Immunostimulatory properties of fructans derived from raw garlic (Allium sativum L.)

Recent advances in dietary polysaccharides from Allium species: Preparation, characterization, and bioactivity

Allium plants, including garlic, onions, shallots, and leeks, belong to the Alliaceae family and are utilized as vegetable, medicinal, and ornamental plants. These plants are consumed both raw and cooked and are noted in traditional medicine for their antibacterial, antitumor, and diuretic properties. Allium plants are a rich source of polyphenols, organosulfur compounds, flavonoids, alkaloids, and polysaccharides, which contribute to their health benefits. As consumer interest in the association between diet and health grows, there is an increasing market demand for foods that promote health, particularly those rich in dietary fiber or non-starch polysaccharides. Allium polysaccharides (APS) have molecular weights of 1 × 103-1 × 106 Da containing small amounts of pectin, glucofructan, or glycoproteins and large amounts of fructans. APS, despite its complex structure, is one of the principal active components of Allium plants but is often overlooked, which restricts its practical application. This paper provides a comprehensive overview of the extraction and purification, structural and functional characteristics, bioactivities, structure-function relationships, and chemical modifications of APS, as well as the effects of APS processing and storage. Additionally, this paper outlines future research directions for APS, which will inform its development and application in the food, pharmaceutical, and cosmetic industries.

Comments on "health-promoting properties of bioactive proteins and peptides of garlic (Allium sativum)", food chemistry 435 (2024) 137632-137,643, DOI: 10.1016/j.foodchem.2023.137632

The article "Health-promoting properties of bioactive proteins and peptides of garlic (Allium sativum)" by Ezeorba et al. (Food Chemistry 435 (2024) 137632-137,643, DOI: https://doi.org/10.1016/j.foodchem.2023.137632), offers a comprehensive review of the literature on the bioactive proteins and peptides found in garlic. This study serves as a valuable resource for professionals in the fields of research, nutrition, and healthcare who are interested in the medicinal and nutritional aspects of garlic. This Letter to the Editor aims to address some inaccuracies and omissions found in the above-mentioned article. It corrects the reported lack of biological activity data for certain peptides, clarifies the immunomodulatory effects attributed to garlic's components, and adjusts the reported protein content range for garlic varieties. These refinements aim to enhance the accuracy and utility of the information presented in this article for future research.

Onion and garlic polysaccharides: A review on extraction, characterization, bioactivity, and modifications

Allium cepa (onion) and Allium sativum (garlic) are important members of the Amaryllidaceae (Alliaceae) family and are being used both as food and medicine for centuries in different parts of the world. Polysaccharides have been extracted from different parts of onion and garlic such as bulb, straw and cell wall. The current literature portrays several studies on the extraction of polysaccharides from onion and garlic, their modification and determination of their structural (molecular weight, monosaccharide unit and their arrangement, type and position of glycosidic bond or linkage, degree of polymerization, chain conformation) and functional properties (emulsifying property, moisture retention, hygroscopicity, thermal stability, foaming ability, fat-binding capacity). In this line, this review, summarizes the various extraction techniques used for polysaccharides from onion and garlic, involving methods like solvent extraction method. Furthermore, the antioxidant, antitumor, anticancer, immunomodulatory, antimicrobial, anti-inflammatory, and antidiabetic properties of onion and garlic polysaccharides as reported in in vivo and in vitro studies is also critically assessed in this review. Different studies have proved onion and garlic polysaccharides as potential antioxidant and immunomodulatory agent. Studies have implemented to improve the functionality of onion and garlic polysaccharides through various modification approaches. Further studies are warranted for utilizing onion and garlic polysaccharides in the food, nutraceutical, pharmaceutical and cosmetic industries.

Bioactive polysaccharides and oligosaccharides from garlic (Allium sativum L.): Production, physicochemical and biological properties, and structure-function relationships

Garlic is a common food, and many of its biological functions are attributed to its components including functional carbohydrates. Garlic polysaccharides and oligosaccharides as main components are understudied but have future value due to the growing demand for bioactive polysaccharides/oligosaccharides from natural sources. Garlic polysaccharides have molecular weights of 1 × 10³ to 2 × 10⁶  Da, containing small amounts of pectins and fructooligosaccharides and large amounts of inulin-type fructans ((2→1)-linked β-d-Fruf backbones alone or with attached (2→6)-linked β-d-Fruf branched chains). This article provides a detailed review of research progress and identifies knowledge gaps in extraction, production, composition, molecular characteristics, structural features, physicochemical properties, bioactivities, and structure-function relationships of garlic polysaccharides/oligosaccharides. Whether the extraction processes, synthesis approaches, and modification methods established for other non-garlic polysaccharides are also effective for garlic polysaccharides/oligosaccharides (to preserve their desired molecular structures and bioactivities) requires verification. The metabolic processes of ingested garlic polysaccharides/oligosaccharides (as food ingredients/dietary supplements), their modes of action in healthy humans or populations with chronic conditions, and molecular/chain organization-bioactivity relationships remain unclear. Future research directions related to garlic polysaccharides/oligosaccharides are discussed.

Recent advances in research on Allium plants: functional ingredients, physiological activities, and applications in agricultural and food sciences

Fruits and vegetables (FVs) have long been a major source of nutrients and dietary phytochemicals with outstanding physiological properties that are essential for protecting humans from chronic diseases. Moreover, the growing demand of consumers for nutritious and healthy foods is greatly promoting the increased intake of FVs. Allium (Alliaceae) is a perennial bulb plant genus of the Liliaceae family. They are customarily utilized as vegetable, medicinal, and ornamental plants and have an important role in agriculture, aquaculture, and the pharmaceutical industry. Allium plants produce abundant secondary metabolites, such as organosulfur compounds, flavonoids, phenols, saponins, alkaloids, and polysaccharides. Accordingly, Allium plants possess a variety of nutritional, biological, and health-promoting properties, including antimicrobial, antioxidant, antitumor, immunoregulatory, antidiabetic, and anti-inflammatory effects. This review aims to highlight the advances in the research on the bioactive components, physiological activities and clinical trials, toxicological assessment for safety, and applications of different Allium plants. It also aims to cover the direction of future research on the Allium genus. This review is expected to provide theoretical reference for the comprehensive development and utilization of Allium plants in the fields of functional foods, medicine, and cosmetics.

Immunoadjuvant and Humoral Immune Responses of Garlic (Allium sativum L.) Lectins upon Systemic and Mucosal Administration in BALB/c Mice

Dietary food components have the ability to affect immune function; following absorption, specifically orally ingested dietary food containing lectins can systemically modulate the immune cells and affect the response to self- and co-administered food antigens. The mannose-binding lectins from garlic (Allium sativum agglutinins; ASAs) were identified as immunodulatory proteins in vitro. The objective of the present study was to assess the immunogenicity and adjuvanticity of garlic agglutinins and to evaluate whether they have adjuvant properties in vivo for a weak antigen ovalbumin (OVA). Garlic lectins (ASA I and ASA II) were administered by intranasal (50 days duration) and intradermal (14 days duration) routes, and the anti-lectin and anti-OVA immune (IgG) responses in the control and test groups of the BALB/c mice were assessed for humoral immunogenicity. Lectins, co-administered with OVA, were examined for lectin-induced anti-OVA IgG response to assess their adjuvant properties. The splenic and thymic indices were evaluated as a measure of immunomodulatory functions. Intradermal administration of ASA I and ASA II had showed a four-fold and two-fold increase in anti-lectin IgG response, respectively, vs. the control on day 14. In the intranasal route, the increases were 3-fold and 2.4-fold for ASA I and ASA II, respectively, on day 50. No decrease in the body weights of animals was noticed; the increases in the spleen and thymus weights, as well as their indices, were significant in the lectin groups. In the adjuvanticity study by intranasal administration, ASA I co-administered with ovalbumin (OVA) induced a remarkable increase in anti-OVA IgG response (~six-fold; p < 0.001) compared to the control, and ASA II induced a four-fold increase vs. the control on day 50. The results indicated that ASA was a potent immunogen which induced mucosal immunogenicity to the antigens that were administered intranasally in BALB/c mice. The observations made of the in vivo study indicate that ASA I has the potential use as an oral and mucosal adjuvant to deliver candidate weak antigens. Further clinical studies in humans are required to confirm its applicability.

Anti-Inflammatory and Intestinal Microbiota Modulation Properties of Jinxiang Garlic (Allium sativum L.) Polysaccharides toward Dextran Sodium Sulfate-Induced Colitis

Garlic polysaccharides are great potential agents because of their anti-inflammation, antioxidation, and immunomodulation properties. However, few studies have reported their anti-inflammatory effects on improving the colon system and corresponding intestinal microbiota. Herein, a water-soluble garlic polysaccharide (WSGP) was extracted from Jinxiang garlic to evaluate its effects on ameliorating dextran sulfate sodium (DSS)-induced colitis in a mouse model. The results showed that (1) after administration of the WSGP (200 or 400 mg/kg/day), the feed intake, body weight, and colon length of colitic mice were increased, while the disease activity index and the histological score of colitic mice were decreased; (2) the WSGP reduced the colonic tissue damage and inhibited the expression of inflammatory factors (interleukin 6, interleukin 1 beta , and tumor necrosis factor alpha); and (3) the WSGP enhanced the production of short-chain fatty acids and improved the composition of intestinal microbiota. The key microorganisms, including Muribaculaceae, Lachnospiraceae, Lachnospiraceae_NK4A136_group, Mucispirillum, Helicobacter, Ruminococcus_1, and Ruminiclostridium_5, were identified to be associated with inflammatory bowel diseases. Taken together, this study proved that WSGP supplementation could alleviate DSS-induced colitis by improving mucosal barriers, blocking proinflammatory cytokines, and modulating gut microbiota.

Physicochemical characteristics and in vitro biological activities of polysaccharides derived from raw garlic (Allium sativum L.) bulbs via three-phase partitioning combined with gradient ethanol precipitation method

In the present study, three-phase partitioning (TPP) coupled with gradient ethanol precipitation (GEP) was developed for the first time to extract and isolate polysaccharides (GPSs) from raw garlic (Allium sativum L.) bulbs. Four kinds of fructose polymers, namely, GPS35, GPS50, GPS65, and GPS80, were obtained at the final ethanol precipitation concentrations of 35%, 50%, 65%, and 80% (v/v), respectively, and their physicochemical characteristics and in vitro biological activities were investigated. Results indicated that GPS80 had higher carbohydrate (86.68% ± 0.90%) and uronic acid (12.89% ± 0.09%) contents, lower weight-average molecular weight (8.93 × 10³ Da), and looser surface morphology than the other three GPSs. Furthermore, among the four GPSs, GPS80 exhibited the strongest antioxidant capacities, inhibitory effects on α-amylase and α-glycosidase, and nitric oxide stimulatory activity on RAW264.7 macrophage cells in vitro. Therefore, this study provides a simple and feasible technological strategy for producing bioactive polysaccharides from raw Allium vegetables.

Mechanistic Paradigms of Natural Plant Metabolites as Remedial Candidates for Systemic Lupus Erythromatosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder involving a dysregulated immune response which ultimately leads to multiple organ failure. Several immunological and cellular checkpoints are available as drug targets. However, the available chemosynthetic drugs such as non-steroidal anti-inflammatory drugs and corticosteroids provide limited therapy with extreme toxicities. Moreover, the disease heterogeneity in SLE is very difficult to manage by a single drug component. Hence, it is imperative to utilize the holistic capabilities of natural plant products as immunomodulators and intracellular signaling regulators, thereby providing an auxiliary option of treatment. Additionally, the herbal drugs also serve as symptomatic relief providers, thereby serving as a prophylactic remedy in case of cerebrovascular, hepatic, nephropathological, hematological, cardiopulmonary, mucocutaneous and musculoskeletal manifestations of SLE. The present review attempts to showcase the current state of knowledge regarding the utility of plant-derived phyto-metabolites with their probable mechanistic roles in treating SLE, by means of targeting the signaling cascade, proinflammatory cytokine production and B–T cell co-stimulation. It is hoped that further preclinical and clinical studies will be embarked upon in order to understand the underlying therapeutic and mechanistic aspects of these medicinal herbs.

Fructans as Immunomodulatory and Antiviral Agents: The Case of Echinacea

Throughout history, medicinal purposes of plants have been studied, documented, and acknowledged as an integral part of human healthcare systems. The development of modern medicine still relies largely on this historical knowledge of the use and preparation of plants and their extracts. Further research into the human microbiome highlights the interaction between immunomodulatory responses and plant-derived, prebiotic compounds. One such group of compounds includes the inulin-type fructans (ITFs), which may also act as signaling molecules and antioxidants. These multifunctional compounds occur in a small proportion of plants, many of which have recognized medicinal properties. Echinacea is a well-known medicinal plant and products derived from it are sold globally for its cold- and flu-preventative and general health-promoting properties. Despite the well-documented phytochemical profile of Echinacea plants and products, little research has looked into the possible role of ITFs in these products. This review aims to highlight the occurrence of ITFs in Echinacea derived formulations and the potential role they play in immunomodulation.

A new methodology for sensory quality assessment of garlic based on metabolomics and an artificial neural network

This study has established a new method for the sensory quality determination of garlic and garlic products on the basis of metabolomics and an artificial neural network. A total of 89 quality indicators were obtained, mainly through the metabolomics analysis using gas chromatography/mass spectrometry (GC/MS) and high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The quality indicator data were standardized and fused at a low level, and then seven representative indicators including the a* (redness) value, and the contents of S-methyl-l-cysteine, 3-vinyl-1,2-dithiacyclohex-5-ene, glutamic acid, l-tyrosine, d-fructose and propene were screened by partial least squares discriminant analysis (PLS-DA), analysis of variance (ANOVA) and correlation analysis (CA). Subsequently, the seven representative indicators were employed as the input data, while the sensory scores for the garlic obtained by a traditional sensory evaluation were regarded as the output data. A back propagation artificial neural network (BPANN) model was constructed for predicting the sensory quality of garlic from four different areas in China. The R² value of the linear regression equation between the predicted scores and the traditional sensory scores for the garlic was 0.9866, with a mean square error of 0.0034, indicating that the fitting degree was high and that the BPANN model built in this study could predict the sensory quality of garlic accurately. In general, the method developed in this study for the sensory quality determination of garlic and garlic products is rapid, simple and efficient, and can be considered as a potential method for application in quality control in the food industry.

This study has established a new method for the sensory quality determination of garlic and garlic products on the basis of metabolomics and an artificial neural network.

Extracts of black garlic exhibits gastrointestinal motility effect

In this studied, extracts of black garlic on the improvement of gastrointestinal function, antioxidant activity, total polyphenols, total flavonoids and total polysaccharides were evaluated. Results showed that the black garlic n-butanol fraction extract (BA) had significantly increased effect within small intestine in vitro, while the ethyl acetate fractions had no significant effect on small intestine in vitro. Increase of 5-HT₄ content effectively stimulated the gastrointestinal peristalsis, which enhanced its gastrointestinal tract emptying, and promoted defecation. As for antioxidant activity test, the water extract was more effective in SOD activity test, DPPH radical scavenging rates, ferric reducing antioxidant power and reducing power. In addition, the water fraction was simulated by gastric acid digestion and hydrolysis, and the small intestine was isolated after acid hydrolysis (AW). It was found that the water fraction extract after acid hydrolysis did significantly improve the intestinal contraction rate. In short, extract of black garlic could effectively promote gastrointestinal motility and promote defecation. The active compounds were highly polar ingredients since water extract of black garlic exhibits most significant effect on improving gastrointestinal function.

Investigation of the dynamic changes in the chemical constituents of Chinese “Laba” garlic during traditional processing

In this study, the whole chemical constituents influencing colour, flavor and physiological function of “Laba” garlic during traditional processing have been investigated.