On the pharmacology of oxidative burst of human neutrophils.

The effect of three therapeutically used drugs and five polyphenolic compounds on the mechanism of oxidative burst was compared in whole blood and isolated neutrophils at cellular and molecular level. In 10 microM concentration, the compounds investigated decreased the oxidative burst of whole blood in the rank order of potency: N-feruloylserotonin (N-f-5HT) > curcumin (CUR) > quercetin (QUER) > arbutin (ARB) > resveratrol (RES) > dithiaden (DIT) > carvedilol (CARV) > brompheniramine (BPA). The ratio between the percentage inhibition of extracellular versus intracellular chemiluminescence (CL) followed the rank order QUER > N-f-5HT > RES > CUR > DIT and is indicative of the positive effect of the compounds tested against oxidative burst of neutrophils, demonstrating suppression of reactive oxygen species extracellularly with minimal alteration of intracellular reactive oxygen species (ROS). Activation of protein kinase C was significantly decreased by DIT, CUR, QUER and N-f-5HT. CARV, DIT, QUER and ARB reduced activated neutrophil myeloperoxidase release more significantly compared with the effect on superoxide anion generation. All compounds tested increased the activity of caspase-3 in cell-free system. It is suggested that other regulatory mechanisms than protein kinase C might participate in the inhibition of neutrophil activation with the compounds tested. Different mechanisms are concerned in controlling the assembly of NADPH oxidase and the regulatory role of calcium ions is suggested. Compounds decreasing the amount of extracellular ROS generation, yet affecting but minimally intracellular ROS generation, are promising for further investigation in vivo.

The selective effect of N-feruloylserotonins isolated from Leuzea carthamoides on nociception and anxiety in rats.

The effects of N-feruloylserotonins, substances isolated from the seeds of Leuzea carthamoides (WILLD.) DC., on nociception and anxiety were studied in Wistar rats. Nociceptive responses were measured using the plantar and tail-flick tests which were administered before and after swimming stress (3 min, water temperature 32 degrees C). Anxiety was evaluated using an elevated plus maze. In Experiment I, neither basal nociception nor stress-induced analgesia was influenced significantly. Separating the animals into groups based on their basal nociceptive sensitivity, either high- or low-pain threshold revealed that N-feruloylserotonins have selective effects, especially on rats with high-pain thresholds. In these animals, N-feruloylserotonins reduced the stress-induced analgesia that followed swimming stress. In Experiment II, basal nociceptive sensitivity correlated with indicators of anxiety; high-pain threshold rats were more anxious in the elevated plus maze, with less frequent visits to open arms. The opposite effect was seen in low-pain threshold rats. N-feruloylserotonins did not influence anxiety in low-pain threshold rats, although it reduced anxiety in the high-pain threshold rats as indicated by the increased ratio of open arm visit frequency compared to closed arm visit frequency in the elevated plus maze. From these results we concluded that N-feruloylserotonins have selective stress-reducing effects in stress-sensitive animals.

Chromatographic procedures for the isolation of plant steroids.

In this review, we consider the general principles and specific methods for the purification of different classes of phytosteroids which have been isolated from plant sources: brassinosteroids, bufadienolides, cardenolides, cucurbitacins, ecdysteroids, steroidal saponins, steroidal alkaloids, vertebrate-type steroids and withanolides. For each class we give a brief summary of the characteristic structural features, their distribution in the plant world and their biological effects and applications. Most classes are associated with one or a few plant families, e.g., the withanolides with the Solanaceae, but others, e.g., the saponins, are very widespread. Where a compound class has been extensively studied, a large number of analogues are present across a range of species. We discuss the general principles for the isolation of plant steroids. The predominant methods for isolation are solvent extraction/partition followed by column chromatography and thin-layer chromatography/HPLC.

Synergistic insecticidal mode of action between sesquiterpene lactones and a phototoxin, alpha-terthienyl.

The synergistic insecticidal action of characteristic defensive substances produced by the plant family Asteraceae was investigated under controlled laboratory conditions. Sesquiterpene lactones isolated from Asteraceae that may form, through a Michael addition process, conjugates with glutathione were administered in a meridic diet to a herbivorous insect, Manduca sexta. By administering sesquiterpenes, variable in vivo reduced glutathione levels were observed in the insect larvae. When the Asteraceae-derived photooxidant alpha-terthienyl was co-administered, lipid peroxidation and larval mortality were significantly enhanced in the treated groups of insects with lowered in vivo glutathione levels.

Biological activity of natural and synthetic ecdysteroids in the BII bioassay.

The potencies of 19 ecdysteroids are compared in the BII bioassay, which reflects the affinity of binding to the ligand binding site of the Drosophila melanogaster ecdysteroid receptor. The compounds tested represent either natural products isolated from plants (phytoecdysteroids) or fungi (mycoecdysteroids) or synthetic analogues based on insect metabolites (zooecdysteroids). None of the tested compounds showed any antagonistic activity, but all possessed quantifiable agonistic activity. All the mycoecdysteroids were less potent than the major insect ecdysteroid, 20-hydroxyecdysone (20E). Also, conjugation of 20E with a glucose moiety results, as expected, in considerable reduction in biological activity, but the remaining activity is dependent on the position of conjugation. The implications of these findings for the structure/activity relationship of ecdysteroids are discussed.

Effects of pyrrolizidine alkaloids and sesquiterpenes on snail feeding.

We determined in the laboratory the feeding response of two populations of the generalist herbivorous snail Arianta arbustorum (Helicidae) towards the composite Adenostyles alliariae and towards various allelochemicals. These were: a pyrrolizidine alkaloid (PA) extract of Adenostyles leaves; senecionine (a PA present in Adenostyles); retrorsine (a PA not present in Adenostyles) and two sesquiterpene (ST) fractions from Adenostyles: a mixture of the STs adenostylone and neoadenostylone, and deacyladenostylone. Tertiary PAs and PA N-oxides were tested separately. For each allelochemical, we tested whether it was deterrent or whether it induced changes of feeding behaviour (i.e. whether it had pre- or postingestive effects), and whether the effects were more pronounced with younger (smaller) snails. The tertiary PA extract from Adenostyles was deterrent, especially for young snails, but did not induce changes of feeding behaviour. Tertiary PA senecionine was deterrent for young snails only and induced changes of feeding behaviour. Also, consumption of untreated Petasites was higher after this treatment. Tertiary PA retrorsine was not deterrent, but induced changes of feeding behaviour. The PA N-oxides showed no activity against the snails. The mixture of adenostylone and neoadenostylone was deterrent and induced feeding aversions. Deacyladenostylone was highly deterrent, but did not induce changes of feeding behaviour. At the Jura site, PA content of Adenostyles was lower than at the Black Forest site. The snails from Jura consumed much less Adenostyles than the snails from Black Forest, and also ate a little less of the treated leaf discs. The PAs which are encountered by the snails in their natural food plants (PA extract and senecionine) were more deterrent than retrorsine (a novel compound). This suggests that the snails have mechanisms for the rejection of allelochemicals which they encounter in their natural food plants, but not for novel allelochemicals. The results suggest two hypotheses regarding the function of the allelochemicals in Adenostyles: (1) The allelochemicals act mainly on very young snails. (2) PAs render Adenostyles toxic, while STs act as feeding deterrents.