Antioxidant activity of proanthocyanidins-rich fractions from Choerospondias axillaris peels using a combination of chemical-based methods and cellular-based assay

Extraction of bioactive compounds from pecan nutshell: An added-value and low-cost alternative for an industrial waste

The pecan nutshell [Carya illinoinensis (Wangenh) C. Koch] (PNS) is a source of bioactives with important beneficial properties for the human health. PNS represents between 40-50 % of total mass of the nut, resulting as waste without any added value for the food industry. Even though a variety of methods were already developed for bioactive extraction from this waste, unconventional methodologies, or those which apart from green chemistry principles, were discarded considering the cost of production, the sustainable development goals of United Nations and the feasibility of real inclusion of the technology in the food chain. Then, to add-value to this waste, a low-cost, green and easy-scalable extraction methodology was developed based on the determination of seven relevant factors by means of a factorial design and a Response Surface Methodology, allowing the extraction of bioactives with antioxidant capacity. The pecan nutshell extract had a high concentration of phenolic compounds (166 mg gallic acid equivalents-GAE/g dry weight-dw), flavonoids (90 mg catechin equivalent-CE/g dw) and condensed tannins (189 mg CE/g dw) -related also to the polymeric color (74.6 %)-, with high antioxidant capacities of ABTS+. radical inhibition (3665 µmol Trolox Equivalent-TE/g dw) and of iron reduction (1305 µmol TE/g dw). Several compounds associated with these determinations were identified by HPLC-ESI-MS/MS, such as [Epi]catechin-[Epi]catechin-[Epi]gallocatechin, myricetin, dihydroquercetins, dimers A and B of protoanthocyanidins, ellagitannins and ellagic acid derivatives. Hence, through the methodology developed here, we obtained a phenolic rich extract with possible benefits for human health, and of high industrial scalability for this co-product transformation.

Undescribed Cyclohexene and Benzofuran Alkenyl Derivatives from Choerospondias axillaris, a Potential Hypoglycemic Fruit

The fruit of Choerospondias axillaris (Anacardiaceae), known as south wild jujube in China, has been consumed widely in several regions of the world to produce fruit pastille and leathers, juice, jam, and candy. A comprehensive chemical study on the fresh fruits led to the isolation and identification of 18 compounds, including 7 new (1-7) and 11 known (8-18) comprised of 5 alkenyl (cyclohexenols and cyclohexenones) derivatives (1-5), 3 benzofuran derivatives (6-8), 6 flavonoids (9-14) and 4 lignans (15-18). Their structures were elucidated by extensive spectroscopic analysis. The known lignans 15-18 were isolated from the genus Choerospondias for the first time. Most of the isolates exhibited significant inhibitory activity on α-glucosidase with IC50 values from 2.26 ± 0.06 to 43.9 ± 0.96 μM. Molecular docking experiments strongly supported the potent α-glucosidase inhibitory activity. The results indicated that C. axillaris fruits could be an excellent source of functional foods that acquire potential hypoglycemic bioactive components.

Fructus choerospondiatis: A comprehensive review of its traditional uses, chemical composition, pharmacological activities, and clinical studies

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Choerospondiatis is the dried and mature fruit of Choerospondias axillaris (Roxb.) Burtt et Hill. It has been used for a long time in Tibetan and Mongolian medicine, first recorded in the ancient Tibetan medicine book "Medicine Diagnosis of the King of the Moon" in the early 8th century. Fructus Choerospondiatis shows multiple pharmacological activities, especially in treating cardiovascular diseases.

AIM OF THIS REVIEW

This paper reviews the progress in research on the botanical characteristics, traditional uses, chemical constituents, pharmacological activity, clinical studies, and quality control of Fructus Choerospondiatis. This review aims to summarize current research and provide a reference for further development and utilization of Fructus Choerospondiatis resources.

METHOD

The sources for this review include the Pharmacopeia of the People's Republic of China (2020), theses, and peer-reviewed papers (in both English and Chinese). Theses and papers were downloaded from electronic databases including Web of Science, PubMed, SciFinder, Scholar, Springer, and China National Knowledge Infrastructure.The search terms used were "Choerospondias axillaris", "C. axillaris", "Choerospondias axillaris (Roxb.) Burtt et Hill", "Fructus choerospondiatis", "Guangzao", "Lapsi", and "Lupsi".

RESULTS

Fructus Choerospondiatis contains polyphenols, organic acids, amino acids, fatty acids, polysaccharides, and other chemical components. These ingredients contribute to its diverse pharmacological activities such as antioxidant activity, protection against myocardial ischemia-reperfusion injury, anti-myocardial fibrosis, heart rhythm regulation, anti-tumor, liver protection, and immunity enhancement. It also affects the central nervous system, with the ability to repair damaged nerve cells.

CONCLUSION

Fructus Choerospondiatis, with its various chemical compositions and pharmacological activities, is a promising medicinal resource. However, it remains under-researched, particularly in pharmacodynamic material basis and quality control. These areas require further exploration by researchers in the future.

Development of antifogging double-layer film using cellulose nanofibers and carboxymethyl chitosan for white Hypsizygus marmoreus preservation

Films with simultaneously excellent mechanical and anti-fog properties are of great importance for food packaging. A novel strategy is described here to prepare long-lasting anti-fog film with antibacterial and antioxidant capabilities via a simple, green approach. The CMC (carboxymethyl chitosan) gel was integrated with CNF/TA (cellulose nanofibers/tannic acid) composite solution based on layer-by-layer assembly to form a membrane with a bilayer structure. The anti-fog performance of the bilayer film could be adjusted by regulating the CNF/TA layer thickness. On the whole, the developed anti-fog film had high mechanical strength and excellent UV shielding properties, as well as good antibacterial and antioxidant properties, and could be non-fogging for a long time under water vapor (40 °C). The effect of double layer anti-fog film (3%CmFT-3) on the fresh-keeping effect of white Hypsizygus marmoreus was compared at room temperature (28 °C) with commercially available anti-fog PVC film. The results showed that the bilayer anti-fog film could effectively prevent the generation of fog, delay the Browning, inhibit mildew, improve the overall acceptability, and effectively extend the shelf life of white Hypsizygus marmoreus. This biomass-based anti-fog film offers great potential for the development of multifunctional green food packaging.

Thermally Induced Covalent Cross-Linking of Proanthocyanidins and Pectin in Processed Fruit-Based Foods

The covalent interactions between proanthocyanidins (PAs) and pectin during thermal processing was investigated. An acid-butanol assay clearly showed that PAs were covalently bound to pectin. Computational studies indicated that a nucleophilic substitution reaction occurred between the carbocation generated by the PAs and carboxyl or hydroxyl groups on the pectin, leading to the formation of PAs-pectin adducts. Thermal processing and PAs significantly affected the physicochemical, functional, and biological properties of pectin. Thermal processing reduced the molecular weight and increased the gelling properties of pectin, whereas PAs increased both the molecular weight and the gelling properties. Finally, we found that the covalent attachment of PAs to pectin greatly enhanced its antioxidant, prebiotic, and α-glucosidase inhibitory activity. Overall, our results suggest that the thermal processing of fruits has the potential to induce a covalent interaction between PAs and pectin, which would impact the physicochemical characteristics and functional properties of pectin.

Antioxidant activity and semi-solid emulsification of a polysaccharide from coffee cherry peel

In order to further improve the economic benefits of the coffee industry chain, we carried out the following systematic research on processing by-products. In this research, the obtained coffee cherry peel polysaccharide (CCP) which was removed from the coffee cherry peel by hot acid method had a galacturonic acid content of 20.50 % and a molecular weight of 3.05 kg/mol. According to the results of monosaccharide analysis, Fourier transform infrared spectroscopy, molecular weight distribution, and thermal analysis, CCP was a typical high methoxy polysaccharide. In vitro antioxidant results showed that CCP had better antioxidant capacity than commercial citrus polysaccharide (APC). When it came to emulsification performance, the water-oil bonding ability and disturbance resistance to the fluid of CCP were also significantly higher than that of APC. Specially, we found that 0.50 % (wt%) CCP could form a solid-liquid gel with very high plasticity at low oil phase fraction. In conclusion, the coffee cherry peel could be used as a natural source of a novel emulsifier, providing a promising alternative for polysaccharide in the food industry.

Collagen hydrolysates improve the efficiency of sodium alginate-encapsulated tea polyphenols in beads and the storage stability after commercial sterilization

This study showed that sodium alginates (SA)-based beads reinforced with collagen hydrolysates (CHs) significantly increased an encapsulation rate of tea polyphenols (TP) from 34.54 % to 85.06 % when the mass ratio of SA: CHs increased from1.5:0 to 1.5:0.5. And after the 30-day storage at 37 °C, the retention rate of TP in beads with CHs at the solutions with pH = 4.0 or pH = 7.0 increased from 61.10 % to 80.21 %, or from 67.72 % to 80.47 % after sterilization at 98 °C or 121 °C for 30 min, respectively. Also, the addition of CHs at 0.5 % resulted in a greater retention of the polyphenolic compositions values of TP determined by UPLC-Orbitrap-MS system. Additionally, the DPPH and ABTS⁺ free-radical scavenging capacities and ferric-reducing antioxidant power of beads with CHs after sterilization at 98 °C or 121 °C for 30 min were significantly higher than which without CHs. Physical phenomena based on ζ-potential, particle size, fluorescence, UV spectroscopy and confocal laser scanning microscope showed that tightly non-covalent complexes of CHs in combination to TP could be uniformly and stably distributed in the network of SA solution for encapsulating TP in SA-based beads. These findings provided suggestions for the co-encapsulation design and development of hydrophilic nutritive compounds based on CHs in SA-based beads.

Enhancement of lycopene bioaccessibility in tomatoes using excipient emulsions: Effect of dark tea polysaccharides

This study fabricated a novel excipient emulsion by adding dark tea polysaccharides to improve the bioaccessibility of lycopene from tomatoes. Results indicated that addition of tea polysaccharides greatly increased the antioxidant activity of excipient emulsions. Additionally, tea polysaccharides markedly improved the physical stability of excipient emulsion when being mixed with tomato puree and passing through a simulated gastrointestinal tract, contributing to an increase in electrostatic and steric repulsion between the droplets. Besides, certain amount of tea polysaccharides (0.05 - 0.2 wt%) could increase the rate and extent of lipid digestion in tomato-emulsion mixtures. Finally, lycopene bioaccessibility was significantly increased (from 16.95 % to 26.21 %) when 0.1 wt% tea polysaccharides were included, which was mainly ascribed to the ability of tea polysaccharides to increase lipid digestion and reduce carotenoid oxidation within the gastrointestinal tract. These results suggest that well-designed excipient emulsions may increase carotenoids bioavailability in the complex food matrices.

Peanut skin phenolics obtained by green solvent extraction: characterization and antioxidant activity in pure chia oil and chia oil in water (O/W) emulsion

BACKGROUND

The peanut skin (PS) is considered as an industrial waste with undervalued applications. Although several studies report potent antioxidant capacities of PS phenolics, the effectiveness in highly unsaturated lipid systems has not yet been evaluated. The objectives of the present study were two-fold: (i) to characterize a PS phenolic extract (PSE) obtained by means of a green technology and (ii) to evaluate its antioxidant efficacy on pure chia oil and chia oil in water (O/W) acid emulsion.

RESULTS

PSE was composed mainly of monomeric and condensed flavonoids (procyanidin and proanthocyanidin oligomers). PSE displayed strong antioxidant properties as measured by different reducing power and radical scavenging capacities [IC₅₀  = 0.36 μg dry extract (DE) mL^-1 for ferric reducing antioxidant power; IC₅₀  = 4.96 μg DE mL^-1 for 2,2-diphenyl-1-picrylhydrazyl (DPPH)^• ; IC₅₀  = 6.01 μg DE mL^-1 for 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS)^•+ ; IC₅₀  = 2.62 μg DE mL^-1 for HO^• ]. It also showed high antioxidant efficacy when tested in pure chia oil under accelerated oxidation conditions (Rancimat, 100 °C). When added to the O/W emulsions maintained at 40 °C for 15 days, the PSE was more effective than a synthetic antioxidant (tert-butylhydroquinone) with respect to minimizing the formation and degradation of lipid hydroperoxides.

CONCLUSIONS

The antioxidant efficacy of PSE was primarily attributed to the abundance of compounds with a high number of phenolic-OH groups. Because they were found to cover a relatively wide range of partition coefficients, the antioxidant properties could be also enhanced by effect of both interfacial and solubility phenomena. All of these features allow the potential use of PSE as a natural antioxidant in different types of foods, including acid emulsion systems. © 2021 Society of Chemical Industry.

TiO2 nanoparticles negatively impact the bioavailability and antioxidant activity of tea polyphenols

This study was to investigate the influence of TiO₂ nanoparticles (NPs) on the stability, bioavailability, and antioxidant activity of co-ingested tea polyphenols extract using an in vitro digestion model. The tea polyphenol contents decreased significantly after addition of 0.5 % (w/w) TiO₂ NPs. The gallocatechin gallate level decreased the most, changing from 101.9 to 27.2 µg/mL (about 73.3%). The TiO₂ NPs also reduced the bioavailability of the tea polyphenols in a dose-dependent manner, which was ascribed to the formation of large polyphenol-TiO₂ NP complex aggregates that could not pass through the pores in the dialysis tube used to simulate the gut wall. Additionally, the TiO₂ NPs decreased the antioxidant activity of the tea polyphenols within the simulated gastrointestinal tract. In summary, our results show that high levels of TiO₂ NPs (but within the current legal limits in many countries) may negatively impact the bioavailability and bioactivity of polyphenols in foods.

Microencapsulated procyanidins by extruding starch improved physicochemical properties, inhibited the protein and lipid oxidant of chicken sausages

Microencapsulated procyanidins by extruding starch (MPS) were used in meat and meat products as an antioxidant for their simple production process and high stability. This study investigated the controlled released properties of MPS and their effect on antioxidant capacity, physicochemical properties, and sensory qualities of chicken sausages during 4°C storage within 28 days. Antioxidant capacity, particle size analysis, and simulated digestion in vitro demonstrated that microencapsulation by extruding starch delayed the procyanidins release. The reduced crystal structure of MPS was determined by the morphology observation (SEM) and the decrease of the typical diffraction peak at 2θ of 20.9° (XRD). The MPS-added sausage had a higher (p < 0.05) ABTS and DPPH radical scavenging ratio (97.6% and 67.3%) and sulfhydryl contents (114.69 nmol/g protein) than other groups. Moreover, lower (p < 0.05) thiobarbituric acid reactive substances (TBARS) (0.67 mg MDA/kg sausage) and carbonyl values (3.24 nmol/mg protein) were detected in MPS-added sausages than others at the end of storage. The MPS addition increased redness (a* value) and decreased the lightness (L* value). The sensory analysis suggested that the sausage with the increased redness was favorable. These results denominated that MPS was an alternative antioxidant in chicken sausages. Practical Application: In this study, microencapsulated procyanidins were prepared by extrusion technology, and the effect on the quality of chicken sausages was investigated, which provides an alternative natural antioxidant for meat and meat products.

Impact of Polyphenol Interactions with Titanium Dioxide Nanoparticles on Their Bioavailability and Antioxidant Activity

Titanium dioxide is widely utilized as a pigment in the food industry to enhance the whiteness or brightness of foods and beverages. The powdered forms of titanium dioxide used as food ingredients contain a substantial fraction of nanoparticles (d < 100 nm), which may have adverse effects on human health. This is a model study that investigated the molecular interactions between TiO₂ nanoparticles and selected polyphenols, as well as their influence on the in vitro bioavailability and antioxidant activity of the polyphenols. Our results showed that the chemical structure of polyphenols significantly influenced their binding affinity to TiO₂ nanoparticle surfaces, with those possessing vicinal trihydroxy groups having the highest binding affinities. The presence of TiO₂ nanoparticles was shown to reduce the bioavailability of polyphenols using an in vitro digestion model. This effect was mainly ascribed to the formation of large TiO₂ nanoparticle-polyphenol complex agglomerates that could not pass through the pores in the dialysis tube used to simulate the epithelium layer. Additionally, the binding of polyphenols to the surfaces of TiO₂ nanoparticles reduced their antioxidant activity. This study provides valuable insights into the impact of inorganic nanoparticles on the bioavailability and bioactivity of polyphenols.

Polysaccharide conjugates from Chin brick tea (Camellia sinensis) improve the physicochemical stability and bioaccessibility of β-carotene in oil-in-water nanoemulsions

A natural antioxidant emulsifier, tea polysaccharide conjugate (TPC), was isolated from Chin brick tea. The impact of TPC on β-carotene stability and bioaccessibility in oil-in-water nanoemulsions was assessed. TPC exhibited strong antioxidant activity and could be used to fabricate stable nanoemulsions (d < 140 nm). The extent of lipid digestion was considerably lower for lipid droplets coated by TPC (68%) than Tween 80 (94%) or whey protein isolate (WPI) (89%), probably because TPC formed interfacial layers that hindered the access of lipases to lipids. The chemical stability of β-carotene in TPC-nanoemulsions was markedly higher than in those formulated with Tween 80 or WPI due to the high antioxidant activity of TPC. The bioaccessibility of β-carotene (20-30%) was independent of emulsifier type. TPC from Chin brick tea can therefore be used as a dual-purpose functional ingredient in emulsified foods.

Chitosan and procyanidin composite films with high antioxidant activity and pH responsivity for cheese packaging

Chitosan-procyanidin composite films (CS-PC films) with different mass ratios were prepared by solution casting method. Their structural, thermal, physical, and antioxidant properties, antibacterial activity and pH responsivity were determined. Compared with CS-control film, CS-PC films exhibited lower solubility and higher tensile strength. The antimicrobial properties against Escherichia coli and Aspergillus niger were improved by 20.0% and 30.4%, respectively. CS-PC films indicated good antioxidant activity through their DPPH and ABTS⁺ scavenging rates, which were 2.45 times higher than CS-control film. pH responsivity was represented by the outstanding changes in color, which were visible to the naked eye. Food packaging film with high antioxidant activity, bacteriostatic properties and pH responsivity was prepared by CS and PC. Compared with the initial properties of cheese, the characteristics of cheese packaged with CS-PC films were obviously better than those of the control groups.

Antioxidant, Antimicrobial and Anti-Inflammatory Activities of Essential Oil Derived from the Wild Rhizome of Atractylodes macrocephala

The present study investigated the chemical composition, antioxidant, antimicrobial, and anti-inflammatory activities of essential oil (EO) derived from the wild rhizomes of Atractylodes macrocephala Koidz. (AMA) growing in Qimen County (eastern China). GC/MS analysis identified fifteen compounds, representing 92.55 % of AMA EO. The major compounds were atractylone (39.22 %), β-eudesmol (27.70 %), thymol (5.74 %), hinesol (5.50 %), and 11-isopropylidenetricyclo[4.3.1.1(2,5)]undec-3-en-10-one (4.71 %). Ferricyanide reducing, 1,1-diphenyl-2-picyrlhydrazyl (DPPH) and 3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) scavenging assays revealed that AMA EO exhibited strong antioxidant capacities. Additionally, AMA EO showed inhibitory effects on growth of Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, and Bacillus subtilis, with the minimum inhibitory concentrations (MIC) ranging from 0.5 to 2.0 mg/mL. Treatments with AMA EO also significantly inhibited nitric oxide (NO) and prostaglandin E₂ (PGE₂ ) production in lipopolysaccharide-stimulated RAW264.7 cells, indicating anti-inflammatory activity of AMA EO. Furthermore, treatments with AMA EO decreased the transcriptional levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), which might be the molecular mechanisms underlying its anti-inflammatory effects. Overall, these results provide a theoretical basis for further study and application of AMA EO in food and medicine products.

Low-Cost Ru/C-Catalyzed Depolymerization of the Polymeric Proanthocyanidin-Rich Fraction from Bark To Produce Oligomeric Proanthocyanidins with Antioxidant Activity

A new method has been developed for the high-value utilization of larch bark, which is regarded as a low-value byproduct of the logging industry. Polymeric proanthocyanidins (PPCs) were extracted from the Larix gmelinii bark and depolymerized by catalytic hydrogenolysis, using ruthenium/carbon (Ru/C) as the catalyst. The method has been found that although the molecular weight of the depolymerized product was significantly lower, the basic structural units were not destroyed, and the product retained a condensed flavanol polyphenol structure; the depolymerized product contains very little Ru metal and thus complies with food safety standards; the antioxidant properties of both the depolymerized products and PPCs were better than those of the commonly used antioxidant 2,6-di-tert-butyl-4-methylphenol. The relative molecular weight and steric hindrance of the depolymerized products were lower than those of the PPCs, leading to better antioxidant performance. A new technical route for the depolymerization of PPCs from the L. gmelinii bark is provided. The route offers practical and commercial advantages, and the product could have many applications as an antioxidant.

Vitellaria paradoxa nutshells from seven sub-Saharan countries as potential herbal medicines for treating diabetes based on chemical compositions, HPLC fingerprints and bioactivity evaluation

The aim of the study was to determine the feasibility of the Vitellaria paradoxa nutshell as a new medicinal resource for treating diabetes. A total of forty-one compounds were identified by HPLC-DAD-Q-TOF-MS and phytochemical methods in V. paradoxa nutshell methanol extract. Based on HPLC fingerprints, four characteristic constituents were quantified and the origin of twenty-eight V. paradoxa nutshells from seven sub-Saharan countries was compared, which were classified into three groups with chemometric method. Twenty-eight samples contained high total phenolic content, and exhibited moderate-higher antioxidant activity and strong α-glucosidase inhibitory activity. Furthermore, all fractions and isolated compounds were evaluated for their antioxidant and α-glucosidase inhibitory activities, and α-glucosidase inhibitory action mechanism of four characteristic constituents including protocatechuic acid, 3, 5, 7-trihydroxycoumarin, (2R, 3R)-(+)-taxifolin and quercetin was investigated via molecular docking method, which were all stabilized by hydrogen bonds with α-glucosidase. The study provided an effective approach to waste utilization of V. paradoxa nutshell, which would help to resolve waste environmental pollution and provide a basis for developing potential herbal resource for treating diabetes.

In silico approach to study the metabolism and biological activities of oligomeric proanthocyanidin complexes

OBJECTIVES:

Over the past three decades, numerous studies have focused on the biological activities of oligomeric proanthocyanidins (OPCs) in the prevention of many diseases such as neurodegeneration, atherosclerosis, tumorigenesis, and microbial infections. OPC has redox-active metabolites which could modulate the intracellular redox equilibrium to maintain the antioxidant homeostasis. This redox-modulating efficiency of OPC could provide new insights into therapeutic approaches that could reduce the burden of cardiovascular diseases. The main objective of this study was to explore the biological and metabolic activities of OPC using in silico approaches.

METHODS:

To validate the above objective, chemoinformatic tools were used to predict the metabolism of OPC after ingestion, based on both the ligand and structure of the constituent compounds.

RESULTS:

OPC showed possible sites for Phase I metabolism by cytochrome P450, and the metabolites obtained thereafter may be responsible for its biological activities. Absorption, distribution, metabolism, elimination, and toxicity properties showed efficient absorption, distribution, and metabolism of OPC, without toxicity.

CONCLUSION:

Thus, from the results obtained, OPC could be strongly recommended as a cardioprotective drug.

Characterisation of phenolics in fruit septum of Juglans regia Linn. by ultra performance liquid chromatography coupled with Orbitrap mass spectrometer

Walnut (Juglans regia L.) is an abundant source of polyphenols. Although phenolic species in the walnut kernel have been studied comprehensively, their compositional profile in the internal fruit septum, a traditional nutraceutical material in China, has been rarely explored. In the current study, the methanolic extract of the walnut septum was analysed by Ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry. Totally seventy-five phenolics belonging to flavonoids, tannins and phenolic acids were identified based on mass spectra, references and literatures. Among them, quercetin-3-O-galactoside, quercetin-rhamnose-pentoside, quercetin-3-O-glucoside, quercetin-rhamnose-hexoside, kaempferol-rhamnoside, and two isomers of quercetin-rhamnoside were reported for the first time in walnut. The total polyphenol content was found to be 122.78 ± 2.55 mg GAE/g dry weight in septum. This study is the first to comprehensively investigate and identify phenolic compounds in the fruit septum of walnut and indicates that the septum to be a rich resource of polyphenols.

Honey and Its Role in Relieving Multiple Facets of Atherosclerosis

Honey, a natural sweetener has been used universally as a complete food and in complementary medicine since early antiquity. Honey contains over 180 substances, including sugars mainly fructose and glucose, water and a plethora of minor constituents such as vitamins, minerals and phytochemicals. The chemical composition of honey varies depending on floral origin, environment and geographical conditions. The sugar components dominate honey composition and they are accountable for sensory and physicochemical properties in food industry. Although present in small quantities, non-sugar components are the major contributors to the health benefits of honey. Our review summarizes and discusses composition of honey, its protective effects and possible action modes on risk factors of atherosclerosis.

Analytical Profiling of Proanthocyanidins from Acacia mearnsii Bark and In Vitro Assessment of Antioxidant and Antidiabetic Potential

The proanthocyanidins from ethanol extracts (80%, v/v) of Acacia mearnsii (A. mearnsii) bark on chemical-based and cellular antioxidant activity assays as well as carbolytic enzyme inhibitory activities were studied. About 77% of oligomeric proanthocyanidins in ethanol extracts of A. mearnsii bark were found by using normal-phase HPLC. In addition, HPLC-ESI-TOF/MS and MALDI-TOF/TOF MS analyses indicated that proanthocyanidins from A. mearnsii bark exhibited with a degree of polymerization ranging from 1 to 11. These results of combined antioxidant activity assays, as well as carbolytic enzyme inhibitory activities of proanthocyanidins from A. mearnsii bark, indicated an encouraging antioxidant capacity for the high polyphenol content and a potential for use as alternative drugs for lowering the glycemic response.

Antityrosinase and antioxidant properties of mung bean seed proanthocyanidins: Novel insights into the inhibitory mechanism

This study investigated the structure, antioxidant activity, antityrosinase activity and mechanism of proanthocyanidins from mung bean seed [Vigna radiata (L.) Wilczek]. The structural composition were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), electrospray ionization-full-mass spectrometry (ESI-Full-MS), and high-pressure liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) techniques. The mung bean seed proanthocyanidins were composed of procyanidins, prodelphinidins, and their rhamnosides. According to enzyme kinetic analysis, these compounds were potent, reversible, and mixed-type inhibitors of tyrosinase. They inhibited the enzyme activity by interacting with enzyme as well as substrates. The results of molecular docking showed that the interaction between mung bean seed proanthocyanidins and tyrosinase was driven by hydrogen bond, hydrophobic and electrostatic interactions. In addition, mung bean seed proanthocyanidins were demonstrated as powerful antioxidants. Therefore, this study confirmed a novel tyrosinase inhibitor and would lay a scientific foundation for their utilization in pharmaceutical and food industries.

DPPH-HPLC-MS assisted rapid identification of endothelial protective substances from Xiao-Ke-An

ETHNOPHARMACOLOGICAL RELEVANCE

Xiao-Ke-An formula (XKA) is a Chinese medicine widely used for treating diabetes and associated complications. Endothelial protection is thought to be one of its therapeutic mechanisms. However, the protective effect of XKA on endothelial cells remains unclear, especially in oxidative injury induced endothelial dysfunction.

MATERIALS AND METHODS

A novel strategy to rapidly screen and identify potential endothelial protective substances from XKA was established by combining the 2,2'-diphenyl-1-picrylhydrazyl high performance liquid chromatography coupled with mass spectrometry (DPPH-HPLC-MS) approach with cell-based verification. Firstly, the DPPH-HPLC-MS approach was employed to identify the antioxidants in XKA. Then, the potent endothelial protective effect of XKA, and the potential active substances and mechanism of action were revealed in EA.hy926 cells injured by tert-butyl hydroperoxide (t-BHP).

RESULTS

XKA exhibited potent antioxidant activity and endothelial protective effect. Phenolic acids derived from Salvia miltiorrhiza Bunge, root and rhizome, xanthones from Anemarrhena asphodeloides Bunge, rhizome, and acteoside from Rehmannia glutinosa (Gaertn.) DC., root, were identified as the major endothelial protective components in XKA.

CONCLUSIONS

An efficient method for rapid identifying endothelial protective substances from complex mixtures was developed and used to identify the major endothelial protective components in XKA. This method would help reveal the material base of herbal medicine with endothelial protective effect, and could also be applied to discover novel natural-origin endothelial protective substances.

Biochemical properties, antibacterial and cellular antioxidant activities of buckwheat honey in comparison to manuka honey

The biochemical properties of buckwheat honey, including contents of sugars, proteins, total phenols, methylglyoxal (MGO), minerals and phenolic compounds, were determined in comparison with those of manuka honey. Buckwheat honey has higher contents of sugars, proteins and total phenols but a lower content of MGO than manuka honey. Buckwheat honey contains abundant minerals involved in a number of vital functions of the human body as does manuka honey, and has even higher contents of Fe, Mn and Zn. In buckwheat honey, p-hydroxybenzoic acid, chlorogenic acid and p-coumaric acid are the dominant phenolic compounds. Moreover, the antibacterial and cellular antioxidant activities of buckwheat honey were compared with those of manuka honey. Buckwheat honey exhibits antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, comparable with manuka honey, and the cellular antioxidant activity of buckwheat honey is higher than that of manuka honey. Our results suggest that buckwheat honey has great nutritional and commercial potentials.

Screening and evaluation of active compounds in polyphenol mixtures by HPLC coupled with chemical methodology and its application

An off-line high performance liquid chromatography (HPLC) coupled with chemical methods has been developed to evaluate antioxidant activity of 11 standard polyphenol compounds (SPCs) and vitamin C (Vc) in terms of radical scavenging abilities. The structure-activity relationships of each SPC were also discussed. SPCs showed different abilities in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethyl-benzthiazoline-6-sulphonate (ABTS+) and hydroxyl (OH) free radicals. Among SPCs, quercetin and kaempferol, as typical flavonoids, displayed the greatest radical-scavenging activities and even exhibited higher activity in OH radical removal ability than that of Vc. Furthermore, the proposed method was also applied to screening polyphenolic antioxidant components from Cichorium endivia L. (C. endivia) seed extract. The results indicated that cynarin in the extract was a more active compound to scavenge DPPH and ABTS+ radicals than chlorogenic acid, while chlorogenic acid had stronger capacity in scavenging OH free radicals.

Optimized Extraction, Preliminary Characterization, and In Vitro Antioxidant Activity of Polysaccharides from Glycyrrhiza Uralensis Fisch

Background

This study performed optimized extraction, preliminary characterization, and in vitro antioxidant activities of polysaccharides from Glycyrrhiza uralensis Fisch.

Material/Methods

Three parameters (extraction temperature, ratio of water to raw material, and extraction time) were optimized for yields of G. uralensis polysaccharides (GUP) using response surface methodology with Box-Behnken design (BBD). The GUP was purified using DEAE cellulose 32-column chromatography. The main fraction obtained from G. uralensis Fisch was GUP-II, which was composed of rhamnose, arabinose, galactose, and glucose monosaccharide, was screened for antioxidant properties using DP Hand hydroxyl radical scavenging assays. In addition, immunological activity of GUP-II was determined by nitric oxide and lymphocyte proliferation assays.

Results

Optimization revealed maximum GUP yields with an extraction temperature of 99°C, water: raw material ratio of 15: 1, and extraction duration of 2 h. GUP-II purified from G. uralensis Fisch had good in vitro DPPH and hydroxyl radical scavenging abilities. Immunologically, GUP-II significantly stimulated NO production in RAW 264.7 macrophages, and significantly enhanced LPS-induced lymphocyte proliferation.

Conclusions

Extraction of GUP from G. uralensis Fisch can be optimized with respect to temperature, extraction period, and ratio of water to material, using response surface methodology. The purified product (GUP-II) possesses excellent antioxidant and immunological activities.

Phytochemical profiles and antioxidant activity of processed brown rice products

The phytochemical profiles and antioxidant activity of free, soluble-conjugated, and bound fractions of brown rice and its processed products (textured rice, cooked rice and rice noodle) were studied. Nineteen phenolic acids were identified. Trans-ferulic acid was the most abundant monomeric phenolic acid with trans-trans-8-O-4' diferulic acid being most abundant diferulic acid. Processing increased the content of free phenolic acids, but decreased the content of soluble-conjugated phenolic acids. The content of bound phenolic acids was increased by improved extrusion cooking technology and cooking, but not affected by rice noodle extrusion. The total phenolic contents and antioxidant activities of free and soluble-conjugated fractions were decreased after processing, whereas those of bound fraction were increased by improved extrusion cooking technology and cooking, but not affected by rice noodle extrusion. Results indicated that whole foods designed for reducing chronic disease risk need to consider the effects of processing on phytochemical profiles and antioxidant activity of whole grains.

[Dmt(1)]DALDA analogues modified with tyrosine analogues at position 1

Analogues of [Dmt(1)]DALDA (H-Dmt-d-Arg-Phe-Lys-NH2; Dmt=2',6'-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity were prepared by replacing Dmt with various 2',6'-dialkylated Tyr analogues, including 2',4',6'-trimethyltyrosine (Tmt), 2'-ethyl-6'-methyltyrosine (Emt), 2'-isopropyl-6'-methyltyrosine (Imt) and 2',6'-diethyltyrosine (Det). All compounds were selective μ opioid agonists and the Tmt(1)-, Emt(1) and Det(1)-analogues showed subnanomolar μ opioid receptor binding affinities. The Tmt(1)- and Emt(1)-analogues showed improved antioxidant activity compared to the Dmt(1)-parent peptide in the DPPH radical-scavenging capacity assay, and thus are of interest as drug candidates for neuropathic pain treatment.