Antifeedant C20 diterpene alkaloids.

We have tested the insect antifeedant and toxic activity of 21 C20 diterpenoid alkaloids on Spodoptera littoralis and Leptinotarsa decemlineata. The antifeedant effects of the test compounds were structure- and species-dependent. The most active antifeedants to L.

Antifeedant/insecticidal terpenes from asteraceae and labiatae species native to Argentinean semi-arid lands.

To validate the potential as added-value resources of Asteraceae and Labiatae species of Argentinean semi-arid lands, we have selected 13 of their major terpenoids belonging to several chemical classes and tested their insect antifeedant and toxic activity on the herbivorous insects Spodoptera littoralis and Leptinotarsa decemlineata. The antifeedant effects of the test compounds were structure- and species-dependent. The most active antifeedant to L.

Diterpenes from Salvia broussonetii transformed roots and their insecticidal activity.

The new diterpenes brussonol (1) and iguestol (6alpha,11-dihydroxy-12-methoxy-abieta-8,11,13-triene) (2) with an icetexane and a dehydroabietane skeleton, respectively, have been isolated from hairy root cultures of Salvia broussonetii. Other previously known diterpenes, 7-oxodehydroabietane, 11-hydroxy-12-methoxyabietatriene, taxodione, inuroyleanol, ferruginol, deoxocarnosol 12-methyl ether, cryptojaponol, pisiferal, sugiol, isomanool, 14-deoxycoleon U, 6alpha-hydroxydemethylcryptojaponol, demethylsalvicanol, and demethylcryptojaponol, were also obtained from these roots. The insect antifeedant and toxic effects of several of these compounds were investigated against the insect pests Spodoptera littoralis and Leptinotarsa decemlineata.

Bioactive cinchona alkaloids from Remijia peruviana.

Three known Cinchona alkaloids of the quinine type, quinine (1), cupreine (2), cinchonine (3), and the possible artifact cinchonine-HCl (3-HCl), along with two new ones, acetylcupreine (4) and N-ethylquinine (5), have been isolated from the bark of Remijia peruviana (Rubiaceae). Their stereochemical structures were established by high resolution NMR spectroscopy. Alkaloids 2-4 had antifeedant effects on Leptinotarsa decemlineata with varying potencies.

Structural diversity and defensive properties of norditerpenoid alkaloids.

We have tested the insect antifeedant and toxic activity of 43 norditerpenoid alkaloids on Spodoptera littoralis and Leptinotarsa decemlineata including eserine (physostigmine), anabasine, and atropine. Antifeedant effects of the test compounds were structure- and species-dependent. The most active antifeedants to L.

Allelochemical potential of Callicarpa acuminata.

The allelochemical potential of Callicarpa acuminata (Verbenaceae) was investigated by using a biodirected fractionation study as part of a long-term project to search for bioactive compounds among the rich biodiversity of plant communities in the Ecological Reserve El Eden, Quintana Roo, Mexico. Aqueous leachate, chloroform-methanol extract, and chromatographic fractions of the leaves of C. acuminata inhibited the root growth of test plants (23-70%).

Insecticidal sesquiterpene pyridine alkaloids from Maytenus chiapensis.

The new sesquiterpene pyridine alkaloids chiapenines ES-I (1), ES-II (2), ES-III (3), and ES-IV (4), in addition to the known alkaloids wilfordine (5), alatamine (6), wilforidine (7), alatusinine (8), euonine (9), euonymine (10), ebenifoline E-I (11), forrestine (12), mayteine (13), and 4-hydroxy-7-epi-chuchuhuanine E-V (14), were isolated from the leaves of Maytenus chiapensis. Their structures were elucidated by 1D and 2D NMR spectroscopy, including homonuclear and heteronuclear correlation (COSY, ROESY, HSQC, and HMBC) experiments. Wilfordine, alatusinine, and euonine exhibited strong antifeedant activity against Spodoptera littoralis.

Selective action of acetogenin mitochondrial complex I inhibitors.

Five annonaceous acetogenins, rolliniastatin-1 [structure: see text], rolliniastatin-2 [structure: see text], laherradurin [structure: see text], squamocin [structure: see text], annonacin [structure: see text], and rotenone as a reference, differing in their NADH oxidase inhibition activity, have been evaluated for antifeedant, insecticidal, trypanocidal and cytotoxic effects on insect, mammalian and tumor cells. All the test compounds were toxic to Leptinotarsa decemlineata, demonstrated selective cytotoxicity to insect Sf9 cells and a panel of tumor cell lines with the multidrug-resistant SW480 (P-glycoprotein+, Pgp+) being the most sensitive one. Compounds [structure: see text] and rotenone had post-ingestive effects against Spodoptera littoralis larvae while [structure: see text] and rotenone were active against Trypanosoma cruzi.

Antifeedant effects of marine halogenated monoterpenes.

In this work the antifeedant effects of the halogenated monoterpenes 1-13 were tested against several divergent insect species. These compounds have been isolated from Plocamium cartilagineum (6 was isolated as an acetyl derivative), except for 4, which was isolated from Pantoneura plocamioides. We have also included the semisynthetic derivatives 1a, 2a, and 7.

Antifeedant Delphinium Diterpenoid Alkaloids. Structure-Activity Relationships.

The insect antifeedant and toxic activity of the Delphinium diterpene alkaloids 15-acetylcardiopetamine, cardiopetamine along with its amino alcohol, the beta,gamma unsaturated ketone, and the acetylated ketone derivatives were studied in Spodoptera littoralis and Leptinotarsadecemlineata. Cardiopetamine and 15-acetylcardiopetamine strongly inhibited the feeding activity of S. littoralis and L.

Insecticidal and mutagenic evaluation of two annonaceous acetogenins.

Annonaceous acetogenins represent a new class of bioactive compounds whose primary mode of action is the inhibition of NADH-ubiquinone oxidoreductase. Given the potential pesticidal use of such a class of compounds, we have further evaluated the antifeedant and insecticidal effects of squamocin and annonacin, two annonaceous acetogenins, on Spodoptera littoralis, Leptinotarsa decemlineata, and Myzus persicae. Additionally, to partially assess their environmental risk, we have also tested their mutagenicity in Salmonella typhimurium strains TA98, TA100, and TA102 in the presence and absence of a metabolic activation system.

Evolution and coordination of the alternative methods in Spain.

The present work is the introductory contribution to the workshop on 'Alternative methods for toxicity assessment' held during the 2nd Iberian Congress of Environmental Contamination and Toxicology (University of the Basque Country, Leioa, June 1998). Other contributions presented at the workshop are reported by Castano et al., Repetto et al.

Development of a new bioluminescent mutagenicity assay based on the Ames test.

A newly developed rapid mutagenicity assay based on the adenosine triphosphate (ATP)-bioluminescence technique and the Ames test is described. Salmonella typhimurium strains TA98 and TA100 were exposed in an appropriate liquid medium to the direct mutagens 4-nitroquinoline-N-oxide and methyl methanesulphonate, respectively, and to the indirect mutagen 2-aminoanthracene. Both auxotrophic and prototrophic growth were monitored throughout the incubation period as variations in the intracellular ATP levels by means of the luciferin-luciferase assay.

Genotoxicity of the insecticide rotenone in cultured human lymphocytes.

We have investigated the genotoxic activity of rotenone on three genetic endpoints, sister-chromatid exchanges (SCE), chromosome aberrations (CA) and micronuclei (MN) in human lymphocyte cultures in the presence and absence of a metabolic activation system (S9 mix). Our results indicate that rotenone increases the frequency of binucleated micronucleated (BNMN) cells and causes a delay in the cell cycle but does not increase the frequency of CA and SCE at the concentrations used. The presence of S9 mix reduces the genotoxic activity of rotenone.

Diminished expression of insulin-like growth factor (IGF) binding protein-5 and activation of IGF-I-mediated autocrine growth in simian virus 40-transformed human fibroblasts.

The reduced growth factor requirements of murine fibroblasts transformed by simian virus 40 (SV 40) have been attributed to insulin-like growth factor (IGF)-I induction by T antigen and consequent activation of IGF-I receptor signaling. The present study shows that the autonomous growth of SV 40-transformed human fibroblasts also requires type-I IGF-I receptor activation but that this is not due to de novo induction of IGF-I gene expression since untransformed human fibroblasts, which fail to proliferate in the absence of serum, also showed IGF-I gene expression under serum-free conditions. DNA synthesis assays confirmed that untransformed cells were responsive to exogenous IGF and indicated that transformed cells were already maximally stimulated.

Insulin resistance in genetically obese (fa/fa) rats: changes in the glycosyl-phosphatidylinositol signaling system in isolated hepatocytes.

In different types of mammalian cells, insulin has been shown to promote the release of an inositol phosphate glycan (InsP-glycan) through the hydrolysis of a glycosyl-phosphatidylinositol (glycosyl-PtdIns). This InsP-glycan, which has been demonstrated to be taken up by intact cells, may mediate some of the biological effects of insulin. We have investigated how the insulin resistance expressed in genetically obese (fa/fa) rats affects the glycosyl-PtdIns signaling system in isolated hepatocytes compared to what occurs in hepatocytes isolated from lean (Fa/-) rats.

Changes in the insulin-sensitive glycosyl-phosphatidyl-inositol signalling system with aging in rat hepatocytes.

An inositol-phosphate glycan (InsP glycan), which is the polar head group of an insulin-sensitive glycosyl-phosphatidylinositol (glycosyl-PtdIns), has been reported to mimic some insulin actions when added to different types of cells. In connection with this, a specific, time-dependent and energy-dependent transport system for this InsP glycan has been identified in isolated rat hepatocytes [Alvarez, J. F.

Impairment of glycosyl-phosphatidylinositol-dependent insulin signaling system in isolated rat hepatocytes by streptozotocin-induced diabetes.

The addition to different types of cells of an inositol-phosphate glycan, generated by the phospholipase C-catalyzed hydrolysis of a insulin-sensitive glycosyl-phosphatidylinositol (glycosyl-PI), mimics some of the biological effects of this hormone. Recently, a specific, time-, dose-, and energy-dependent transport system for this inositol-phosphate glycan has been identified in isolated rat hepatocytes. Here, we show that streptozotocin-induced diabetes mellitus reduced (by about 60%) the basal content of the insulin-sensitive glycosyl-PI in isolated rat hepatocytes.

Transport in isolated rat hepatocytes of the phospho-oligosaccharide that mimics insulin action. Effects of adrenalectomy and glucocorticoid treatment.

The addition to intact cells of an inositol phospho-oligosaccharide (POS), which is the polar head-group of an insulin-sensitive glycosylphosphatidylinositol, mimics and may mediate some of the biological effects of this hormone. Here we report the existence of a POS transport system in hepatocytes. This POS transport system is specific and time- and dose-dependent.

Modulation of casein kinase II activity by the polar head group of an insulin-sensitive glycosyl-phosphatidylinositol.

A phospho-oligosaccharide, whose production is stimulated by insulin, modulated the activity of partially purified casein kinase II. Whereas at 2 microM the phospho-oligosaccharide stimulated casein kinase II 1.3-fold, higher concentrations of this molecule were inhibitory.