Phytotoxic activity of Ulex europaeus, an invasive plant on Chilean ecosystems: separation and identification of potential allelochemicals.

Despite its worldwide relevance as an invasive plant, there are few studies on Ulex europaeus (gorse) and its allelopathic activity is almost unexplored. The allelochemical profile of gorse was analysed through methanolic extract of pods and roots, and its phytotoxic effects on Lactuca sativa germination. The methanolic extract of pods had no effect in germination, while extract of roots resulted in a U-shaped dose-response curve: reducing the germination at concentration 0.5 mg mL-1. GC-MS analysis detected compounds with proven antimicrobial and antioxidant activities in the pods and cytotoxic compounds in the roots, which could explain the bioassay results. The quinolizidine alkaloids (QAs) composition was evaluated to predict possible biological functions. It showed the presence of QAs in gorse that are absent in their native range, indicating broad defense strategies against bacteria, fungi, plants, and insects in the Chilean ecosystem. This could explain the superiority of gorse in the invaded areas.

A Bitter-Sweet Story: Unraveling the Genes Involved in Quinolizidine Alkaloid Synthesis in Lupinus albus.

Alkaloids are part of a structurally diverse group of over 21,000 cyclic nitrogen-containing secondary metabolites that are found in over 20% of plant species. Lupinus albus are naturally containing quinolizidine alkaloid (QA) legumes, with wild accessions containing up to 11% of QA in seeds. Notwithstanding their clear advantages as a natural protecting system, lupin-breeding programs have selected against QA content without proper understanding of quinolizidine alkaloid biosynthetic pathway. This review summarizes the current status in this field, with focus on the utilization of natural mutations such as the one contained in pauper locus, and more recently the development of molecular markers, which along with the advent of sequencing technology, have facilitated the identification of candidate genes located in the pauper region. New insights for future research are provided, including the utilization of differentially expressed genes located on the pauper locus, as candidates for genome editing. Identification of the main genes involved in the biosynthesis of QA will enable precision breeding of low-alkaloid, high nutrition white lupin. This is important as plant based high quality protein for food and feed is an essential for sustainable agricultural productivity.

Chemosystematic and evolutionary trends of the genistoid clade sensu stricto (Papilionoideae, Fabaceae).

The Papilionoideae, which comprises 503 genera and approximately 14,000 species, is the largest and most diverse subfamily of the Fabaceae family. In this subfamily, the Crotalarieae, Genisteae, Podalyrieae, Thermopsideae, Sophoreae and Euchresteae tribes are closely related by micro and macromolecular features, thus forming the genistoid clade. This group combines well-known genera, whereas other genera lack phytochemical and chemotaxonomic studies. Thus, this work aimed to characterize the special metabolites in these genera in order to define the chemical profile, the micromolecular markers and the chemical diversity, as well as to evaluate the group evolutionary trends. Flavonoids and alkaloids were identified as chemosystematic markers for the studied tribes due to high occurrence number and structural diversity. Among flavonoids, the flavones and isoflavones predominated. Low protection indexes of flavonoid hydroxyls by O-glycosylation or O-methylation were observed, whereas C-prenylation and C-glycosylation were frequent, mainly at C-6 and C-8 positions. The flavone/flavonol ratio shows the predominance of the flavones. Quinolizidine and piperidine alkaloids were present in most genera. Pyrrolizidine alkaloids were found in a few genera from Thermopsideae, Genisteae and Crotalarieae, which suggests a mechanism of adaptive convergence. Cluster analysis allowed separation of genera for each tribe by chemical similarities. The micromolecular trends of protection of flavonoid hydroxyls and alkaloid oxidation indicate the genistoid clade is through evolutionary transition, which is consistent with its phylogenetic position in the Papilionoideae subfamily.

Effects of two debittering processes on the alkaloid content and quality characteristics of lupin (Lupinus mutabilis Sweet).

BACKGROUND: The presence of quinolizidine alkaloids (QAs) in the species Lupinus mutabilis Sweet limits the expansion of its consumption and use, despite its high protein content. The objective of this research was therefore to determine the effect of two thermal treatments, aqueous (ATT) and saline (STT), on the QAs and total protein content, as well as on the texture (fracturability and hardness), visual perception attributes - hue (H*), luminosity (L*) and chromatism (C*) - and grain size in three lupin varieties (INIAP-450, INIAP-451, and Criollo). The water consumption required by each treatment was also measured. RESULTS: The debittering process with ATT helped to concentrate the total nitrogen by 560 g kg-1 and decreased the grain hardness to 2037 gf (grams of force) in the Criollo variety, while the chromatic parameters H* and C* increased in the three varieties. The STT treatment was more efficient than the ATT treatment in terms of the time required and the volume of water used to reduce the QAs to safe levels for consumption (2.5-3.5 g kg-1 ). The size of the grain increased to four times its original size; the luminosity L* decreased during cooking to a value of 41.49 in the Criollo variety and then increased to 57.42 during grain washing. CONCLUSIONS: The STT treatment is advisable for lupin debittering, although the extent of the effect was dependent on the variety. © 2020 Society of Chemical Industry.

Different processing methods change the oral toxicity induced by Sophora alopecuroides seeds and the contents of five main toxic alkaloids from the ethanol extracts determined by a validated UHPLC-MS/MS assay

Abstract This study investigated the influence of different processing methods on the oral toxicity of Sophora alopecuroides L., Fabaceae, seeds in mice and on the contents of five known toxic-effective quinolizidine alkaloids from the ethanol extracts quantified by ultra-performance liquid chromatography coupled to tandem quadrupole mass spectrometry. It provides an evidence to elucidate the possible reasons why vinegar-processing and parching methods significantly decrease the acute oral toxicity induced by S. alopecuroides and why wine-processing method increases it instead (demonstrated by measurement of LD50 and histopathological analysis). The analytical performance for the determination of the five analytes was evaluated by linearity, stability, repeatability, precision and accuracy, and recovery test. The lowest limit of quantification was determined to be 5 ng/ml for each substance and the precision and accuracy at lowest limit of quantification were below 20%. Cytisine, the most toxic alkaloid among the five alkaloids, declined 11.26, 3.98, and 2.73 folds after being vinegar-processed and fried in a ceramic or iron pan, respectively and had a very close correlation with the toxicity of S. alopecuroides seeds (r = 0.8589). Other matrine-type alkaloids with lower toxicity including matrine, sophcarpine, and sophoridine decreased after being wine-processed and fried in a ceramic pan, but increased 4.44, 7.20, and 7.23 folds when being processed by vinegar. Oxymatrine declined in all groups. It, therefore, reveals that vinegar-processing method reduces the oral toxicity of S. alopecuroides mainly due to a sharp decrease of cytisine, thus improves its clinical safety.

Identification of brain areas sensitive to the toxic effects of sparteine.

Sparteine is one of the most toxic quinolizidine alkaloids found in leguminous plants. Several studies have demonstrated that sparteine affects the nervous system, blocking the nervous ganglion, producing antimuscarinic effects, depressing the central nervous system and causing neuronal necrosis. However, there are no reports identifying the areas of the brain that are sensitive to the toxic effects of this alkaloid. 32 adult Wistar rats were on study, sixteen were implanted with an intracerebral stainless steel cannula and randomly assigned to a control or experimental group (n=8). Animals, control and experimental, received daily intraventricular (ICV) injections of a sparteine or a sterile water solution for five consecutive days. Additionally, two groups of animals (8 rats each) received daily intraperotineal injections (IP) of a sparteine or sterile water solution for five consecutive days. 72h after the last dose, the animals were sacrificed, their brains removed, fixed and embedded in paraffin to obtain 10µm tissue slices. Brain slices were stained with H&E and evaluated under a light microscope. The main brain structures sensitive to sparteine were the cerebral cortex (frontal, fronto-parietal and striate) olfactory and amygdaloid areas, the ventromedial hypothalamic nucleus, the Purkinje cells in the cerebellum, and the CA1, CA3 and dentate gyrus regions of the hippocampus. Administration of sparteine, via ICV or IP, caused neuronal necrosis in brain structures, mainly related with cholinergic pathways.

Filling in the gaps of the papilionoid legume phylogeny: the enigmatic Amazonian genus Petaladenium is a new branch of the early-diverging Amburaneae clade.

Recent deep-level phylogenies of the basal papilionoid legumes (Leguminosae, Papilionoideae) have resolved many clades, yet left the phylogenetic placement of several genera unassessed. The phylogenetically enigmatic Amazonian monospecific genus Petaladenium had been believed to be close to the genera of the Genistoid Ormosieae clade. In this paper we provide the first DNA phylogenetic study of Petaladenium and show it is not part of the large Genistoid clade, but is a new branch of the Amburaneae clade, one of the first-diverging lineages of the Papilionoideae phylogeny. This result is supported by the chemical observation that the quinolizidine alkaloids, a chemical synapomorphy of the Genistoids, are absent in Petaladenium. Parsimony and Bayesian phylogenetic analysis of nuclear ITS/5.8S and plastid matK and trnL intron agree with a new interpretation of morphology that Petaladenium is sister to Dussia, a genus comprising ∼18 species of trees largely confined to rainforests in Central America and northern South America. Petaladenium, Dussia, and Myrospermum have papilionate flowers in a clade otherwise with radial floral symmetry, loss of petals or incompletely differentiated petals. Our phylogenetic analyses also revealed well-supported resolution within the three main lineages of the ADA clade (Angylocalyceae, Dipterygeae, and Amburaneae). We also discuss further molecular phylogenetic evidence for the undersampled Amazonian genera Aldina and Monopteryx, and the tropical African Amphimas, Cordyla, Leucomphalos, and Mildbraediodendron.