Biomedical subjects

R Vila

Publications and source records attributed to R Vila.

At least 19 recordsLinked to original sources

PubMed2003

Essential oil composition and antimicrobial activity of Santiria trimera bark.

The composition and the antimicrobial activity of the bark oil of Santiria trimera (Oliv.) Aubrév., a plant widely used by the traditional healers in S. Tomé and Príncipe, especially for wound healing, are reported for the first time. The analysis of the essential oil was carried out by GC and GC-MS. The oil contains a high content of monoterpenes, alpha-pinene (66.6 %) being the major constituent, followed by beta-pinene (20.0 %). The essential oil was active against both bacteria and fungi strains, except Staphylococcus epidermidis and Aspergillus niger. It exhibited significant antimicrobial activity against Proteus vulgaris and Cryptococcus neoformans with MICs values of 1.11 microl/ml and lower than 0.71 microl/ml, respectively.

Anti-Bacterial Agents↗

PubMed2001

DNA-induced alpha-helical structure in the NH2-terminal domain of histone H1.

It is important to establish the structural properties of linker histones to understand the role they play in chromatin higher order structure and gene regulation. Here, we use CD, NMR, and IR spectroscopy to study the conformation of the amino-terminal domain of histone H1 degrees, free in solution and bound to the DNA. The NH(2)-terminal domain has little structure in aqueous solution, but it acquires a substantial amount of alpha-helical structure in the presence of trifluoroethanol (TFE). As in other H1 subtypes, the basic residues of the NH(2)-terminal domain of histone H1 degrees are clustered in its COOH-terminal half. According to the NMR results, the helical region comprises the basic cluster (Lys(11)-Lys(20)) and extends until Asp(23). The fractional helicity of this region in 90% TFE is about 50%. His(24) together with Pro(25) constitute the joint between the NH(2)-terminal helix and helix I of the globular domain. Infrared spectroscopy shows that interaction with the DNA induces an amount of alpha-helical structure equivalent to that observed in TFE. As coulombic interactions are involved in complex formation, it is highly likely in the complexes with DNA that the minimal region with alpha-helical structure is that containing the basic cluster. In chromatin, the high positive charge density of the inducible NH(2)-terminal helical element may contribute to the binding stability of the globular domain.

Amino Acid Sequence↗

PubMed2001

Induction of secondary structure in a COOH-terminal peptide of histone H1 by interaction with the DNA: an infrared spectroscopy study.

We have studied the conformation of the peptide Ac-EPKRSVAFKKTKKEVKKVATPKK (CH-1), free in solution and bound to the DNA, by Fourier-transform infrared spectroscopy. The peptide belongs to the COOH-terminal domain of histone H1(0) (residues 99-121) and is adjacent to the central globular domain of the protein. In aqueous (D(2)O) solution the amide I' is dominated by component bands at 1643 cm(-1) and 1662 cm(-1), which have been assigned to random coil conformations and turns, respectively. In accordance with previous NMR results, the latter component has been interpreted as arising in turn-like conformations in rapid equilibrium with unfolded states. The peptide becomes fully structured either in 90% trifluoroethanol (TFE) solution or upon interaction with the DNA. In these conditions, the contributions of turn (1662 cm(-1)) and random coil components virtually disappear. In TFE, the spectrum is dominated by the alpha-helical component (1654 cm(-1)). The band at 1662 cm(-1) shifts to 1670 cm(-1), and has been assigned to the COOH-terminal TPKK motif in a more stable turn conformation. A band at 1637 cm(-1), also present in TFE, has been assigned to 3(10) helical structure. The amide I' band of the complexes with the DNA retains the components that were attributed to 3(10) helix and the TPKK turn. In the complexes with the DNA, the alpha-helical component observed in TFE splits into two components at 1657 cm(-1) and 1647 cm(-1). Both components are inside the spectral region of alpha-helical structures. Our results support the presence of inducible helical and turn elements, both sharing the character of DNA-binding motifs.

Amino Acid Sequence↗

PubMed2001

Composition and chemical polymorphism of the essential oils from Piper lanceaefolium.

Essential oils obtained by hydrodistillation from leaves and spikes of Piper lanceaefolium H.B.K. of Costa Rica were analysed by GC-FID, GC-MS and 13C-NMR methods. Main constituents found in the oil from leaves were sesquiterpene hydrocarbons - especially beta-caryophyllene and germacrene D - and phenylpropanoids, of which elemicin and parsley apiol were the major ones. The volatile oil from spikes showed monoterpene hydrocarbons, namely alpha- and beta-pinene, and the same phenylpropanoids as in the oil from leaves as the major constituents. Results obtained in the analysis by GC-FID and GC-MS of the essential oils from individual plants of different geographic origin were submitted to chemometric cluster analysis and principal component analysis, showing the presence of three different types of oils (i) parsley apiol/elemicin, (ii) elemicin/parsley apiol/dill apiol, and (iii) parsley apiol/dill apiol.

Journal Article↗

PubMed2001

Chemical composition of the essential oil from the leaves of Piper fulvescens, a plant traditionally used in Paraguay.

The essential oil from the leaves of the aromatic aniseed smelling plant Piper fulvescens, obtained by hydrodistillation, was investigated by GC and GC-MS, as well as by 13C-NMR after fractionation of the oil by column chromatography. A total of 37 constituents, representing 78.2% of the oil were identified. The main compounds were trans-anethole (26.4%) and ishwarane (12.1%), an unusual sesquiterpene hydrocarbon.

Gas Chromatography-Mass Spectrometry↗

PubMed2001

Antifungal activity of Paraguayan plants used in traditional medicine.

The antifungal activity of aqueous, dichloromethane and methanol extracts from 14 Paraguayan plants used in traditional medicine for the treatment of skin diseases was assayed in vitro by the agar disk diffusion method against 11 fungal strains comprising several filamentous fungi and yeasts. Among them, the dichloromethane extracts of Acanthospermum australe, Calycophyllum multiflorum, Geophila repens and Tabebuia avellanedae, as well as the aqueous and methanol extracts of the latter, showed the highest activity.

Antifungal Agents↗

PubMed2001

Essential oil composition and antimicrobial activity of three Zingiberaceae from S.Tomé e Príncipe.

The essential oil composition of three Zingiberaceae widely used as medicinal aromatic plants from S. Tomé and Príncipe: Aframomum danielli (Hook. f.) K. Schum., Curcuma longa L. and Zingiber officinale Rosc. was studied. Two samples of the essential oils from fruit of A. danielli and from rhizomes of the other two species, were obtained by hydrodistillation and analyzed by GC, GC-MS, and (13)C-NMR. The essential oil from fruits of A. danielli has been studied for the first time and was characterised by its high content of monoterpenes, with 1,8-cineole (25.5 - 34.4 %) the major constituent, followed by beta-pinene (14.1 - 15.2 %) and alpha-terpineol (9.9 - 12.1 %). Essential oils from the rhizomes of C. longa contained a lower content of ar-turmerone (4.0 - 12.8 %) than those reported in the literature for C. longa from other origins (24.7 - 31.4 %), whereas the results for Z. officinale essential oils were in accordance with the literature data. The essential oils of A. danielli and Z. officinale showed antimicrobial activity against all Gram-positive and Gram-negative bacteria tested, as well as against yeasts and filamentous fungi, using the agar diffusion method.

Anti-Bacterial Agents↗

PubMed2001

Antifungal principles from Piper fulvescens.

Activity-guided fractionation of the dichloromethane extract from leaves of Piper fulvescens, using an agar overlay bioautographic method, led to the isolation of three antifungal neolignans identified as conocarpan, eupomatenoid 5 and eupomatenoid 6. The minimal inhibitory concentration of these three neolignans against five fungi strains were determined. Conocarpan showed the widest activity, whereas eupomatenoid 6 was the most active against dermatophytes.

Antifungal Agents↗

PubMed2001

Improvement in endothelial dysfunction in patients with hypoalphalipoproteinemia and coronary artery disease treated with bezafibrate.

Isolated low high-density lipoprotein cholesterol (HDLc) is a well-known risk factor for cardiovascular disease and is associated with arterial endothelium dysfunction. Several studies have shown that cholesterol lowering in patients with hypercholesterolemia improves endothelial function, but the effect of treating low HDLc levels remains unknown. We studied the effect of increasing HDLc on endothelial function in patients with coronary artery disease (CAD) and isolated low HDLc (HDLc) <0.91 mM, low-density lipoprotein cholesterol (LDLc) <4.1 mM, and triglycerides <2.8 mM. Flow-mediated endothelium-dependent dilatation (FMD) in response to reactive hyperemia was measured by brachial ultrasound, before and after bezafibrate treatment (400 mg daily for 6 months) in 16 patients with CAD and impaired FMD (<10%). After bezafibrate therapy, HDLc increased from 0.79-1.0 mM (p = 0.0008) at the expense of both HDL2 and HDL3 subfractions, apolipoprotein A-I increased from 1.04-1.19 g/l (p = 0.0012), and fibrinogen decreased from 4.45-3.39 g/l (p = 0.0007). The impaired FMD increased after bezafibrate treatment from a median of 2.5-12.3% (p = 0.0004). Endothelial function was normalized in eight patients (50%), improved in four (25%), and did not change in four (25%). These observations indicate that in patients with isolated low HDLc and CAD, bezafibrate treatment improves endothelial function of brachial arteries, increases HDLc and apolipoprotein A-I, and lowers fibrinogen concentrations.

Aged↗

PubMed2000

Chemotaxonomic study on Thymus villosus from Portugal.

The composition of the essential oils of four populations of Thymus villosus subsp. lusitanicus (Boiss.) Coutinho from Portugal was investigated by GC and GC-MS. To study the chemical polymorphism the results obtained from GC analyses of the volatile oils from individual plants from four populations were submited to Principal Component and Cluster analyses. A comparision with the essential oil of T. villosus subsp. villosus, previously studied by us was done. Important differences with regard to the major constituents in these two taxa were found. Linalool, geranyl acetate, geraniol and terpinen-4-ol were the main components of the essential oils of T. villosus subsp. lusitanicus, whereas in the oil of T. villosus subsp. villosus p-cymene, myrcene and alpha-terpineol were the major ones. Although, both taxa showed chemical polymorphism, different types of essential oils were characterized in each one: linalool; linalool/ terpinen-4-ol/trans-sabinene hydrate; linalool/1,8-cineole; geranyl acetate/geraniol; geranyl acetate/geraniol/1,8-cineole in T. villosus subsp. lusitanicus and p-cymene/camphor/linalool; p-cymene/borneol; linalool/geraniol/geranyl acetate; alpha-terpineol/camphor/myrcene in T. villosus subsp. villosus. Thus, the two subspecies of T. villosus can be easely differenciated by the composition of their essential oils.

Journal Article↗

PubMed2000

Essential oil composition and variability of Thymus lotocephalus and Thymusxmourae.

The composition of the essential oils of four populations of Thymus lotocephalus G. López and R. Morales and one population of T.xmourae Paiva and Salgueiro, two endemic taxa from Portugal, was investigated mainly by GC and GC-MS. Txmourae is a natural hybrid between T. lotocephalus and T. mastichina (L.) L. subsp. donyanae R. Morales, which essential oil was analysed for the first time. In its oil, it was possible to find compounds of both parents, which could enable us to confirm its intermediate status between those two taxa. 1,8-Cineole and borneol were the main constituents in the essential oil of T.xmourae, whereas linalool, geranyl acetate and 1,8-cineol were the major ones in T. lotocephalus. Intermedeol was also an important constituent in the oils of both taxa. Nevertheless, the volatile oils of the four populations investigated of T. lotocephalus showed important differences among the main constituents. In order to study their infraspecific variability, the results obtained in the analysis of individual plants were submitted to a Principal Component and Chemometric Cluster Analyses. Five types of essential oils were found: linalool, 1,8-cineole, linalool/1,8-cineole, linalyl acetate/linalool and geranyl acetate.

Journal Article↗

PubMed2000

Anti-inflammatory activity of dichloromethane extract of Heterotheca inuloides in vivo and in vitro.

The dichloromethane extract from the dried flowers of Heterotheca inuloides Cass. was investigated on several pharmacological models of inflammation in vivo and in vitro. It showed anti-inflammatory activity on the croton oil-induced oedema test in mouse ear, at 1 mg/ear. The compound isolated from this extract, 7-hydroxy-3,4-dihydrocadalin, showed anti-inflammatory effect on the same experimental model (ED50 of 0.9 mumol/ear), as well as on COX-1 and COX-2 catalysed prostaglandin biosynthesis assays, with IC50 values of 22 microM and 526 microM, respectively. No effect was observed on carrageenan-induced oedema and on fMLP/PAF-induced exocytosis of human neutrophils. The COX-1 inhibitory effect showed by 7-hydroxy-3,4-dihydrocadalin might be related to the anti-inflammatory activity on the topical oedema induced by croton oil.

Animals↗

PubMed2000

Antimicrobial activity and chemical composition of the bark oil of Croton stellulifer, an endemic species from S. Tomé e Príncipe.

The composition and the antimicrobial activity of the bark oil of Croton stellulifer, an endemic and rare species of these islands (S. Tomé and Príncipe) are reported. Analysis was carried out by GC, GC/MS and 13C-NMR. The major constituents were alpha-phellandrene (15.4-18.6%), p-cymene (14.4-17.7%), linalool (12.0-12.6%) and alpha-pinene (8.1-9.1%). Kessane, a sesquiterpenoid oxide, not yet reported in the genus Croton, was identified by NMR. The essential oil of C. stellulifer was active against both bacterial and fungal strains, except Aspergillus niger.

Anti-Infective Agents↗

PubMed2000

A helix-turn motif in the C-terminal domain of histone H1.

The structural study of peptides belonging to the terminal domains of histone H1 can be considered as a step toward the understanding of the function of H1 in chromatin. The conformational properties of the peptide Ac-EPKRSVAFKKTKKEVKKVATPKK (CH-1), which belongs to the C-terminal domain of histone H1(o) (residues 99-121) and is adjacent to the central globular domain of the protein, were examined by means of 1H-NMR and circular dichroism. In aqueous solution, CH-1 behaved as a mainly unstructured peptide, although turn-like conformations in rapid equilibrium with the unfolded state could be present. Addition of trifluoroethanol resulted in a substantial increase of the helical content. The helical limits, as indicated by (i,i + 3) nuclear Overhauser effect (NOE) cross correlations and significant up-field conformational shifts of the C(alpha) protons, span from Pro100 to Val116, with Glu99 and Ala117 as N- and C-caps. A structure calculation performed on the basis of distance constraints derived from NOE cross peaks in 90% trifluoroethanol confirmed the helical structure of this region. The helical region has a marked amphipathic character, due to the location of all positively charged residues on one face of the helix and all the hydrophobic residues on the opposite face. The peptide has a TPKK motif at the C-terminus, following the alpha-helical region. The observed NOE connectivities suggest that the TPKK sequence adopts a type (I) beta-turn conformation, a sigma-turn conformation or a combination of both, in fast equilibrium with unfolded states. Sequences of the kind (S/T)P(K/R)(K/R) have been proposed as DNA binding motifs. The CH-1 peptide, thus, combines a positively charged amphipathic helix and a turn as potential DNA-binding motifs.

Amino Acid Sequence↗

PubMed1999

Antiinflammatory activity of some extracts from plants used in the traditional medicine of north-African countries (II).

Aqueous, ethanol and chloroform extracts from Corrigiliola telephiifolia, Echinops spinosus, Kundmannia sicula, Tamarindus indica and Zygophyllum gaetulum were evaluated for antiinflammatory properties in mice (ear oedema induced by arachidonic acid) and rats (subplantar oedema induced by carrageenan) after topical or i.p. administration, respectively. Our results showed that all the plants exhibit antiinflammatory activity, since at least one extract from each plant was active in one of the experimental models. Whereas all the extracts of Corrigiliola telephiifolia and Echinops spinosus were highly active on all the experimental models assayed (values of inflammation inhibition well above 50%), poorer activity profiles were recorded in Kundmannia sicula, Tamarindus indica and Zygophyllum gaetulum. These results support the traditional uses for these plants but indicate that the active principles in the chloroform extracts are probably more active and/or are contained in larger concentrations than the principles in the polar extracts used in the traditional medicine of North-African countries.

Administration, Cutaneous↗

PubMed1999

Composition and antimicrobial activity of the essential oil of Peumus boldus leaves.

The composition and the antimicrobial activity of the essential oil from the leaves of Peumus boldus is investigated. Analyses of the oil obtained by hydrodistillation were carried out by GC and GC-MS using columns of two different stationary phases. Fractionation of the essential oil by column chromatography on silica gel was performed to improve identification of some constituents. More than 90% of the total oil (46 components) was identified, major constituents being monoterpenes (90.5%), among which limonene (17.0%), p-cymene (13.6%), 1.8-cineole (11.8%), and beta-phellandrene (8.4%) reached the highest percentages. Determination of the minimal bactericidal or fungicidal concentration against several microorganisms showed interesting activities towards Streptococcus pyogenes, Micrococcus sp., and Candida sp.

Anti-Infective Agents↗

PubMed1998

Effect of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages.

The effects of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages of small diameter were investigated. During pre-ripening (day 5), levels of lactic acid bacteria and yeasts were slightly higher in nitrite-made sausages than in those made with nitrate. In contrast, nitrite discouraged the growth of psychrotrophs as occurs in fermented sausages. By the end of ripening (day 26), levels of microorganisms were similar in both batches of sausages except for psychrotrophs being higher in those made with nitrite. Nitrate-made sausages showed higher aroma and taste intensity.

Animals↗

PubMed1998

Antiinflammatory activity of Anthurium cerrocampanense Croat in rats and mice.

Aqueous (AE), ethanol (EE) and dichloromethane (DE) extracts from the whole plant of Anthurium cerrocampanense Croat, endemic to Panama, were assayed for antiinflammatory activity by carrageenan-induced rat paw edema and croton oil-induced mouse ear edema tests. The extracts were administered i.p. and topically, respectively. The best antiinflammatory activity in the carrageenan-induced rat paw edema test, was shown by DE (31% inhibition), which did not show any irritant effect in the peritoneal examination 4 h after administration of the extracts. Furthermore, the highest activity in the croton oil-induced mouse ear edema test was also exhibited by DE (93% inhibition). Since DE was the most effective of the extracts in both tests, it's activity was assessed in various inflammation models in rats. At 100 mg/kg, DE markedly inhibited inflammation produced by dextran (66.6% inhibition) and decreased weakly the edema induced by zymosan A, carrageenan and C16-platelet activation factor (C16-PAF) (33.2, 31.6 and 23.8%, respectively). At 50 mg/kg, DE only significantly reduced the swelling caused by dextran (36.2%). No effect was observed at the same doses in arachidonic acid-induced edema. A clear dose-related antiinflammatory activity of DE was seen in the croton oil-induced mouse ear edema test, and ED50 calculated was found to be 25.5 microg/ear. which was much lower than ED50 obtained for indomethacin (56.1 microg/ear).

Animals↗