•Toxicity threshold for ryegrass staggers is lowered the longer perennial ryegrass is fed.•Sub-chronic (>60 day) threshold for lolitrem B is 1554 µg/kg in Angus beef cattle.•Lolitrem B accumulates in ...fat tissue in a dose- and time-responsive manner.
Lolitrem B is a potent tremorgen responsible for the syndrome known as “ryegrass staggers” in livestock consuming perennial ryegrass (Lolium perenne) infected with the endophyte fungus Epichloë festucae var. lolii. We evaluated clinical signs in cattle continuously fed endophyte-infected perennial ryegrass straw at four concentrations of lolitrem B (LB)/ergovaline (EV) (groups: I-2256/638, II-1554/373, III-1012/259 or IV-<300/0 µg/kg LB/EV, n=5-6 steers/group) over 64 days to establish a sub-chronic threshold of toxicity for this mycotoxin; animals were supplemented with 1 kg grain mix/day. Most animals in groups I and II developed clinical signs consistent with ryegrass staggers by day 64; thus, it is recommended that a threshold level of 1554 µg/kg LB should not be exceeded for extended feeding regimens using endophyte-infected perennial ryegrass feed material alone. This toxicity threshold is lower than that observed with shorter feeding periods, i.e. 1800–2000 µg/kg LB when fed for less than 30 days. No clinical signs associated with ergovaline toxicosis (i.e. decreased weekly weight gain) were observed. As adipose tissue appears to be the main compartment where LB is deposited, the concentration of LB and its metabolic derivatives in fat samples was determined at 37 and 64 days. Lolitrem B and three previously defined metabolites bioaccumulated in a dose- and time-dependent manner throughout the feeding experiment in fat tissue, at levels similar to those found in past research. Ratios of metabolites to LB were consistent across time points and dose groups, indicating that the enzyme(s) responsible for LB metabolism were not saturated. In summary, LB toxicity thresholds are dependent upon specificities of the dietary program including the duration feed material is fed, and should be considered when formulating safe livestock feeding regimens.
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Monoterpenes are a highly diverse group of chemical scents that originate from plant secondary metabolic processes, one purpose of which is to serve as a defense against herbivores. Plant-derived ...monoterpenes produced from Lamiaceae species have demonstrated acaricidal activity against pest mites and ticks. However, the mechanism by which these compounds carry out the demise of this group of arachnids is poorly understood. Here, we review the chemistry and bioactivity of these promising compounds and subsequently assess their potential toxicity to mites and ticks through measurement of their docking ability to amino acid residues of the binding pocket of Drosophila melanogaster acetylcholinesterase (AChE). We identified 27 monoterpenes of the Lamiaceae family from the literature that were effective against mite (Varroidae, Tetranychidae, Eriophyidae) and tick (Ixodidae) species that are problematic in agricultural production. Screening of these compounds showed that monoterpenoids possessing methyl groups, such as carvacrol, linalool, α-terpineol, bornyl acetate, and terpine-4-ol, strongly bind to D. melanogaster AChE. Linalool, which fits into the binding pocket in the amino acid catalytic triad of AChE (oxyanion hole residues, hydrogen bond interaction with GLU 237, and anionic binding with TRP 83), was identified as the most promising target for further optimization studies. We propose that monoterpenes which interact strongly with amino acid residues of the AChE receptor be targeted for development of effective, naturally produced biocontrol pesticides, as this model demonstrates potential for discovery of new acaricide compounds in a high throughput manner.
•Monoterpenes from the Lamiaceae family were effective insecticides against mites and ticks.•Monoterpenoids that have a methyl group bind strongly to D. melanogaster acetylcholinesterase.•Linalool is the most promising compound targeting acetylcholinesterase activity.
Plant species in the family Solanaceae are the usual hosts of potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psylloidea: Triozidae). However, the psyllid has also been shown to develop on ...some species of Convolvulaceae (bindweeds and morning glories). Developmental success on Convolvulaceae is surprising given the rarity of psyllid species worldwide associated with this plant family. We assayed 14 species of Convolvulaceae across four genera (Convolvulus, Calystegia, Ipomoea, Turbina) to identify species that allow development of potato psyllid. Two populations of psyllids were assayed (Texas, Washington). The Texas population overlaps extensively with native Convolvulaceae, whereas Washington State is noticeably lacking in Convolvulaceae. Results of assays were overlain on a phylogenetic analysis of plant species to examine whether Convolvulaceae distantly related to the typical host (potato) were less likely to allow development than species of Convolvulaceae more closely related. Survival was independent of psyllid population and location of the plant species on our phylogenetic tree. We then examined whether presence of a fungal symbiont of Convolvulaceae (Periglandula spp.) affected psyllid survival. These fungi associate with Convolvulaceae and produce a class of mycotoxins (ergot alkaloids) that may confer protection against plant-feeding arthropods. Periglandula was found in 11 of our 14 species, including in two genera (Convolvulus, Calystegia) not previously known to host the symbiont. Of these 11 species, leaf tissues from five contained large quantities of two classes of ergot alkaloids (clavines, amides of lysergic acid) when evaluated by LC-MS/MS. All five species also harbored Periglandula. No ergot alkaloids were detected in species free of the fungal symbiont. Potato psyllid rapidly died on the five species that harbored Periglandula and contained ergot alkaloids, but survived to adulthood on seven of the nine species in which ergot alkaloids were not detected. These results support the hypothesis that a plant-fungus symbiotic relationship affects the suitability of certain Convolvulaceae to potato psyllid.
To compare hepatic metabolism of pyrrolizidine alkaloids (PAs) between sheep and cattle and elucidate the protective mechanism of sheep.
Liver microsomes and cytosol from 8 sheep and 8 cattle.
The PA ...senecionine, senecionine N-oxide (nontoxic metabolite) and 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP; toxic metabolite) were measured in microsomal incubations. The kcat (turnover number) was determined for DHP and N-oxide formation. Chemical and immunochemical inhibitors were used to assess the role of cytochrome P450s, flavin-containing monooxygenases (FMOs), and carboxylesterases in senecionine metabolism. The CYP3A, CYP2B, and FMO concentrations and activities were determined, in addition to the role of glutathione (GSH) in senecionine metabolism.
DHP concentration did not differ between species. Sheep formed more N-oxide, had higher N-oxide kcat, and metabolized senecionine faster than cattle. The P450 concentrations and isoforms had a large influence on DHP formation, whereas FMOs had a large influence on N-oxide formation. In cattle, CYP3A played a larger role in DHP formation than in sheep. FMO activity was greater in sheep than in cattle. Addition of GSH to in vitro microsomal incubations decreased DHP formation; addition of cytosol decreased N-oxide formation.
Hepatic metabolism differences alone do not account for the variation in susceptibility seen between these species. Rather, increased ruminal metabolism in sheep appears to be an important protective mechanism, with hepatic enzymes providing a secondary means to degrade any PAs that are absorbed from the rumen.
The chemical composition of essential oils extracted from Xylopia frutescens Aubl. (Annonaceae) fruit (collected in Pernambuco, Brazil) was examined by TLC and GC/MS. TLC analysis detected compounds ...from the flavonoid and terpenoid groups. GC/MS detected 23 terpenoid compounds, in which the principal components were germacrene D (24.2%), linalool (12.1%), β-pinene (8.0%), cis-sabinene hydrate (7.9%), trans-pinocarveol (7.8%), α-copaene (7.0%) and limonene (5.6%). Other constituents found were sabinene, m-cymene, 1,8-cineole, β-ocimene, perillene, cis-sabinol, α-campholenal, isopinocamphone, terpinen-4-ol, verbenone, trans-carveol, carvone, perillyl alcohol, α-cubebene, β-cadinene and elemol. Most of these compounds have not been detected in fruit extracts of X frutescens before; therefore this study represents the most comprehensive analysis to date of the chemical components in the fruits of this plant.
The manufacturing processes of royal demolition explosive (RDX), or hexahydro-1,3,5-trinitro-1,3,5-triazine, have resulted in serious water contamination. As a potential carcinogen, RDX can cause a ...broad range of harmful effects to humans and animals. The ovine rumen is capable of rapid degradation of nitroaromatic compounds, including RDX. While ruminal RDX-degrading bacteria have been identified, the genes and pathways responsible for RDX degradation in the rumen have yet to be characterized. In this study, we characterized the metabolic potential of the ovine rumen using metagenomic approaches. Sequences homologous to at least five RDX-degrading genes cloned from environmental samples (diaA, xenA, xenB, xplA, and xplB) were present in the ovine rumen microbiome. Among them, diaA was the most abundant, likely reflective of the predominance of the genus Clostridium in the ovine rumen. At least ten genera known to harbor RDX-degrading microorganisms were detectable. Metagenomic sequences were also annotated using public databases, such as Pfam, COG, and KEGG. Five of the six Pfam protein families known to be responsible for RDX degradation in environmental samples were identified in the ovine rumen. However, increased substrate availability did not appear to enhance the proliferation of RDX-degrading bacteria and alter the microbial composition of the ovine rumen. This implies that the RDX-degrading capacity of the ovine rumen microbiome is likely regulated at the transcription level. Our results provide metagenomic insights into the RDX-degrading potential of the ovine rumen, and they will facilitate the development of novel and economic bioremediation strategies.
Essential oil extracts from the leaves of two Lantana species (L. radula Sw. and L. canescens Kunth), for which no prior analysis has been reported, were analyzed by GC-MS. This information was ...utilized to propose chemical markers for Lantana species so that identification between physically similar plant species can be achieved through chemical analysis. Results showed 33 constituents for L. canescens, among which β-caryophyllene (43.9%), β-cubebene (10.1%), elixene (8.6%), β-phellandrene (6.1%), α-caryophyllene (2.6%) and dehydro-aromadendrene (2.6%) were the principle components. L. radula revealed the presence of 21 compounds, the most abundant of which were β-cubebene (31.0%), β-caryophyllene (20.8%), elixene (10.0%), α-salinene (6.4%), β-phellandrene (6.1%), copaene (4.9%) cadinene (1.4%) and psi-limonene (1.4%). The high concentration of β-caryophyllene in the samples tested here and those in the literature make it a good candidate for a chemical marker for Lantana species, with β-cubebene, elixene and β-phellandrene following as minor compounds identified more sporadically in this genus. On the other hand, Lippia species, which are morphologically similar to those from the Lantana genus, would contain limonene, citral, carvacrol, β-myrcene, camphor and thymol as the main chemical markers. These chemical markers would be a powerful tool for maintaining quality control in the extraction of essential oils for use in medicinal applications, as well as in identification of plant specimens to a taxonomist.
The distribution of iridoid glucosides in plants from the genus Lippia (Verbenaceae) is described. In the present work, three known iridoids (theviridoside, mussaenoside and gardoside) were isolated ...from the roots of L. alba and were confirmed by NMR (1H and 13C) spectroscopic data. This information was combined with previous work on seven other Lippia species (obtained through a literature review) to give a thorough account of the iridoid glucosides currently found in this genus.
Lippia alba (Mill.) N.E. Brown (Verbenaceae), also known as Lippia geminata HBK or Lantana alba (Mill.), is a shrub about 3 m tall. In Brazilian traditional medicine, it is commonly known as ...Erva-Cidreira, Chá do Tabuleiro, and Salsa Limão. The present work was conducted in order to compare the phytochemistry of the roots and leaves and to determine the acute toxicity of the aqueous extracts from the roots of L. alba. The main components in the leaf extract were citral, β-citral, carvone, hemimelitene, germacrene D, and d-limonene. The main components in the root extract were durene, carvone, patchoulane and hemimellitene. To our knowledge, this is the first report of a phytochemical analysis of the root extract from Lippia alba. The LD50 for the aqueous root extract was calculated to be 1156.25 mgkg−1. The animals presented stimulant and depressive behaviors, showing moderate toxicity, most likely due to the presence of iridoids and phenylpropanoids.
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