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

Ethnobotany, phytochemistry, pharmacology, and toxicology of the genus Sambucus L. (Viburnaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Sambucus L. (Viburnaceae) consists of about 29 recognized species distributed in all regions of the world except the extremely cold and desert areas. Some species have been used as traditional medicines to treat various disorders such as bone fractures, rheumatism, diabetes, respiratory and pulmonary disorders, skin diseases, inflammatory ailments, diarrhea, and others. However, the currently available data on traditional and pharmacological uses have not been comprehensively reviewed.

STUDY AIM

The present review is designed to provide information on the ethnobotanical uses, phytochemistry, toxicity, and the known biological properties of Sambucus, to understand their connotations and provide a scientific basis and gaps for further research.

MATERIALS AND METHODS

The information was obtained from different bibliographic databases, Google Scholar, Springer Link, Web of Science, PubMed, and Science Direct along with other literature sources such as dissertation before August 2021. The scientific names were validated using The Plant List and World Flora Online websites.

RESULTS

Twelve Sambucus species were found to be frequently mentioned in ethnomedical uses recorded in China, Korea, Turkey, Iran, and other countries. Traditionally, they have been used as remedies to numerous health complications among others, bone fractures and rheumatism, diabetes, wounds, inflammatory diseases, diarrhea, menstrual pains, respiratory and pulmonary complaints, skin disorders, headaches, snakebites, and urinary tract infections. To date, only eleven species have been studied for their chemical compounds and a total of 425 bioactive constituents, including phenolic compounds, terpenoids, fatty acids, cyanogenic glycosides, phytosterols, lectins, organic acids, alkaloid, coumarin, anthraquinone, and others have been reported. The crude extracts and the isolated chemical constituents exhibited diverse outstanding pharmacological activities including antioxidant, antimicrobial, antidiabetic, anti-inflammatory, antidepressant, analgesic, anti-giardial, immunomodulatory, scolicidal, anti-ulcerogenic, antiradical, bone-protective, anti-glycemic, antiosteoporotic, hypolipidemic, anti-glycation, and wound-healing properties.

CONCLUSION

This study summarized and scrutinized the data on traditional uses, pharmacological activities, phytochemicals, and toxicity of Sambucus species, which indicate they have interesting chemical compounds with diverse biological activities. Many traditional uses of some species from this genus have now been confirmed by pharmacological activities, such as antioxidant, antimicrobial, bone-protective, wound healing, anti-inflammatory, and analgesic properties. However, the currently available data has several gaps in understanding the traditional uses of all Sambucus species. Thus, we strongly recommend further investigations into the scientific connotations between traditional medicinal uses and pharmacological activities, mode of action of the isolated bioactive constituents, and toxicity of other Sambucus species to unravel their efficacy and therapeutic potential for safe clinical application. The current extensive study avails valuable information on therapeutic use of Sambucus species and paves way for further investigations of other useful species, as well as drug discovery.

Are Dietary Lectins Relevant Allergens in Plant Food Allergy?

Lectins or carbohydrate-binding proteins are widely distributed in seeds and vegetative parts of edible plant species. A few lectins from different fruits and vegetables have been identified as potential food allergens, including wheat agglutinin, hevein (Hev b 6.02) from the rubber tree and chitinases containing a hevein domain from different fruits and vegetables. However, other well-known lectins from legumes have been demonstrated to behave as potential food allergens taking into account their ability to specifically bind IgE from allergic patients, trigger the degranulation of sensitized basophils, and to elicit interleukin secretion in sensitized people. These allergens include members from the different families of higher plant lectins, including legume lectins, type II ribosome-inactivating proteins (RIP-II), wheat germ agglutinin (WGA), jacalin-related lectins, GNA (Galanthus nivalis agglutinin)-like lectins, and Nictaba-related lectins. Most of these potentially active lectin allergens belong to the group of seed storage proteins (legume lectins), pathogenesis-related protein family PR-3 comprising hevein and class I, II, IV, V, VI, and VII chitinases containing a hevein domain, and type II ribosome-inactivating proteins containing a ricin B-chain domain (RIP-II). In the present review, we present an exhaustive survey of both the structural organization and structural features responsible for the allergenic potency of lectins, with special reference to lectins from dietary plant species/tissues consumed in Western countries.

Bioactive properties of Sambucus nigra L. as a functional ingredient for food and pharmaceutical industry

European black elderberry naturally occurs in most of Europe and has been introduced into various parts of the world for fruit and flower production. Elderberry is rich in nutrients, such as carbohydrates, proteins, fats, fatty acids, organic acids, minerals, vitamins and essential oils. Elderberry also contains cyanogenic glycosides which are potentially toxic. Polyphenols, known for their free radical scavenging (antioxidant) activity, are the most important group of bioactive compounds present in elderberry in relatively high concentration. The high antioxidant activity of elderberry fruit and flowers is associated with their therapeutic properties. Elderberry has for a long time been used in folk medicine as a diaphoretic, antipyretic and diuretic agent. In recent years it was also found to have antibacterial, antiviral antidepressant and antitumour and hypoglycemic properties, and to reduce body fat and lipid concentration. Due to its health-promoting and sensory properties, elderberry is used primarily in food and pharmaceutical industry.

Typhonium giganteum Lectin Exerts A Pro-Inflammatory Effect on RAW 264.7 via ROS and The NF-κB Signaling Pathway

Typhonii rhizoma, a widely used herb in traditional Chinese medicine, has acute irritating toxicity related to Typhonium giganteum lectin (TGL). TGL exhibits acute inflammatory effects, but the underlying molecular mechanisms are largely unknown. This paper is designed to assess the pro-inflammatory response of TGL on RAW 264.7 cells. RAW 264.7 treated with 6.25, 12.5, 25, and 50 µg/mL TGL showed elevated levels of inflammatory factors (TNF-α, IL-1β) and of p-IκB and p-p65, all dose-dependent, indicating that TGL had a substantial inflammatory effect and mobilized the nuclear factor-κB (NF-κB) pathway. All four TGL treatments also induced the up-regulation of reactive oxygen species (ROS) and cytosolic free Ca²⁺ and down-regulation of mitochondrial membrane potential (MMP). The production of cytokines and p-IκB, p-p65 were reduced by N-acetylcysteine (NAC), an ROS scavenger, which somewhat abrogated ROS production. The results showed the TGL-activated inflammatory signaling pathway NF-κB to be associated with the overproduction of ROS. Moreover, 50 μg/mL treatment with TGL led to cell apoptosis after 1 h and increased necrosis over time. These results provided potential molecular mechanisms for the observed inflammatory response to TGL including up-regulation of ROS and cytosolic free Ca²⁺, down-regulation of MMP, the mobilization of the NF-κB pathway, and the subsequent overproduction of pro-inflammatory factors resulting in apoptosis. Long-term stimulation with TGL resulted in strong toxic effects related to inflammation that induced necrosis in macrophages.

Biological Effects and Clinical Applications of Dwarf Elder ( Sambucus ebulus L): A Review

Dwarf elder ( Sambucus ebulus L) is one of the best known medicinal herbs since ancient times. In view of its benefits as a widely applicable phytomedicine, it is still used in folk medicine of different parts of the world. In addition to its nutritional values, dwarf elder contains different phytochemicals among which flavonoids and lectins are responsible for most of its therapeutic effects. Dwarf elder has been used for different ailments including: joint pains, cold, wounds, and infections. Nevertheless, recent evidence has revealed its potentials for making attempts at treating cancer and metabolic disorders. This review aimed to provide a comprehensive description of dwarf elder regarding its traditional uses and modern findings which may contribute to the development of novel natural-based therapeutic agents.

Lectin Digestibility and Stability of Elderberry Antioxidants to Heat Treatment In Vitro

Elderberry contains healthy low molecular weight nutraceuticals and lectins which are sequence-related to the elderberry allergen Sam n1. Some of these lectins are type II ribosome-inactivating proteins. The sensitivity of native lectins present in elderberry fruits and bark to the proteolysis triggered by in vitro simulated gastric and duodenal fluids has been investigated. It was found that these lectins are refractory to proteolysis. Nonetheless, incubation for 5-10 min in a boiling water bath completely sensitized them to the hydrolytic enzymes in vitro. Under these conditions neither total Folin-Ciocalteau's reagent reactive compounds, total anthocyanins and the mixture of cyanidin-3-glucoside plus cyanidin-3-sambubioside, nor antioxidant and free-radical scavenging activities were affected by more than 10% for incubations of up to 20 min. Therefore, short-time heat treatment reduces potential allergy-related risks deriving from elderberry consumption without seriously affecting its properties as an antioxidant and free-radical scavenging food.

Cryogels with affinity ligands as tools in protein purification

Affinity chromatography is one of the well-known separation techniques especially if high purity is desired. Introducing ligands on monolithic structure gives the possibility for purifying complex media such as plasma and crude extract. This chapter is focusing on the preparation of cryogels as monolithic column and immobilization of concanavalin A on its surface as ligand for capturing the glycoprotein horseradish peroxidase.

Ebulin from dwarf elder (Sambucus ebulus L.): a mini-review

Sambucus ebulus L. (dwarf elder) is a medicinal plant, the usefulness of which also as food is restricted due to its toxicity. In the last few years, both the chemistry and pharmacology of Sambucus ebulus L. have been investigated. Among the structural and functional proteins present in the plant, sugar-binding proteins (lectins) with or without anti-ribosomal activity and single chain ribosome-inactivating proteins (RIPs) have been isolated. RIPs are enzymes (E.C. 3.2.2.22) that display N-glycosidase activity on the 28S rRNA subunit, leading to the inhibition of protein synthesis by arresting the step of polypeptide chain elongation. The biological role of all these proteins is as yet unknown. The evidence suggests that they could be involved in the defense of the plant against predators and viruses or/and a nitrogen store, with an impact on the nutritional characteristics and food safety. In this mini-review we describe all the isoforms of ebulin that have to date been isolated from dwarf elder, as well as their functional characteristics and potential uses, whilst highlighting concern regarding ebulin toxicity.

Toxicity of the anti-ribosomal Lectin Ebulin f in lungs and intestines in elderly mice

All parts of dwarf elder (Sambucus ebulus L.) studied so far contain a ribosome-inactivating protein with lectin activity (ribosome-inactivating lectin; RIL), known as ebulin. Green fruits contain ebulin f, the toxicity of which has been studied in six-week-old mice, where it was found that the intestines were primary targets for it when administered intraperitoneally (i.p.). We performed experiments to assess whether ebulin f administration to six- and 12-month-old mice would trigger higher toxicity than that displayed in six-week-old mice. In the present report, we present evidence indicating that the toxicological effects of ebulin f after its i.p. administration to elderly mice are exerted on the lungs and intestines by an increased rate of apoptosis. We hypothesize that the ebulin f apoptosis-promoting action together with the age-dependent high rate of apoptosis result in an increase in the lectin’s toxicity, leading to a higher lethality level.

Elderberries: a source of ribosome-inactivating proteins with lectin activity

Sambucus (Adoxaceae) species have been used for both food and medicine purposes. Among these, Sambucus nigra L. (black elder), Sambucus ebulus L. (dwarf elder), and Sambucus sieboldiana L. are the most relevant species studied. Their use has been somewhat restricted due to the presence of bioactive proteins or/and low molecular weight compounds whose ingestion could trigger deleterious effects. Over the last few years, the chemical and pharmacological characteristics of Sambucus species have been investigated. Among the proteins present in Sambucus species both type 1, and type 2 ribosome-inactivating proteins (RIPs), and hololectins have been reported. The biological role played by these proteins remains unknown, although they are conjectured to be involved in defending plants against insect predators and viruses. These proteins might have an important impact on the nutritional characteristics and food safety of elderberries. Type 2 RIPs are able to interact with gut cells of insects and mammals triggering a number of specific and mostly unknown cell signals in the gut mucosa that could significantly affect animal physiology. In this paper, we describe all known RIPs that have been isolated to date from Sambucus species, and comment on their antiviral and entomotoxic effects, as well as their potential uses.