Schinus terebinthifolius leaf extract causes midgut damage, interfering with survival and development of Aedes aegypti larvae

In this study, a leaf extract from Schinus terebinthifolius was evaluated for effects on survival, development, and midgut of A. aegypti fourth instar larvae (L4), as well as for toxic effect on Artemia salina. Leaf extract was obtained using 0.15 M NaCl and evaluated for phytochemical composition and lectin activity. Early L4 larvae were incubated with the extract (0.3–1.35%, w/v) for 8 days, in presence or absence of food. Polymeric proanthocyanidins, hydrolysable tannins, heterosid and aglycone flavonoids, cinnamic acid derivatives, traces of steroids, and lectin activity were detected in the extract, which killed the larvae at an LC50 of 0.62% (unfed larvae) and 1.03% (fed larvae). Further, the larvae incubated with the extract reacted by eliminating the gut content. No larvae reached the pupal stage in treatments at concentrations between 0.5% and 1.35%, while in the control (fed larvae), 61.7% of individuals emerged as adults. The extract (1.0%) promoted intense disorganization of larval midgut epithelium, including deformation and hypertrophy of cells, disruption of microvilli, and vacuolization of cytoplasms, affecting digestive, enteroendocrine, regenerative, and proliferating cells. In addition, cells with fragmented DNA were observed. Separation of extract components by solid phase extraction revealed that cinnamic acid derivatives and flavonoids are involved in larvicidal effect of the extract, being the first most efficient in a short time after larvae treatment. The lectin present in the extract was isolated, but did not show deleterious effects on larvae. The extract and cinnamic acid derivatives were toxic to A. salina nauplii, while the flavonoids showed low toxicity. S. terebinthifolius leaf extract caused damage to the midgut of A. aegypti larvae, interfering with survival and development. The larvicidal effect of the extract can be attributed to cinnamic acid derivatives and flavonoids. The data obtained using A. salina indicates that caution should be used when employing this extract as a larvicidal agent

Lectins, Interconnecting Proteins with Biotechnological/Pharmacological and Therapeutic Applications

Lectins are proteins extensively used in biomedical applications with property to recognize carbohydrates through carbohydrate-binding sites, which identify glycans attached to cell surfaces, glycoconjugates, or free sugars, detecting abnormal cells and biomarkers related to diseases. These lectin abilities promoted interesting results in experimental treatments of immunological diseases, wounds, and cancer. Lectins obtained from virus, microorganisms, algae, animals, and plants were reported as modulators and tool markers in vivo and in vitro; these molecules also play a role in the induction of mitosis and immune responses, contributing for resolution of infections and inflammations. Lectins revealed healing effect through induction of reepithelialization and cicatrization of wounds. Some lectins have been efficient agents against virus, fungi, bacteria, and helminths at low concentrations. Lectin-mediated bioadhesion has been an interesting characteristic for development of drug delivery systems. Lectin histochemistry and lectin-based biosensors are useful to detect transformed tissues and biomarkers related to disease occurrence; antitumor lectins reported are promising for cancer therapy. Here, we address lectins from distinct sources with some biological effect and biotechnological potential in the diagnosis and therapeutic of diseases, highlighting many advances in this growing field

Extrato de flores de Moringa oleifera: atividade larvicida e efeito sobre tripsina e acetilcolinesterase de larvas de Aedes aegypti

Dengue é uma arbovirose transmitida pelo Aedes aegypti e o controle do mosquito é fundamental para reduzir a propagação da doença. As larvas de A. aegypti têm desenvolvido resistência a inseticidas organofosforados. O uso de compostos naturais que promovam mortalidade pode evitar a emergência de larvas resistentes, devido à rotatividade dos inseticidas. Este trabalho relata a atividade larvicida (CL50 de 0.925%, p/v) do extrato de flores de Moringa oleifera sobre o quarto instar larval (L4) de A. aegypti. Inibidor de tripsina de natureza protéica (MoFTI, 169,9 kDa, Ki: 0,38 nM), triterpeno (β-amirina), esteróide (β- sitosterol) e flavonóides (kaempferol e quercetina) foram detectados no extrato; lectina não foi detectada. Tripsina do extrato do intestino de L4 foi inibida por MoFTI (Ki: 0,6 nM); entretanto, a atividade de acetilcolinesterase (AChE) do extrato de L4 inteiras não foi alterada. Ensaio em condições in vivo mostrou que a atividade de tripsina do intestino de L4 tratadas com o extrato de flores de M. oleifera diminuiu ao longo do tempo (0 a 1440 min) e foi fortemente inibida (98,6 %) após 310 min de incubação; a atividade de AChE do extrato de L4 inteiras não foi afetada neste período. O estudo aponta o extrato de flores de M. oleifera como uma ferramenta biodegradável para o controle de larvas de A. aegypti e sugere que o mecanismo larvicida envolve a inibição da tripsina do intestino das L4 por MoFT

Resistance of maize cultivars to Sitophilus zeamais (Coleoptera: Curculionidae)

ABSTRACT: Five Zea mays cultivars (BRS Caatingueiro, BRS Gorutuba, BRS Sertanejo, BRS Asa Branca and BR 106) were evaluated considering their effect on the nutrition of the maize weevil Sitophilus zeamais, by analysis of total protein in adult fed with these cultivars and for the presence of lectins and trypsin inhibitors in grains. In addition, free-choice and no-choice assays were performed to investigate the resistance of grains of the Z. mays cultivars to an attack by S. zeamais. The BR 106 cultivar showed the lowest susceptibility index, followed by BRS Caatingueiro, BRS Asa Branca, BRS Sertanejo and BRS Gorutuba. The number of emerged adults in the Z. mays cultivars ranged from 213.17 to 74.0, and the lowest number of insects was recorded for the BR 106 cultivar. The insects were able to feed on grains of all cultivars, but the BR 106 cultivar showed the least reduction in dried biomass. Lectins were detected in extracts from BR 106, BRS Asa Branca, BRS Sertanejo and BRS Gorutuba, and the highest activity was shown by BR 106. The lowest protein assimilation was detected in the insects from treatments with BRS Asa Branca. The extracts from all cultivars were able to inhibit the activity of bovine trypsin, but this effect was not related to the resistance degree of Z. mays cultivars. The results suggest the resistance of BR 160 to the attack of S. zeamais, as well as indicating that the presence of lectin in the grains is the cause of this resistance

Inhibition of Carrageenan-Induced Acute Inflammation in Mice by the Microgramma vacciniifolia Frond Lectin (MvFL)

Most anti-inflammatory drugs used nowadays have an excessive cost and their prolonged use has been connected with several injurious effects. Thus, the search for new anti-inflammatory agents is increasing. Lectins are carbohydrate-interacting proteins that can modulate immune response and the release of inflammation mediators. The Microgramma vacciniifolia frond lectin (MvFL) was previously reported to be an immunomodulatory agent in vitro. This work aimed to evaluate the effects of MvFL on the in vivo inflammatory status in the carrageenan-induced peritonitis and paw edema, using female Swiss mice. The animals were pretreated intraperitoneally with MvFL (5 and 10 mg/kg). In the peritonitis assay, the total and differential migration of white blood cells was evaluated, as well as the levels of cytokines, nitric oxide (NO), and total proteins in the peritoneal fluid. In the paw edema evaluation, the paw volume was measured in the early (from 30 min–2 h) and late (3–4 h) phases of edema formation. MvFL (5 and 10 mg/kg) was efficient in reducing neutrophil infiltration, pro-inflammatory cytokines (IL-6, IL-17, and TNF-α), NO, and protein content in the peritoneal fluid. It also repressed the edema formation in the late phase of the assay. In conclusion, MvFL showed inhibitory effects in in vivo acute inflammation, which encouraged future studies exploiting its immunomodulatory ability

Inhibition of Carrageenan-Induced Acute Inflammation in Mice by the <i>Microgramma vacciniifolia</i> Frond Lectin (MvFL)

Most anti-inflammatory drugs used nowadays have an excessive cost and their prolonged use has been connected with several injurious effects. Thus, the search for new anti-inflammatory agents is increasing. Lectins are carbohydrate-interacting proteins that can modulate immune response and the release of inflammation mediators. The Microgramma vacciniifolia frond lectin (MvFL) was previously reported to be an immunomodulatory agent in vitro. This work aimed to evaluate the effects of MvFL on the in vivo inflammatory status in the carrageenan-induced peritonitis and paw edema, using female Swiss mice. The animals were pretreated intraperitoneally with MvFL (5 and 10 mg/kg). In the peritonitis assay, the total and differential migration of white blood cells was evaluated, as well as the levels of cytokines, nitric oxide (NO), and total proteins in the peritoneal fluid. In the paw edema evaluation, the paw volume was measured in the early (from 30 min–2 h) and late (3–4 h) phases of edema formation. MvFL (5 and 10 mg/kg) was efficient in reducing neutrophil infiltration, pro-inflammatory cytokines (IL-6, IL-17, and TNF-α), NO, and protein content in the peritoneal fluid. It also repressed the edema formation in the late phase of the assay. In conclusion, MvFL showed inhibitory effects in in vivo acute inflammation, which encouraged future studies exploiting its immunomodulatory ability

Screening of Caatinga plants as sources of lectins and trypsin inhibitors

<div><p>Although it is one of the most threatened areas in the Earth, there are few studies on the biotechnological potential of the Caatinga. This work evaluated 36 extracts from 27 Caatinga plants for lectin and trypsin inhibitor activities. The presence of lectin was detected in 77.7% of samples by haemagglutinating assay. The highest values of specific haemagglutinating activity were found in extracts of leaves from <i>Mimosa lewesii</i>, <i>Bauhinia acuruana</i> and <i>Manilkara rufula</i> and in branches from <i>Myracrodruon urundeuva</i>. Trypsin inhibitor activity was detected in 63.9% of the tested extracts, strong inhibitory effect (>70%) being found in 11 samples. This work demonstrates that Caatinga is a potential source of bioactive plant proteins that can be isolated and studied for several applications. The biochemical prospecting of Caatinga is essential for collection of bioactive principles so as to add conservation value to the region.</p></div

A trypsin inhibitor from Tecoma stans leaves inhibits growth and promotes ATP depletion and lipid peroxidation in Candida albicans and Candida krusei

Tecoma stans (yellow elder) has shown medicinal properties and antimicrobial activity. Previous reports on antifungal activity of T. stans preparations and presence of trypsin inhibitor activity from T. stans leaves stimulated the investigation reported here. In this work, we proceeded to the purification and characterization of a trypsin inhibitor (TesTI), which was investigated for anti-Candida activity. Finally, in order to determine the potential of TesTI as a new natural chemotherapeutic product, its cytotoxicity to human peripheral blood mononuclear cells (PBMCs) was evaluated. TesTI was isolated from saline extract by ammonium sulphate fractionation followed by ion exchange and gel filtration chromatographies. Antifungal activity was evaluated by determining the minimal inhibitory (MIC) and fungicide (MFC) concentrations using fungal cultures containing only yeast form or both yeast and hyphal forms. Candida cells treated with TesTI were evaluated for intracellular ATP levels and lipid peroxidation. Cytotoxicity of TesTI to PBMCs was evaluated by MTT assay. TesTI (39.8 kDa, pI 3.41, Ki 43 nM) inhibited similarly the growth of both C. albicans and C. krusei culture types at MIC of 100 µg/mL. The MFCs were 200 µg/mL for C. albicans and C. krusei. Time-response curves revealed that TesTI (at MIC) was more effective at inhibiting the replication of C. albicans cells. At MIC, TesTI promoted reduction of ATP levels and lipid peroxidation in the Candida cells, being not cytotoxic to PBMCs. In conclusion, TesTI is an antifungal agent against C. albicans and C. krusei, without toxicity to human cells

Toluidine Blue stained histological sections of the midgut of <i>Aedes aegypti</i> L4 from control (A) and incubated for 12 h with the <i>Schinus terebinthifolius</i> leaf extract (B).

<p>Midgut from control larva (A) showed a single-layered epithelium (ep) comprised of digestive (dc) and regenerative cells (rc) with preserved morphology (C). L, midgut lumen; m, muscle; n, digestive cell nuclei. Midgut from treated larva (B) showed intense disorganization of the epithelial layer (ep) with several spaces between cells (*) and some hypertrophied digestive cells (dc). Tissue/cell debris (arrowhead) is seen in the midgut lumen. m, muscle; n, digestive cell nucleus; pm, peritrophic matrix. Details of columnar digestive cells for control (C) and treated (D) larvae. Structure resembling vacuoles (v) are seen in D. n, cell nucleus; N, nucleolus; B, brush border.</p

<i>Aedes aegypti</i> L₄ larvae incubated for 12 h with <i>Schinus terebinthifolius</i> leaf extract (1.0%, w/v).

<p>(A) Larva eliminating the gut content covered by the peritrophic matrix. (B) Shrunken and pigmented midgut dissected from a larva incubated with the leaf extract. (C) Midgut dissected from a control larvae, after removal of gut content and peritrophic matrix, without apparent alterations. (D) Midgut dissected from a larva incubated with the leaf extract containing the 0.01 M phenylthiourea (PTU), a phenoloxidase inhibitor. (E) Midgut dissected from a larva incubated with 0.01 M PTU.</p