Antioxidant properties of 3-deoxyanthocyanidins and polyphenolic extracts from Côte d’Ivoire’s red and white sorghums assessed by ORAC and in vitro LDL oxidisability tests

Effects of Red Sorghum-Derived Deoxyanthocyanidins and Their O-β-D-Glucosides on E-Cadherin Promoter Activity in PC-3 Prostate Cancer Cells

Although much less common than anthocyanins, 3-Deoxyanthocyanidins (3-DAs) and their glucosides can be found in cereals such as red sorghum. It is speculated that their bioavailability is higher than that of anthocyanins. Thus far, little is known regarding the therapeutic effects of 3-DAs and their O-β-D-glucosides on cancer, including prostate cancer. Thus, we evaluated their potential to decrease cell viability, to modulate the activity of transcription factors such as NFκB, CREB, and SOX, and to regulate the expression of the gene CDH1, encoding E-Cadherin. We found that 4',7-dihydroxyflavylium chloride (P7) and the natural apigeninidin can reduce cell viability, whereas 4',7-dihydroxyflavylium chloride (P7) and 4'-hydroxy-7-O-β-D-glucopyranosyloxyflavylium chloride (P3) increase the activities of NFkB, CREB, and SOX transcription factors, leading to the upregulation of CDH1 promoter activity in PC-3 prostate cancer cells. Thus, these compounds may contribute to the inhibition of the epithelial-to-mesenchymal transition in cancer cells and prevent the metastatic activity of more aggressive forms of androgen-resistant prostate cancer.

Development of sorghum arabinoxylan-soy protein isolate composite nanoparticles for delivery of curcumin: Effect of polysaccharide content on stability and in vitro digestibility

The purpose of this study was to fabricate composite nanoparticles using soy protein isolate (SPI) and sorghum bran arabinoxylan (AX) for the delivery of curcumin (Cur). The influences of AX concentrations on the physicochemical characteristic, stability and bioaccessibility of curcumin were investigated. The findings showed that the encapsulation efficiency of curcumin obviously increased upon incorporating AX in comparison to SPI-Cur particles. Hydrogen bonds and hydrophobic interactions were the primary driving forces for the formation of SPI-Cur-AX nanoparticles (SCA). SCA nanoparticles with 1.00 % AX exhibited a uniform size with orderly distribution, suggesting its remarkable physical stability due to the strengthened electrostatic repulsion. However, excessive AX led to aggregation of particles, a noticeable increase in size, and subsequently, a reduction in stability. Due to the heightened free radical scavenging capacity of sorghum AX, SCA nanoparticles exhibited superior antioxidant capabilities. Compared to free curcumin, encapsulation within composite particles significantly enhanced the retention rate and bioaccessibility of curcumin. This improvement was attributed to the potent emulsification ability of AX, which coordinated with bile salt to promote the transfer of curcumin into micelles. The research provides an effective strategy for developing food-grade delivery carriers aimed at enhancing dispersibility, stability and bioaccessibility of the fat-soluble bioactives.

Aflatoxin B1-induced dysfunction in male rats' reproductive indices were abated by Sorghum bicolor (L.Moench) hydrophobic fraction

The burden of infertility distresses millions of families worldwide. The harmful effects of aflatoxin B1 (AFB1) on the reproductive system involve oxidative stress, culminating in inflammation and cellular apoptosis. The phytochemical in Sorghum bicolor is rich in antioxidants and anti-inflammatory activities. The effect of Sorghum bicolor (L.) Moench (SBE-HP) extract -hydrophobic fraction- enriched in Apigenin (API) was investigated in rats chronically dosed with AFB1 and the likely mechanism (s) of SBE-HP to protect against AFB1-induced reproductive toxicity. Adult Wistar male rats (twenty-four) were selected randomly and allocated into four groups. Cohort 1 was administered 0.05 % carboxymethyl cellulose (CMC); cohort 2 received AFB1 (50 µg/kg) alone; while cohorts 3 and 4 received 5 & 10 mg/kg of (SBE-HP) respectively, along with 50 µg/kg of AFB1. After 28 days, AFB1 induced remarkable reproductive toxicity as evidenced by increased sperm abnormalities, lowered sperm quality and motility, altered serum hormonal levels and testicular enzyme activities, decreased anti-oxidants, increased pro-oxidants, apoptotic and inflammatory biomarkers, as well as altered histoarchitectural structure of the testis, epididymis, and hypothalamus of rats. API-enriched extract of S. bicolor reduced AFB1-induced oxidative, inflammatory, apoptotic, and histological derangement by improving sperm function parameters, testicular enzymes, and reproductive hormones. Anti-oxidant levels and anti-inflammatory mediators were increased while decreases in the activities and levels of pro-oxidants, pro-inflammatory molecules and caspase-9 occurred in the rats' testes, epididymis, and hypothalamus. API-enriched S. bicolor protected the testes, epididymis, and hypothalamus of male rats exposed to AFB1 by modulating oxidative stress, inflammation, and apoptosis.

Extraction, Identification and Antioxidant Activity of 3-Deoxyanthocyanidins from Sorghum bicolor L. Moench Cultivated in China

3-deoxyanthocyanidins (3-DAs) are typical flavonoids found in sorghum bran, and they have received much attention in recent years owing to their bioactivities. To further enhance the resource utilization of sorghums cultivated in China, three brewing sorghum cultivars (Liaoza-48, Liaonuo-11, and Liaonian-3) commonly used in China were selected as raw materials for the construction of an extraction technology system for 3-DAs and the clarification of their structures and bioactivities. Based on single-factor experiments and response surface analysis, the optimized system for the extraction of 3-DAs from sorghum grains was as follows: a hydrochloric acid-methanol solution (1:100, v/v) was the extraction solvent, the solid-liquid ratio was 1:20 (g/mL), the extraction time was 130 min, and the temperature was 40 °C. This extraction system was simple and feasible. High performance liquid chromatography analysis suggested that the main monomeric compounds of the extracted 3-DAs were Apigeninidin (AE) and Luteolinidin (LE). Among the three selected sorghum grains, Liaoza-48 had the highest amount of AE (329.64 μg/g) and LE (97.18 μg/g). Antioxidant experiments indicated that the 3-DAs extracted from Liaoza-48 showed higher free-radical scavenging activities for DPPH, ABTS⁺, and hydroxyl radicals than those extracted from Liaonuo-11 and Liaonian-3. These results provide basic data and technical support for the high-value and comprehensive utilization of sorghums in China.

Millet shell polyphenols ameliorate atherosclerosis development by suppressing foam cell formation

Polyphenols are bioactive compounds that occur naturally in plants, and they are widely used for disease prevention and health maintenance. In present study, the effects of millet shell polyphenols (MSPs) in thwarting atherosclerosis were explored. The results found that MSPs effectively inhibited the ability of macrophages to phagocytose lipids, and reduced the secretion of inflammatory factors IL-1β and TNF-α by obstructing the expression of STAT3 and NF-κB in macrophages. Eventually, MSPs hindered the formation of macrophage-derived foam cells. On the other hand, MSPs promoted the transformation of HASMCs from synthesis to contraction by regulating the gene expression levels of smooth muscle myosin heavy chain (SMMHC), desmin (DES), smoothelin (SMTN) and elastin (ELN). Lipid phagocytosis inhibited along with this process, thereby reducing the formation of smooth muscle cell-derived foam cells. In addition, experiments in ApoE^-/- mice also showed that MSPs increased high-density lipoprotein cholesterol (HDL-C). Collectively, MSPs play a role in preventing atherosclerosis by impeding foam cell production. This study offers an integrative strategy for thwarting plaque formation in the early stages of atherosclerosis in cardiovascular disease.

Stability, Morphology, and Effects of In Vitro Digestion on the Antioxidant Properties of Polyphenol Inclusion Complexes with β-Cyclodextrin

Polyphenols are inversely associated with the incidence of chronic diseases, but therapeutic use is limited by poor stability and bioaccessibility. Encapsulation has been shown to overcome some of these limitations. A selection of polyphenols (catechin, gallic acid, and epigallocatechin gallate) and their combinations were encapsulated in beta-cyclodextrin (βCD). Encapsulation was characterized and the thermal and storage stability was evaluated using the 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The samples were then subjected to in vitro digestion using a simple digestion (SD) model (gastric and duodenal phases) and a more complex digestion (CD) model (oral, gastric, and duodenal phases). Thereafter, the chemical (oxygen radical absorbance capacity assay) and cellular (dichlorofluorescein diacetate assay in Caco-2 cells) antioxidant and antiglycation (advanced glycation end-products assay) activities were determined. Inclusion complexes formed at a 1:1 molar ratio with a high encapsulation yield and efficiency. Encapsulation altered the morphology of the samples, increased the thermal stability of some and the storage stability of all samples. Encapsulation maintained the antioxidant activity of all samples and significantly improved the antiglycation and cellular antioxidant activities of some polyphenols following SD. In conclusion, the formed inclusion complexes of βCD with polyphenols had greater storage stability, without altering the beneficial cellular effects of the polyphenols.

Potential micro-/nano-encapsulation systems for improving stability and bioavailability of anthocyanins: An updated review

Anthocyanins (ACNs) are notable hydrophilic compounds that belong to the flavonoid family, which are available in plants. They have excellent antioxidants, anti-obesity, anti-diabetic, anti-inflammatory, anticancer activity, and so on. Furthermore, ACNs can be used as a natural dye in the food industry (food colorant). On the other hand, the stability of ACNs can be affected by processing and storage conditions, for example, pH, temperature, light, oxygen, enzymes, and so on. These factors further reduce the bioavailability (BA) and biological efficacy of ACNs, as well as limit ACNs application in both food and pharmaceutics field. The stability and BA of ACNs can be improved via loading them in encapsulation systems including nanoemulsions, liposomes, niosomes, biopolymer-based nanoparticles, nanogel, complex coacervates, and tocosomes. Among all systems, biopolymer-based nanoparticles, nanohydrogels, and complex coacervates are comparatively suitable for improving the stability and BA of ACNs. These three systems have excellent functional properties such as high encapsulation efficiency and well-stable against unfavorable conditions. Furthermore, these carrier systems can be used for coating of other encapsulation systems (such as liposome). Additionally, tocosomes are a new system that can be used for encapsulating ACNs. ACNs-loaded encapsulation systems can improve the stability and BA of ACNs. However, further studies regarding stability, BA, and in vivo work of ACNs-loaded micro/nano-encapsulation systems could shed a light to evaluate the therapeutic efficacy including physicochemical stability, target mechanisms, cellular internalization, and release kinetics.

Phenolic Compounds in Whole Grain Sorghum and Their Health Benefits

Sorghum grain (Sorghum bicolor L. Moench) is a staple food grown across the globe, and is mainly cultivated in the semi-arid regions of Africa and Asia. Recently, sorghum grain is increasingly utilized for human consumption, due to the gluten-free nature and potential phenolic-induced health benefits. Sorghum grain is rich in bioactive phenolic compounds, such as ferulic acid, gallic acid, vanillic acid, luteolin, and apigenin, 3-deoxyanthocyanidins (3-DXA), which are known to provide many health benefits, including antioxidant, anti-inflammatory, anti-proliferative, anti-diabetic, and anti-atherogenic activities. Given an increasing trend of sorghum consumption for humans, this article reviews the content and profile of phenolics in sorghum. It covers aspects of their health benefits and explores their mechanisms of action. The impact of thermal processing, such as boiling, steaming, roasting, and extrusion on sorghum phenolics is also discussed. Compelling data suggest the biological functions of sorghum phenolics, however, further investigations appear warrant to clarify the gap in the current research, and identify promising research topics in future.

Chemical Composition Profiling and Biological Activities of Phenolic Compounds in Eleven Red Sorghums

The profiles of soluble and insoluble phenolic compounds in 11 commercial red sorghums (B11, B12, B13, B14, J124, J127, J138, J140, J142, J152, and J158) were investigated using ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) analysis. A total of 48 phenolic compounds including 35 phenolic acids and their derivatives, 12 flavonoids, and 1 proanthocyanidin were identified, and 8 phenolic compounds were reported for the first time in sorghums. Four major 3-deoxyanthocyanidins were also quantified, with their soluble forms accounting for 99.75-99.87% of the total contents. Pearson's correlation analyses indicated that 3-deoxyanthocyanidins significantly contributed to the antioxidant capacities of the red sorghums and that 5-methoxy-luteolinidin showed the strongest correlation. Besides, the soluble phenolic fraction of B13 dose-dependently inhibited the proliferation of Caco-2 cells and the secretion of IL-1β and NO in RAW264.7 macrophages, which might be attributed to its relatively high total phenolic (TPC), flavonoid (TFC), and proanthocyanidin content (TPAC) values and radical scavenging capacities.

Progress and Achievements in Glycosylation of Flavonoids

In recent years, the chemistry of flavonoid glycosylation has undergone significant developments. This mini-review is devoted to summarizing existing strategies and methods for glycosylation of natural and synthetic flavonoids. Herein we overviewed the reaction conditions of flavonoid glycosylation depending on the position of hydroxyl groups in a parent molecule, the degree of it conjugation with the π-system, the presence of steric factors, the formation of intramolecular hydrogen bonds, etc. Especial attention was given to the choice of the glycosyl donor moiety, which has a significant effect on the yield of the final glycosidated products. Finally, a general strategy for regioselective glycosylation of flavonoids containing several hydroxyl groups is outlined.

Sorghum (Sorghum bicolor L.) as a potential source of bioactive substances and their biological properties

Sorghum is the fifth cereal most produced in the world after wheat, rice, maize, and barley. In some regions, this crop is replacing maize, due to its high yield, resistance to drought and heat. There are several varieties of sorghum, whose coloration varies from cream, lemon-yellow, red, and even black. Pigmented sorghum grain is a rich source of antioxidants like polyphenols, mainly tannins, which have multiple benefits on human health such as, antiproliferative properties associated with the prevention of certain cancers, antioxidant activities related to the prevention of associated diseases to oxidative stress, antimicrobial and anti-inflammatory effects, it also improves glucose metabolism. Despite having these types of compounds, it is not possible to assimilate them, their use in the food industry has been limited, since sorghum is considered a food of low nutritional value, due to the presence of anti-nutritional factors such as strong tannins which form complexes with proteins and iron, thus reducing their digestibility. Based on these restrictions that this product has had as food for humans, the analysis of this review emphasizes the valorization of sorghum as a source of bioactive substances and the importance they confer on human health because of the biological potential it has.

Protection of natural antioxidants against low-density lipoprotein oxidation

This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.

Microencapsulation of Red Sorghum Phenolic Compounds with Esterified Sorghum Starch as Encapsulant Materials by Spray Drying

Phenolic compounds with antioxidant properties are highly sensitive molecules, which limits their application. In response, extruded esterified starch has been proposed as efficient encapsulating material. In this work, we aim to describe the encapsulation of red sorghum phenolic compounds by spray drying using extruded phosphorylated, acetylated and double esterified sorghum starch as wall material. Their respective encapsulation yields were 77.4, 67.4 and 56.8%, and encapsulation efficiency 91.4, 89.7 and 84.6%. Degree of substitution confirmed esterification of the sorghum starch and Fourier transform infrared spectroscopy showed the significant chemical and structural changes in the extruded esterified starch loaded with phenolic compounds. Microcapsules from phosphorylated sorghum starch showed the highest endothermic transition (173.89 °C) and provided a greater protection of the phenolic compounds during storage at 60 °C for 35 days than the other wall materials. Extruded esterified sorghum starch proved to be effective material for the protection of phenolic compounds due to its high encapsulation efficiency and stability during storage.

3-Deoxyanthocyanidin Colorant: Nature, Health, Synthesis, and Food Applications

3-Deoxyanthocyanidins are a rare type of anthocyanins that are present in mosses, ferns, and some flowering plants. They are water-soluble pigments and impart orange-red and blue-violet color to plants and play a role as phytoalexins against microbial infection and environmental stress. In contrast to anthocyanins, the lack of a hydroxyl group at the C-3 position confers unique chemical and biochemical properties. They are potent natural antioxidants with a number of potential health benefits including cancer prevention. 3-Deoxyanthocyanidin pigments have attracted much attention in the food industry as natural food colorants, mainly due to their higher stability during processing and handling conditions compared with anthocyanins. They are also photochromic compounds capable of causing a change in "perceived" color, when exposed to UV light, which can be used to design novel foods and beverages. Due to their interesting properties and potential industrial applications, great efforts have been made to synthesize these compounds. For biosynthesis, researchers have discovered the 3-deoxyanthocyanidin biosynthetic pathway and their biosynthetic genes. For chemical synthesis, advances have been made to synthesize the compounds in a simpler and more efficient way as well as looking for its novel derivative with enhanced coloration properties. This review summarizes the developments in the research on 3-deoxyanthocyanidin as a colorant, from natural sources to chemical syntheses and from health benefits to applications and future prospects, providing comprehensive insights into this group of interesting compounds.

The Potential Protective Effects of Phenolic Compounds against Low-density Lipoprotein Oxidation

BACKGROUND

The exact mechanism(s) of atherosclerosis in humans remains elusive, but one theory hypothesizes that this deleterious process results from the oxidative modification of low-density lipoprotein (LDL). Research suggests that foods rich in dietary phenolic compounds with antioxidant activity can mitigate the extent of LDL oxidation in vivo. With regard to the different classes of flavonoids, there appears to be a structurefunction relationship between the various moieties/constituents attached to the flavonoids' three ring system and their impact at retarding LDL oxidation.

METHODS

This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. Three bases: SCOPUS, Web Science, and PubMed were used for search.

RESULTS

An often used method for the determination of antioxidant properties of natural phenolic compounds is the LDL oxidation assay. LDLs are isolated from human plasma and their oxidation is induced by Cu2+ ions or 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The sample is incubated with a phenolic extract or individual/isolated phenolic compounds. LDL oxidation is then monitored by various chemical methods (e.g., measurement of the generation of conjugated dienes and trienes). This technique confirmed the antioxidant properties of several extracts as obtained from plant material (e.g., grapes, berries, orange, grapefruit, coffee, tea, chocolate, olives, nuts) as well as the individual phenolic compounds (e.g., luteolinidin, apigenidin, caffeic acid, chlorogenic acid, catechin, quercetin, rutin). Several studies in vivo confirmed protective effects of phenolic compounds against LDL oxidation. They covered the healthy subjects with hyperlipidaemia, overweight, obesity, metabolic syndrome, heavy smokers, patients receiving haemodialysis, patients with peripheral vascular disease, and subjects at high cardiovascular risk. The studies comprise individuals of all ages, and the number of participants in the different experiments varied widely.

CONCLUSION

Properly designed double-blind, placebo-controlled randomised clinical trials offer stronger evidence as to the impact of dietary phenolics consumption at retarding LDL oxidation. More such clinical trials are needed to strengthen the hypothesis that foods rich in dietary phenolic compounds with antioxidant activity can mitigate the extent of LDL oxidation in vivo.

Phytochemical concentrations and biological activities of Sorghum bicolor alcoholic extracts

Sorghum is an important cereal with reported health benefits. The objectives of this study were to measure the biological activities of alcoholic extracts of ten sorghum varieties and to determine the association between the color of the extracts and their biological activities. Variation on concentrations of bioactives among sorghum varieties was observed with ethanolic extracts giving higher concentrations than methanolic extracts. The color of the extracts significantly correlated with the concentrations of bioactives and with nitric oxide scavenging activity. Freeze-dried ethanol extract is more potent than freeze-dried methanol extract and caused cytotoxicity to A27801AP and PTX-10 OVCA with ED50 values of 0.69 and 1.29 mg mL(-1), respectively. Pre-treatment of OVCA with ethanol extract led to chemosensitization to paclitaxel and the proliferation and colony formation of OVCA cells were reduced by 14.7 to 44.6% and 36.4 to 40.1%, respectively. Sorghum is a potential source of colorants with health promoting properties. This is the first report on the capability of sorghum alcoholic extracts to cause cytotoxicity and chemosensitize ovarian cancer cells in vitro.

Antioxidant Activity/Capacity Measurement. 3. Reactive Oxygen and Nitrogen Species (ROS/RNS) Scavenging Assays, Oxidative Stress Biomarkers, and Chromatographic/Chemometric Assays

There are many studies in which the antioxidant potential of different foods have been analyzed. However, there are still conflicting results and lack of information as a result of unstandardized assay techniques and differences between the principles of the methods applied. The measurement of antioxidant activity, especially in the case of mixtures, multifunctional or complex multiphase systems, cannot be evaluated satisfactorily using a simple antioxidant test due to the many variables influencing the results. In the literature, there are many antioxidant assays that are used to measure the total antioxidant activity/capacity of food materials. In this review, reactive oxygen and nitrogen species (ROS/RNS) scavenging assays are evaluated with respect to their mechanism, advantages, disadvantages, and potential use in food systems. On the other hand, in vivo antioxidant activity (AOA) assays including oxidative stress biomarkers and cellular-based assays are covered within the scope of this review. Finally, chromatographic and chemometric assays are reviewed, focusing on their benefits especially with respect to their time saving, cost-effective, and sensitive nature.

Sorghum [Sorghum bicolor(L.) Moench] Genotypes with Contrasting Polyphenol Compositions Differentially Modulate Inflammatory Cytokines in Mouse Macrophages

This study sought to characterize and compare anti-inflammatory effects of twenty sorghum accessions with contrasting grain polyphenol concentrations but similar genetic backgrounds (based on a genomewide estimate of relatedness). Cell viability, tumor necrosis factor- (TNF-)α, and interleukin- (IL-) 6 were measured in RAW 264.7 macrophages treated with increasing doses (0, 15, 30, and 60 μg/mL) of sorghum ethanol extracts and stimulated with lipopolysaccharide (LPS). Extract dose had a significant effect on TNF-αand IL-6, with a trend of cytokines decreasing between 0 μg/mL and 15 μg/mL of sorghum extract. Genotype also had a significant effect on the cytokines, with extracts from four accessions significantly decreasing TNF-αand/or IL-6. Cells treated with 3-deoxyanthocyanidin-containing accessions had less cytokine production than non-3-deoxyanthocyanidin accessions, whereas cells treated with proanthocyanidin-containing accessions had more cytokine production than cells treated with nonproanthocyanidin accessions. Additionally, there was a significant effect of theTannin1allele on TNF-αand IL-6. Our results demonstrate that sorghum genotypes differentially modulate induction of inflammatory cytokine production in RAW 264.7 macrophages and that specialty grain has the potential to be tailored by controlling traits at the nucleotide level. This study adds to our knowledge of sorghum health effects and contributes to efforts aimed at developing health-promoting sorghum grain.

Osmanthus fragrans Flower Extract and Acteoside Protect Against d-Galactose-Induced Aging in an ICR Mouse Model

Osmanthus fragrans flower extract (OFE) is an organic extract from O. fragrans flower, which exhibits neuroprotective, free radical scavenging, and antioxidant effects. Therefore, the protective effect of OFE and acteoside against aging was studied. An aging ICR mouse model was established by chronically administering d-galactose (250 mg/kg) for 8 weeks. d-galactose induced spatial learning and memory impairments that were successfully inhibited by OFE and acteoside, which could shorten escape latency, improve platform crossing times, and increase zone time. The antioxidant potential of OFE and acteoside in vivo was evaluated by estimating the following: activities of antioxidant enzymes, such as glutathione peroxidase and aging-related enzyme, particularly monoamine oxidase; contents of lipid peroxidation methane dicarboxylic aldehyde, advanced glycation end products, and 8-hydroxy-2'-deoxyguanosine (a DNA damage product); and levels of nuclear factor-erythroid 2-related factor 2. OFE and acteoside also inhibited d-galactose-induced neurological aging by suppressing the increase in glial fibrillary acidic protein and neurotrophin-3. Considering the dose-dependent protective effects of OFE and acteoside, we concluded that OFE, rich in acteoside, was a good source of natural antiaging compounds.

Chemically synthesized glycosides of hydroxylated flavylium ions as suitable models of anthocyanins: binding to iron ions and human serum albumin, antioxidant activity in model gastric conditions

Polyhydroxylated flavylium ions, such as 3',4',7-trihydroxyflavylium chloride (P1) and its more water-soluble 7-O-β-d-glucopyranoside (P2), are readily accessible by chemical synthesis and suitable models of natural anthocyanins in terms of color and species distribution in aqueous solution. Owing to their catechol B-ring, they rapidly bind FeIII, weakly interact with FeII and promote its autoxidation to FeIII. Both pigments inhibit heme-induced lipid peroxidation in mildly acidic conditions (a model of postprandial oxidative stress in the stomach), the colorless (chalcone) forms being more potent than the colored forms. Finally, P1 and P2 are moderate ligands of human serum albumin (HSA), their likely carrier in the blood circulation, with chalcones having a higher affinity for HSA than the corresponding colored forms.

Red card for pathogens: phytoalexins in sorghum and maize

Cereal crop plants such as maize and sorghum are constantly being attacked by a great variety of pathogens that cause large economic losses. Plants protect themselves against pathogens by synthesizing antimicrobial compounds, which include phytoalexins. In this review we summarize the current knowledge on phytoalexins produced by sorghum (luteolinidin, apigeninidin) and maize (zealexin, kauralexin, DIMBOA and HDMBOA). For these molecules, we highlight biosynthetic pathways, known intermediates, proposed enzymes, and mechanisms of elicitation. Finally, we discuss the involvement of phytoalexins in plant resistance and their possible application in technology, medicine and agriculture. For those whose world is round we tried to set the scene in the context of a hypothetical football game in which pathogens fight with phytoalexins on the different playing fields provided by maize and sorghum.