Eloy Rodriguez

Chemistry of preen gland secretions of passerines: different pathways to same goal? why?

Summary.Passeriformes is the largest order of birds and includes one third of the bird species of the world, living in very diverse habitats. We investigated the chemistry of preen gland secretions of some groups of passerines from temperate regions found in diverse microhabitats. Some of the common components were mixtures of homologous monoesters made up of long chain acids and alcohols. Individual species had characteristic distribution of esters and was unique to a given species, although there were some individual variations. We compared the composition of acids and alcohols that formed same molecular weight esters in different species and we found that the combination of acids and alcohols to arrive at same molecular compositions varied distinctly between species. To compare compositions of over all acids and alcohols that formed the esters, the representative samples of secretions from the individual species were transesterfied the produce methyl esters and alcohols. We found that there were distinct differences in number of acids and alcohols that produced the combination of homologous mixtures of esters. Also they differed both qualitatively and quantitatively. There were also seasonal differences in the secretion components. Thus though the intact mixtures of esters in individual species had some similarities, they were very complex mixtures and differed characteristically for individual species. Here we discuss possible causes for evolution of these variations. We suggest that the evolution in variation of preen gland secretion is probably due to selective pressures caused by ectosymbionts such as feather-mites and feather-chewing lice that live on feathers and probably feed on the secretions and surrounding environments

In vitro neuropharmacological evaluation of piperovatine, an isobutylamide from Piper piscatorum (Piperaceae)

Piperovatine, a sialogogic, piscicidal, and buccal local anesthesia producing isobutyl amide from the amazonian piscicidal and toothache-relieving plant, Piper piscatorum Trelease et Yuncker (Piperaceae), was evaluated for its ability to induce changes in neuronal intracellular calcium concentration. Ratiometric calcium imaging of Periplaneta americana neuronal cell cultures upon piperovatine application revealed that this compound induced dramatic increases in intracellular calcium concentration. Calcium flux was not affected by co-application of the muscarinic acetylcholine receptor antagonist, atropine, indicating that the parasympathomimetic system was not involved in piperovatines sialogogic actions. Calcium flux was, however, totally eliminated by co-application of the voltage-gated sodium channel blocker, tetrodotoxin (TTX). This, in conjunction with the repetitive calcium spikes observed in the assay and previous radioligand binding studies on the chemical class, strongly suggest that activation of voltage-gated sodium channels characterizes piperovatines mode of action

Piscicidal properties of piperovatine from Piper piscatorum (Piperaceae)

Extraction of the roots of the Amazonian medicinal plant, Piper piscatorum Trelease and Yuncker, with MeOH and subsequent bioassay guided fractionation using the guppy, Girardina guppii yielded the active amide, N-isobutyl-6-(p-methoxyphenyl) 2E, 4E-hexadieneamide (piperovatine) and a second inactive amide, N-isobutyl-(E)-7-(3,4-methylenedioxyphenyl)hept-2-enamide (pipercallosidine). The former displayed an LC50 of 115 ng/ml in toxicity tests and proved to be the constituent responsible for the dual ethnobotanical uses of this plant: that of fish stupefacient (barbasco) and oral local anesthetic.

Phenolics, Sugars, Antimicrobial and Free-Radical-Scavenging Activities of Melicoccus bijugatus Jacq. Fruits from the Dominican Republic and Florida

Edible fruits of the native South American tree Melicoccus bijugatus Jacq. are consumed fresh or in traditional food, drink and medicinal preparations. Some therapeutic effects of these fruits may be due to phenolics and sugars. Aqueous acetone, methanol or ethanol tissue extracts of different cultivars or collections of M. bijugatus fruits from the Dominican Republic and Florida were analyzed for total phenolics and free radical scavenging activity by UV-vis spectroscopy, sugars by gas chromatography, and antimicrobial activity by the disc diffusion assay. Total phenolics and free radical scavenging activities ranked: seed coat > embryo > pulp extracts. Montgomery cultivar fruits had the highest total phenolics. For sugars: pulp > embryo and highest in Punta Cana fruit pulp. In all extracts: sucrose > glucose and fructose. Glucose:fructose ratios were 1:1 (pulp) and 0.2:1 (embryo). Pulp extracts had dose-response antibacterial activity and pulp and embryo extracts had antifungal activity against one yeast species. Phenolics and sugars were confirmed with thin-layer chromatography and nuclear magnetic resonance. Sugar-free pulp fractions containing phenolics had slightly more antimicrobial activity than H2O-soluble pulp fractions with sugars. Results indicate M. bijugatus fruits contain phenolics, sugars and other H2O-soluble compounds consistent with therapeutic uses.

Biology of House Finch feather mites, Proctophyllodes pinnatus (Acari: Proctophyllodidae), parallels variation in preen gland secretions

ABSTRACT Except for Dubinins classic works in the 1950s, there is very little information on the natural history or population dynamics of feather mites (Astigmata: Acariformes, Pterolichoidea). We studied variation in numbers of the different life stages of the feather mite Proctophyllodes pinnatus (Nitzsch) (Analgoidea: Proctophyllodidae) on captive House Finches Carpodacus mexicanus (Müller) (Passeriformes: Fringillidae) from December 2003 to November 2004. Simultaneously, we also studied how preen gland secretion varied in those birds. We monitored 20 House Finches (10 individuals of each sex) for the presence of mites on their wing feathers. There was seasonal variation in the abundance and prevalence of mites on different individual birds. Most birds did not show any mites from December to April. Mite numbers started to increase in July and peaked in August–September. In September, we observed more mites of early stages than in any other months. We also observed higher proportions of adults in August and October and fewer adults than expected in September, suggesting that more than one generation was involved. By November, very few mites were present on the wing feathers. The variation in mite numbers paralleled variation in the composition and quantity of preen gland secretions produced by the host House Finches. In most of the captive birds, secretion peaked in the month following peak mite-abundance. During the period when mite abundance was highest, secretions contained a higher diversity of chemicals. Prevalence of mites on wild House Finches showed similar trends to those observed in captive birds. Relative abundances of life stages on wild birds collected in July were similar to those observed for captive House Finches in the same month.

Fate of the chromene encecalin in the interaction ofEncelia farinosa and its specialized herbivoreTrirhabda geminata

Leaf beetles of the speciesTrirhabda geminata are specialized herbivores that are able to feed on the chemically well-protected foliage of the desert sunflowerEncelia farinosa, which contains the insecticidal chromene derivative encecalin. Chemical analysis of the beetles and their fecal excretions indicated that encecalin is present only in the alimentary canal and is not absorbed across the gut membrane, as previously shown for other herbivorous insects (e.g., the Egyptian armyworm,Spodoptera littoralis) that are susceptible to this chromene derivative. Further differences betweenT. geminata and nonadapted insects were observed with regard to the metabolism of encecalin. Whereas the encecalin-resistent leaf beetles metabolize encecalin mainly to encecalol by reduction of the acetyl group, susceptible insects, such as larvae ofS. littoralis, metabolize encecalin mainly by exoxidation of the 3,4 double bond, which creates a powerful alkylating agent and is responsible for the toxicity of encecalin. Reductive rather than oxidative metabolism of encecalin therefore seems important for the resistance ofT. geminata against the chemical defense of their host plantE. farinosa.