Antifeedant activity and toxicity of leaf extracts from Porteresia coarctata Takeoka and their effects on the physiology of Spodoptera litura (F.)

Abstract  Antifeeding and toxic effects of chemical extracts from Porteresia coarctata Takeoka on the insect pest Spodoptera litura (F.) were investigated in the laboratory. Hexane extracts of P. coarctata leaves were re-dissolved in dimethyl sulfoxide and applied in water to leaves of Ricinus communis L. (castor). A concentration of 1,000 and 2,000 ppm extract exhibited significant antifeeding and toxic effects to third instar larvae when compared to the same concentration of dimethyl sulfoxide in water as control. One day after feeding on extract-treated castor leaves, the mortality of S. litura larvae was 50%. Mortality increased to 95% after 11 days at a dosage of 2,000 ppm. Compared to the control, third instar larvae fed on castor leaves treated with P. coarctata leaf extract at different concentrations showed significant reduction in protein and DNA content in the fat body and midgut tissues. Results demonstrate the insecticidal and antifeedant properties of P. coarctata leaf extract against the generalist pest S. litura leading to biochemical changes in the insect body. Thus, P. coarctata contains phytochemicals, and the extract, in crude and pure form, has potential as a botanical insecticide in alternative control strategies against Lepidoptera pests.

Antidiabetic effect of novel modulating peptides of G-protein-coupled kinase in experimental models of diabetes

AbstractAims/hypothesis  G-protein-coupled receptor kinases (GRKs) play a key role in agonist-induced desensitisation of G-protein-coupled receptors (GPCRs) that are involved in metabolic regulation and glucose homeostasis. Our aim was to examine whether small peptides derived from the catalytic domain of GRK2 and -3 would ameliorate Type 2 diabetes in three separate animal models of diabetes.

Antidiabetic actions of estrogen: Insight from human and genetic mouse models

Abstract  There is increasing evidence both in humans and rodents linking the endogenous estrogen 17β-estradiol (E2) to the maintenance of glucose homeostasis. Postmenopausal women develop visceral obesity and insulin resistance and are at increased risk for type 2 diabetes mellitus, but hormone replacement therapy leads to a reduction in the incidence of diabetes. In various spontaneous rodent models of type 2 diabetes, female rodents are protected against hyperglycemia unless they are ovariectomized, and E2 perfusion reverses diabetes in male rodents. Finally, the study of transgenic mice and mice with genetic alteration of E2 secretion or E2 action has shed light on the antidiabetic properties of E2 at a tissue-specific level. Thus, E2 secretion and action in rodents seems to be implicated 1) in adipose tissue biology and the prevention of obesity, 2) in the stimulation of liver fatty acid metabolism and suppression of hepatic glucose production, and 3) in the protection of pancreatic β-cell function/survival and insulin secretion in conditions of oxidative stress.

Anti-cyanobacterial fatty acids released from Myriophyllum spicatum

Abstract  This study was carried out to identify unknown allelochemicals released from Myriophyllum spicatum and to investigate their anti-cyanobacterial effects. A series of analyses of culture solutions and methanol extracts of M. spicatum using gas chromatograph equipped with a mass selective detector revealed that M. spicatum released fatty acids, specifically, nonanoic, tetradecanoic, hexadecanoic, octadecanoic, and octadecenoic acids. Nonanoic, cis-6-octadecenoic, and cis-9-octadecenoic acids significantly inhibited growth of Microcystis aeruginosa, whereas tetradecanoic, hexadecanoic, and octadecanoic acids did not show any effect. When the inhibitory effect of nonanoic acid was compared with those of 4 polyphenols and eugeniin, which are anti-cyanobacterial compounds previously reported to be released by M. spicatum, nonanoic acid was found to be the most inhibitory to M. aeruginosa. These results indicate that not only polyphenols and eugeniin but also fatty acids such as nonanoic acid must be studied to reveal how M. spicatum exerts its allelopathic effect on M. aeruginosa.

Antibacterial activity of a bacteriocin-like substance produced by Bacillus sp. P34 that targets the bacterial cell envelope

Abstract  The objective of this study was to investigate the mode of action of BLS P34, a bacteriocin-like substance (BLS) produced by a novel Bacillus sp. strain P34 isolated from the Amazon basin. The effect of the BLS was tested against Listeria monocytogenes, showing a bactericidal effect at 200 AU (activity units) ml−1, while no inhibition of spore outgrowth of Bacillus cereus was observed with a dose of 1,600 AU ml−1. Growth of Escherichia coli and Salmonella Enteritidis was inhibited, but only when the chelating agent EDTA was co-added with the BLS. The effect of BLS P34 on L. monocytogenes was also investigated by Fourier transform infrared spectroscopy. Treated cells showed an important frequency increase in 1,452 and 1,397 cm−1 and decrease in 1,217 and 1,058 cm−1, corresponding assignments of fatty acids and phospholipids. Transmission electron microscopy showed damaged cell envelope and loss of protoplasmic material. BLS P34 was bactericidal to Gram-positive, and also showed inhibitory effect against Gram-negative bacteria. There is evidence that its mode of action corresponds to that of a membrane-active substance. The knowledge about the mode of action of this BLS is essential to determine its effective application as an antimicrobial agent.

Antiatherogenic components of olive oil

Abstract  Olive oil is the principal source of fat in the Mediterranean diet, which has been associated with a lower incidence of coronary heart disease and certain cancers. Olive oil is characterized by a high proportion of monounsaturated oleic acid, but the main peculiarity of extra-virgin oil is the presence of remarkable quantities of phenolic compounds, notably hydroxytyrosol and oleuropein, that provide high stability and strong taste. Recently, several studies have demonstrated that olive oil phenolics are powerful antioxidants, both in vitro and in vivo, and exert additional potent biologic activities that could partially account for the observed cardioprotective effects of the Mediterranean diet.

Antiarrhythmic and electrophysiological effects of long-chain ω-3 polyunsaturated fatty acids

Abstract  Recent studies indicate that a diet enriched in -3 polyunsaturated fatty acids may prevent sudden cardiac death. The goal of the present study was to elucidate how -3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and -linolenic acid (ALA; 1–20 M) may affect the cardiac activation and repolarization pattern. For this reason, DHA, EPA or ALA was infused in spontaneously beating isolated rabbit heart (Langendorff technique) and subjected to 256 electrodes epicardial mapping. All compounds exhibited a negative inotropic and chronotropic effect. EPA and ALA, but not DHA, prolonged QTc. The dispersion was enhanced at higher concentrations (>5 M) by DHA and less (or not affected) by the others. The total activation time, reflecting ventricular conduction, was prolonged predominantly by DHA and to a lower extent by the other drugs. Atrioventricular conduction time was slowed only by DHA and EPA. To analyze of the pattern of activation, we determined the timepoint of activation as t(dU/dtmin) for all 256 electrodes. The beat-to-beat similarity of these patterns was moderately reduced by all drugs. Regarding antiarrhythmic activity we found that the threshold for elicitation of a ventricular extrasystole was concentration-dependently enhanced by DHA and EPA, but not by ALA. DHA dose-dependently reduced longitudinal propagation velocity VL and to a lower extent transverse velocity VT. Anisotropy was not significantly changed. EPA and ALA did not exhibit a systematic effect on VL or VT. These results clearly demonstrate that DHA, EPA, and ALA exhibit direct electrophysiological effects with different profiles.