Allelochemical effects of eudesmane and eremophilane sesquiterpenes on Tribolium castaneum larvae

UHPLC-Q/Orbitrap/MS/MS Fingerprinting, Free Radical Scavenging, and Antimicrobial Activity of Tessaria absinthiodes (Hook. & Arn.) DC. (Asteraceae) Lyophilized Decoction from Argentina and Chile

The decoction of Tessaria absinthioides is used in traditional medicine of South America as hypocholesterolemic, balsamic, and expectorant; but it is also useful for the prevention of hepatitis, renal insufficiency, and diabetes, and is used as digestive. A lyophilized decoction from the aerial parts of this plant (TLD) collected in San Juan (TLDSJ) and Mendoza (TLDM) provinces (Argentina) and one collection from Antofagasta, Chile (TLDCH) were characterized regarding antioxidant and antibacterial activities, phenolics and flavonoids content, and ultrahigh resolution liquid chromatography Orbitrap MS analysis UHPLC-PDA-OT-MS/MS metabolite profiling. The antioxidant properties were carried out "in vitro" using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and trolox equivalent antioxidant activity (TEAC) methods, ferric-reducing antioxidant power (FRAP), and lipoperoxidation in erythrocytes (LP). The antibacterial activity was evaluated following the Clinical and Laboratory Standards Institute (CLSI) rules. TLDSJ, TLDM, and TLDCH displayed a strong DPPH scavenging activity (EC50 = 42, 41.6, and 43 µg/mL, respectively) and inhibition of lipoperoxidation in erythrocytes (86-88% at 250 µg TLD/mL), while a less effect in the FRAP and TEACantioxidant assays was found. Additionally, the decoctions showed a content of phenolics compounds of 94 mg gallic acid equivalents (GAE)/g, 185 GAE/g, and 64 GAE/g, for TLDSJ, TLDM, and TLDCH samples, respectively. Regarding the flavonoid content, the Chilean sample was highlighted with 19 mg quercetin equivalents (QE)/g. In this work, several phenolic compounds, including sesquiterpenes, flavonoids, and phenolic acids, were rapidly identified in TLDSJ, TLDM, and TLDCH extracts by means UHPLC-PDA-OT-MS/MS for the first time, which gave a first scientific support to consider this medicinal decoction from both countries as a valuable source of metabolites with antioxidant effects, some with outstanding potential to improve human health.

Impact of sesquiterpenes from Inula racemosa (Asteraceae) on growth, development and nutrition of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND

The use of botanical pesticides for protecting crops from insect pests has assumed greater importance all over the world owing to growing awareness of harmful effects of indiscriminate use of synthetic pesticides. Inula racemosa Hook. f. (Asteraceae), a medicinally important perennial herb, is rich in sesquiterpenes with many biological activities. The present studies were conducted with the objective to evaluate the sesquiterpenes isolated from I. racemosa for insecticidal activity against Spodoptera litura (F.).

RESULTS

Alantolactone and isoalantolactone isolated from I. racemosa exerted growth inhibitory effects on S. litura. Addition of both the sesquiterpenes to larval diet extended the development period and reduced pupation as well as adult emergence. The dietary utilisation experiments on third-instar larvae of S. litura revealed reduction in consumption and growth rates of larvae as well as efficiency of conversion of ingested and digested food owing to alantolactone and isoalantolactone.

CONCLUSION

The root extract of I. racemosa, which is rich in two sesquiterpenes, i.e. alantolactone and isoalantolactone, has the potential for management of S. litura. However, there is a need to understand the specific mechanism of action of these compounds. © 2016 Society of Chemical Industry.

Does plant apparency matter? Thirty years of data provide limited support but reveal clear patterns of the effects of plant chemistry on herbivores

According to the plant-apparency hypothesis, apparent plants allocate resources to quantitative defenses that negatively affect generalist and specialist herbivores, while unapparent plants invest more in qualitative defenses that negatively affect nonadapted generalists. Although this hypothesis has provided a useful framework for understanding the evolution of plant chemical defense, there are many inconsistencies surrounding associated predictions, and it has been heavily criticized and deemed obsolete. We used a hierarchical Bayesian meta-analysis model to test whether defenses from apparent and unapparent plants differ in their effects on herbivores. We collected a total of 225 effect sizes from 158 published papers in which the effects of plant chemistry on herbivore performance were reported. As predicted by the plant-apparency hypothesis, we found a prevalence of quantitative defenses in woody plants and qualitative defenses in herbaceous plants. However, the detrimental impacts of qualitative defenses were more effective against specialists than generalists, and the effects of chemical defenses did not significantly differ between specialists and generalists for woody or herbaceous plants. A striking pattern that emerged from our data was a pervasiveness of beneficial effects of secondary metabolites on herbivore performance, especially generalists. This pattern provides evidence that herbivores are evolving effective counteradaptations to putative plant defenses.

Insect growth regulatory effects of linear diterpenoids and derivatives from Baccharis thymifolia

Linear diterpenes isolated from aerial parts of Baccharis thymifolia ( 1- 3) were tested for insect growth inhibitory activity against Tenebrio molitor larvae. Compounds 4- 16 were prepared by various chemical transformations. The diterpenes 6,10-( E,E)-thymifodioic acid ( 1), the butenolide 3, and the derivatives 4, 11, and 14 produced developmental deficiencies in assays using topical application on fifth instar larvae of T. molitor. Compound 3 is a new natural product.

Effects of solvents and surfactant agents on the female and larvae of cattle tick Boophilus microplus

Many natural compounds have low water solubility and need to be dissolved in organic solvents, or surfactant agents must be used before addition into experimental systems. Therefore, it is necessary to determine their toxicity. Experiments were performed aiming to select solvents to be used in the bioassays, searching new acaricide agents from plants. Laboratory tests were carried out on larvae and adults of the cattle tick Boophilus microplus to determine the sensibility of B. microplus female and larvae to different solvents (acetone, methanol, ethanol and 1% dimethyl sulfoxide) and surfactant agents (1% Tween 80 and 5% Triton X-100) using the larval immersion test (LIT) and adult immersion test (AIT). In the AIT, the effect of the treatments on engorged females was assessed by measuring egg production and hatching rate. Acetone was toxic to the adults promoting mortality of 100%. Methanol and ethanol caused 45.3 and 14.2% of mortality, respectively. The other tested substances were not toxic to the engorged females of B. microplus. In the LIT, it was observed that the larvae were more resistant; after 48 h, about 100% of the larvae were alive in all the treatments except with acetone that caused a mortality of 10%.

Antifeedant activity of neo-clerodane diterpenes from Baccharis flabellata Hook & Arn var. flabellata toward Tribolium castaneum Herbst: structure–activity relationships

In order to establish structure-activity relationships, nine neo-clerodane diterpenes isolated from the acetone extract of aerial parts of Baccharis flabellata Hook & Arn var. fabellata were assayed for antifeedant activity against Tribolium castaneum (Coleoptera: Tenebrionidae). Compounds exhibiting maximal antifeedant activities showed an alpha,beta-unsaturated carbonyl group on the decalin portion and a furan ring at the side chain. Stereoelectronic studies indicate that the distance between the furan heteroatom and the more electrophilic carbon of the decaline moiety, as well as the electrostatic charge on that atom, were important features for antifeedant activity. Compounds possesing an alpha,beta,gamma,delta-unsaturated carbonyl group or an acetoxyl group at C-2, were inactive. Theoretical calculations were performed in order to find some structure-activity relationships.

Eudesmane sesquiterpenoids from the Asteraceae family

This review covers the structures and biological activities of eudesmane-type sesquiterpenoids from the plants of the Asteraceae family. Biosynthetic studies or chemical syntheses leading to the revision of structures or stereochemistries have also been included, and 593 references are cited.

Toxic and repellent effects of Baccharis salicifolia essential oil on Tribolium castaneum

Allelochemical effects were observed when Tribolium castaneum (Herbst) adults were treated with Baccharis salicifolia (Ruiz & Pavon) Pers essential oil. The main biological activities were toxicity and repellence. Terpenes present in the essential oil were identified by GC-MS, and some authentic samples were tested to assess their activity individually. The most acutely toxic compounds after 3 days were beta-pinene and pulegone. Most of the monoterpenes elicited symptoms indicative of neurotoxicity. The most repellent compound was alpha-terpineol. Toxic and repellent effects of chemical derivatives of the major sesquiterpene present in B salicifolia essential oil, as well as a series of monoterpenes, were evaluated in order to investigate structure-activity relationships. The reduced derivatives of the monoterpenes and sesquiterpenes were more repellent that their carbonyl analogues. In addition, unsaturation in the germacrane skeleton enhanced repellent activity.

Iridoids as allelochemicals and DNA polymerase inhibitors

Growth inhibitory activities and nutritional indices of catalpol (1), 8-O-acetylharpagide (2), and harpagide (3) were determinated in larvae and adults of Tribolium castaneum, respectively. Compound 1 produced a series of allelochemical effects probably related with the DNA synthesis. This iridoid possessed the highest inhibitory activity against DNA polymerase. Molecular orbital calculations suggest that a pi-pi charge transfer recognition model could explain the action of iridioids toward nucleic acid synthesis.