed against POP. Parallel artificial membrane permeability assay of ethyl acetate fractions of both species showed that the metabolite that can effectively pass through the lipid membrane is 4, the aglycone form of 2, 3 and 5.

Structure-activity relationship of benzophenanthridine alkaloids from Zanthoxylum rhoifolium having antimicrobial activity.

Zanthoxylum rhoifolium (Rutaceae) is a plant alkaloid that grows in South America and has been used in Brazilian traditional medicine for the treatment of different health problems. The present study was designed to evaluate the antimicrobial activity of the steam bark crude methanol extract, fractions, and pure alkaloids of Z. rhoifolium. Its stem bark extracts exhibited a broad spectrum of antimicrobial activity, ranging from 12.5 to 100 µg/mL using bioautography method, and from 125 to 500 µg/mL in the microdilution bioassay. From the dichloromethane basic fraction, three furoquinoline alkaloids (1-3), and nine benzophenanthridine alkaloids (4-12) were isolated and the antimicrobial activity of the benzophenanthridine alkaloids is discussed in terms of structure-activity relationships. The alkaloid with the widest spectrum of activity was chelerythrine (10), followed by avicine (12) and dihydrochelerythrine (4). The minimal inhibitory concentrations of chelerythrine, of 1.50 µg/mL for all bacteria tested, and between 3.12 and 6.25 µg/mL for the yeast tested, show this compound to be a more powerful antimicrobial agent when compared with the other active alkaloids isolated from Z. rhoifolium. To verify the potential importance of the methylenedioxy group (ring A) of these alkaloids, chelerythrine was selected to represent the remainder of the benzophenanthridine alkaloids isolated in this work and was subjected to a demethylation reaction giving derivative 14. Compared to chelerythrine, the derivative (14) was less active against the tested bacteria and fungi. Kinetic measurements of the bacteriolytic activities of chelerythrine against the bacteria Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) were determined by optical density based on real time assay, suggesting that its mechanism of action is not bacteriolytic. The present study did not detect hemolytic effects of chelerythrine on erythrocytes and found a protective effect considering the decrease in TBARS and AOPP (advanced oxidized protein products) levels when compared to the control group.

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.

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.

Antimicrobial activity of Schinus lentiscifolius (Anacardiaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Schinus lentiscifolius Marchand (syn. Schinus weinmannifolius Engl) is a plant native to Rio Grande do Sul (Southern Brazil) and has been used in Brazilian traditional medicine as antiseptic and antimicrobial for the treatment of many different health problems as well as to treat leucorrhea and to assist in ulcer and wound healing. Although it is a plant widely used by the population, there are no studies proving this popular use. MATERIAL AND METHODS: The crude aqueous extract, the crude neutral methanol extract, fractions prepared from this extract (n-hexane, ethyl acetate, and n-butanol), pure compounds isolated from these fractions, and derivatives were investigated in vitro for antimicrobial activities against five Gram positive bacteria: Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus pyogenes, three Gram negative bacteria: Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnei, and four yeasts: Candida albicans, Candida tropicalis, Cryptococcus neoformans, and Saccharomyces cerevisiae. The isolated compound moronic acid, which is the most active, was tested against a range of other bacteria such as two Gram positive bacteria, namely, Bacillus cereus, Enterococcus spp, and six Gram negative bacteria, namely, Burkholderia cepacia, Providencia stuartii, Morganella morganii, Enterobacter cloacae, Enterobacter aerogenes, and Proteus mirabilis. RESULTS: The leaf aqueous extract (decoction) of Schinus lentiscifolius showed a broad spectrum of antibacterial activity, ranging from 125 to 250 µg/ml (MIC) against the tested bacteria and fungi. The n-hexane extract, despite being very little active against bacteria, showed an excellent antifungal activity, especially against Candida albicans (MIC=25 µg/ml), Candida tropicalis (MIC=15.5 µg/ml), and Cryptococcus neoformans, (MIC=15.5 µg/ml). From the acetate fraction (the most active against bacteria), compounds 1-6 were isolated: nonadecanol (1), moronic acid (2), gallic acid methyl ester (3), gallic acid (4), quercetin (5) and quercitrin (6). The minimal inhibitory concentration (MIC) of moronic acid between 1.5 and 3 µg/ml against most of the tested bacteria shows that it is one of the metabolites responsible for the antibacterial activity of Schinus lentiscifolius. CONCLUSION: The antimicrobial activity and some constituents of Schinus lentiscifolius are reported for the first time. The results of the present study provide scientific basis for the popular use of Schinus lentiscifolius for a number of different health problems.

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.

Flavonoids with prolyl oligopeptidase inhibitory activity isolated from Scutellaria racemosa Pers.

Prolyl oligopeptidase (POP) is a serine protease highly expressed in the brain that hydrolyses peptide bonds at the carboxyl terminal of prolyl residues. There is evidence that this enzyme participates in several functions of the central nervous system. Scutellaria racemosa Pers demonstrated significant and selective POP inhibition. Fractionation of the hydroalcoholic extract resulted in the isolation of four main constituents identified for the first time from S. racemosa Pers, the triterpenoid lupeol (1) and the flavonoids oroxylin A (5,7-dihydroxy-6-methoxyflavone, 2), hispidulin (4',5,7-trihydroxy-6-methoxyflavone, 3), and oroxyloside (oroxylin A 7-O-glucuronide, 4). Inhibitory assays indicated that 3 and 4 at a concentration of 100 microM inhibit 43 and 34% of total POP activity, respectively.

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.