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Biomedical subjects

A D Rodríguez

Publications and source records attributed to A D Rodríguez.

At least 19 recordsLinked to original sources
PubMed1998

Methoxyamericanolide B.

The title compound, C16H20O5, was isolated from the gorgonian coral P. americana found in the Caribbean zone of the West Indies. The compound belongs to a well known family of sesquiterpenoid lactones. Its structure features a guaiane skeleton incorporating three types of oxygen functionalities. Thus, the five O atoms that are incorporated in the skeleton form two epoxy groups, a lactone moiety and an ether link. This study assigns the relative stereochemistry at the six chiral centers as 1R, 2R, 4S, 5S, 8R, 10S.

Animals↗
PubMed1998

New cembranolides from the gorgonian Eunicea succinea.

A new chemical study of the Caribbean gorgonian Eunicea succinea collected in Puerto Rico afforded seven new cembranolides (1-5, 7, and 8). Excepting 1, the new compounds described here possess an unusual unsaturation at either position C-1, C-6, or C-8, and all but 8 possess the C-12R, C-13S stereochemistry usually ascribed to cembranolides from E. succinea. Their chemical structures were carefully established by a combination of chemical and spectroscopic methods in addition to detailed NMR spectral comparisons with known cembranolide models.

Animals↗
PubMed1998

Pseudopterane and norcembrane diterpenoids from the Caribbean sea plume Pseudopterogorgia acerosa.

A chemical study of the common Caribbean sea plume Pseudopterogorgia acerosa from Puerto Rico has produced two previously undescribed secondary metabolites. One of them, 1, is a new representative of the pseudopterane family of diterpenes possessing the uncommon 3,4;5,6 diepoxyfuran moiety. The other metabolite, 2, is a rare norcembranolide diterpene. Their chemical structures, including relative stereochemistry, were established by detailed analysis of the spectral data in addition to NMR spectral comparisons with known pseudopterane and cembrane models.

Animals↗
PubMed1998

Identification and total synthesis of novel fatty acids from the Caribbean sponge Calyx podatypa.

The phospholipid fatty acid composition of the Caribbean sponge Calyx podatypa was studied, and 85 different fatty acids were identified, in particular the 11-methylpentadecanoic acid and 10-tricosenoic acid, which have no literature precedence. Structural characterization was accomplished by means of gas chromatography-mass spectrometry on their corresponding methyl esters and dimethyl disulfide derivatives. The structure of 11-methylpentadecanoic acid was further confirmed by total synthesis (17% overall yield) starting from commercially available 10-hydroxydecanoic acid.

Animals↗
PubMed1998

Resistance management strategies in malaria vector mosquito control. Baseline data for a large-scale field trial against Anopheles albimanus in Mexico.

A high level of DDT resistance and low levels of resistance to organophosphorus, carbamate and pyrethroid insecticides were detected by discriminating dose assays in field populations of Anopheles albimanus in Chiapas, southern Mexico, prior to a large-scale resistance management project described by Hemingway et al. (1997). Biochemical assays showed that the DDT resistance was caused by elevated levels of glutathione S-transferase (GST) activity leading to increased rates of metabolism of DDT to DDE. The numbers of individuals with elevated GST and DDT resistance were well correlated, suggesting that this is the only major DDT resistance mechanism in this population. The carbamate resistance in this population is conferred by an altered acetylcholinesterase (AChE)-based resistance mechanism. The level of resistance observed in the bioassays correlates with the frequency of individuals homozygous for the altered AChE allele. This suggests that the level of resistance conferred by this mechanism in its heterozygous state is below the level of detection by the WHO carbamate discriminating dosage bioassay. The low levels of organophosphate (OP) and pyrethroid resistance could be conferred by either the elevated esterase or monooxygenase enzymes. The esterases were elevated only with the substrate pNPA, and are unlikely to be causing broad spectrum OP resistance. The altered AChE mechanism may also be contributing to the OP but not the pyrethroid resistance. Significant differences in resistance gene frequencies were obtained from the F1 mosquitoes resulting from adults obtained by different collection methods. This may be caused by different insecticide selection pressures on the insects immediately prior to collection, or may be an indication that the indoor- and outdoor-resting A. albimanus collections are not from a randomly mating single population. The underlying genetic variability of the populations is currently being investigated by molecular methods.

Acetylcholinesterase↗
PubMed1998

Characterization of cembranoid interaction with the nicotinic acetylcholine receptor.

The class of diterpenoids with a 14-carbon cembrane ring, the cembranoids, includes both competitive and noncompetitive inhibitors of the nicotinic acetylcholine receptor (AChR). All 20 coelenterate-derived cembranoids studied in this report inhibited [piperidyl-3,4-3H]-phencyclidine ([3H]-PCP) binding to its high-affinity site on the electric organ AChR, with IC50s ranging from 0.9 microM for methylpseudoplexaurate to 372 microM for lophotoxin. Inhibition was complete with all cembranoids but lophotoxin and most Hill coefficients were close to 1. Methylpseudoplexaurate and [3H]-PCP binding was competitive. Methylpseudoplexaurate and the fourth most potent cembranoid, eunicin, competed with each other for [3H]-PCP displacement, indicating that there exist one or more cembranoid sites on the AChR. Cembranoid affinity for the AChR correlated with hydrophobicity, but was also dependent on other features. Methylpseudoplexaurate and n-octanol also competed with each other for [3H]-PCP displacement, indicating that the cembranoid site is linked to the n-octanol site on the AChR. Unlike lophotoxin, the five cembranoids tested did not inhibit [125I]Tyr54-alpha-bungarotoxin binding to the AChR agonist sites. All seven cembranoids tested on oocyte-expressed electric organ AChR reversibly blocked acetylcholine-induced currents, although the inhibitor concentration curves were shallow and the inhibition was incomplete.

Acetylcholine↗
PubMed1997

Euniciniatin.

Euniciniatin [4(S),7(R)-epoxy-3(R)-hydroxy-1(R),11(S) -dolabella-8(Z),12(18)-dien-13-one; (1R,3R,4S,7R,11S) -3-hydroxy-12-isopropylidene-15-oxa-1,4,8-trimethyltricyclo [9.3.0.1(4,7)]pentadec-8(Z)-3n-13-one], C20H30O3, was synthesized from a known dolabellane constituent of E. laciniata, namely, dolabellatrienone. The structure of this compound has a trans-bicyclo[9.3.0]tetradecane nucleus containing an additional 4,7-oxa bridge. The three O atoms in the molecule all belong to different functional groups, i.e. one is part of an ether bridge [O(3)-C(4) 1.452 (5) and O(3)-C(7) 1.429 (5) A], one an alcohol [O(2)-C(3) 1.429 (6) A] and one a ketone [O(1)-C(13) 1.233 (5) A].

Crystallography, X-Ray↗
PubMed1997

Identification of the novel antimicrobial fatty acid (5Z,9Z)-14-methyl-5,9-pentadecadienoic acid in Eunicea succinea.

The phospholipid fatty acid composition of Eunicea succinea was investigated, and the novel (5Z,9Z)-14-methyl-5,9-pentadecadienoic acid was identified. Structural characterization was accomplished by means of mass spectrometry of its pyrrolidide derivative, NMR, FT1R, and total synthesis. Other interesting phospholipid fatty acids in E. succinea were the tetracosapolyenoic acids 6,9,12,15,18,21-tetracosahexaenoic acid (24:6) and 6,9,12,15,18-tetracosapentaenoic acids (24:5). The title compound was particularly active against Gram-positive bacteria such as Staphylococcus aureus (MIC 0.24 mumol/mL) and Streptococcus faecalis (MIC 0.16 mumol/ mL).

Animals↗
PubMed1997

The calyxolanes: new 1,3-diphenylbutanoid metabolites isolated from the Caribbean marine sponge Calyx podatypa.

Calyxolanes A (1) and B (2) are rare 1,3-diphenylbutanoid compounds isolated from the marine sponge Calyx podatypa collected in Puerto Rico. Their structures, including relative stereochemistry, have been determined by spectroscopic methods. The unique 2,4-diphenyloxolane function in 1 and 2 was established by 2D 1H-1H and 1H-13C NMR correlation experiments and confirmed by mass spectral analysis. A suggestion is made as to their biogenetic origin.

Animals↗
PubMed1997

Calyxamines A and B, novel piperidine alkaloids from the Caribbean sea sponge Calyx podatypa.

Calyxamines A (1) and B (2) are 2,2,4,6,6-pentasubstituted piperidine alkaloids possessing novel carbon skeletons isolated from the marine sponge Calyx podatypa collected in Puerto Rico. Their structures, after derivatization with trifluoroacetic acid, have been determined by a combination of X-ray and spectroscopic methods. A plausible biogenetic pathway to the calyxamines is suggested.

Alkaloids↗
PubMed1997

A comparison of two collection methods for estimating abundance and parity of Anopheles albimanus in breeding sites and villages of southern Mexico.

The abundance and age structure of Anopheles albimanus populations were estimated by UV updraft light traps and human landing catches within villages and in nearby breeding sites of southern México. Four villages and 5 breeding sites were selected for the study. Light trap and human landing catches were simultaneously carried out in each breeding site and each village. Anopheles albimanus was the most abundant malaria vector caught in breeding sites and in villages. Significant differences in overall An. albimanus abundance among villages and among breeding sites were detected only by human landing catches. In both villages and breeding sites, more mosquitoes were captured by 1 human bait (34.3 +/- 6.3 and 14.6 +/- 2.9, respectively) than by one light trap (15.9 +/- 3.3 and 2.4 +/- 0.3 respectively) collection. After pooling, no significant differences were detected in the abundance estimated by each method in breeding sites and villages. A significant correlation of numbers of specimens between methods was detected. Age structure was different between samples from breeding sites and villages, with more gravid females collected in breeding sites, whereas more nulipars were collected in villages. By collection method, age structure was also different both in breeding sites and in villages. In breeding sites, the percentage of parous females was significantly higher in human landing catches, whereas the percentage of gravid females was significantly higher in light traps. In villages, only the percentage of gravid females was significantly higher in light traps. Our results suggests that UV light traps could be used to measure several entomological parameters of An. albimanus populations because both abundance variations and parity rates were similarly detected by both methods.

Animals↗
PubMed1996

Phospholipid fatty acid composition of gorgonians of the genus Pseudopterogorgia: identification of tetracosapolyenoic acids.

The phospholipid fatty acid composition of the Caribbean gorgonians Pseudopterogorgia acerosa (Pallas), Pseudopterogorgia americana (Gmelin), Pseudopterogorgia bipinnata (Verrill) and Pseudopterogorgia rigida (Bielschowsky) is described for the first time. The main phospholipids identified were phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine. All four gorgonians presented a similar phospholipid fatty acid composition. The main fatty acids were 16:0, 18:3(n-6), 18:4(n-3), 20:4(n-6), 22:6(n-3), 24:5(n-6) and 24:6(n-3). In all of the studied Pseudopterogorgia gorgonians, high amounts of the tetracosapolyenoic fatty acids 24:5(n-6) and 24:6(n-3) were identified. In the four gorgonians studied, n-6 polyunsaturated fatty acids predominated. These results suggest that the occurrence of tetracosapolyenoic fatty acids in the Gorgoniidae is more general than previously recognized.

Animals↗
PubMed1996

Five new pseudopterane diterpenes from the Caribbean sea plume Pseudopterogorgia acerosa Pallas, Gorgonacea.

Five new pseudopteranoid diterpenes, pseudopteradiene (2), pseudopteradienoic acid (3), 11-pseudopteranol (4), pseudopteranoic acid (5), and diepoxygorgiacerodiol (7), along with five previously described analogues, have been isolated from Puerto Rican specimens of the gorgonian octocoral Pseudopterogorgia acerosa. Detailed analysis of the spectral data and chemical methods were used to establish their structures and to define the relative stereochemistry.

Animals↗
PubMed1995

Effect of alkaloid toxins from tropical marine sponges on membrane sodium currents.

Dibromosceptrin and clathrodin are alkaloid compounds purified from tropical marine sponges of the genus Agelas. Experiments done using the whole cell configuration of the patch clamp technique revealed that these compounds have neurotoxic activity. Both compounds decreased by 27-40% the average maximum amplitudes of pharmacologically isolated inward sodium currents in cells isolated from chick embryo sympathetic ganglia. Current-voltage data, fitted using Boltzmann's equation, did not show any effect of these agents on the voltage dependence of current activation. However, the voltage dependence of current inactivation was shifted toward more negative potentials by dibromosceptrin, changing by an average of 20 mV the voltage for 50% inactivation. In contrast, clathrodin shifted this voltage dependence of inactivation toward more positive potentials and changed the voltage for 50% inactivation by 14 mV. Time for current reactivation was not altered by clathrodin but was slightly prolonged by dibromosceptrin. Similarly, dibromosceptrin was more effective than clathrodin in delaying the time course of current decay. Thus, these two alkaloids appear to be new sodium channel neurotoxins acting through different mechanisms, dibromosceptrin modifying the channel inactivation characteristics and clathrodin probably influencing channel ionic conductance.

Alkaloids↗
PubMed1995

Additional dolabellane diterpenes from the Caribbean gorgonian octocoral Eunicea laciniata.

The Caribbean gorgonian octocoral Eunicea laciniata from the coasts of Palomino Island, Puerto Rico, has yielded four known and five new diterpenes based on the dolabellane ring system. The structures of the novel compounds 3-7 were established by interpretation of their spectral data. Some of these new compounds showed weak cytotoxicity against HeLa cells.

Animals↗
PubMed1995

Studies on the minor constituents of the Caribbean gorgonian octocoral Briareum asbestinum Pallas. Isolation and structure determination of the eunicellin-based diterpenoids briarellins E--I.

Five new eunicellin-type diterpenoids, briarellins E--I, along with several known diterpenoids of the asbestinane, briarane and eunicellane classes, were isolated from the Caribbean gorgonian octocoral Briareum asbestinum collected in Puerto Rico. The structures of these compounds were established on the basis of spectroscopic evidence.

Animals↗