Biomedical subjects

R Mata

Publications and source records attributed to R Mata.

At least 19 recordsLinked to original sources

PubMed2006

Endothelium-independent relaxation of aorta rings by two stilbenoids from the orchids Scaphyglottis livida.

Gigantol (1) and 3,7-dihydroxy-2,4-dimethoxyphenanthrene (2) from the orchid Scaphyglottis livida induced a significant concentration-dependent relaxation of the contractions evoked by noradrenaline (NA) in endothelium-intact and denuded rat aorta rings. Incubation with N(G)-nitro-L-arginine methyl ester (L-NAME, 1x10(-5) M) or methylene blue (MB, 1x10(-7) M) significantly reduced the relaxation induced by the stilbenoids 1 and 2. The results suggested that two or more mechanisms are involved in the vasorelaxant effects of both compounds.

Animals↗

PubMed2004

Spasmolytic stilbenoids from Maxillaria densa.

2,5-dihydroxy-3,4-dimethoxyphenanthrene (1), fimbriol-A (2), nudol (3), gymnopusin (4) and erianthridin (5) isolated from Maxillaria densa provoked a concentration-dependent inhibition of the spontaneous contractions of the rat ileum with potencies comparable to papaverine. In order to establish the mode of action of stilbenoids 1-5, their effect on the contractions induced by different spasmogens (histamine, barium chloride and L-NAME) was investigated. In general, the results suggested that the relaxant activity of the products does not involve a direct nitrergic or antihistaminergic mode of action or an interference with calcium influx into the smooth muscle cells.

Animals↗

PubMed2002

Phytotoxicity and ultrastructural effects of gymnopusin from the orchid Maxillaria densa on duckweed (Lemna pausicostata) frond and root tissues.

Two phenanthrene derivatives, characterized as erianthridin (9,10-dihydro-2,7-dihydroxy-3,4-dimethoxyphenanthrene) and gymnopusin (2,7-dihydroxy-3,4,9-trimethoxyphenanthrene), were isolated from an extract of the orchid Maxillaria densa, using phytotoxicity with amaranth (Amaranthus hypochondriacus) to guide fractionation. Gymnopusin and erianthridin inhibited radicle elongation of A. hypochondriacus seedlings with IC(50) values of 330 and 58.2 microM, respectively. The phytoxicity of the two phenanthrene derivatives was also assessed on duckweed (Lemna pausicostata), and compared with mammalian toxicity estimated in vitro with four mammalian cell lines. On duckweed, both phenanthrene derivatives caused electrolyte leakage, chlorophyll loss and photobleaching. Ultrastructural examination of duckweed frond and root tissues treated with gymnopusin (100 microM) revealed membrane damage to the tonoplast after 12 h of exposure. Effects on membrane integrity followed a time course similar to that of electrolyte leakage. Both phenanthrene derivatives exhibited moderate cytotoxicity to all mammalian cells tested, which precludes their use as a bioherbicide.

Amaranthus↗

PubMed2001

Phytotoxic naphthopyranone derivatives from the coprophilous fungus Guanomyces polythrix.

Reinvestigation of the fermentation broth and mycelium of the coprophilous fungus Guanomyces polythrix, grown in static conditions, led to the isolation of several phytotoxic compounds, including two new naphthopyranone derivatives, namely (2S, 3R)-5-hydroxy-6,8-dimethoxy-2,3-dimethyl-2,3-dihydro-4H-naphtho[2,3-b]-pyran-4-one and (2S, 3R)-5-hydroxy-6,8,10-trimethoxy-2,3-dimethyl-2,3-dihydro-4H-naphtho[2,3-b]-pyran-4-one. The structures of the new compounds were established by spectral and chiroptical methods. In addition, the structure of 8-hydroxy-6-methyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ester was unambiguously determined by X-ray analysis. The isolates caused significant inhibition of radicle growth of two weed seedlings (Amaranthus hypochondriacus and Echinochloa crusgalli) and interacted with both spinach and bovine brain calmodulins.

Amaranthus↗

PubMed2001

Antiprotozoal activity of the constituents of Conyza filaginoides.

Bioassay-guided fractionation of the antiprotozoal extract of Conyza filaginoides led to the isolation of three new flavonol caffeoyl glycosides, namely, kaempferol 3-O-(6' '-O-E-caffeoyl)-beta-D-galactopyranoside (1), isorhamnetin 3-O-(6' '-O-E-caffeoyl)-beta-D-galactopyranoside (2), and quercetin 3-O-(6' '-O-E-caffeoyl)-beta-D-glucopyranoside (3). In addition, seven known compounds, erythrodiol (4), beta-caryophyllene-4,5-alpha-oxide (5), astragalin (6), isoquercitrin (7), nicotiflorin (8), narcissin (9), and rutin (10), were obtained. The structures of the new isolates were elucidated by spectroscopic and chemical methods. Compounds were also assessed for antiamoebic and antigiardial activities, but none was significantly active compared to the standard drugs evaluated.

Animals↗

PubMed2001

Biological and mechanistic activities of xanthorrizol and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol isolated from Iostephane heterophylla.

Xanthorrizol (1) and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol (2) were identified as the principal antimicrobial components of a CH(2)Cl(2)-MeOH (1:1) extract derived from Iostephane heterophylla. Compound 2 is a new natural product, but has been synthesized. Both compounds exhibited low level activity (MICs of 16-32 microg/mL) against methicillin-resistant staphylococci and vancomycin-resistant enterococci. They were either inactive or poorly active against Gram-negative bacteria and yeast. Mechanistic studies performed in Escherichia coli imp suggested nonspecific inhibition of DNA, RNA, and protein synthesis by both of these compounds. Compound 1 was tested in an in vivo model; it did not provide protection to mice infected with Staphylococcus aureus.

Animals↗

PubMed2001

Geranins C and D, additional new antiprotozoal A-type proanthocyanidins from Geranium niveum.

Two new additional A-type proanthocyanidins have been isolated from Geranium niveum. Their structures were determined by spectroscopic, chemical and chiroptical methods as epi-afzelechin-(4beta-->8,2beta-->O-->7)-gallocatechin (1) and epi-afzelechin-(4beta-->8,2beta-->O-->7)-afzelechin-(4beta-->8,2beta-->O-->7)-afzelechin (2). Proanthocyanidins 1 and 2 were given the trivial names of geranins C and D, respectively. Compound 2 showed moderate antiprotozoal activity against Entamoeba histolytica and Giardia lamblia, whereas 1 exhibited weak activity toward E. histolytica.

Animals↗

PubMed2000

Effect of lichen metabolites on thylakoid electron transport and photophosphorylation in isolated spinach chloroplasts.

Investigation of the lichen Parmotrema tinctorum led to the isolation of several known compounds. Among them, lecanorin (1), methyl-beta-orcinol carboxylate, methyl orsellinate, orcinol, and methyl haematommate (3) caused significant inhibition of the radicle growth and germination of seedlings of Amaranthus hypochondriacus and Echinochloa crusgalli. In addition, lecanorin (1) and gyrophoric acid (2) significantly inhibited the light-dependent synthesis of ATP and uncoupled electron transfer on the reducing side of photosystem II in freshly lysed, illuminated spinach chloroplasts. The targets of 1 and 2 were located at the water-splitting enzyme level and in one of the redox enzymes in the range of electron transport from P(680) to Q(A), respectively.

Chloroplasts↗

PubMed2000

Phytotoxic compounds from the new coprophilous fungus guanomyces polythrix.

Bioactivity-directed fractionation of the fermentation broth and mycelium of the coprophilous fungus Guanomyces polythrix led to the isolation of several phytotoxic compounds, including five new naphthopyranone derivatives (1-5). In addition, rubrofusarin B, emodin, citrinin, and 4-hydroxybenzoic acid methyl ester were obtained. The structures of the new compounds were established by spectral and chiroptical methods. The isolates caused significant inhibition of radicle growth of two weed seedlings (Amaranthus hypochondriacus and Echinochloa crusgalli) and interacted with both spinach and bovine brain calmodulins.

Animals↗

PubMed2000

New phenylethanoids from Buddleja cordata subsp. cordata.

Bioassay-guided fractionation of a crude extract of the stem bark of Buddleja cordata subsp. cordata with significant antimycobacterial activity led to the isolation of a mixture composed by ten new long-chain esters of 2[4'-hydroxyphenyl]-ethanol (1-10), along with the lichen metabolites methyl beta-orcinolcarboxylate (11) and beta-orcinolcarboxylate (12). Extensive HPLC allowed the separation of the major components of the mixture, which were characterized by spectral means as 2[4'-hydroxyphenyl]-ethyl stearate (3), 2[4'-hydroxyphenyl]-ethyl behenate (6), and 2[4'-hydroxyphenyl]-ethyl lignocerate (8). The minor esters were identified as 2[4'-hydroxyphenyl]-ethyl palmitate (1), 2[4'-hydroxyphenyl]-ethyl heptadecanoate (2), 2[4'-hydroxyphenyl]-ethyl nonadecanoate (4), 2[4'-hydroxyphenyl]-ethyl arachidate (5), 2[4'-hydroxyphenyl]-ethyl tricosanoate (7), 2[4'-hydroxyphenyl]-ethyl pentacosanoate (9), and 2[4'-hydroxyphenyl]-ethyl hexacosanoate (10) by GC-MS analysis of the methyl esters derivatives of the fatty acids obtained by alkaline hydrolysis of the mixture. Compound 8 exhibited moderate antibacterial activity against Mycobacterium tuberculosis (MIC = 64 micrograms/ml).

Glucosides↗

PubMed2000

Bioactive compounds from Celaenodendron mexicanum.

Bioactivity-directed fractionation of the CHCl3-MeOH extract of the leaves of Celaenodendron mexicanum by means of the brine shrimp lethality test and chromatographic techniques led to the isolation of three carboxylic acid triterpenes, the new tirucalla-type triterpene, 3 alpha-hydroxytirucalla-7,24Z-dien-26-oic acid, 3-oxotirucalla-7,24Z-dien-26-oic acid, and epi-oleanolic acid, and three biflavonoids amentoflavone, podocarpusflavone A, and podocarpusflavone B. Four non-active compounds friedelin, maytensifolin B, 3 beta-hydroxyfriedelan-16-one, and celaenodendrolide were also obtained. epi-Oleanolic acid was the most active against brine shrimps with LC50 value of 23.3 microM. In addition, all isolates were tested for in vitro antiprotozoal and cytotoxic activities. 3-Oxotirucalla-7,24Z-dien-26-oic acid and epi-oleanolic acid showed the highest activity against Leishmania donovani promastigotes with IC50 values of 13.7 and 18.8 microM, respectively. Only 3-oxotirucalla-7,24Z-dien-26-oic acid showed activity against Trypanosoma brucei brucei bloodstream forms with IC50 value of 16.8 microM.

Animals↗

PubMed2000

Phytotoxic compounds from Xanthocephalum gymnospermoides var. eradiatum.

Investigation of the aerial parts of Xanthocephalum gymnospermoides var eradiatum led to the isolation of two new labdane-type of diterpenes, namely, 8 alpha,13S-epoxylabdane-14S,15-diol (1) and methyl grindelate (2). In addition, grindelic acid (3), 7 alpha, 8 alpha-epoxygrindelic acid (4), 7 alpha-hydroxy-8(17)dehydrogrindelic acid (5), 17-hydroxygrindelic acid (6) and 4,5-epoxy-beta-caryophyllene (7) were obtained. The isolated compounds were characterized by spectral means. The absolute configuration of compound 1 was established by chemical correlation with 8 alpha,13S-epoxy-15-nor-labdan-14-oic acid methyl ester of known absolute stereochemistry and by using the advanced Mosher's ester methodology. The results of the present investigation indicated that the known compound barbatol (8) could be an enantiomer of compound 1. Compounds 1-3 and 7 caused significant inhibition of the radicle growth of seedlings of Amaranthus hypochondriacus.

Asteraceae↗

PubMed1999

Purpuracenin: a new cytotoxic adjacent bis-tetrahydrofuran annonaceous acetogenin from the seeds of Annona purpurea.

Purpuracenin, a novel cytotoxic acetogenin and annaglaucin, a known compound, were isolated from the seeds of Annona purpurea. Their structures were elucidated by a combination of chemical and spectral methods including MS and NMR spectral measurements. The absolute configurations of both compounds are presented. The new compound and annoglaucin exhibited potent cytotoxic activity in vitro against six human solid tumor cell lines.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Effect of selected coumarins on spinach chloroplast photosynthesis.

Xanthyletin (1), 3-(1',1'-dimethylallyl)xanthyletin (2), and chalepensin (3), the major coumarins isolated from Stauranthus perforatus, inhibit ATP synthesis from water to methylviologen in spinach thylakoids in a concentration-dependent manner. At low concentration chalepensin (3) inhibits basal and phosphorylating electron flow from water to K(3)[Fe(CN)(6)] without affecting uncoupled electron flow but accelerating Mg(2+)-ATPase activity. Thus, at low concentration the compound behaves as an energy transfer inhibitor. However, at higher concentrations this coumarin acts as an uncoupler because it enhances basal and phosphorylating electron transfer. On the other hand, coumarins 1 and 2 act as Hill reaction inhibitors, although 2 exhibited also uncoupler properties because it induces stimulation of basal and phosphorylating electron flow from water to ferricyanide. The site of interference of xanthyletin was located at the b(6)f-PC level of the electron transport chain.

Ca(2+) Mg(2+)-ATPase↗

PubMed1999

Geranins A and B, new antiprotozoal A-type proanthocyanidins from Geranium niveum.

Bioassay-guided fractionation of the antiprotozoal extract of Geranium niveum led to the isolation of two new A-type proanthocyanidins, epi-afzelechin-(4beta-->8, 2beta-->O-->7)-afzelechin (1) and epi-catechin-(4beta-->8, 2beta-->O-->7)-afzelechin (2). Compounds 1 and 2 were given the trivial names of geranins A and B, respectively. In addition, five known compounds, mahuannin B (3), reynoutrin (4), hyperin (5), methyl gallate (6), and 3-beta-caffeoyl-12-oleanen-28-oic acid (7), were obtained. The structures of the new proanthocyanidins were elucidated by spectroscopic and chemical methods as well as CD measurements. Compounds 1, 2, and 4-7 were tested against axenically grown trophozoites of Giardia lamblia and Entamoeba histolytica.

Animals↗

PubMed1999

New phenanthrene derivatives from maxillaria densa(1)

Two new phenanthrene derivatives, 2,5-dihydroxy-3, 4-dimethoxyphenanthrene (1) and 9,10-dihydro-2,5-dihydroxy-3, 4-dimethoxyphenanthrene (2), were isolated from an extract prepared from the whole plant of the orchid Maxillaria densa with spasmolytic activity. In addition, four known compounds, namely 2,7-dihydroxy-3, 4-dimethoxyphenanthrene, 9,10-dihydro-2,7-dihydroxy-3, 4-dimethoxyphenanthrene (3), 2,5-dihydroxy-3,4, 9-trimethoxyphe-nanthrene, and 2,7-dihydroxy-3,4, 9-trimethoxyphenanthrene, were obtained. The structures of the isolated compounds were elucidated by spectroscopic methods. In the case of phenanthrene derivatives 1 and 3, the structures were unambiguously assigned by X-ray analysis.

Journal Article↗

PubMed1999

Tryptamine derived amides and acetogenins from the seeds of Rollinia mucosa.

Bioactivity-directed fractionation of a CHCl(3)-MeOH (1:1) extract prepared from the seeds of Rollinia mucosa led to the isolation of a mixture of eight novel tryptamine amides. Extensive HPLC allowed the isolation of the major component of the mixture, which was characterized as N-lignoceroyltryptamine (6) using a combination of spectroscopic and chemical methods. The minor amides were identified by GC-MS analysis as N-palmitoyltryptamine (1), N-stearoyltryptamine (2), N-arachidoyltryptamine (3), N-behenoyltryptamine (4), N-tricosanoyltryptamine (5), N-pentacosanoyltryptamine (7), and N-cerotoyltryptamine (8). Two lignans (pinoresinol dimethyl ether and magnolin) and six acetogenins [membranacin (9), desacetyluvaricin (10), rolliniastatin 1, bullatacin, squamocin, and motrilin] were also isolated. The cytotoxicity of membranacin (9) and desacetyluvaricin (10) against six human solid tumor cell lines was determined. The absolute configuration of the former is reported.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Nitric oxide/cGMP mediates the spasmolytic action of 3,4'-dihydroxy-5,5'-dimethoxybibenzyl from Scaphyglottis livida.

Five aromatic compounds, 3,4'-dihydroxy-5,5'-dimethoxybibenzyl (1), batatasin III (2), coelonin (3), 3,7-dihydroxy-2,4-dimethoxyphenanthrene (4), and 3,7-dihydroxy-2,4,8-trimethoxyphenanthrene (5) were isolated from the orchid Scaphyglottis livida (Lindley) Schltr. Compounds 1-5 induced a concentration-dependent inhibition of the spontaneous contractions of the rat ileum with potencies comparable or higher to that of papaverine. The relaxation evoked by compounds 1-4 was blocked by L-NAME, an inhibitor of nitric oxide synthase. It was also demonstrated that 1 increased cyclic GMP content in rat ileum rings. Compound 1-induced elevation of cGMP was inhibited by L-NAME and ODQ, inhibitors of nitric oxide synthase and soluble guanylyl cyclase, respectively. These results indicate that nitric oxide/cGMP formation constitute the signaling pathway in the spasmolytic action of compound 1.

Animals↗