Non-covalent binding of chlorogenic acid to myofibrillar protein improved its bio-functionality properties and metabolic fate

As natural antioxidants added to meat products, polyphenols can interact with proteins, and the acid-base environment influenced the extent of non-covalent and covalent interactions between them. This study compared the bio-functional characteristics and metabolic outcomes of the myofibrillar protein-chlorogenic acid (MP-CGA) complexes binding in different environments (pH 6.0 and 8.5). The results showed that CGA bound with MP significantly enhanced its antioxidant activity and inhibitory effect on metabolism enzymes. CGA bound deeply into the MP structure hydrophobic cavity at pH 6.0, which reduced its degradation by digestive enzymes, thus increasing its bio-accessibility from 59.5% to 71.6%. The digestion products of the two complexes exhibited significant differences, with the non-covalent MP-CGA complexes formed at pH 6.0 showing significantly higher concentrations of rhetsinine and piplartine, two well-known compounds to modulate diabetes. This study demonstrated that non-covalent binding between protein and polyphenol in the acidic environment held greater promising prospects for improving health.

Synergistic improvement of antioxidant and antibacterial properties of carbon quantum complexes with zinc doping and chlorogenic acid for longan preservation

The deterioration of fruit could reduce the shelf life, decreased marketability and substantial economic value. Thus, a safe, simple, economical and environmentally friendly preservation technology for fruit is of great significance. Here, the postharvest preservation technology was investigated with zinc-doped carbon quantum dots and chlorogenic acid (Zn-CQDs/CGA) composite. Zn-CQDs/CGA composite were synthesized, which exhibits superior antioxidant and antibacterial activities. The binding mechanism of the Zn-CQDs/CGA composite was investigated, which revealed that the bindings of two components were mainly driven by hydrogen bonding and van der Waals forces to create a novel composite. The Zn-CQDs/CGA composite was applied to longan preservation and was found to significantly reduce the incidence of mildew spot, browning of fruit endocarp and pulp, as well as the degree of degradation of quality indexes. These results suggest that the Zn-CQDs/CGA composite has the potential for inhibiting browning and preserving the quality of longan during storage.

Anti-Atherosclerotic Properties of Aronia melanocarpa Extracts Influenced by Their Chemical Composition Associated with the Ripening Stage of the Berries

The high content of bioactive compounds in Aronia melanocarpa fruit offers health benefits. In this study, the anti-atherosclerotic effect of Aronia extracts was assessed. The impact on the level of adhesion molecules and the inflammatory response of human umbilical vein endothelial cells (HUVECs) was shown in relation to the chemical composition and the stage of ripening of the fruits. Samples were collected between May (green, unripe) and October (red, overripe) on two farms in Poland, which differed in climate. The content of chlorogenic acids, anthocyanins, and carbohydrates in the extracts was determined using HPLC-DAD/RI. The surface expression of ICAM-1 and VCAM-1 in HUVECs was determined by flow cytometry. The mRNA levels of VCAM-1, ICAM-1, IL-6, and MCP-1 were assessed using the quantitative real-time PCR method. The farms' geographical location was associated with the quantity of active compounds in berries and their anti-atherosclerotic properties. Confirmed activity for green fruits was linked to their high chlorogenic acid content.

Reducing the allergenicity of tropomyosin in shrimp by covalent conjugation with quercetin and chlorogenic acid

The study aimed to assay the allergenicity of shrimp tropomyosin (TM) following covalent conjugation with quercetin (QR) and chlorogenic acid (CA). The structure of the TM-polyphenol covalent conjugates was examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD), fluorescence, differential scanning calorimetry (DSC), and Fourier Transform infrared spectroscopy (FTIR). Potential allergenicity was evaluated using in vitro and in vivo methods. The results showed that QR and CA induced structural changes in TM through aggregation. RBL-2H3 cell results showed that TM-QR and TM-CA covalent conjugates reduced the release of β-hexosaminidase and histamine, respectively. In the mice model, TM-QR and TM-CA covalent conjugates reduced the level of IgE, IgG, IgG1, histamine, and mMCP-1 in sera. Furthermore, the allergenicity was reduced by suppressing Th2-related cytokines (IL-4, IL-5, IL-13) and promoting Th1-related cytokines (IFN-γ). These research findings demonstrate that the covalent binding of TM with QR and CA, modifies the allergenic epitopes of shrimp TM, thereby reducing its potential allergenicity. This approach holds practical applications in the production of low-allergenicity food within the food industry.

Bioactive functions of chlorogenic acid and its research progress in pig industry

Chlorogenic acid (CGA), also known as 3-caffeioylquinic acid or coffee tannin, is a water-soluble polyphenol phenylacrylate compound produced through the shikimate pathway by plants during aerobic respiration. CGA widely exists in higher dicotyledons, ferns and many Chinese medicinal materials, and enjoys the reputation of 'plant gold'. Here, we summarized the source, chemical structure, biological activity functions of CGA and its research progress in pigs, aiming to provide a more comprehensive understanding and theoretical basis for the prospect of CGA replacing antibiotics as a pig feed additive.

Antioxidant, antimicrobial and healing properties of an extract from coffee pulp for the development of a phytocosmetic

Consumer demand for natural, chemical-free products has grown. Food industry residues, like coffee pulp, rich in caffeine, chlorogenic acid and phenolic compounds, offer potential for pharmaceutical and cosmetic applications due to their antioxidant, anti-inflammatory, and antibacterial properties. Therefore, the objective of this work was to develop a phytocosmetic only with natural products containing coffee pulp extract as active pharmaceutical ingredient with antioxidant, antimicrobial and healing activity. Eight samples from Coffea arabica and Coffea canephora Pierre were analyzed for caffeine, chlorogenic acid, phenolic compounds, tannins, flavonoids, cytotoxicity, antibacterial activity, and healing potential. The Robusta IAC-extract had the greatest prominence with 192.92 μg/mL of chlorogenic acid, 58.98 ± 2.88 mg GAE/g sample in the FRAP test, 79.53 ± 5.61 mg GAE/g sample in the test of total phenolics, was not cytotoxic, and MIC 3 mg/mL against Staphylococcus aureus. This extract was incorporated into a stable formulation and preferred by 88% of volunteers. At last, a scratch assay exhibited the formulation promoted cell migration after 24 h, therefore, increased scratch retraction. In this way, it was possible to develop a phytocosmetic with the coffee pulp that showed desirable antioxidant, antimicrobial and healing properties.

Conjugation of lesser mealworm (Alphitobius diaperinus) larvae protein with polyphenols for the development of innovative antioxidant emulsifiers

Lesser mealworm protein concentrate (LMPC) was conjugated with chlorogenic acid (CA) or tannic acid (TA) using an alkaline method. The impact of polyphenol type and concentration on the physicochemical and structural characteristics, antioxidant, interfacial, and emulsifying properties of the LMPC-polyphenol conjugates were investigated. Under the conditions tested, TA demonstrated higher affinity for LMPC compared to CA. The conjugation of LMPC induced conformational changes as showed by intrinsic fluorescence and FT-MIR raw spectra analysis. The surface hydrophobicity of the conjugates was reduced, leading to increased interfacial tension values for LMPC-TA conjugates without impairment of the emulsifying activity. The antioxidant properties were significantly improved by the conjugation. Flaxseed oil-in-water (O/W) emulsions stabilized by the conjugates and LMPC remained physically stable for 12 days at 50 °C with a notable reduction of secondary oxidation products when conjugates were used. LMPC-TA and LMPC-CA exhibited potential to be used as novel antioxidant emulsifiers in O/W emulsions.

Combination of a Deep Eutectic Solvent and Macroporous Resin for Green Recovery of Iridoids, Chlorogenic Acid, and Flavonoids from Eucommia ulmoides Leaves

To increase the effectiveness of using typical biomass waste as a resource, iridoids, chlorogenic acid, and flavonoids from the waste biomass of Eucommia ulmoides leaves (EULs) were extracted by deep eutectic solvents (DESs) in conjunction with macroporous resin. To optimize the extract conditions, the experiment of response surface was employed with the single-factor of DES composition molar ratio, liquid-solid ratio, water percentage, extraction temperature, and extraction time. The findings demonstrated that the theoretical simulated extraction yield of chlorogenic acid (CGA), geniposidic acid (GPA), aucubin (AU), geniposide (GP), rutin (RU), and isoquercetin (IQU) were 42.8, 137.2, 156.7, 5.4, 13.5, and 12.8 mg/g, respectively, under optimal conditions (hydrogen bond donor-hydrogen bond acceptor molar ratio of 1.96, liquid-solid ratio of 28.89 mL/g, water percentage of 38.44%, temperature of 317.36 K, and time of 55.59 min). Then, 12 resins were evaluated for their adsorption and desorption capabilities for the target components, and the HPD950 resin was found to operate at its optimum. Additionally, the HPD950 resin demonstrated significant sustainability and considerable potential in the recyclability test. Finally, the hypoglycemic in vitro, hypolipidemic in vitro, immunomodulatory, and anti-inflammatory effects of EUL extract were evaluated, and the correlation analysis of six active components with biological activity and physicochemical characteristics of DESs by heatmap were discussed. The findings of this study can offer a theoretical foundation for the extraction of valuable components by DESs from waste biomass, as well as specific utility benefits for the creation and development of natural products.

Improving the functionality of pea protein with laccase-catalyzed crosslinking mediated by chlorogenic acid

The influences of laccase-catalyzed crosslinking on the structural, emulsifying and gelling properties of pea protein with chlorogenic acid were intensively probed. Molecular weight analysis illustrated the formation of pea protein aggregates by laccase-induced polymerization in the presence of chlorogenic acid and the increase of incubation time facilitated the aggregation. Particle size of pea protein-laccase-chlorogenic acid progressively enhanced increasing incubation time. Laccase-induced polymerization possessed remarkable impacts on the secondary and tertiary structure of pea protein, confirmed by circular dichroism, and fluorescence spectroscopy. Surface hydrophobicity of pea protein appreciably enhanced with laccase-induced crosslinking due to the exposure of interior hydrophobic amino acid residues. Emulsifying activity, emulsifying capacity, gel strength, and water-holding capacity of pea protein can be considerably enhanced with laccase-catalyzed crosslinking with chlorogenic acid, suggesting excellent functionalities for pea protein were accomplished after being modified by laccase with chlorogenic acid. The obtained information will widen pea protein's application in food systems.

A surface multiple imprinting layers membrane with well-oriented recognition sites for selective separation of chlorogenic acid from Ficus carica L

Chlorogenic acid (CGA), known as an important natural antioxidative compound in Ficus carica L, has valuable application prospects on health food, functional food, nutrition and dietary formulations. In this study, a surface multiple imprinting layers membrane (SMILM) was developed and applied to separate CGA from F. carica. Two different imprinting layers were integrated onto the membrane surface in sequence. The first imprinting layer was formed by dopamine polymerization and the second imprinting layer was fabricated by atom transfer radical polymerization (ATRP) and boronate affinity. The prepared SMILM with well-oriented multiple recognition sites exhibited high adsorption capacity (52.08 mg·g-1 in 60 min) for CGA and specific selectivity with imprinting factor (IF) of 3.06. Furthermore, the recognition mechanism of SMILM was clarified by molecular simulation and NMR. The SMILM was successfully applied to separate CGA from the fruits, peels and leaves of F. carica with recoveries of 90.22, 83.31 and 84.95 %, respectively.

Synergistic interaction of Cu(II) with caffeic acid and chlorogenic acid in α-glucosidase inhibition

BACKGROUND

Phenolic acids are widespread in foods and are beneficial to human health. However, the role of metal ions in influencing the binding of proteins with phenolic acids that contain the same parent nucleus structure remains unclear. This study investigated the inhibitory effect of caffeic acid (CA) and chlorogenic acid (CHA) on α-glucosidase and the biological effect of copper on this process.

RESULTS

It was found that the esterification of CA with quinic acid could increase the fluorescence quenching, conformational change, and inhibitory effect of CHA on α-glucosidase. Copper ions reduced their fluorescence quenching and conformation-changing ability by binding to the neighboring phenolic hydroxyl group but also increased their ability to alter secondary structure and to inhibit α-glucosidase and in vitro anti-glycation.

CONCLUSION

Overall, this study shows that the binding of copper ions to the phenolic hydroxyl group adjacent to CA and CHA synergistically inhibited α-glucosidase. The findings will offer a theoretical basis for investigating the properties of metal ions and phenolic acid in food chemistry and their potential applications in the prevention and treatment of diabetes mellitus. © 2023 Society of Chemical Industry.

Chlorogenic acid-chitosan copolymers: Synthesis, characterization and application in O/W emulsions for enhanced β-carotene stability

In this study, chlorogenic acid-chitosan (CA-CS) copolymers were prepared with varying Chitosan (CS): chlorogenic acid (CA)ratios and characterized for their water solubility, antioxidant capacity, and emulsions stability. Results showed that CA-CS samples exhibited up to 90.5 % increase in DPPH scavenging efficiency and 20 % increase in hydroxyl radical scavenging efficiency compared to CS alone. CA-CS copolymers used to stabilize oil in water (O/W) emulsions, which were evaluated for their potential in encapsulating and protecting β-carotene. Microscopic observations revealed homogeneous spherical droplets in stable emulsions, suggesting effective interfacial structures. The selected CA-CS-stabilized O/W emulsions demonstrated encapsulation efficiencies of 74.8 % and 75.26 % for β-carotene. The CA-CS stabilized O/W emulsions provided the most effective protection against β-carotene degradation under UV exposure, retaining over 80 % of β-carotene content after 12 h of testing. These findings indicate that CA-CS-based O/W emulsions show promise as carriers and protectors for bioactive compounds, due to their improved antioxidant capacity, emulsions stability, and protection against degradation.

Sustained release of chlorogenic acid by co-encapsulation of sodium alginate binding to the Northern pike (Esox Lucius) liver ferritin

Ferritin has a unique hollow spherical structure, which makes it a promising nanocarrier for food functional substances. In this study, a new ferritin was successfully extracted from the liver of Northern pike, purified, and identified. We used the reversible self-assembly characteristics of ferritin to fabricate chlorogenic acid (CA)-loaded apoferritin (Apo) complex (Apo-CA) and sodium alginate (SA)-apoferritin (Apo) co-encapsulate system. Apo-CA was encapsulated into the SA system to form SA-Apo-CA. The fabricated composites were analyzed using particle size, UV-Vis absorption spectroscopy, fluorescence spectroscopy, flourier transform infrared spectroscopy and transmission electron microscope. Physicochemical property of analysis confirmed th successful preparation of Apo-CA/SA-Apo-CA and improved thermal and UV radiation stability. The effect of sustained-release of CA were tested in vitro of simulated gastrointestinal tract digestion. SA-Apo-CA exhibited greater release ability than unencapsulated CA and Apo-CA. This study provides a new strategy for designing a multilayer delivery system with improved stability and sustained-release property.

Effects of Covalent or Noncovalent Binding of Different Polyphenols to Acid-Soluble Collagen on Protein Structure, Functionality, and Digestibility

In this study, the structure, function, and digestibility of noncovalent complexes and covalent conjugates formed by acid-soluble collagen with polyphenols of different structures (quercetin, epicatechin, gallic acid, chlorogenic acid, procyanidin, and tannic acid) were investigated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that polyphenols were covalently bound to collagen by laccase catalytic oxidation. Biolayer interferometry revealed that the noncovalent binding strength of polyphenols to collagen from high to low was quercetin > gallic acid > chlorogenic acid > epicatechin, which was consistent with the trend of covalent polyphenol binding. Procyanidin and tannic acid had strong noncovalent binding, but their covalent binding ability was weak. Compared with the pure collagen, the complexes improved emulsification and antioxidant properties (more than 2.5 times), and the conjugates exhibited better thermal stability (99.4-106.8 °C) and antidigestion ability (reduced by more than 37%). The finding sheds new light on the use of collagen as a functional food ingredient in the food industry.

An optimized 3D-printed capsule scaffold utilizing artificial neural network for the targeted delivery of chlorogenic acid to the colon

Chlorogenic acid (CGA) is an important bioactive polyphenol with extensive biological properties. This study aimed to fabricate an optimized three-dimensional (3D)-printed capsule scaffold and CGA capsules for targeted delivery of hydrophobic CGA to the colon. The optimized printing parameters identified using the neural network model were a temperature of 170 °C, a printing speed of 20 mm/s, and a nozzle diameter of 0.3 mm. The capsules exhibited slow releasing properties of CGA, and the releasing rates of Eudragit®FS 30D-sealed capsules (due to more cracks and voids) were faster than those of Eudragit®S100-sealed capsules. The Ritger-peppas model was the best fitting model to describe the releasing process of CGA from 8 CGA capsules (R2 ≥ 0.98). All CGA capsules exhibited shear-thinning properties with stable sol-gel viscosity at low shear rates. FTIR spectra confirmed the formation of non-covalent bonds between CGA and the sol. Overall, the obtained 3D-printed capsules provided a promising carrier for the targeted delivery of CGA in the development of personalized dietary supplements.

Evaluation the binding of chlorogenic acid with bovine serum albumin: Spectroscopic methods, electrochemical and molecular docking

Chlorogenic acid(CGA) is the common active phenolic acid in Chinese medicinal materials such as honeysuckle and eucommia. It is a class of small molecules with multiple activities such as antioxidant, inhibiting cancer cells, lowering blood sugar and lowering blood pressure. In this paper, UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism, molecular dynamics simulation and cyclic voltammetry (CV) electrochemical analysis were used to investigate the mechanism about interaction between CGA and BSA. Based on fluorescence quenching analysis, CGA quenched the inherent fluorescence of BSA remarkably through a static mechanism. The obtained value of binding constant (K_b = 5.75 × 10⁵ L·mol^-1) revealed a high binding affinity between CGA and BSA. The simulated molecular docking showed that hydrophobic force were also involved in the interaction between BSA and CGA. This paper also investigate the effect of temperature and metal ions on the binding of CGA and BSA. When the temperature increased, the binding of BSA and CGA was destroyed. Metal ions affect both the structure of BSA and the combination of BSA and CGA. By studying the mechanism of CGA interaction with BSA, we elucidated the storage and transport mechanism of CGA in vivo under simulated human environment and temperature conditions.

The Chemopreventive Effects of Chlorogenic Acids, Phenolic Compounds in Coffee, against Inflammation, Cancer, and Neurological Diseases

Coffee is one of the most widely consumed beverages, which has several effects on the human body. In particular, current evidence suggests that coffee consumption is associated with a reduced risk of inflammation, various types of cancers, and certain neurodegenerative diseases. Among the various constituents of coffee, phenolic phytochemicals, more specifically chlorogenic acids, are the most abundant, and there have been many attempts to utilize coffee chlorogenic acid for cancer prevention and therapy. Due to its beneficial biological effect on the human body, coffee is regarded as a functional food. In this review article, we summarize the recent advances and knowledge on the association of phytochemicals contained in coffee as nutraceuticals, with a particular focus on phenolic compounds, their intake, and nutritional biomarkers, with the reduction of disease risk, including inflammation, cancer, and neurological diseases.

Phenolic Acid-Amino Acid Adducts Exert Distinct Immunomodulatory Effects in Macrophages Compared to Parent Phenolic Acids

Caffeic acid (CA) and chlorogenic acid (CGA) are commonly found phenolic acids in plant-derived foods and beverages. Their corresponding adducts with cysteine (Cys) have been detected in coffee-containing beverages. However, despite the well-documented antioxidant and anti-inflammatory activity of CA and CGA, the immunomodulatory activities of the Cys adducts (CA-Cys and CGA-Cys) are unknown. The adducts were therefore synthesized, and their immunomodulatory effects were studied in lipopolysaccharide (LPS)-treated RAW 264.7 cells and compared to the activity of the parent phenolic acids. CA and CGA generally down-regulated the inflammatory responses. However, RNA-sequencing showed that the LPS-induced pathways related to Toll-like receptor signaling, chemokine signaling, and NOD-like receptor signaling, and JAK-STAT/MAPK signaling pathways were upregulated in adduct-treated cells relative to parent phenolic acids, while neurodegenerative disorder-related pathways and metabolic pathways were downregulated. Production of prostaglandin E₂ (PGE₂), interleukin-6, tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS) was all inhibited by CA and CGA (P < 0.05). PGE₂ and TNF-α were further suppressed in adduct-stimulated cells (P < 0.05), but ROS production was increased. For example, TNF-α produced by 100 μM CGA-stimulated cells and 100 μM CGA-Cys adduct-stimulated cells were 4.46 ± 0.23 and 1.61 ± 0.18 ng/mL, respectively. Thus, the addition of the Cys moiety drastically alters the anti-inflammatory activity of phenolic compounds.

Matrix-Specific Effects on Caffeine and Chlorogenic Acid Complexation in a Novel Extract of Whole Coffea arabica Coffee Cherry by NMR Spectroscopy

Coffee cherry is a rich source of caffeine and chlorogenic acids. In this study we investigate the structural analysis of caffeine-enriched whole coffee cherry extracts, CEWCCE by using ¹H and ¹³C NMR spectroscopy. The changes in ¹H chemical shift data in NMR spectra of CEWCCE compared to pure caffeine indicated the formation of complexes between caffeine and chlorogenic acids in aqueous solution. The effect of complexation on the peak position of caffeoylquinic acid and caffeine resonance with increasing addition of caffeine was investigated. 2D NOESY experiments show the presence of cross-peaks that are due to the proximity of chlorogenic acid and caffeine molecules in stable complexes in protic solvents. The quantification data of caffeine by ¹H qNMR was found to be in close agreement with the data obtained by HPLC analysis.

Assessment of Correlation Analysis, Phytochemical Profile, and Biological Activities of Endemic Scorzonera Species from Turkey

Scorzonera species belong to the Asteraceae family comprising more than 25000 species. The present study aimed to examine the phytochemical profiles and biological activities of S. sandrasica Hartvig et Strid, S. coriacea A. Duran&Aksoy, and S. ahmet-duranii Makbul&Coskuncelebi which are endemic species to Turkey. Flavonoids such as hyperoside, isoquercitrin, rutin, isoorientin, orientin, 7-O-methyl isoorientin, luteolin-7-O-β-glycoside, apigenin-7-O-β-glucoside, vitexin, isovitexin as well as caffeoylquinic acid derivatives including chlorogenic acid, 4,5-O-dicaffeoylquinic acid, and 1,5-O-dicaffeoylquinic acid contents were analyzed to clarify phytochemical content of the extracts. Aerial parts of the investigated extracts were determined as contain flavonoids in high amounts. Chlorogenic acid and its derivatives were detected in all investigated species, in varying amounts, both in the roots and aerial parts. S. coriacea aerial parts contained the highest total phenolic and flavonoids. The strongest inhibitory activities on ABTS and DPPH radicals were also observed with S. coriacea aerial parts by 8.07±0.28 and 13.94±0.53 μg/ml of IC50 values, respectively. Total phenolic contents of the extracts were significantly correlated with DPPH (r=-0.9842, p=0.0004) and ABTS free radical scavenging (r=-0.9870, p=0.0003) and total antioxidant capacity (r=0.8173, p=0.0470), as well as total flavonoid contents (r=0.8820, p=0.0201). S. sandrasica aerial parts and S. ahmet-duranii roots exhibited the greatest red blood cell membrane protection and protein denaturation inhibition, respectively. From the phytochemical point of view, all the selected species were analyzed for the first time.

Combination of Sea Sand Disruption Method and Ion-Pair Solid-Phase Extraction for Effective Isolation and Purification of Chlorogenic Acid from Plants Prior to the HPLC Determination

Chlorogenic acid (CQA) is one of phenolics commonly found in higher plants, possessing numerous health-promoting effects on humans. Unfortunately, it is easily degraded/transformed into other substances during extraction. Therefore, its reliable analysis requires a special approach that does not involve high temperatures. This paper presents a very simple method of CQA isolation using the sea sand disruption method with subsequent purification of the extract using the ion-pair solid-phase extraction process, followed by HPLC–DAD detection. It was found that control of the ion pairing reagent concentration and sample pH is crucial to improve purification, and that the best results, with recovery exceeding 98%, were obtained for 0.05 M tetrabutylammonium bisulfate at pH 7 when the ion pairs were formed directly in the extract and eluted from the C18 sorbent using an acidified methanol–water mixture. The practical potential of the developed procedure was verified by using it for CQA isolation from different plants. The approach represents one of the contemporary analytical trends and current advances in the solid phase extraction, in which several sorption extraction techniques are combined to ensure high-quality analytical results.

Analysis of the binding selectivity and inhibiting mechanism of chlorogenic acid isomers and their interaction with grass carp endogenous lipase using multi-spectroscopic, inhibition kinetics and modeling methods

Polyphenols are inhibitors for lipase, but the binding selectivity and mechanism of polyphenol isomers and how they interact with lipase are not clear. Here, chlorogenic acid (CGA) isomers, neochlorogenic acid (NCGA) and cryptochlorogenic acid (CCGA) were used to explore the binding selectivity and mechanism of lipase. An inhibition assay indicated that both CGA isomers had dose-dependent inhibitory effects on lipase; however, the inhibitory effect of NCGA was better (IC₅₀: 0.647 mg/mL) than that of CCGA (IC₅₀: 0.677 mg/mL). NCGA and CCGA formed complexes with lipase at a molar ratio of 1:1, and the electrostatic interaction force plays a major role in the lipase-CCGA system. Molecular dynamics studies demonstrated that NCGA had a greater impact on the structure of lipase. The multi-spectroscopic and modeling results explained the effects of micro-structural changes on the binding site, the interaction force and the inhibition rate of the isomers when they combined with lipase.

A review on polyphenols and their potential application to reduce food allergenicity

This review summarized recent studies about the effects of polyphenols on the allergenicity of allergenic proteins, involving epigallocatechin gallate (EGCG), caffeic acid, chlorogenic acid, proanthocyanidins, quercetin, ferulic acid and rosmarinic acid, etc. Besides, the mechanism of polyphenols for reducing allergenicity was discussed and concluded. It was found that polyphenols could noncovalently (mainly hydrophobic interactions and hydrogen bonding) and covalently (mainly alkaline, free-radical grafting, and enzymatic method) react with allergens to induce the structural changes, resulting in the masking or/and destruction of epitopes and the reduction of allergenicity. Oral administration in murine models showed that the allergic reaction might be suppressed by regulating immune cell function, changing the levels of cytokines, suppressing of MAPK, NF-κb and allergens-presentation pathway and improving intestine function, etc. The outcome of reduced allergenicity and suppressed allergic reaction was affected by many factors such as polyphenol types, polyphenol concentration, allergen types, pH, oral timing and dosage. Moreover, the physicochemical and functional properties of allergenic proteins were improved after treatment with polyphenols. Therefore, polyphenols have the potential to produce hypoallergenic food. Further studies should focus on active concentrations and bioavailability of polyphenols, confirming optimal intake and hypoallergenic of polyphenols based on clinical trials.

Identification and Quantitation of Reaction Products from Chlorogenic Acid, Caffeic Acid, and Their Thermal Degradation Products with Odor-Active Thiols in Coffee Beverages

A holistic ultraperformance liquid chromatography (UPLC)-time of flight (TOF)-mass spectrometry-based approach was used to screen for storage-induced reaction products consisting of the volatile key coffee thiols methanethiol, 2-furfurylthiol, 2-methyl-3-furanthiol, 3-mercapto-3-methylbutanol, and 3-mercapto-2-butanone and low-molecular weight phenolic constituents of coffee beverages including chlorogenic acid, caffeic acid, and their thermal degradation products hydroxyhydroquinone, catechol, and 4-ethylcatechol. Multiple marker compounds could be detected in thiol-enriched coffee brews after UPLC-TOF-MS profiling and statistical data analysis. Subsequently, marker compounds were synthesized and structurally characterized via high-resolution mass spectrometry and 1D- and 2D-NMR experiments. Quantification of these reaction products in fresh and stored coffee beverages was realized in native coffee and after stir bar sorptive extraction with liquid desorption by means of UHPLC-MS/MS. The quantitative data revealed the biggest influence of storage time on the formation of reaction products between hydroxyhydroquinone and methanethiol and 2-furfurylthiol, while other reaction products were only slightly affected by storage and thus most likely formed during the roasting process.

Unexpected Antioxidant Efficiency of Chlorogenic Acid Phenolipids in Fish Oil-in-Water Nanoemulsions: An Example of How Relatively Low Interfacial Concentrations Can Make Antioxidants to Be Inefficient

Selecting effective antioxidants is challenging since their efficiency in inhibiting lipid oxidation depends on the rate constants of the chemical reactions involved and their concentration at the reaction site, i.e., at the interfacial region. Accumulation of antioxidants at the interface of emulsions is key to modulate their efficiency in inhibiting lipid oxidation but its control was not well understood, especially in emulsions. It can be optimized by modifying the physicochemical properties of antioxidants or the environmental conditions. In this work, we analyze the effects of surfactant concentration, droplet size, and oil to water ratio on the effective interfacial concentration of a set of chlorogenic acid (CGA) esters in fish oil-in-water (O/W) emulsions and nanoemulsions and on their antioxidant efficiency. A well-established pseudophase kinetic model is used to determine in the intact emulsified systems the effective concentrations of the antioxidants (AOs). The relative oxidative stability of the emulsions is assessed by monitoring the formation of primary oxidation products with time. Results show that the concentration of all AOs at the interfacial region is much higher (20–90 fold) than the stoichiometric one but is much lower than those of other phenolipid series such as caffeic or hydroxytyrosol derivatives. The main parameter controlling the interfacial concentration of antioxidants is the surfactant volume fraction, Φ_I, followed by the O/W ratio. Changes in the droplet sizes (emulsions and nanoemulsions) have no influence on the interfacial concentrations. Despite the high radical scavenging capacity of CGA derivatives and their being concentrated at the interfacial region, the investigated AOs do not show a significant effect in inhibiting lipid oxidation in contrast with what is observed using other series of homologous antioxidants with similar reactivity. Results are tentatively interpreted in terms of the relatively low interfacial concentrations of the antioxidants, which may not be high enough to make the rate of the inhibition reaction faster than the rate of radical propagation.

Synthesis and in vitro evaluation of chlorogenic acid amides as potential hypoglycemic agents and their synergistic effect with acarbose

Type 2 Diabetes mellitus is a chronic disease considered one of the most severe global health emergencies. Chlorogenic acid (1) has been shown to delay intestinal glucose absorption by inhibiting the activity of α-glucosidase (α-Glu) and α-amylase (α-Amy). In the present work, eleven chlorogenic acid amides have been synthesized and evaluated for their antioxidant properties (as DPPH and ORAC) and inhibition activity towards the two enzymes and, with the aim to obtain dual-action antidiabetic agents. The two most promising hypoglycemic compounds, bearing a tertiary amine function on an alkyl chain (8) and a benzothiazole scaffold (11), showed IC₅₀ values lower than that of (1) (45.5 µM α-Glu; 105.2 µM α-Amy). Amides 8 and 11 were by far more potent α-Glu inhibitors than the antidiabetic drug acarbose (IC₅₀ = 268.4 µM) and about twice less active toward α-Amy than acarbose (IC₅₀ = 34.4 µM). Kinetics experiments on amides 8 and 11 indicated these compounds as mixed-type inhibitors of α-Glu with K'_i values of 13.3 and 6.3 µM, respectively. The amylase inhibition occurred with a competitive mechanism in the presence of 8 (K_i = 79.7 µM) and with a mixed-type mechanism with 11 (K_i = 19.1 µM; K'_i = 93.6 µM). Molecular docking analyses supported these results, highlighting the presence of additional binding sites in both enzymes. Fluorescence experiments confirmed the grater affinity of amides 8 and 11 towards the two enzymes respect to (1). Moreover, a significant enhancement in acarbose efficacy was observed when inhibition assays were performed adding acarbose and amide 11. The above outcomes pinpointed the benzothiazole-based amide 11 as a promising candidate for further studies on type 2 diabetes treatment, both alone or combined with acarbose.

Protective effects of rutin and chlorogenic acid against antihypoxic conditions in mice

Almost all plants contain polyphenols. Literature shows that polyphenols exhibit many biological activities. Little has known about their protective effects against hypoxia-induced lethality. The protective effects of rutin (1) and chlorogenic acid (2) against hypoxia conditions in mice were determined by three different experimental models. Antihypoxic activity was especially pronounced in asphytic hypoxia. Both compounds (1&2) showed statistically significant (p>0.05) activities respect to the control. Compound (1) significantly prolonged the latency for death with respect to control (39.20±8.70 vs. 13.20±2.58min, p<0.001). Compound (1) was the most effective compound in circulatory hypoxia. It significantly prolonged the latency for death with respect to control (14.44±2.82 vs. 9.82±0.79 min, p<0.01). On the other hand, Chlorogenic acid (2) at a dose of 100 mg kg^-1 kept mice alive for 12.76±1.30min (p>0.05). None of two phenolic acids had any activity in haemic hypoxia when compared to control.

Supercritical Antisolvent Fractionation of Antioxidant Compounds from Salvia officinalis

The increasing interest towards greener antioxidants obtained via natural sources and more sustainable processes encourages the development of new theoretical and experimental methods in the field of those compounds. Two advanced separation methods using supercritical CO2 are applied to obtain valuable antioxidants from Salvia officinalis, and a first approximation to a QSAR model relating molecular structure with antioxidant activity is explored in order to be used, in the future, as a guide for the preselection of compounds of interest in these processes. Separation experiments through antisolvent fractionation with supercritical CO2 were designed using a Response Surface Methodology to study the effect of pressure and CO2 flow rate on both mass yields and capability to obtain fractions enriched in three antioxidant compounds: chlorogenic acid, caffeic acid and rosmarinic acid which were tracked using HPLC PDA. Rosmarinic acid was completely retained in the precipitation vessel while chlorogenic and caffeic acids, though distributed between the two separated fractions, had a major presence in the precipitation vessel too. The conditions predicted for an optimal overall yield and enrichment were 148 bar and 10 g/min. Although a training dataset including much more compounds than those now considered can be recommended, descriptors calculated from the σ-profiles provided by COSMO-RS model seem to be adequate for estimating the antioxidant activity of pure compounds through QSAR.

Effect of Filtrated Osmotic Solution Based on Concentrated Chokeberry Juice and Mint Extract on the Drying Kinetics, Energy Consumption and Physicochemical Properties of Dried Apples

BACKGROUND

Filtration of osmotic solution affects selective penetration during osmotic dehydration (OD), and after drying is finished, this can influence the chemical composition of the material, which is also modified by OD.

METHODS

Osmotic dehydration was carried out in filtrated and non-filtrated concentrated chokeberry juice with the addition of mint infusion. Then, this underwent convective drying, vacuum-microwave drying and combined convective pre-drying, followed by vacuum-microwave finishing drying. Drying kinetics were presented and mathematical models were selected. The specific energy consumption for each drying method was calculated and the energy efficiency was determined.

RESULTS AND DISCUSSION

The study revealed that filtration of osmotic solution did not have significant effect on drying kinetics; however, it affected selective penetration during OD. The highest specific energy consumption was obtained for the samples treated by convective drying (CD) (around 170 kJ·g-1 fresh weight (fw)) and the lowest for the samples treated by vacuum-microwave drying (VMD) (around 30 kJ·g-1 fw), which is due to the differences in the time of drying and when these methods are applied.

CONCLUSIONS

Filtration of the osmotic solution can be used to obtain the desired material after drying and the VMD method is the most appropriate considering both phenolic acid content and the energy aspect of drying.

Graphene Oxide Loaded with Protocatechuic Acid and Chlorogenic Acid Dual Drug Nanodelivery System for Human Hepatocellular Carcinoma Therapeutic Application

Hepatocellular carcinoma or hepatoma is a primary malignant neoplasm that responsible for 75-90% of all liver cancer in humans. Nanotechnology introduced the dual drug nanodelivery method as one of the initiatives in nanomedicine for cancer therapy. Graphene oxide (GO) loaded with protocatechuic acid (PCA) and chlorogenic acid (CA) have shown some anticancer activities in both passive and active targeting. The physicochemical characterizations for nanocomposites were conducted. Cell cytotoxicity assay and lactate dehydrogenase were conducted to estimate cell cytotoxicity and the severity of cell damage. Next, nanocomposite intracellular drug uptake was analyzed using a transmission electron microscope. The accumulation and localization of fluorescent-labelled nanocomposite in the human hepatocellular carcinoma (HepG2) cells were analyzed using a fluorescent microscope. Subsequently, Annexin V- fluorescein isothiocyanate (FITC)/propidium iodide analysis showed that nanocomposites induced late apoptosis in HepG2 cells. Cell cycle arrest was ascertained at the G2/M phase. There was the depolarization of mitochondrial membrane potential and an upregulation of reactive oxygen species when HepG2 cells were induced by nanocomposites. In conclusion, HepG2 cells treated with a graphene oxide-polyethylene glycol (GOP)-PCA/CA-FA dual drug nanocomposite exhibited significant anticancer activities with less toxicity compared to pristine protocatechuic acid, chlorogenic acid and GOP-PCA/CA nanocomposite, may be due to the utilization of a folic acid-targeting nanodrug delivery system.

Multiple co-pigments of quercetin and chlorogenic acid blends intensify the color of mulberry anthocyanins: insights from hyperchromicity, kinetics, and molecular modeling investigations

BACKGROUND

The effect of multiple co-pigments on the color intensification of mulberry anthocyanins (ACs) using spectroscopic techniques in combination with a molecular docking study was studied. The hyperchromicity of ACs co-pigmented with chlorogenic acid (CH) and quercetin (Q) blends was measured and their color stability in liquid and encapsulated particle models was evaluated.

RESULTS

Multiple co-pigments exhibited higher hyperchromicity, pK_H -values, and heat-stability than their individual counterparts. Surflex-docking findings confirmed that stronger binding occurred between multiple ligands and AC than single ones due to their extra -OH, -COOH groups, and delocalization systems. The binding was allowed by increased H-bonding, van der Waals forces, and π-π sites by the extra groups of the multiple co-pigments with AC in aqueous juice and whey particle-based models.

CONCLUSION

This is the first report of the ternary mixture of phenolic acid-flavonol-anthocyanin which could be used as promising food red-colorants. © 2020 Society of Chemical Industry.

Alkaloid and phenolic compounds of Xylopia aromatica inhibits tumor growth by down-regulating matrix metalloproteinase-2 (MMP-2) expression

Annonacea species have been reported to possess antitumor properties. However, the in vitro and in vivo antitumor activities of Xylopia aromatica (Annonacea) have not yet been elucidated. This study aimed to investigate the effects of Xylopia aromatica leaves hexane fraction (XaHF) on Ehrlich ascites carcinoma cells lines (EAC), both in vitro and in vivo. In vitro assays revealed a significant cytotoxic effect with the two lower XaHF concentrations (62.5 and 32.3mg/mL). EAC (2.5x10⁶ cells) were inoculated in the right flank of Swiss mice, and the animals were treated intraperitoneally with 32.3mg kg^-1 of XaHF daily, for 20 days. Our findings indicate that XaHF suppressed the growth of EAC in vivo, with a significant decrease (46%) in tumor volume. There was also a decrease in the necrosis area (71%), inflammatory infiltrate, and MMP-2 expression. High-Performance Liquid Chromatography with Diode Array Detector (HPLC-DAD) identified secondary metabolites possibly related to phenolic acids, flavonoids, and alkaloids. Thus, the results confirmed the antitumoral activity that may be related to the presence of the identified metabolites in XaHF extract.

Antimicrobial potential of resin matrices loaded with coffee compounds

This study evaluated the biological behavior of the coffee compounds Trigonelline (T), chlorogenic acid (C), and nicotinic acid (N), correlating with their release from a resin matrix. Minimum inhibitory concentration (MIC) was evaluated against Streptococcus mutans UA159, and cytotoxicity was assessed by methyl tetrazolium salt on OD-21 cells. Resin matrices (bisphenol A-glycidyl-dimethacrylate/triethylene glycol-dimethacrylate 70/30 wt%, camphorquinone/ethyl 4-dimethyl aminobenzoate 0.5/1 wt%) were doped with coffee compounds in different concentrations (10/20/30/40/50 wt%), performing 15 groups (T10-T50, C10-C50, N10-N50), and a control group with no coffee compound. Degree of conversion (DC%) was analyzed by Fourier transform infrared spectroscopy. Antimicrobial properties were evaluated by bioluminescence (Luciferase assay). The release from loaded matrices was analyzed over time (24 hr, 6, 14, 21 and 28 days), using high-performance liquid chromatography (HPLC). Data were submitted to ANOVA/Tukey's test (α = 0.05). MIC for T and C was 6 mg/ml, and 4 mg/ml for N. None of them were cytotoxic. Only T50 and C50 showed lower DC% than control (α < 0.05). Some groups (T30/T40/T50/C40/C50/N50) were strongly antimicrobial, reducing bacterial activity approximately five times compared to control (α < 0.05). For T30, T40, T50, C40, and C50, the HPLC showed a release above or closer to MIC values mainly in 24 hr, but for N50, up to 28 days. In conclusion, the coffee compounds presented antimicrobial activity, depending on their concentration when added in resin matrices, being found a correlation with their release.

Identification and Quantitation of Reaction Products from Quinic Acid, Quinic Acid Lactone, and Chlorogenic Acid with Strecker Aldehydes in Roasted Coffee

To gain comprehensive insight into the interactions of key coffee odorants, like the Strecker aldehydes, acetaldehyde, propanal, methylpropanal, 2- and 3-methylbutanal, and methional, and the nonvolatile fraction of coffee, an untargeted metabolomics approach was applied. Ultra performance liquid chromatography (UPLC)-time of flight (TOF)-mass spectrometry (ESI^-) profiling followed by statistical data analysis revealed a marker substance for a coffee beverage spiked with acetaldehyde with an accurate mass of 217.0703 [M - H]^-. This compound could be identified as a reaction product of quinic acid (QA) and acetaldehyde linked by acetalization at the cis-diol function of QA. Consequently, the acetalization of aldehydes, QA, 5-O-caffeoyl quinic acid (CQA), and quinic acid γ-lactone (QAL) was investigated by means of model reactions, followed by synthesis, isolation, and structure elucidation via UPLC-TOF-MS and 1D and 2D NMR techniques. UHPLC-MS/MS_MRM screening and the quantification of aldehyde adducts in coffee beverages revealed the presence of QA/acetaldehyde, -/propanal, -/methylpropanal, and -/methional reaction products and CQA/acetaldehyde, -/propanal, -/methylpropanal, -/2- and 3-methylbutanal, and -/methional and QAL/acetaldehyde adducts for the first time, in concentrations of 12-270 μg/L for QA/aldehydes, 5-225 μg/L for CQA/aldehydes, and 62-173 μg/L for QAL/acetaldehyde. The sensory characterization of the identified compounds showed bitter taste recognition thresholds of 48-297 μmol/L for CQA adducts and 658 μmol/L for QAL/acetaldehyde, while the QA adducts showed no bitter taste (<2000 μmol/L).

Inhibition of Human Cathepsins B and L by Caffeic Acid and Its Derivatives

Caffeic acid (CA) and its derivatives caffeic acid phenethyl ester (CAPE) and chlorogenic acid (CGA) are phenolic compounds of plant origin with a wide range of biological activities. Here, we identify and characterize their inhibitory properties against human cathepsins B and L, potent, ubiquitously expressed cysteine peptidases involved in protein turnover and homeostasis, as well as pathological conditions, such as cancer. We show that CAPE and CGA inhibit both peptidases, while CA shows a preference for cathepsin B, resulting in the strongest inhibition among these combinations. All compounds are linear (complete) inhibitors acting via mixed or catalytic mechanisms. Cathepsin B is more strongly inhibited at pH 7.4 than at 5.5, and CA inhibits its endopeptidase activity preferentially over its peptidyl-dipeptidase activity. Altogether, the results identify the CA scaffold as a promising candidate for the development of cathepsin B inhibitors, specifically targeting its endopeptidase activity associated with pathological proteolysis of extracellular substrates.

A novel feruloyl esterase with high rosmarinic acid hydrolysis activity from Bacillus pumilus W3

A novel feruloyl esterase (BpFae12) with rosmarinic acid (RA) hydrolysis activity was isolated from Bacillus pumilus W3 and expressed in Escherichia coli BL21 (DE3). With RA as a substrate, the optimal pH and temperature of BpFae12 were pH 8.0 and 50 °C, respectively. The specific enzyme activity was 12.8 U·mg-1. BpFae12 showed the highest activity and substrate affinity toward RA (Vmax of 13.13 U·mg-1, Km of 0.41 mM). Moreover, it also presented strong hydrolysis performance against chlorogenic acid (190.17 U·mg-1). RA was effectively Hydrolyzed into more bioactive caffeic acid and 3,4-dihydroxyphenyllactic acid by BpFae12, which have potential applications in the food industry.

Topical Application of Aronia melanocarpa Extract Rich in Chlorogenic Acid and Rutin Reduces UVB-Induced Skin Damage via Attenuating Collagen Disruption in Mice

Aronia melanocarpa, a black chokeberry, contains high levels of phenolic acids and polyphenolic flavonoids and displays antioxidative and anti-inflammatory effects. Through high-performance liquid chromatography for extracts from Aronia melanocarpa, we discovered that the extract contained chlorogenic acid and rutin as major ingredients. In this study, we examined the protective effects of the extract against ultraviolet B- (UVB)-induced photodamage in the dorsal skin of institute of cancer research (ICR) mice. Their dorsal skin was exposed to UVB, thereafter; the extract was topically applied once a day for seven days. Photoprotective properties of the extract in the dorsal skin were investigated by clinical skin severity score for skin injury, hematoxylin and eosin staining for histopathology, Masson's trichrome staining for collagens. In addition, we examined change in collagen type I and III, and matrix metalloproteinase (MMP)-1 and MMP-3 by immunohistochemistry. In the UVB-exposed mice treated with the extract, UVB-induced epidermal damage was significantly ameliorated, showing that epidermal thickness was moderated. In these mice, immunoreactivities of collagen type I and III were significantly increased, whereas immunoreactivities of MMP-1 and 3 were significantly decreased compared with those in the UVB-exposed mice. These results indicate that treatment with Aronia melanocarpa extract attenuates UV-induced photodamage by attenuating UVB-induced collagen disruption: these findings might be a result of the chlorogenic acid and rutin contained in the extract. Based on the current results, we suggest that Aronia melanocarpa can be a useful material for developing photoprotective adjuvant.

Anti-Cancer Effects of Green Tea Epigallocatchin-3-Gallate and Coffee Chlorogenic Acid

Tea and coffee are consumed worldwide and epidemiological and clinical studies have shown their health beneficial effects, including anti-cancer effects. Epigallocatechin gallate (EGCG) and chlorogenic acid (CGA) are the major components of green tea polyphenols and coffee polyphenols, respectively, and believed to be responsible for most of these effects. Although a large number of cell-based and animal experiments have provided convincing evidence to support the anti-cancer effects of green tea, coffee, EGCG, and CGA, human studies are still controversial and some studies have suggested even an increased risk for certain types of cancers such as esophageal and gynecological cancers with green tea consumption and bladder and lung cancers with coffee consumption. The reason for these inconsistent results may have been arisen from various confounding factors. Cell-based and animal studies have proposed several mechanisms whereby EGCG and CGA exert their anti-cancer effects. These components appear to share the common mechanisms, among which one related to reactive oxygen species is perhaps the most attractive. Meanwhile, EGCG and CGA have also different target molecules which might explain the site-specific differences of anti-cancer effects found in human studies. Further studies will be necessary to clarify what is the mechanism to cause such differences between green tea and coffee.

Interaction of chlorogenic acid with model lipid membranes and its influence on antiradical activity

Chlorogenic acid (CGA) is a strong phenolic antioxidant with antibacterial properties composed by a caffeoyl ester of quinic acid. Although a number of benefits has been reported and related to interactions with the red blood cell membranes, details on its membrane action and how composition and membrane state may affect it, is not yet well defined. In this work, the interaction of CGA with lipid monolayers and bilayers composed by 1,2-dimiristoyl-sn-glycero-3-phosphocholine (DMPC); 1,2-di-O-tetradecyl-sn-glycero-3-phosphocholine (14:0 diether PC); 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-di-O-hexadecyl-sn-glycero-3-phosphocholine (16:0 diether PC) were studied at different surface pressures (π). The kinetics of interaction was found to be more rapid in DMPC than in the absence of carbonyl groups. Measurements by FTIR-ATR at different water activities confirm specific interactions of CGA with carbonyl and phosphate groups affecting water level along hydrocarbon region. The antioxidant activity of CGA in the presence of DMPC unilamellar vesicles, evidenced by the absorbance reduction of the radical cation ABTS^•+, is significantly different with respect to aqueous solution. The influence of CGA on antiradical activity (ARA) with lipid membranes depending on the hydration state of the lipid interface is discussed.

Characterization of Cultivated Eggplant and its Wild Relatives Based on Important Fruit Biochemical Traits

BACKGROUND AND OBJECTIVES

The modern-day eggplant consumers desire varieties with a higher content of chlorogenic acid, but the cultivated varieties of eggplant are with a lower content of chlorogenic acid. Whereas, the wild relatives of eggplant are higher in phenolic acids. Therefore, this study characterized the cultivated eggplant and its wild relatives for the fruit dry matter content, total fruit phenolics and chlorogenic acid content.

MATERIALS AND METHODS

Fruits of the accessions of cultivated eggplant, one primary genepool species, nine secondary genepool species and three tertiary genepool species were characterized for dry matter content (%), total phenolics and the fruit chlorogenic acid content (mg g-1). The chlorogenic acid content in the fruit flesh was determined by using the High Performance Liquid Chromatography (HPLC).

RESULTS

Highest content of dry matter content of around 29% was determined for the species S. tomentosum and S. elaeagnifolium. Whereas, the highest content of total fruit phenolics were determined in the secondary genepool species S. linnaeanum. The most top content of chlorogenic acid around 4.5 mg g-1 of fruit dry weight was present in the species S. linnaeanum and S. torvum. Different clustering approaches were able to cluster the primary genepool species with the cultivated eggplant.

CONCLUSION

Overall, this work provides important information about the wild relatives of eggplant concerning their dry matter content, total phenolics and chlorogenic acid content. This information can be used to engineer eggplant varieties rich in fruit phenolics.

Aronia melanocarpa Fruits as a Rich Dietary Source of Chlorogenic Acids and Anthocyanins: 1H-NMR, HPLC-DAD, and Chemometric Studies

Aronia melanocarpa (Michx.) Elliott's (chokeberry) besides anthocyanins contains significant amounts of hydroxycinnamic acids: Chlorogenic and its isomer neochlorogenic acid. They exhibit antioxidant, anti-inflammatory, antidiabetic, and antibacterial activities, thus they can have a significant impact on the health-promoting properties of Aronia. The aim of our research was to determine the changes in the content of chlorogenic acids (CGAs) and anthocyanins during fruit development and ripening, with a particular emphasis on acids. Aronia fruit samples were collected from July to October on two organic farms in Poland. The chemical composition of the extracts was determined by NMR spectroscopy and HPLC-DAD. ¹H-NMR and HPLC data were analyzed using chemometric analysis and multivariate statistics (PCA). The results showed that the content of chlorogenic acids and anthocyanins changes during ripening and depends on the time of harvest and the region of cultivation. A correlation between the time of CGAs reduction and the appearance of anthocyanins was also noticed. The result of our research was also a database in the form of NMR parameters, which allows analysis of the metabolite profile and tracking of its changes. The ¹H-NMR spectrum showing anthocyanin and CGA resonance can be considered the Aronia berry fingerprint.

Interactions of Calcium with Chlorogenic and Rosmarinic Acids: An Experimental and Theoretical Approach

Chlorogenic (CA) and rosmarinic (RA) acids are two natural bioactive hydroxycinnamic acids whose antioxidant properties can be modulated by the chelation of metal ions. In this work, the interactions of these two carboxylic phenols with calcium ions and the impact of such interactions on their antioxidant activity were investigated. UV-Vis absorbance, mass spectroscopy and 1H and 13C liquid NMR were used to identify complexes formed by CA and RA with calcium. Antioxidant activities were measured by the Bois method. Density functional theory (DFT) calculations were performed to evaluate the most stable configurations and correlated with NMR data. Taken together, these data suggest that calcium ions mainly interact with the carboxylate groups of both molecules but that this interaction modifies the reactivity of the catechol groups, especially for RA. These results highlight the complex interplay between metal chelation and antioxidant properties of natural carboxylic phenols.

Classification of Brazilian roasted coffees from different geographical origins and farming practices based on chlorogenic acid profiles

Sixty-seven roasted coffee samples from different regions of Brazil cultivated using organic, conventional and biodynamic farming practices were analysed and quantified using high performance liquid chromatography coupled with mass spectrometry, and treated with supervised (PLS-DA) and unsupervised (PCA) multivariate statistical tools. The profile of the chlorogenic acids constituents were analysed by high resolution and tandem mass spectrometry, which allowed the identification of mono- caffeoyl-, feruloyl-, para-Coumaroylquinic acids and their respective regio-isomers. This study provides a comprehensive analysis of absolute quantitative data set of chlorogenic acids constituents (CQA, FQA and pCoQA isomers) in Brazilian coffee beans produced from different regions of the country. Variations in the chlorogenic acids compositions were observed if organic and conventional roasted coffee beans were compared. The use of multivariate statistical tools allowed the identification of suitable biomarkers for determining significant differences between the three coffee agricultural practices, while coffees produced from the diverse geographical regions showed no significant difference.

Chemical Diversity of Bastard Balm (Melittis melisophyllum L.) as Affected by Plant Development

The phytochemical diversity of Melittis melissophyllum was investigated in terms of seasonal changes and age of plants including plant organs diversity. The content of phenolics, namely: coumarin; 3,4-dihydroxycoumarin; o-coumaric acid 2-O-glucoside; verbascoside; apiin; luteolin-7-O-glucoside; and o-coumaric; p-coumaric; chlorogenic; caffeic; ferulic; cichoric acids, was determined using HPLC-DAD. Among these, luteolin-7-O-glucoside, verbascoside, chlorogenic acid, and coumarin were the dominants. The highest content of flavonoids and phenolic acids was observed in 2-year-old plants, while coumarin in 4-year-old plants (272.06 mg 100 g-1 DW). When considering seasonal changes, the highest content of luteolin-7-O-glucoside was observed at the full flowering, whereas verbascoside and chlorogenic acid were observed at the seed-setting stage. Among plant organs, the content of coumarin and phenolic acids was the highest in leaves, whereas verbascoside and luteolin-7-O-glucoside were observed in flowers. The composition of essential oil was determined using GC-MS/GC-FID. In the essential oil from leaves, the dominant was 1-octen-3-ol, whilst from flowers, the dominant was α-pinene.

Optimization of an Extraction Solvent for Angiotensin-Converting Enzyme Inhibitors from Hibiscus sabdariffa L. Based on Its UPLC-MS/MS Metabolic Profiling

Hibiscus species (Malvaceae) have been long used as an antihypertensive folk remedy. The aim of our study was to specify the optimum solvent for extraction of the angiotensin-converting enzyme inhibiting (ACEI) constituents from Hibiscus sabdariffa L. The 80% methanol extract (H2) showed the highest ACEI activity, which exceeds that of the standard captopril (IC50 0.01255 ± 0.00343 and 0.210 ± 0.005 µg/mL, respectively). Additionally, in a comprehensive metabolomics approach, an ultra-performance liquid chromatography (UPLC) coupled to the high resolution tandem mass spectrometry (HRMS) method was used to trace the metabolites from each extraction method. Interestingly, our comprehensive analysis showed that the 80% methanol extract was predominated with secondary metabolites from all classes including flavonoids, anthocyanins, phenolic and organic acids. Among the detected metabolites, phenolic acids such as ferulic and chlorogenic acids, organic acids such as citrate derivatives and flavonoids such as kaempferol have been positively correlated to the antihypertensive potential. These results indicates that these compounds may significantly contribute synergistically to the ACE inhibitory activity of the 80% methanol extract.

Effect of Different Durations of Solid-Phase Fermentation for Fireweed (Chamerion angustifolium (L.) Holub) Leaves on the Content of Polyphenols and Antioxidant Activity In Vitro

Fireweed has recently been recognized as a plant with high antioxidant potential and phenolic content. Its leaves can be fermented to prepare an infusion with ideal antioxidant activity. The aim of this study was to investigate and to determine the influence of solid-phase fermentation of different durations on the variation of polyphenols in the leaves of fireweed. Laboratory experiments were conducted in 2017-2018. The leaves of fireweed, naturally growing, were fermented for different periods of time: not fermented (control) and fermented for 24 and 48 h. The evaluation of polyphenols and antioxidant activity in leaves was performed using high- performance liquid chromatography (HPLC). Additionally, principal component analysis was used to characterize differences in bioactive compounds between fireweed samples fermented at different durations. Solid-phase fermented leaves were characterized by higher contents of oenothein B, quercetin and benzoic acid but had lower contents of quercetin-3-O-rutinoside, luteolin and chlorogenic and gallic acids. Antioxidant activity in short- (24 h) and long-term (48 h) fermentation (compared to control) gave the highest level of regression in 2017, but in 2018 the effect was observed only with short-term fermentation and control. In conclusion, solid-phase fermentation can be used to modulate biologically active compounds in fireweed leaves.

Effects of chlorogenic acid on thermal stress tolerance in C. elegans via HIF-1, HSF-1 and autophagy

BACKGROUND

Chlorogenic acid (CGA) is a polyphenol widely distributed in plants and plant-derived food with antioxidant and protective activities against cell stress. Caenorhabditis elegans is a model organism particularly useful for understanding the molecular and biochemical mechanisms associated with aging and stress in mammals. In C. elegans, CGA was shown to improve resistance to thermal, while the underlying mechanisms that lead to this effect require further understanding.

PURPOSE

The present study was conducted to investigate the underlying molecular mechanisms behind CGA response conferring thermotolerance to C. elegans.

METHODS AND RESULTS

Signaling pathways that could be involved in the CGA-induced thermotolerance were evaluated in C. elegans strains with loss-of-function mutation. CGA-induced thermotolerance required hypoxia-inducible factor HIF-1 but no insulin pathway. CGA exposition (1.4 µM CGA for 18 h) before thermal stress treatment increased HIF-1 levels and activity. HIF-1 activation could be partly attributed to an increase in radical oxygen species and a decrease in superoxide dismutase activity. In addition, CGA exposition before thermal stress also increased autophagy just as hormetic heat condition (HHC), worms incubated at 36 °C for 1 h. RNAi experiments evidenced that autophagy was increased by CGA via HIF-1, heat-shock transcription factor HSF-1 and heat-shock protein HSP-16 and HSP-70. In contrast, autophagy induced by HHC only required HSF-1 and HSP-70. Moreover, suppression of autophagy induction showed the significance of this process for adapting C. elegans to cope with thermal stress.

CONCLUSION

This study demonstrates that CGA-induced thermotolerance in C. elegans is mediated by HIF-1 and downstream, by HSF-1, HSPs and autophagy resembling HHC.

Hydrolysis of chlorogenic acid in apple juice using a p-coumaryl esterase of Rhizoctonia solani

BACKGROUND

Apple juice is rich in polyphenolic compounds, especially in chlorogenic acid. A sour and bitter taste has been attributed to the compound. Chlorogenic acid in coffee powder was quickly hydrolysed by a p-coumaryl esterase of Rhizoctonia solani (RspCAE) at its optimal pH of 6.0. It was unknown, however, if RspCAE would also degrade chlorogenic acid under the strongly acidic conditions (pH 3.3) present in apple juice.

RESULTS

Treatment of apple juice with RspCAE led to a chlorogenic acid degradation from 53.38 ± 0.94 mg L^-1 to 21.02 ± 1.47 mg L^-1 . Simultaneously, the caffeic acid content increased from 6.72 ± 0.69 mg L^-1 to 19.33 ± 1.86 mg/L^-1 . The aroma profile of the enzymatically treated sample and a control sample differed in only one volatile. Vitispirane had a higher flavour dilution factor in the treated juice. Sensory analysis showed no significant difference in the taste profile ( p < 0.05).

CONCLUSION

These results demonstrated a high stability and substrate specificity of RspCAE. An increase in caffeic acid and a concurrent decrease in chlorogenic acid concentration may exert a beneficial effect on human health. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Interaction of Structurally Diverse Phenolic Compounds with Porcine Pancreatic α-Amylase

A blood glucose level lowering effect is postulated for polyphenols (PPs), which is in part attributed to the inhibition of α-amylase. To estimate structure-effect relationships, chlorogenic acid (CA), phlorizin (PHL), epigallocatechin gallate (EGCG), epicatechin (EC), and malvidin-3-glucoside (Mlv-3-glc) were used as inhibitors in an enzyme assay, on the basis of the conversion of GalG₂CNP by α-amylase. The detection of CNP was performed by UV/vis spectroscopy. The data reveal that the inhibitor strength decreases as follows: EGCG > Mlv-3-glc > EC > PHL ∼ CA. Detection of the substrate conversion by isothermal titration calorimetry supports these results. All PPs showed mixed inhibition, except for CA and EGCG wherein the competitive proportion was predominant. Investigations by saturation transfer difference NMR revealed interaction of PPs with α-amylase prevalently based on interactions with the aromatic or conjugated system. A correlation between the extent of the conjugated system and the IC₅₀ of the PP could be found.