An antifungal peptide from passion fruit (Passiflora edulis) seeds with similarities to 2S albumin proteins

Antifungal Effect of Bauhinia variegata Lectin (BvL) on Bipolaris oryzae

The search for less harmful, ecologically efficient, more specific, and natural alternatives for the control of pathogens is essential. Bauhinia variegata lectin (BvL) is a protein that has numerous biological activities, including antifungal. The present study examines the potential in vitro of B. variegata lectin against the fungus Bipolaris oryzae, responsible for agricultural losses in southern Brazil, due to damage to rice fields during seed germination. Bioassays to assess the inhibition potential of BvL were performed, including fungal growth, spore formation, and germination, in concentrations of 0, 25, 50, and 100 µg mL-1. Only the concentration of 100 µg mL-1 successfully inhibited mycelial growth and spore germination, while in spore formation, all treatments inhibited sporulation. In addition, fluorescence microscopy analysis demonstrated the ability of lectin to bind to the fungus and the lack of detection in the presence of lactose, suggesting its interaction with the fungal cell wall structures. This study highlights the potential of B. variegata seed lectin to control mycelial growth, sporulation, and germination of the phytopathogenic fungus B. oryzae, posing as a new biotechnological possibility for biological control.

Comprehensive Review on Fruit Seeds: Nutritional, Phytochemical, Nanotechnology, Toxicity, Food Biochemistry, and Biotechnology Perspective

Fruit seeds are leftovers from a variety of culinary sectors. They are generally unutilized and contribute greatly to global disposals. These seeds not only possess various nutritional attributes but also have many heath-beneficial properties. One way to make use of these seeds is to extract their bioactive components and create fortified food items. Nowadays, researchers are highly interested in creating innovative functional meals and food components from these unconventional resources. The main objective of this manuscript was to determine the usefulness of seed powder from 70 highly consumed fruits, including Apple, Apricot, Avocado, Banana, Blackberry, Blackcurrant, Blueberry, Cherry, Common plum, Cranberry, Gooseberry, Jackfruit, Jamun, Kiwi, Lemon, Mahua, Mango, Melon, Olive, Orange, and many more have been presented. The nutritional attributes, phytochemical composition, health advantages, nanotechnology applications, and toxicity of these fruit seeds have been fully depicted. This study also goes into in-depth detailing on creating useful food items out of these seeds, such as bakery goods, milk products, cereal-based goods, and meat products. It also identifies enzymes purified from these seeds along with their biochemical applications and any research openings in this area.

Food Allergens of Plant Origin

This review presents an update on the physical, chemical, and biological properties of food allergens in plant sources, focusing on the few protein families that contribute to multiple food allergens from different species and protein families recently found to contain food allergens. The structures and structural components of the food allergens in the allergen families may provide further directions for discovering new food allergens. Answers as to what makes some food proteins allergens are still elusive. Factors to be considered in mitigating food allergens include the abundance of the protein in a food, the property of short stretches of the sequence of the protein that may constitute linear IgE binding epitopes, the structural properties of the protein, its stability to heat and digestion, the food matrix the protein is in, and the antimicrobial activity to the microbial flora of the human gastrointestinal tract. Additionally, recent data suggest that widely used techniques for mapping linear IgE binding epitopes need to be improved by incorporating positive controls, and methodologies for mapping conformational IgE binding epitopes need to be developed.

The potential of plant proteins as antifungal agents for agricultural applications

Fungal pathogens induce a variety of diseases in both plants and post-harvest food crops, resulting in significant crop losses for the agricultural industry. Although the usage of chemical-based fungicides is the most common way to control these diseases, they damage the environment, have the potential to harm human and animal life, and may lead to resistant fungal strains. Accordingly, there is an urgent need for diverse and effective agricultural fungicides that are environmentally- and eco-friendly. Plants have evolved various mechanisms in their innate immune system to defend against fungal pathogens, including soluble proteins secreted from plants with antifungal activities. These proteins can inhibit fungal growth and infection through a variety of mechanisms while exhibiting diverse functionality in addition to antifungal activity. In this mini review, we summarize and discuss the potential of using plant antifungal proteins for future agricultural applications from the perspective of bioengineering and biotechnology.

Plant derived antimicrobial peptides: Mechanism of target, isolation techniques, sources and pharmaceutical applications

Antimicrobial resistance is a global health and development threat which is caused by the excess and prolonged usage of antimicrobial compounds in agriculture and pharmaceutical industries. Resistance of pathogenic microorganisms to the already existing drugs represent a serious risk to public health. Plant sources such as cereals, legumes, fruits and vegetables are potential substrates for the isolation of antimicrobial peptides (AMP) with broad spectrum antimicrobial activity against bacteria, fungi and viruses with novel immunomodulatory activities. Thus, in the quest of new antimicrobial agents, AMPs have recently gained interest. Therefore, AMP can be used in agriculture, pharmaceutical and food industries. This review focuses on various explored and unexplored plant based food sources of AMPs, their isolation techniques and antimicrobial mechanism of peptides. Therefore, the literature discussed in this review paper will prove beneficial the research purposes for agriculture, pharmaceutical and food industries. PRACTICAL APPLICATIONS: Isolation of antimicrobial peptides (AMPs) can be done on industrial scale. AMP isolated from food sources can be used in pharmaceutical and agriculture industries. AMP from natural sources mitigate the problem of antimicrobial resistance. AMP isolated from food products can be used as nutraceutical.

Plant-Derived Antimicrobial Peptides: Novel Preservatives for the Food Industry

Food spoilage is a widespread issue brought on by the undesired growth of microbes in food products. Thousands of tons of usable food or food products are wasted every day due to rotting in different parts of the world. Several food preservation techniques are employed to prevent food from rotting, including the use of natural or manufactured chemicals or substances; however, the issue persists. One strategy for halting food deterioration is the use of plant-derived antimicrobial peptides (AMPs), which have been investigated for possible bioactivities against a range of human, plant, and food pathogens. The food industry may be able to benefit from the development of synthetic AMPs, produced from plants that have higher bioactivity, better stability, and decreased cytotoxicity as a means of food preservation. In order to exploit plant-derived AMPs in various food preservation techniques, in this review, we also outline the difficulties in developing AMPs for use as commercial food preservatives. Nevertheless, as technology advances, it will soon be possible to fully explore the promise of plant-derived AMPs as food preservatives.

Antifungal Peptides and Proteins to Control Toxigenic Fungi and Mycotoxin Biosynthesis

The global challenge to prevent fungal spoilage and mycotoxin contamination on food and feed requires the development of new antifungal strategies. Antimicrobial peptides and proteins (AMPs) with antifungal activity are gaining much interest as natural antifungal compounds due to their properties such as structure diversity and function, antifungal spectrum, mechanism of action, high stability and the availability of biotechnological production methods. Given their multistep mode of action, the development of fungal resistance to AMPs is presumed to be slow or delayed compared to conventional fungicides. Interestingly, AMPs also accomplish important biological functions other than antifungal activity, including anti-mycotoxin biosynthesis activity, which opens novel aspects for their future use in agriculture and food industry to fight mycotoxin contamination. AMPs can reach intracellular targets and exert their activity by mechanisms other than membrane permeabilization. The mechanisms through which AMPs affect mycotoxin production are varied and complex, ranging from oxidative stress to specific inhibition of enzymatic components of mycotoxin biosynthetic pathways. This review presents natural and synthetic antifungal AMPs from different origins which are effective against mycotoxin-producing fungi, and aims at summarizing current knowledge concerning their additional effects on mycotoxin biosynthesis. Antifungal AMPs properties and mechanisms of action are also discussed.

Recent advances in Penicillium expansum infection mechanisms and current methods in controlling P. expansum in postharvest apples

One of the most significant challenges associated with postharvest apple deterioration is the blue mold caused by Penicillium expansum, which leads to considerable economic losses to apple production industries. Apple fruits are susceptible to mold infection owing to their high nutrient and water content, and current physical control methods can delay but cannot completely inhibit P. expansum growth. Biological control methods present promising alternatives; however, they are not always cost effective and have application restrictions. P. expansum infection not only enhances disease pathogenicity, but also inhibits the expression of host-related defense genes. The implementation of new ways to investigate and control P. expansum are expected with the advent of omics technology. Advances in these techniques, together with molecular biology approaches such as targeted gene deletion and whole genome sequencing, will lead to a better understanding of the P. expansum infectious machinery. Here, we review the progress of research on the blue mold disease caused by P. expansum in apples, including physiological and molecular infection mechanisms, as well as various methods to control this common plant pathogen.

Isolation and functionalities of bioactive peptides from fruits and vegetables: A reviews

Bioactive peptides have recently gained more research attention as potential therapies for the management of bodily disorders and metabolic syndromes of delicate health importance. On another note, there is a rising trend on a global scale for the consumption and adoption of fruit and vegetables for the fulfilment of dietary and health needs. Furthermore, fruits and vegetables are being more studied as base materials for the isolation of biologically functional components and accordingly, they have been investigated for their concomitant bioactive peptides. This review focuses on isolation and bio-functional properties of bioactive peptides from fruits and vegetables. This manuscript is potential in serving as a material collection for fundamental consultancy on peptides derived from fruits and vegetables, and further canvasses the necessitation for the use of these food materials as primal matter for such.

Passiflora edulis: An Insight Into Current Researches on Phytochemistry and Pharmacology

Passiflora edulis, also known as passion fruit, is widely distributed in tropical and subtropical areas of the world and becomes popular because of balanced nutrition and health benefits. Currently, more than 110 phytochemical constituents have been found and identified from the different plant parts of P. edulis in which flavonoids and triterpenoids held the biggest share. Various extracts, fruit juice and isolated compounds showed a wide range of health effects and biological activities such as antioxidant, anti-hypertensive, anti-tumor, antidiabetic, hypolipidemic activities, and so forth. Daily consumption of passion fruit at common doses is non-toxic and safe. P. edulis has great potential development and the vast future application for this economically important crop worldwide, and it is in great demand as a fresh product or a formula for food, health care products or medicines. This mini-review aims to provide systematically reorganized information on physiochemical features, nutritional benefits, biological activities, toxicity, and potential applications of leaves, stems, fruits, and peels of P. edulis.

Role of membrane sterol and redox system in the anti-candida activity reported for Mo-CBP2, a protein from Moringa oleifera seeds

Plant proteins are emerging as an alternative to conventional treatments against candidiasis. The aim of this study was to better understand the mechanism of action of Mo-CBP₂ against Candida spp, evaluating redox system activity, lipid peroxidation, DNA degradation, cytochrome c release, medium acidification, and membrane interaction. Anti-candida activity of Mo-CBP₂ decreased in the presence of ergosterol, which was not observed with antioxidant agents. C. albicans treated with Mo-CBP₂ also had catalase and peroxidase activities inhibited, while superoxide dismutase was increased. Mo-CBP₂ increased the lipid peroxidation, but it did not alter the ergosterol profile in live cells. External medium acidification was strongly inhibited, and cytochrome c release and DNA degradation were detected. Mo-CBP₂ interacts with cell membrane constituents, changes redox system enzymes in C. albicans and causes lipid peroxidation by ROS overproduction. DNA degradation and cytochrome c release suggest apoptotic or DNAse activity. Lipid peroxidation and H⁺-ATPases inhibition may induce the process of apoptosis. Finally, Mo-CBP₂ did not have a cytotoxic effect in mammalian Vero cells. This study highlights the biotechnological potential of Mo-CBP₂ as a promising molecule with low toxicity and potent activity. Further studies should be performed to better understand its mode of action and toxicity.

Gene expression and spatiotemporal localization of antifungal chitin-binding proteins during Moringa oleifera seed development and germination

Chitin-binding proteins behave as storage and antifungal proteins in the seeds of Moringa oleifera. Moringa oleifera is a tropical multipurpose tree. Its seed constituents possess coagulant, bactericidal, fungicidal, and insecticidal properties. Some of these properties are attributed to a group of polypeptides denominated M. oleifera chitin-binding proteins (in short, Mo-CBPs). Within this group, Mo-CBP₂, Mo-CBP₃, and Mo-CBP₄ were previously purified to homogeneity. They showed high amino acid similarity with the 2S albumin storage proteins. These proteins also presented antimicrobial activity against human pathogenic yeast and phytopathogenic fungi. In the present study, the localization and expression of genes that encode Mo-CBPs and the biosynthesis and degradation of the corresponding proteins during morphogenesis and maturation of M. oleifera seeds at 15, 30, 60, and 90 days after anthesis (DAA) and germination, respectively, were assessed. The Mo-CBP transcripts and corresponding proteins were not detected at 15 and 30 days after anthesis (DAA). However, they accumulated at the latter stages of seed maturation (60 and 90 DAA), reaching the maximum level at 60 DAA. The degradation kinetics of Mo-CBPs during seed germination by in situ immunolocalization revealed a reduction in the protein content 48 h after sowing (HAS). Moreover, Mo-CBPs isolated from seeds at 60 and 90 DAA prevented the spore germination of Fusarium spp. Taken together, these results suggest that Mo-CBPs play a dual role as storage and defense proteins in the seeds of M. oleifera.

Molecular cloning, expression, purification and functional characterization of an antifungal cyclophilin protein from Panax ginseng

Cyclophilins (CyPs), a member of peptidyl-prolyl cis-trans isomerases (PPIases), are ubiquitously distributed in organisms such as bacteria, yeast, plants and animals. CyPs have diverse biological functions, with some exhibiting antifungal and antiviral activities. In this study, Panax ginseng cyclophilin (pgCyP), a novel gene encoding an antifungal protein from Panax ginseng, was cloned, and its protein product was expressed in Escherichia coli, and then fractionated by affinity chromatography. The open reading frame of the pgCyP full-length coding sequence was found to encode a single-domain CyP-like protein of 174 amino residues with a calculated molecular weight of 18.7 kDa. The pGEX system was used to express pgCyP fused to glutathione S-transferase. After affinity purification, the protein showed a strong fungal resistance effect on Phytophthora cactorum. In addition, pgCyP showed high PPIase activity. To the best of our knowledge, the present study is the first successful effort to clone and characterize a CyP-like protein gene from Panax ginseng.

The arms race between heliconiine butterflies and Passiflora plants - new insights on an ancient subject

Heliconiines are called passion vine butterflies because they feed exclusively on Passiflora plants during the larval stage. Many features of Passiflora and heliconiines indicate that they have radiated and speciated in association with each other, and therefore this model system was one of the first examples used to exemplify coevolution theory. Three major adaptations of Passiflora plants supported arguments in favour of their coevolution with heliconiines: unusual variation of leaf shape within the genus; the occurrence of yellow structures mimicking heliconiine eggs; and their extensive diversity of defence compounds called cyanogenic glucosides. However, the protection systems of Passiflora plants go beyond these three features. Trichomes, mimicry of pathogen infection through variegation, and production of extrafloral nectar to attract ants and other predators of their herbivores, are morphological defences reported in this plant genus. Moreover, Passiflora plants are well protected chemically, not only by cyanogenic glucosides, but also by other compounds such as alkaloids, flavonoids, saponins, tannins and phenolics. Heliconiines can synthesize cyanogenic glucosides themselves, and their ability to handle these compounds was probably one of the most crucial adaptations that allowed the ancestor of these butterflies to feed on Passiflora plants. Indeed, it has been shown that Heliconius larvae can sequester cyanogenic glucosides and alkaloids from their host plants and utilize them for their own benefit. Recently, it was discovered that Heliconius adults have highly accurate visual and chemosensory systems, and the expansion of brain structures that can process such information allows them to memorize shapes and display elaborate pre-oviposition behaviour in order to defeat visual barriers evolved by Passiflora species. Even though the heliconiine-Passiflora model system has been intensively studied, the forces driving host-plant preference in these butterflies remain unclear. New studies have shown that host-plant preference seems to be genetically controlled, but in many species there is some plasticity in this choice and preferences can even be induced. Although much knowledge regarding the coevolution of Passiflora plants and heliconiine butterflies has accumulated in recent decades, there remain many exciting unanswered questions concerning this model system.

Antimicrobial Peptides from Fruits and Their Potential Use as Biotechnological Tools-A Review and Outlook

Bacterial resistance is a major threat to plant crops, animals and human health, and over the years this situation has increasingly spread worldwide. Due to their many bioactive compounds, plants are promising sources of antimicrobial compounds that can potentially be used in the treatment of infections caused by microorganisms. As well as stem, flowers and leaves, fruits have an efficient defense mechanism against pests and pathogens, besides presenting nutritional and functional properties due to their multifunctional molecules. Among such compounds, the antimicrobial peptides (AMPs) feature different antimicrobials that are capable of disrupting the microbial membrane and of acting in binding to intra-cytoplasmic targets of microorganisms. They are therefore capable of controlling or halting the growth of microorganisms. In summary, this review describes the major classes of AMPs found in fruits, their possible use as biotechnological tools and prospects for the pharmaceutical industry and agribusiness.

Bioactives from fruit processing wastes: Green approaches to valuable chemicals

Fruit processing industries contribute more than 0.5billion tonnes of waste worldwide. The global availability of this feedstock and its untapped potential has encouraged researchers to perform detailed studies on value-addition potential of fruit processing waste (FPW). Compared to general food or other biomass derived waste, FPW are found to be selective and concentrated in nature. The peels, pomace and seed fractions of FPW could potentially be a good feedstock for recovery of bioactive compounds such as pectin, lipids, flavonoids, dietary fibres etc. A novel bio-refinery approach would aim to produce a wider range of valuable chemicals from FPW. The wastes from majority of the extraction processes may further be used as renewable sources for production of biofuels. The literature on value addition to fruit derived waste is diverse. This paper presents a review of fruit waste derived bioactives. The financial challenges encountered in existing methods are also discussed.

Plant antifungal proteins and their applications in agriculture

Fungi are far more complex organisms than viruses or bacteria and can develop numerous diseases in plants that cause loss of a substantial portion of the crop every year. Plants have developed various mechanisms to defend themselves against these fungi which include the production of low-molecular-weight secondary metabolites and proteins and peptides with antifungal activity. In this review, families of plant antifungal proteins (AFPs) including defensins, lectins, and several others will be summarized. Moreover, the application of AFPs in agriculture will also be analyzed.

Sunroot mediated synthesis and characterization of silver nanoparticles and evaluation of its antibacterial and rat splenocyte cytotoxic effects

A rapid, green phytosynthesis of silver nanoparticles (AgNPs) using the aqueous extract of Helianthus tuberosus (sunroot tuber) was reported in this study. The morphology of the AgNPs was determined by transmission electron microscopy (TEM). Scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS) and X-ray powder diffraction (XRD) analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy (FTIR) analysis revealed that biomolecules in the tuber extract were involved in the reduction and capping of AgNPs. The energy-dispersive spectroscopy (EDS) analysis of the AgNPs, using an energy range of 2–4 keV, confirmed the presence of elemental silver without any contamination. Further, the synthesized AgNPs were evaluated against phytopathogens such as Ralstonia solanacearum and Xanthomonas axonopodis. The AgNPs (1–4 mM) extensively reduced the growth rate of the phytopathogens. In addition, the cytotoxic effect of the synthesized AgNPs was analyzed using rat splenocytes. The cell viability was decreased according to the increasing concentration of AgNPs and 67% of cell death was observed at 100 μg/mL.

The use of versatile plant antimicrobial peptides in agribusiness and human health

Plant immune responses involve a wide diversity of physiological reactions that are induced by the recognition of pathogens, such as hypersensitive responses, cell wall modifications, and the synthesis of antimicrobial molecules including antimicrobial peptides (AMPs). These proteinaceous molecules have been widely studied, presenting peculiar characteristics such as conserved domains and a conserved disulfide bond pattern. Currently, many AMP classes with diverse modes of action are known, having been isolated from a large number of organisms. Plant AMPs comprise an interesting source of studies nowadays, and among these there are reports of different classes, including defensins, albumins, cyclotides, snakins and several others. These peptides have been widely used in works that pursue human disease control, including nosocomial infections, as well as for agricultural purposes. In this context, this review will focus on the relevance of the structural-function relations of AMPs derived from plants and their proper use in applications for human health and agribusiness.

Assessment of total phenolic, antioxidant, and antibacterial activities of Passiflora species

This study focused on total phenolic content (TPC) and antioxidant and antibacterial activities of the leaves and stems of Passiflora quadrangularis, P. maliformis, and P. edulis extracted using three solvents: petroleum ether, acetone, and methanol. The maximum extraction yields of antioxidant components from the leaves and stems were isolated using methanol extracts of P. edulis (24.28%) and P. quadrangularis (9.76%), respectively. Among the leaf extracts, the methanol extract of P. maliformis had the significantly highest TPC and the strongest antioxidant activity, whereas among the stem extracts, the methanol extract of P. quadrangularis showed the highest phenolic amount and possessed the strongest antioxidant activity. The antibacterial properties of the Passiflora species were tested using the disc diffusion method against 10 human pathogenic bacteria. The largest inhibition zone was observed for the methanol extract of P. maliformis against B. subtilis. Generally, extracts from the Passiflora species exhibit distinct inhibition against Gram-positive but not Gram-negative bacteria. Based on the generated biplot, three clusters of bacteria were designated according to their performance towards the tested extracts. The present study revealed that methanol extracts of the Passiflora contain constituents with significant phenolic, antioxidant, and antibacterial properties for pharmaceutical and nutraceutical uses.

The attack of the phytopathogens and the trumpet solo: Identification of a novel plant antifungal peptide with distinct fold and disulfide bond pattern

Phytopathogens cause economic losses in agribusiness. Plant-derived compounds have been proposed to overcome this problem, including the antimicrobial peptides (AMPs). This paper reports the identification of Ps-AFP1, a novel AMP isolated from the Pisum sativum radicle. Ps-AFP1 was purified and evaluated against phytopathogenic fungi, showing clear effectiveness. In silico analyses were performed, suggesting an unusual fold and disulfide bond pattern. A novel fold and a novel AMP class were here proposed, the αβ-trumpet fold and αβ-trumpet peptides, respectively. The name αβ-trumpet was created due to the peptide's fold, which resembles the musical instrument. The Ps-AFP1 mechanism of action was also proposed. Microscopic analyses revealed that Ps-AFP1 could affect the fungus during the hyphal elongation from spore germination. Furthermore, confocal microscopy performed with Ps-AFP1 labeled with FITC shows that the peptide was localized at high concentration along the fungal cell surface. Due to low cellular disruption rates, it seems that the main target is the fungal cell wall. The binding thermogram and isothermal titration, molecular dynamics and docking analyses were also performed, showing that Ps-AFP1 could bind to chitin producing a stable complex. Data here reported provided novel structural-functional insights into the αβ-trumpet peptide fold.

Isolation and identification of a novel polysaccharide–peptide complex with antioxidant, anti-proliferative and hypoglycaemic activities from the abalone mushroom

A novel antioxidant polysaccharide–peptide complex LB-1b from the fruiting bodies of the edible abalone mushroom (Pleurotus abalonus) was purified and identified. The structural characteristic of LB-1b was identified by FTIR (Fourier-transform IR), 13C NMR and 1H NMR spectroscopy. LB-1b is a polysaccharide–peptide complex that contains glucose, rhamnose, glucuronic acid and galactose in the molar ratio of 22.4:1:1.7:1.6 and the N-terminal sequence of its peptide moiety has also been determined. The N-terminal amino acid sequence of LB-1b, IPKERKEFQQAQHLK, showed some resemblance to antioxidant enzymes. LB-1b exhibited high antioxidant activity in erythrocyte haemolysis in vitro and the anti-proliferative activity towards hepatoma HepG2 cells and breast cancer MCF7 cells with an IC50 of 24 and 14 μM respectively. LB-1b also demonstrated hypoglycaemic activity in drug-induced diabetic mice and anti-HIV-1 RT (reverse transcriptase) with an IC50 value of 12.5 μM.

Bactericidal activity identified in 2S Albumin from sesame seeds and in silico studies of structure-function relations

Pathogenic bacteria constitute an important cause of hospital-acquired infections. However, the misuse of available bactericidal agents has led to the appearance of antibiotic-resistant strains. Thus, efforts to seek new antimicrobials with different action mechanisms would have an enormous impact. Here, a novel antimicrobial protein (SiAMP2) belonging to the 2S albumin family was isolated from Sesamum indicum kernels and evaluated against several bacteria and fungi. Furthermore, in silico analysis was conducted in order to identify conserved residues through other 2S albumin antimicrobial proteins (2S-AMPs). SiAMP2 specifically inhibited Klebsiella sp. Specific regions in the molecule surface where cationic (RR/RRRK) and hydrophobic (MEYWPR) residues are exposed and conserved were proposed as being involved in antimicrobial activity. This study reinforces the hypothesis that plant storage proteins might also play as pathogen protection providing an insight into the mechanism of action for this novel 2S-AMP and evolutionary relations between antimicrobial activity and 2S albumins.

Plant storage proteins with antimicrobial activity: novel insights into plant defense mechanisms

Storage proteins perform essential roles in plant survival, acting as molecular reserves important for plant growth and maintenance, as well as being involved in defense mechanisms by virtue of their properties as insecticidal and antimicrobial proteins. These proteins accumulate in storage vacuoles inside plant cells, and, in response to determined signals, they may be used by the different plant tissues in response to pathogen attack. To shed some light on these remarkable proteins with dual functions, storage proteins found in germinative tissues, such as seeds and kernels, and in vegetative tissues, such as tubercles and leaves, are extensively discussed here, along with the related mechanisms of protein expression. Among these proteins, we focus on 2S albumins, Kunitz proteinase inhibitors, plant lectins, glycine-rich proteins, vicilins, patatins, tarins, and ocatins. Finally, the potential use of these molecules in development of drugs to combat human and plant pathogens, contributing to the development of new biotechnology-based medications and products for agribusiness, is also presented.

Identification of a Passiflora alata Curtis dimeric peptide showing identity with 2S albumins

Antifungal proteins and peptides, essential compounds for plant defense, have been isolated from several tissues of various plants. These proteins could be used as a natural alternative to control phytopathogenic fungi. In this report a heterodimeric antifungal protein named Pa-AFP1, showing higher identity with the 2S albumin family, was purified by using 70-100% ammonium sulfate saturation and further purification steps such as anionic exchange Q-Sepharose chromatography associated with HPLC reversed-phase C4 chromatography. Analysis by Tricine-SDS-PAGE revealed two peptidic molecular masses of approximately 4500 Da and 7000 Da, in the presence of β-mercaptoethanol, while by removing the reducing agent a single protein with molecular mass of about 11,500 Da was obtained. Moreover, dimer mass was confirmed by MALDI-TOF analyses (11,569.76 Da). The antifungal protein, named Pa-AFP1, efficiently inhibited the growth of filamentous fungi Colletotrichum gloeosporioides, and was added to a short list of 2S albumins with antimicrobial properties. Otherwise, this same peptide showed no activity toward bacteria and yeasts. In summary, this compound could be used in the future to develop biotechnological products for the control of phytopathogenic fungi.

Isolation, cloning, and characterization of the 2S albumin: a new allergen from hazelnut

SCOPE

2S albumins are the major allergens involved in severe food allergy to nuts, seeds, and legumes. We aimed to isolate, clone, and express 2S albumin from hazelnut and determine its allergenicity.

METHODS

2S albumin from hazelnut extract was purified using size exclusion chromatography and RP-HPLC. After N-terminal sequencing, degenerated and poly-d(T) primers were used to clone the 2S albumin sequence from hazelnut cDNA. After expression in Escherichia coli and affinity purification, IgE reactivity was evaluated by Immunoblot/ImmunoCAP (inhibition) analyses using sera of nut-allergic patients.

RESULTS

N-terminal sequencing of a approximately 10 kDa peak from size exclusion chromatography/RP-HPLC gave two sequences highly homologous to pecan 2S albumin, an 11 amino acid (aa) N-terminal and a 10 aa internal peptide. The obtained clone (441 bp) encoded a 147 aa hazelnut 2S albumin consisting of a putative signal peptide (22 aa), a linker peptide (20 aa), and the mature protein sequence (105 aa). The latter was successfully expressed in E. coli. Both recombinant and natural 2S albumin demonstrated similar IgE reactivity in Immunoblot/ImmunoCAP (inhibition) analyses.

CONCLUSION

We confirmed the postulated role of hazelnut 2S albumin as an allergen. The availability of recombinant molecules will allow establishing the importance of hazelnut 2S albumin for hazelnut allergy.

Passiflin, a novel dimeric antifungal protein from seeds of the passion fruit

The intent was to isolate an antifungal protein from seeds of the passion fruit (Passiflora edulis) and to compare its characteristics with other antifungal proteins and bovine beta-lactoglobulin in view of its N-terminal amino acid sequence similarity to beta-lactoglobulin. The isolation procedure entailed ion-exchange chromatography on Q-Sepharose, hydrophobic interaction chromatography on Phenyl-Sepharose, ion-exchange chromatography on DEAE-cellulose, and FPLC-gel filtration on Superdex 75. The isolated 67-kDa protein, designated as passiflin, exhibited an N-terminal amino acid sequence closely resembling that of bovine beta-lactoglobulin. It is the first antifungal protein found to have a beta-lactoglobulin-like N-terminal sequence. Its dimeric nature is rarely found in antifungal proteins. It impeded mycelial growth in Rhizotonia solani with an IC(50) of 16 microM and potently inhibited proliferation of MCF-7 breast cancer cells with an IC(50) of 15 microM. There was no cross-reactivity of passiflin with anti-beta-lactoglobulin antiserum. Intact beta-lactoglobulin lacks antifungal and antiproliferative activities and is much smaller in molecular size than passiflin. However, it has been reported that hydrolyzed beta-lactoglobulin shows antifungal activity. The data suggest that passiflin is distinct from beta-lactoglobulin.

Comparative proteomical analysis of zygotic embryo and endosperm from Coffea arabica seeds

During coffee seed development, proteins are predominantly deposited in cotyledons and in the endosperm. Reserve proteins of the 11S family are the most abundant globulins in coffee seeds, acting as a nitrogen source during roasting and guaranteeing flavor and aroma. The aim of the present study was to compare the protein profiles of endosperm and zygotic embryos of coffee seeds. Proteins were extracted from whole seed as well as from embryo and endosperm, separately. Total proteins were analyzed by two-dimensional electrophoresis (2-DE) followed by identification by mass spectrometry (MS). The most abundant spots observed in the gels of coffee seeds were excised, digested with trypsin, and identified by MS as subunits of the 11S globulin. Spots with identical pI and molecular masses were also observed in the protein profiles of coffee endosperm and embryo, indicating that 11S protein is also highly expressed in those tissues. Peptide sequence coverage of about 20% of the entire 11S globulin was obtained. Three other proteins were identified in the embryo and endosperm 2-DE profiles as a Cupin superfamily protein, an allergenic protein (Pru ar 1), exclusive to the endosperm 2D map, and a hypothetical protein, observed only in the zygotic embryo profile.

Isolation and characterization of novel peptides from chilli pepper seeds: Antimicrobial activities against pathogenic yeasts

Different types of antimicrobial peptides have been identified in seeds from different plant species. The aim of this study was to isolate and characterize peptides present in chilli pepper seeds (Capsicum annuum L.) and evaluate their toxic activities against some yeast species. Initially, proteins from seed flour were extracted in phosphate buffer, pH 5.4, for 3 h at 4 degrees C and the pellet obtained at 90% saturation with ammonium sulfate was heated at 80 degrees C for 15 min. The resulting suspension was clarified by centrifugation and the supernatant was extensively dialyzed against water; the peptide-rich extract was then named F/0-90. Cation-exchange chromatography was performed to separate low molecular mass proteins. One of the resulting fractions, named F3, enriched with basic proteins of 6-16 kDa, was submitted to reverse-phase chromatography in a C2/C18 column by HPLC, resulting in four fractions denominated RP1, RP2, RP3 and RP4. When these fractions were submitted to N-terminal sequencing, the comparative analysis in databanks revealed homology for two of these peptides, isolated from fractions RP3 and RP4, with sequences of proteinase inhibitors and 2S albumins, respectively. The F3 fraction, rich in peptides, inhibited the growth of yeasts Saccharomyces cerevisiae, Candida albicans, Candida parapsilosis, Candida tropicalis, Pichia membranifaciens, Kluyveromyces marxiannus and Candida guilliermondii. The RP3 and RP4 fractions showed high inhibitory activity against the growth of the yeast S. cerevisiae. The F3 fraction was also able to inhibit glucose-stimulated acidification of the medium by yeast cells of S. cerevisiae and to cause several morphological changes in different yeasts, such as cell wall disorganization, bud formation as well as the formation of pseudohyphae.

The role of plant defence proteins in fungal pathogenesis

SUMMARY It is becoming increasingly evident that a plant-pathogen interaction may be compared to an open warfare, whose major weapons are proteins synthesized by both organisms. These weapons were gradually developed in what must have been a multimillion-year evolutionary game of ping-pong. The outcome of each battle results in the establishment of resistance or pathogenesis. The plethora of resistance mechanisms exhibited by plants may be grouped into constitutive and inducible, and range from morphological to structural and chemical defences. Most of these mechanisms are defensive, exhibiting a passive role, but some are highly active against pathogens, using as major targets the fungal cell wall, the plasma membrane or intracellular targets. A considerable overlap exists between pathogenesis-related (PR) proteins and antifungal proteins. However, many of the now considered 17 families of PR proteins do not present any known role as antipathogen activity, whereas among the 13 classes of antifungal proteins, most are not PR proteins. Discovery of novel antifungal proteins and peptides continues at a rapid pace. In their long coevolution with plants, phytopathogens have evolved ways to avoid or circumvent the plant defence weaponry. These include protection of fungal structures from plant defence reactions, inhibition of elicitor-induced plant defence responses and suppression of plant defences. A detailed understanding of the molecular events that take place during a plant-pathogen interaction is an essential goal for disease control in the future.

Susceptibility of Human Pathogenic Bacteria to Antimicrobial Peptides from Sesame Kernels

Hospital infection caused by Gram-negative bacteria is a serious and common problem, especially in developing countries. Aiming to reduce these infections, this report focuses on the identification and characterization of novel antimicrobial peptides from sesame (Sesamum indicum) kernel meals. Thus, sesame flour was extracted and precipitated with ammonium sulfate (100%). After dialysis, a rich fraction was applied to affinity red-Sepharose CL-6B chromatography, followed by reversed-phase high-performance liquid chromatography. Mass spectrometry analysis indicated the presence of a major peptide with molecular mass of approximately 5.8 kDa in both cultivars. The bactericidal activities of antimicrobial peptides were evaluated against several human pathogens that had been effective only against Klebsiella sp., a Gram-negative bacterium responsible for human urinary infection. These data indicate the biotechnological potential of sesame peptides as an alternative method for hospital infection control and also the decrease of bacterial resistance to synthetic antibiotics.