Alexandra Martins dos Santos Soares

Effect of Methyl Jasmonate on antioxidative enzyme activities and on the contents of ROS and H2O2 in Ricinus communis leaves

Jasmonates are a class of plant hormones that mediate various aspects in gene and metabolic regulation, defense, stress responses, reproduction and, possibly, communication. Oxidative stress stimulates synthesis of antioxidant metabolites and enhances antioxidant enzyme activities that could protect plant tissues. The aim of this study was to verify the effects of methyl jasmonate (JAME) treatment on the reactive oxygen species (ROS) and on the activities of H2O2 scavenging enzymes, such as superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX EC; 1.11.1.1), and guaiacol peroxidase (GPX; EC 1.11.1.7) in Ricinus communis leaves. The activity of CAT and GPX was transient while SOD activity decreased and APX increased after treatment with JAME. In addition, JAME exposure induced ROS accumulation.

A new 2S albumin from Jatropha curcas L. seeds and assessment of its allergenic properties

Significant effort has been made world-wide to boost biofuels with the expectation of a positive contribution to renewable fuel and greenhouse gas reduction. Jatropha curcas L. has proved to be an opportunistic crop in tropical areas, particularly in unfavorable environments. For this reason, analyses of toxicity and allergy caused by its seeds and pollen are necessary. A 12kDa, allergenic 2S albumin, denoted Jat c 1, was isolated from Physic nut (J. curcas) seeds. Jat c 1 binds IgE attached to rat mast cells, inducing histamine release. It also showed strong cross-reactivity with the major allergens from castor bean, Ric c 1 and Ric c 3.

Activation of phospholipase PLA2 actvity in Ricinus communis leaves in response to mechanical wounding

Com o objetivo de avaliar a resposta de defesa da mamona (Ricinus communis) contra predadores, analisaram-se as alteracoes nas atividades de fosfolipases A2 (PLA2) em extratos de folhas de plantas, submetidas a injuria mecânica apos diferentes intervalos de tempo. Observou-se que os niveis dessa enzima aumentaram de forma significativa (cerca de duas vezes) 15 e 60 min apos o ferimento. As atividades que foram induzidas foram sensiveis ao acido aristoloquico (10 mM), um inibidor especifico para PLA2. A enzima induzida apos 15 min foi denominada Rc-PLA2 I e apresentou uma massa molecular aparente, determinada por SDS-PAGE, de 40 kDa. A proteina induzida apos 60 min, RcPLA2 II, apresentou uma massa molecular de 14 kDa. A sequencia N-terminal parcial da Rc-PLAII mostrou homologia com PLA2 de arroz e olmo. As fosfolipases foram parcialmente purificadas por associacao da cromatografia de filtracao em gel, seguida por eluicao das bandas que apresentaram atividade enzimatica apos separacao por PAGE nao desnaturante.

Anthelmintic activity of Leucaena leucocephala protein extracts on Haemonchus contortus

The objective of this study was to evaluate the effects of protein extracts obtained from the plant Leucaena leucocephala on the nematode parasite Haemonchus contortus. The seeds, shell and cotyledon of L. leucocephala were separated and their proteins extracted using a sodium phosphate buffer, and named as TE (total seed extract), SE (shell extract) and CE (cotyledon extract). Soluble protein content, protease, protease inhibitory and chitinase activity assays were performed. Exsheathment inhibition of H. contortus larvae were performed at concentrations of 0.6 mg mL-1, and egg hatch assays were conducted at protein concentrations of 0.8, 0.4, 0.2, 0.1 and 0.05 mg mL-1. The effective concentration for 50% hatching inhibition (EC50) was estimated by probit. Different proportions of soluble proteins, protease and chitinase were found in TE and CE. Protease inhibitory activity was detected in all extracts. The EC50 of the CE and TE extracts were 0.48 and 0.33 mg mL-1, respectively. No ovicidal effects on H. contortus were detected in SE extracts, and none of the protein extracts demonstrated larvicidal effects on H. contortus. We therefore conclude that protein extracts of L. leucocephala had a detrimental effect on nematode eggs, which can be correlated with the high protease and chitinase activity of these extracts.

Long-term effects of drenches with condensed tannins from Acacia mearnsii on goats naturally infected with gastrointestinal nematodes.

In this study, the long-term effects of exposure to a drench containing condensed tannins (CTs) from Acacia mearnsii on gastrointestinal nematodes in goats were investigated. Male cross-bred Anglo-Nubian goat kids between 3 and 5 months of age were dewormed at the beginning of the experiment. The goat kids were divided into one group that received weekly 24 g oral doses of A. mearnsii bark extract dissolved in water containing 16.7% CTs (GCT group, n = 8) and a second group that did not receive CTs (GC group, n = 8). All of the animals were kept in an Andropogon gayanus pasture and grazed with a herd of 100 naturally infected adult goats. Each animal was supplemented daily with 200 g of a concentrated mixture containing 18% crude protein. Fecal egg counts (FECs) were performed weekly for 192 days, and weight measurements and blood collections were done at two-week intervals in this period. The packed cell volume of the blood was calculated, and the plasma was used to determine the total protein, albumin, and glucose concentrations. After 192 days, the animals were slaughtered and the carcasses evaluated, with nematodes harvested for identification and counting. The FECs of the animals treated with CTs from A. mearnsii (GCT group) remained lower than the FECs of the control group animals for the majority of the first half of the experimental period. An observed increase in the FECs for both groups coincided with increased rainfall in the region where the experiment was conducted. The worm burden, scrotal circumference, carcass weight, leg circumference, carcass size and blood analysis were not significantly different between the groups. The packed cell volume (PCV) was constant in all of the animals throughout the experiment. In conclusion, repeated and prolonged treatment of goats with CTs from A. mearnsii helped to maintain low FECs in a period of low challenge but did not reduce nematode infections in the goats.

Biological properties and pharmacological potential of plant exudates

Exudates released from plants, consist of complex mixtures of organic and inorganic molecules that have been used in traditional medicine from several years. They may vary among genera, species or within a genus and mainly include latex, sap, gums, resins, seed or root exudates. Plant exudates are known to possess several biological activities including, antimicrobial, anti-inflammatory, antioxidant, wound healing and anti-nociceptive. Exudates oozed out from plants have also been used as ingredients in medicines, food, perfumes and cosmetics. The present review provides brief overview about the exudates released from plants, their biological properties and beneficial effects for human beings. Due to the presence of various compounds, different methodologies and procedures have been employed for their collection and analyses. Literature studies suggest that plant exudates have extensive therapeutic potential for curing diseases with minimal toxic effects. This aspect could be taken into account in prospective studies regarding the search of new products derived from plant exudates with pharmaceutical value.

In vitro anthelmintic effects of Spigelia anthelmia protein fractions against Haemonchus contortus

Gastrointestinal nematodes are a significant concern for animal health and well-being, and anthelmintic treatment is mainly performed through the use of chemical products. However, bioactive compounds produced by plants have shown promise for development as novel anthelmintics. The aim of this study is to assess the anthelmintic activity of protein fractions from Spigelia anthelmia on the gastrointestinal nematode Haemonchus contortus. Plant parts were separated into leaves, stems and roots, washed with distilled water, freeze-dried and ground into a fine powder. Protein extraction was performed with sodium phosphate buffer (75 mM, pH 7.0). The extract was fractionated using ammonium sulfate (0–90%) and extensively dialyzed. The resulting fractions were named LPF (leaf protein fraction), SPF (stem protein fraction) and RPF (root protein fraction), and the protein contents and activities of the fractions were analyzed. H. contortus egg hatching (EHA), larval exsheathment inhibition (LEIA) and larval migration inhibition (LMIA) assays were performed. Proteomic analysis was conducted, and high-performance liquid chromatography (HPLC) chromatographic profiles of the fractions were established to identify proteins and possible secondary metabolites. S. anthelmia fractions inhibited H. contortus egg hatching, with LPF having the most potent effects (EC50 0.17 mg mL-1). During LEIA, SPF presented greater efficiency than the other fractions (EC50 0.25 mg mL-1). According to LMIA, the fractions from roots, stems and leaves also reduced the number of larvae, with EC50 values of 0.11, 0.14 and 0.21 mg mL-1, respectively. Protein analysis indicated the presence of plant defense proteins in the S. anthelmia fractions, including protease, protease inhibitor, chitinase and others. Conversely, secondary metabolites were absent in the S. anthemia fractions. These results suggest that S. anthelmia proteins are promising for the control of the gastrointestinal nematode H. contortus.

Identification of a Tyrosine Phosphatase Involved in the Response to Mechanical Injury in Leaves of Ricinus Communis

Plants defend themselves against biotic or abiotic stress by triggering intracellular signaling pathways that regulate gene expression and responses to the offending agent. Phosphorylation and dephosphorylation represent major mechanisms for the regulation of plant defense pathways. Therefore, MAP kinases and phosphatases have been the focus of many studies in this area. This study identified three phosphatase activities, namely RcPPase I, II and III. Wounding increased the activity levels of RcPPase III, while the activities of RcPPase I and II remained constant compared to the control. N-terminal partial amino acid sequence, biochemical characterization with use of specific substrates and inhibitors indicated that the RcPPase III belong to the family of tyrosine phosphatases (PTPs).

Myracrodruon urundeuva seed exudates proteome and anthelmintic activity against Haemonchus contortus

Seed exudates are plant-derived natural bioactive compounds consisting of a complex mixture of organic and inorganic molecules. Plant seed exudates have been poorly studied against parasite nematodes. This study was undertaken to identify proteins in the Myracrodruon urundeuva seed exudates and to assess the anthelmintic activity against Haemonchus contortus, an important parasite of small ruminants. M. urundeuva seed exudates (SEX) was obtained after immersion of seeds in sodium acetate buffer. SEX was fractionated with ammonium sulfate at 0–90% concentration to generate the ressuspended pellet (SEXF1) and the supernatant (SEXF2). SEX, SEXF1, and SEXF2 were exhaustively dialyzed against distilled water (cut-off: 12 kDa) and the protein contents determined. Mass spectrometry analyses of SEX, SEXF1, and SEXF2 were done to identify proteins and secondary metabolites. The seed exudates contained protease, protease inhibitor, peptidase, chitinase, and lipases as well as the low molecular weight secondary compounds ellagic acid and quercetin rhamnoside. SEX inhibited H. contortus larval development (LDA) (IC50 = 0.29 mg mL-1), but did not affect larval exsheathment (LEIA). On the other hand, although SEXF1 and SEXF2 inhibited H. contortus LEIA (IC50 = 1.04 and 0.93 mg mL-1, respectively), they showed even greater inhibition efficiency of H. contortus larval development (IC50 = 0.29 and 0.42 mg mL-1, respectively). To the best of our knowledge, this study is the first to show the anthelmintic activity of plant exudates against a gastrointestinal nematode. Moreover, it suggests the potential of exuded proteins as candidates to negatively interfere with H. contortus life cycle.

Structural analysis and anthelmintic activity of Canavalia brasiliensis lectin reveal molecular correlation between the carbohydrate recognition domain and glycans of Haemonchus contortus

Haemonchus contortus is one of the most economically important parasites infecting small ruminants worldwide. This nematode has shown a great ability to develop resistance to anthelmintic drugs, calling for the development of alternative control approaches. Because lectins recognize and bind to specific carbohydrates and glycan structures present in parasites, they can be considered as an alternative to develop new antiparasitic drugs. Accordingly, this work aimed to investigate the anthelmintic effect of Canavalia brasiliensis (ConBr) lectin against H. contortus and to evaluate a possible interaction of ConBr with glycans of this parasite by molecular docking. ConBr showed significant inhibition of H. contortus larval development with an IC50 of 0.26 mg mL-1. Molecular docking assays revealed that glycans containing the core trimannoside [Man(α1-3)Man(α1-6)Man] of H. contortus interact in the carbohydrate recognition domain of ConBr with an interaction value of MDS = -248.77. Our findings suggest that the inhibition of H. contortus larval development is directly related to the recognition of the core trimannoside present in the glycans of these parasites. This work is the first to report on the structure-function relationships of the anthelmintic activity of plant lectins.