Identification of Echinacea Purpurea (L.) Moench Root LysM Lectin with Nephrotoxic Properties.

Echinacea purpurea (L.) Moench (EP) is a well-studied plant used for health benefits. Even though there are a lot of data on EP secondary metabolites, its active proteins are not studied well enough. The aim of our experiment was to purify lectin fraction from EP roots and evaluate its biological activity in vitro as well as its effect on kidney morphology in vivo. An EP root glycoprotein fraction was purified by affinity chromatography, identified by LC-MS/MS, and used for biological activity tests in vitro and in vivo. Identified glycoproteins were homologous with the LysM domain containing lectins from the Asteraceae plants Helianthus annuus L., Lactuca sativa L., Cynara cardunculus L. A purified fraction was tested by hemagglutination and hemagglutination inhibition (by carbohydrate reactions) in vitro. We purified the hemagglutinating active ~40 kDa size lactose, D-mannose, and D-galactose specific glycoproteins with two peptidoglycan binding LysM (lysine motif) domains. Purified LysM lectin was tested in vivo. Eight-week old Balb/C male mice (n = 15) were treated with 5 µg of the purified lectin. Injections were repeated four times per week. At the fifth experimental week, animals were sedated with carbon dioxide, then euthanized by cervical dislocation and their kidney samples were collected. Morphological changes were evaluated in hematoxylin and eosin stained kidney samples. The purified LysM lectin induced a statistically significant (p < 0.05) kidney glomerular vacuolization and kidney tubular necrosis (p < 0.001).

Compatibility and safety of five lectin-binding putative probiotic strains for the development of a multi-strain protective culture for poultry.

The ban on the use of antibiotics as feed additives for animal growth promotion in the European Union and United States and the expectation of this trend to further expand to other countries in the short term have prompted a surge in probiotic research. Multi-species probiotics including safe and compatible strains with the ability to bind different nutritional lectins with detrimental effects on poultry nutrition could replace antibiotics as feed additives. Lactobacillus salivarius LET201, Lactobacillus reuteri LET210, Enterococcus faecium LET301, Propionibacterium acidipropionici LET103 and Bifidobacterium infantis CRL1395 have proved to be compatible as evaluated through three different approaches: the production and excretion of antimicrobial compounds, growth inhibition by competition for essential nutrients and physical contact, and a combination of both. The safety of P. acidipropionici LET103 was confirmed, since no expression of virulence factors or antibiotic resistance was detected. The innocuity of E. faecium LET301 should be further evaluated, since the presence of genes coding for certain virulence factors (gelE, efaAfm and efaAfs) was observed, albeit no expression of gelE was previously detected for this strain and there are no reports of involvement of efaAfm in animal pathogenicity. Finally, a combination of the five strains effectively protected intestinal epithelial cells of broilers from the cytotoxicity of mixtures of soybean agglutinin, wheat germ agglutinin and concanavalin A. To our knowledge, this is the first time that a combination of strains is evaluated for their protection against lectins that might be simultaneously present in poultry feeds.

Effect of Polygonum persicaria (Polygonales: Polygonaceae) Extracted Agglutinin on Life Table and Antioxidant Responses in Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae.

Plant lectins could reduce insect populations by imposing imbalances in biology and physiology. Here, an agglutinin was extracted from Polygonum persicaria L. (PPA; Polygonales: Polygonaceae) and its effects were investigated on life table parameters and antioxidant system of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). PPA significantly changed demographic parameters showing adverse effects on age-stage survival rate (Sxj), age-specific survival rate (lx), age-specific fecundity rate (mx), age stage specific fecundity (fxj), and life expectancy (exj). Also, life table parameters including net reproduction rate (R0) (Offspring/female), intrinsic rate of population increase (rm) (days-1), finite rate of increase (λ) (days-1), gross reproduction rate (GRR) (Offspring/female) significantly decreased in the PPA-treated H. armigera compared to control except for mean generation time (T) (days). Activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CA), peroxidase (POX), glutathione S-transferase (GST) and glucose 6-phosphate dehydrogenase (GPDH) increased statistically in the PPA-treated larvae compared to control while no significant difference was observed in the activity of ascorbate peroxidase (APOX) activity. Moreover, ratio of RSSR/RSH and concentration of malondialdehyde (MDA) were found to be statistically higher in PPA-treated larvae than control. The current results clearly showed that PPA not only had a negative impact on demography of H. armigera but also induced antioxidant raise by releasing free radicals. These released radicals, together with impaired digestion and absorption observed in our previous report, could be considered as a reason for reducing biological fitness of H. armigera.

Contribution of the carbohydrate-binding ability of Vatairea guianensis lectin to induce edematogenic activity.

Vatairea guianensis lectin (VGL), Dalbergiae tribe, is a N-acetyl-galactosamine (GalNAc)/Galactose (Gal) lectin previously purified and characterized. In this work, we report its structural features, obtained from bioinformatics tools, and its inflammatory effect, obtained from a rat paw edema model. The VGL model was obtained by homology with the lectin of Vatairea macrocarpa (VML) as template, and we used it to demonstrate the common characteristics of legume lectins, such as the jellyroll motif and presence of a metal-binding site in the vicinity of the carbohydrate-recognition domain (CRD). Protein-ligand docking revealed favorable interactions with N-acetyl-d-galactosamine, d-galactose and related sugars as well as several biologically relevant N- and O-glycans. In vivo testing of paw edema revealed that VGL induces edematogenic effect involving prostaglandins, interleukins and VGL CRD. Taken together, these data corroborate with previous reports showing that VGL interacts with N- and/or O-glycans of molecular targets, particularly in those presenting galactosides in their structure, contributing to the lectin inflammatory effect.

Studies in a Murine Model Confirm the Safety of Griffithsin and Advocate Its Further Development as a Microbicide Targeting HIV-1 and Other Enveloped Viruses.

Griffithsin (GRFT), a lectin from Griffithsia species, inhibits human immunodeficiency virus-1 (HIV-1) replication at sub-nanomolar concentrations, with limited cellular toxicity. However, in vivo safety of GRFT is not fully understood, especially following parenteral administration. We first assessed GRFT's effects in vitro, on mouse peripheral blood mononuclear cell (mPBMC) viability, mitogenicity, and activation using flow-cytometry, as well as cytokine secretion through enzyme-linked immunosorbent assay (ELISA). Toxicological properties of GRFT were determined after a single subcutaneous administration of 50 mg/kg or 14 daily doses of 10 mg/kg in BALB/c mice. In the context of microbicide development, toxicity of GRFT at 2 mg/kg was determined after subcutaneous, intravaginal, and intraperitoneal administrations, respectively. Interestingly, GRFT caused no significant cell death, mitogenicity, activation, or cytokine release in mPBMCs, validating the usefulness of a mouse model. An excellent safety profile for GRFT was obtained in vivo: no overt changes were observed in animal fitness, blood chemistry or CBC parameters. Following GRFT treatment, reversible splenomegaly was observed with activation of certain spleen B and T cells. However, spleen tissues were not pathologically altered by GRFT (either with a single high dose or chronic doses). Finally, no detectable toxicity was found after mucosal or systemic treatment with 2 mg/kg GRFT, which should be further developed as a microbicide for HIV prevention.

Cytotoxic damage of soybean agglutinin on intestinal epithelial cells of broiler chicks: in vitro protection by Bifidobacterium infantis CRL1395.

Plant lectins, which are proteins/glycoproteins present in a wide range of vegetables, fruits, cereals and beans, are resistant to digestive enzymes and food cooking temperatures. They bind reversibly to specific glycosidic residues expressed on the membrane of intestinal epithelial cells (IEC) and cause anti-nutritional effects in humans and animals. Soybean lectin (SBA) has been detected in poultry diets, and its ability to bind to the intestinal epithelium has been reported. The development of new methods for removing SBA from feeds or to prevent interaction with the intestinal mucosa is of interest. In this study, the in vitro cytotoxicity of SBA on IEC of chicks was demonstrated for the first time. The LD50, assessed after 2 h exposure of IEC to SBA, was 6.13 µg mL(-1) The ability of Bifidobacterium infantis CRL1395 to bind SBA on the bacterial envelope was confirmed, and prevention of IEC cytotoxicity by lectin removal was demonstrated. Safety of B. infantis CRL1395, resistance to gastrointestinal stress and adhesion were also determined. It was concluded that the early administration of B. infantis CRL1395 to chicks would effectively reduce the toxicity of SBA. Besides, it would favour the colonization of the gut with a beneficial microbiota.

Structural analysis of Centrolobium tomentosum seed lectin with inflammatory activity.

A glycosylated lectin (CTL) with specificity for mannose and glucose has been detected and purified from seeds of Centrolobium tomentosum, a legume plant from Dalbergieae tribe. It was isolated by mannose-sepharose affinity chromatography. The primary structure was determined by tandem mass spectrometry and consists of 245 amino acids, similar to other Dalbergieae lectins. CTL structures were solved from two crystal forms, a monoclinic and a tetragonal, diffracted at 2.25 and 1.9 Å, respectively. The carbohydrate recognition domain (CRD), metal-binding site and glycosylation site were characterized, and the structural basis for mannose/glucose-binding was elucidated. The lectin adopts the canonical dimeric organization of legume lectins. CTL showed acute inflammatory effect in paw edema model. The protein was subjected to ligand screening (dimannosides and trimannoside) by molecular docking, and interactions were compared with similar lectins possessing the same ligand specificity. This is the first crystal structure of mannose/glucose native seed lectin with proinflammatory activity isolated from the Centrolobium genus.

Sublethal effects of the insecticidal fusion protein ω-ACTX-Hv1a/GNA on the parasitoid Eulophus pennicornis via its host Lacanobia oleracea.

BACKGROUND: The neurotoxin peptide ω-ACTX-Hv1a, fused to the carrier molecule GNA, presents potential for insect control as a biopesticide, being orally toxic to insect pests from different orders. However, thorough evaluation is required to assure its safety towards non-target invertebrates. Effects of this novel biopesticide on the parasitoid Eulophus pennicornis via its host Lacanobia oleracea are presented. RESULTS: Hv1a/GNA did not cause mortality when injected or fed to fifth-stage L. oleracea, but caused up to 39% reduction in mean larval weight (P < 0.05) and increased developmental time when injected. When fed, GNA, but not Hv1a/GNA, caused ∼35% reduction in larval weight, indicating that host quality was not affected by the fusion protein. Although GNA and Hv1a/GNA were internalised by the hosts following ingestion, and thus were available to higher trophic levels, no significant changes in the rate of E. pennicornis parasitism occurred. Number of parasitoid pupae per host, adult emergence and sex ratio were unaffected by GNA- or Hv1a/GNA-treated hosts (P > 0.05). The fusion protein was degraded by parasitoid larvae, rendering it non-toxic. CONCLUSION: Hv1a/GNA has negligible effects on the parasitoid, even under worst-case scenarios. This low toxicity to these insects is of interest in terms of biopesticide specificity and safety to non-target organisms.

An International Proficiency Test to Detect, Identify and Quantify Ricin in Complex Matrices.

While natural intoxications with seeds of Ricinus communis (R. communis) have long been known, the toxic protein ricin contained in the seeds is of major concern since it attracts attention of those intending criminal, terroristic and military misuse. In order to harmonize detection capabilities in expert laboratories, an international proficiency test was organized that aimed at identifying good analytical practices (qualitative measurements) and determining a consensus concentration on a highly pure ricin reference material (quantitative measurements). Sample materials included highly pure ricin as well as the related R. communis agglutinin (RCA120) spiked into buffer, milk and meat extract; additionally, an organic fertilizer naturally contaminated with R. communis shred was investigated in the proficiency test. The qualitative results showed that either a suitable combination of immunological, mass spectrometry (MS)-based and functional approaches or sophisticated MS-based approaches alone successfully allowed the detection and identification of ricin in all samples. In terms of quantification, it was possible to determine a consensus concentration of the highly pure ricin reference material. The results provide a basis for further steps in quality assurance and improve biopreparedness in expert laboratories worldwide.

Characterization of Ricin and R. communis Agglutinin Reference Materials.

Ricinus communis intoxications have been known for centuries and were attributed to the toxic protein ricin. Due to its toxicity, availability, ease of preparation, and the lack of medical countermeasures, ricin attracted interest as a potential biological warfare agent. While different technologies for ricin analysis have been established, hardly any universally agreed-upon "gold standards" are available. Expert laboratories currently use differently purified in-house materials, making any comparison of accuracy and sensitivity of different methods nearly impossible. Technically challenging is the discrimination of ricin from R. communis agglutinin (RCA120), a less toxic but highly homologous protein also contained in R. communis. Here, we established both highly pure ricin and RCA120 reference materials which were extensively characterized by gel electrophoresis, liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI MS/MS), and matrix-assisted laser desorption ionization-time of flight approaches as well as immunological and functional techniques. Purity reached >97% for ricin and >99% for RCA120. Different isoforms of ricin and RCA120 were identified unambiguously and distinguished by LC-ESI MS/MS. In terms of function, a real-time cytotoxicity assay showed that ricin is approximately 300-fold more toxic than RCA120. The highly pure ricin and RCA120 reference materials were used to conduct an international proficiency test.

Entomotoxic properties of Dioclea violacea lectin and its effects on digestive enzymes of Anagasta kuehniella (Lepidoptera).

Entomotoxic plant lectins have been extensively studied in the past two decades, yet the exact mechanisms underlying their toxic effects remain unknown. This study investigated the effects of Dioclea violacea lectin (DVL) on larval development in Anagasta kuehniella. Chronic exposure of larvae (from neonates to the fourth instar) demonstrated that DVL interfered with larval growth, retarding development and decreasing larval mass without affecting survival. DVL decreased trypsin-like, chymotrypsin-like, and α-amylase activities and proved resistant to proteolysis by midgut proteases up to 24h. Shorter exposures to dietary DVL had no effect on midgut enzyme activity. Feeding fourth-instar larvae with fluorescently-labeled DVL revealed lectin binding to the peritrophic membrane.

Toxalbumin exposures: 12 years' experience of U.S. poison centers.

BACKGROUND: Toxalbumins are natural plant toxins purported to be highly toxic. The purpose was to evaluate toxalbumin exposures reported to U.S. poison centers to determine plants involved and their toxicities. METHODS: A retrospective review of National Poison Data System data on acute toxalbumin exposures with known outcomes from 2000 through 2011 was performed. RESULTS: There were 1164 exposures. The majority involved one route (1135; 97.5%), mostly ingestions (904; 79.7%) or dermal (166; 14.3%). Most patients developed no effects (694; 59.6%) or minor effects (374; 32.1%). Moderate or major effects occurred in 8.3% with 66.6% ingestions and 23.9% dermal. There were no deaths. Exposures to the plants Ricinus communis and Robinia pseudoacacia were most common (33.8% and 32.9%, respectively), with gastrointestinal effects from R. communis (vomiting 19.6%, diarrhea 8.9%, nausea 7.9%) and dermal effects from R. pseudoacacia (puncture 28.7%, dermal irritation/pain 27.9%, and edema 13.3%). CONCLUSIONS: While toxalbumin plant exposures were generally well-tolerated, continued evaluation of risk is warranted since plants were primarily identified by the public. Major effects occurred in under 1% of cases overall, and not at all following unintentional ingestions. These findings should help allay concerns that unintentional ingestions of toxalbumin plants by young children will cause serious toxicity and possibly death.

Antipneumococcal activity of neuraminidase inhibiting artocarpin.

Streptococcus (S.) pneumoniae is a major cause of secondary bacterial pneumonia during influenza epidemics. Neuraminidase (NA) is a virulence factor of both pneumococci and influenza viruses. Bacterial neuraminidases (NAs) are structurally related to viral NA and susceptible to oseltamivir, an inhibitor designed to target viral NA. This prompted us to evaluate the antipneumococcal potential of two NA inhibiting natural compounds, the diarylheptanoid katsumadain A and the isoprenylated flavone artocarpin. Chemiluminescence, fluorescence-, and hemagglutination-based enzyme assays were applied to determine the inhibitory efficiency (IC(50) value) of the tested compounds towards pneumococcal NAs. The mechanism of inhibition was studied via enzyme kinetics with recombinant NanA NA. Unlike oseltamivir, which competes with the natural substrate of NA, artocarpin exhibits a mixed-type inhibition with a Ki value of 9.70 µM. Remarkably, artocarpin was the only NA inhibitor (NAI) for which an inhibitory effect on pneumococcal growth (MIC: 0.99-5.75 µM) and biofilm formation (MBIC: 1.15-2.97 µM) was observable. In addition, we discovered that the bactericidal effect of artocarpin can reduce the viability of pneumococci by a factor of >1000, without obvious harm to lung epithelial cells. This renders artocarpin a promising natural product for further investigations.

Momordica charantia seed lectin: toxicity, bacterial agglutination and antitumor properties.

In last three decades, several studies were carried out on the D-galactose-specific lectin of Momordica charantia seeds (MCL). In the present study, in vitro growth inhibition (8-23 %) at different concentrations (6-24 µg/ml) of MCL was observed against Ehrlich ascites carcinoma (EAC) cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. MCL also showed 28, 45, and 75 % growth inhibitions against EAC cells when administered 1.2, 2.0, and 2.8 mg/kg/day (i.p.), respectively for five consequent days in vivo in mice. After lectin treatment, the level of red blood cell and hemoglobin was increased significantly with the decrease of white blood cell and maintained the normal level when compared with EAC-bearing control and normal mice without EAC cells. Although MCL caused cell cycle arrest at G0/G1 phase of EAC cells, any irregular shape or apoptotic morphological alterations in the lectin-treated EAC cells was not observed by an optical and fluorescence microscope. Lectin showed toxicity against brine shrimp nauplii with an LC50 value of 49.7 µg/ml. Four out of seven pathogenic bacteria were agglutinated by MCL in the absence of inhibitory sugar D-lactose/D-galactose. In conclusion, MCL showed strong cytotoxic effect and therefore can be used as a potent anticancer chemotherapeutic agent.

Cytotoxic and antiproliferative effect of tepary bean lectins on C33-A, MCF-7, SKNSH, and SW480 cell lines.

For many years, several studies have been employing lectin from vegetables in order to prove its toxic effect on various cell lines. In this work, we analyzed the cytotoxic, antiproliferative, and post-incubatory effect of pure tepary bean lectins on four lines of malignant cells: C33-A; MCF-7; SKNSH, and SW480. The tests were carried out employing MTT and 3[H]-thymidine assays. The results showed that after 24 h of lectin exposure, the cells lines showed a dose-dependent cytotoxic effect, the effect being higher on MCF-7, while C33-A showed the highest resistance. Cell proliferation studies showed that the toxic effect induced by lectins is higher even when lectins are removed, and in fact, the inhibition of proliferation continues after 48 h. Due to the use of two techniques to analyze the cytotoxic and antiproliferative effect, differences were observed in the results, which can be explained by the fact that one technique is based on metabolic reactions, while the other is based on the 3[H]-thymidine incorporated in DNA by cells under division. These results allow concluding that lectins exert a cytotoxic effect after 24 h of exposure, exhibiting a dose-dependent effect. In some cases, the cytotoxic effect is higher even when the lectins are eliminated, however, in other cases, the cells showed a proliferative effect.

Novel biopesticide based on a spider venom peptide shows no adverse effects on honeybees.

Evidence is accumulating that commonly used pesticides are linked to decline of pollinator populations; adverse effects of three neonicotinoids on bees have led to bans on their use across the European Union. Developing insecticides that pose negligible risks to beneficial organisms such as honeybees is desirable and timely. One strategy is to use recombinant fusion proteins containing neuroactive peptides/proteins linked to a 'carrier' protein that confers oral toxicity. Hv1a/GNA (Galanthus nivalis agglutinin), containing an insect-specific spider venom calcium channel blocker (ω-hexatoxin-Hv1a) linked to snowdrop lectin (GNA) as a 'carrier', is an effective oral biopesticide towards various insect pests. Effects of Hv1a/GNA towards a non-target species, Apis mellifera, were assessed through a thorough early-tier risk assessment. Following feeding, honeybees internalized Hv1a/GNA, which reached the brain within 1 h after exposure. However, survival was only slightly affected by ingestion (LD50>100 µg bee(-1)) or injection of fusion protein. Bees fed acute (100 µg bee(-1)) or chronic (0.35 mg ml(-1)) doses of Hv1a/GNA and trained in an olfactory learning task had similar rates of learning and memory to no-pesticide controls. Larvae were unaffected, being able to degrade Hv1a/GNA. These tests suggest that Hv1a/GNA is unlikely to cause detrimental effects on honeybees, indicating that atracotoxins targeting calcium channels are potential alternatives to conventional pesticides.

Effects of short-term heating on total polyphenols, anthocyanins, antioxidant activity and lectins of different parts of dwarf elder (Sambucus ebulus L.).

Dwarf elder (Sambucus ebulus L.) berries are rich in health-promoting phytochemicals such as polyphenols and anthocyanins, and display a significant antioxidant activity. They are also rich in two lectins (ebulin f and SELfd) that share amino acid sequence homology with the elderberry allergen Sam n1 present in Sambucus nigra pollen and fruits. Ebulin f displays toxicity by oral ingestion. This study was aimed at eliminating the toxicity of these lectins whilst having little or no effect on the antioxidant properties of dwarf elder berries. We thus investigated the potential effects of incubation in a boiling water bath of extracts from several parts of the plant on total polyphenol content, antioxidant activity, total anthocyanins, cyanidin-3-glycoside content, and the sensitivity of purified dwarf elder fruit lectins to a simulated gastric fluid. The study shows that five minutes of said heat treatment fully sensitized both lectins to pepsin digestion, whilst minimally reducing phenol and antioxidant as well as free radical scavenging activities to below 13%. It proved possible to eliminate the potential risks derived from the presence of lectins in dwarf elder juices without any significant reduction in the content of the antioxidant compounds. Dwarf elder berries may thus be a valuable nutritional source.

Binding of insecticidal lectin Colocasia esculenta tuber agglutinin (CEA) to midgut receptors of Bemisia tabaci and Lipaphis erysimi provides clues to its insecticidal potential.

The insecticidal potential of Galanthus nivalis agglutinin-related lectins against hemipterans has been experimentally proven. However, the basis behind the toxicity of these lectins against hemipterans remains elusive. The present study elucidates the molecular basis behind insecticidal efficacy of Colocasia esculenta tuber agglutinin (CEA) against Bemisia tabaci and Lipaphis erysimi. Confocal microscopic analyses highlighted the binding of 25 kDa stable homodimeric lectin to insect midgut. Ligand blots followed by LC MS/MS analyses identified binding partners of CEA as vacuolar ATP synthase and sarcoplasmic endoplasmic reticulum type Ca(2+) ATPase from B. tabaci, and ATP synthase, heat shock protein 70 and clathrin heavy chain assembly protein from L. erysimi. Internalization of CEA into hemolymph was confirmed by Western blotting. Glycoprotein nature of the receptors was identified through glycospecific staining. Deglycosylation assay indicated the interaction of CEA with its receptors to be probably glycan mediated. Surface plasmon resonance analysis revealed the interaction kinetics between ATP synthase of B. tabaci with CEA. Pathway prediction study based on Drosophila homologs suggested the interaction of CEA with insect receptors that probably led to disruption of cellular processes causing growth retardation and loss of fecundity of target insects. Thus, the present findings strengthen our current understanding of the entomotoxic potentiality of CEA, which will facilitate its future biotechnological applications.

Isolation and molecular characterization of two lectins from dwarf elder (Sambucus ebulus L.) blossoms related to the Sam n1 allergen.

Sambucus species contain a number of lectins with and without antiribosomal activity. Here, we show that dwarf elder (Sambucus ebulus L.) blossoms express two D-galactose-binding lectins that were isolated and purified by affinity chromatography and gel filtration. These proteins, which we named ebulin blo (A-B toxin) and SELblo (B-B lectin)--blo from blossoms--were subjected to molecular characterization and analysis by MALDI-TOF mass spectrometry and tryptic peptide fingerprinting. Both lectins share a high degree of amino acid sequence homology with Sambucus lectins related to the Sam n1 allergen. Ebulin blo, but not SELblo, was highly toxic by nasal instillation to mice. Overall, our results suggested that both lectins would belong to an allergen family exemplified by Sam n1 and could trigger allergy responses. Furthermore, they raise a concern about ebulin blo toxicity.

Insecticidal effect of labramin, a lectin-like protein isolated from seeds of the beach apricot tree, Labramia bojeri, on the Mediterranean flour moth, Ephestia kuehniella.

The objective of this work was to study the insecticidal effect of labramin, a protein that shows lectin-like properties. Labramin was isolated from seeds of the Beach Apricot tree, Labramia bojeri A. DC ex Dubard (Ericales: Sapotaceae), and assessed against the development of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), an important pest of stored products such as corn, wheat, rice, and flour. Results showed that labramin caused 90% larval mortality when incorporated in an artificial diet at a level of 1% (w/w). The presence of 0.25% labramin in the diet affected the larval and pupal developmental periods and the percentage of emerging adults. Treatments resulted in elevated levels of trypsin activity in midgut and fecal materials, indicating that labramin may have affected enzyme-regulatory mechanisms by perturbing peritrophic membranes in the midgut of is. kuehniella larvae. The results of dietary experiments with E. kuehniella larvae showed a reduced efficiency for the conversion of ingested and digested food, and an increase in approximate digestibility and metabolic cost. These findings suggest that labramin may hold promise as a control agent to engineer crop plants for insect resistance.