Inhibitory effect of chlorogenic acid on digestion of potato starch

Chlorogenic acid simultaneously enhances the oxidative protection and anti-digestibility of porous starch

Porous starch (PS) has been utilized as an oral protective carrier to enhance the oxidative stability of liposoluble nutrients. However, PS releases more glucose during digestion, thereby increasing the risk of chronic diseases. Chlorogenic acid (CA) has excellent antioxidant properties and enhances the starch digestion resistance. To simultaneously enhance the oxidative protection and anti-digestibility, PS was blended with CA. Morphological analysis revealed that PSs with pores absorbed liposoluble substances. Surface area, total pore volume, and oxidative stability analyses demonstrated that rice starch (RS) enzymatically hydrolyzed for 12 h (PS12) loaded more substances and exerted a better protective effect in cooperation with CA. Simulated digestion confirmed that PS12-CA1 had the best anti-digestibility among PS12-CAs and a similar digestibility as RS. Additionally, CA treatment resulted in more anti-digestive V-type crystals in PSs, which resisted digestion. This study showed that the combination of PS and CA simultaneously enhanced oxidative protection and reduced the digestibility of PS. Thus, CA treatment makes PS a better oral nutrient delivery.

Integration of Destructive and Non-Destructive Analytical Determinations for Evaluating Quality of Fresh and Roasted Hazelnuts Subjected to Different Processing Temperatures

The internal quality of hazelnuts (Corylus avellana L.), particularly in terms of the degradation of fat components, is widely recognized as a key factor in determining the appropriate type of industrial processing. Additionally, the internal composition and volatile profile of hazelnuts change significantly based on different roasting conditions. The here reported study investigates the efficiency of Electronic Nose (E-nose) and Near-Infrared Spectroscopy (FT-NIR) technologies, combined with multivariate statistical techniques, for the rapid discrimination of hazelnuts subjected to different roasting conditions. Moreover, the study examines the ability of NIR to predict several key quality parameters in fresh and processed hazelnuts. Hazelnut samples were collected throughout the entire industrial processing chain, from delivery to roasting. The influence of three different roasting temperatures (140-150-160°C) was evaluated, keeping the roasting time constant at 24 min. Partial Least Squares models were computed to estimate moisture content, total soluble solids, protein content, acidity, and peroxide index through correlation with FT-NIR spectral data. Excellent regression performances were achieved for all quality parameters, except acidity, with correlations ranging between 0.951 and 0.918. Discriminant analysis models, specifically PLS-DA and Cluster Analysis, were used to assess the ability to discriminate hazelnuts subjected to different roasting conditions using FT-NIR and the Electronic Nose as non-destructive tools. Obtained results from these non-destructive techniques, particularly the volatile characterization GC/MS-performed, accurately reflected the differentiation of samples observed through traditional chemical analyses, effectively distinguishing different groups of samples based on roasting temperature. The use of non-destructive tools such as FT-NIR and E-nose during the post-harvest life and processing of hazelnuts offers an excellent solution for monitoring key quality parameters significantly important for the food industry.

Structure-function relationships in (poly)phenol-enzyme binding: Direct inhibition of human salivary and pancreatic α-amylases

(Poly)phenols inhibit α-amylase by directly binding to the enzyme and/or by forming starch-polyphenol complexes. Conventional methods using starch as the substrate measure inhibition from both mechanisms, whereas the use of shorter oligosaccharides as substrates exclusively measures the direct interaction of (poly)phenols with the enzyme. In this study, using a chromatography-based method and a short oligosaccharide as the substrate, we investigated the detailed structural prerequisites for the direct inhibition of human salivary and pancreatic α-amylases by over 50 (poly)phenols from the (poly)phenol groups: flavonols, flavones, flavanones, flavan-3-ols, polymethoxyflavones, isoflavones, anthocyanidins and phenolic acids. Despite being structurally very similar (97% sequence homology), human salivary and pancreatic α-amylases were inhibited to different extents by the tested (poly)phenols. The most potent human salivary α-amylase inhibitors were luteolin and pelargonidin, while the methoxylated anthocyanidins, peonidin and petunidin, significantly blocked pancreatic enzyme activity. B-ring methoxylation of anthocyanidins increased inhibition against both human α-amylases while hydroxyl groups at C3 and B3' acted antagonistically in human salivary inhibition. C4 carbonyl reduction, or the positive charge on the flavonoid structure, was the key structural feature for human pancreatic inhibition. B-ring glycosylation did not affect salivary enzyme inhibition, but increased pancreatic enzyme inhibition when compared to its corresponding aglycone. Overall, our findings indicate that the efficacy of interaction with human α-amylase is mainly influenced by the type and placement of functional groups rather than the number of hydroxyl groups and molecular weight.

Designing sustainable weaning foods for developing countries: not only a matter of nutrients

Blended complementary foods from cereals and high-protein sources are used worldwide to cope with infants' malnutrition. However, the usefulness of the food matrix during traditional processes reaches suboptimal effectiveness due to cereal gelatinization and viscosity, which reduce consumption. The interplay between nutritional and physical qualities needed for weaning children presents further significant constraints. A combination of processing methods can improve and optimize the overall product quality. This paper investigated the nutritional, functional, and anti-nutritional factors of a complementary infant porridge made by combining fermented sorghum flour with germinated bottle gourd seed flour. Overall, the combination improved the functional and physical properties of the porridge suitable for children of 10 months and over. A serving of 100 g would contribute 115-145% and 23-31% of the recommended nutritional intake of protein and energy, respectively, for low breast milk energy between 6-24 months. The results demonstrate that a combination of strategies and technologies are needed to balance nutritional and physical quality.

Chromogenic Assay Is More Efficient in Identifying α-Amylase Inhibitory Properties of Anthocyanin-Rich Samples When Compared to the 3,5-Dinitrosalicylic Acid (DNS) Assay

The inhibition of carbohydrate digestion by plant bioactive compounds is a potential dietary strategy to counteract type 2 diabetes. Indeed, inhibition of α-amylase, a key enzyme that carries out the bulk of starch digestion, has been demonstrated for a range of bioactive compounds including anthocyanins; however, sample pigmentation often interferes with measurements, affecting colorimetric assay outcomes. Therefore, the present study compared the performance of a direct chromogenic assay, using 2-chloro-4 nitrophenyl α-D-maltotrioside (CNPG3) as a substrate, with the commonly used 3,5-dinitrosalicylic acid (DNS) assay. The direct chromogenic assay demonstrated a 5-10-fold higher sensitivity to determine α-amylase inhibition in various samples, including acarbose as a reference, pure anthocyanins, and anthocyanin-rich samples. The IC50 values of acarbose presented as 37.6 μg/mL and 3.72 μg/mL for the DNS assay and the direct chromogenic assay, respectively, whereas purified anthocyanins from blackcurrant showed IC50 values of 227.4 µg/mL and 35.0 µg/mL. The direct chromogenic assay is easy to perform, fast, reproducible, and suitable for high-throughput screening of pigmented α-amylase inhibitors.

Microwave-Induced Behavior and Digestive Properties of the Lotus Seed Starch-Chlorogenic Acid Complex

The effect of chlorogenic acid (CA) on the dielectric response of lotus seed starch (LS) after microwave treatment, the behavior and digestive characteristics of the resulting starch/chlorogenic acid complex (LS-CA) at different degrees of gelatinization and the inhibition of α-amylase by chlorogenic acid were investigated. The variation in dielectric loss factor, ε″, and dielectric loss tangent, tanδε, of the microwave thermal conversion indicated that LS-CA had a more efficient microwave-energy-to-thermal-energy conversion efficiency than LS. This gelatinized LS-CA to a greater extent at any given temperature between 65 and 85 °C than LS, and it accelerated the degradation of the starch crystalline structure. The greater disruption of the crystal structure decreased the bound water content and increased the thermal stability of LS-CA compared to LS. The simulated in vitro digestion found that the presence of the LS-CA complex improved the slow-digestion property of lotus seed starch by increasing its content of resistant and slowly digested starch. In addition, the release of chlorogenic acid during α-amylase hydrolysis further slowed starch digestion by inhibiting α-amylase activity. These findings provide a foundation for understanding the correlation between the complex behavior and digestive properties of naturally polyphenol-rich, starch-based foods, such as LS, under microwave treatment, which will facilitate the development of starch-based foods with tailored digestion rates, lower final degrees of hydrolysis and glycemic indices.

Health-Promoting compounds in Potatoes: Tuber exhibiting great potential for human health

Potatoes are consumed worldwide because of their high accessibility, low cost, taste, and diversity of cooking methods. The high carbohydrate content of potatoes masks the presence of -vitamins, polyphenols, minerals, amino acids, lectins and protein inhibitors in the minds of consumers. The consumption of potatoes faces challenges among health-conscious people. This review paper attempted to provide up-to-date information on new metabolites reported in potatoes that play role in disease prevention and overall human well-being. We tried to compile information on antidiabetic, antihypertensive, anticancer, antiobesity, antihyperlipidemic, and anti-inflammatory potential of potato along with role in improving gut health and satiety. In-vitro studies, human cell culture, and experimental animal and human clinical studies showed potatoes to exhibit a variety of health-enhancing properties. This article will not only popularize potato as a healthy food, but will also improve its use as a staple for the foreseeable future.

The Quality Characteristics Comparison of Stone-Milled Dried Whole Wheat Noodles, Dried Wheat Noodles, and Commercially Dried Whole Wheat Noodles

To explore the quality differences between dried wheat noodles (DWNs), stone-milled dried whole wheat noodles (SDWWNs), and commercially dried whole wheat noodles (CDWWNs), the cooking quality, texture properties, microstructure, protein secondary structure, short-range order of starch, antioxidant activity, in vitro digestive properties, and estimated glycemic index (eGI) of the noodles were investigated. The results showed that the cooking loss of SDWWNs was significantly lower than that of CDWWNs. The springiness, cohesiveness, gumminess, chewiness, and resilience of SDWWNs reached the maximum, and the tensile strength was significantly increased. The continuity of the gluten network of SDWWNs was reduced, and more holes appeared. The protein secondary structure of the SDWWNs and CDWWNs was mainly dominated by the β-sheet and β-turn, and the differences in the starch short-range order were not significant. Prior to and after the in vitro simulated digestion, the DPPH radical scavenging activity, the hydroxyl radical scavenging activity, and the total reducing power of the SDWWNs were the highest. Although the digested starch content of SDWWNs did not differ significantly from that of CDWWNs, the eGI was significantly lower than that of the CDWWNs and DWNs. Overall, the SDWWNs had certain advantages, in terms of quality characteristics.

Hypoglycemic and antioxidative activity evaluation of phenolic compounds derived from walnut diaphragm produced in Xinjiang

Walnut diaphragm is defined as a dry wood septum located between the walnut shell and kernel. In this work, seven phenolic compounds from walnut diaphragm were purified and characterized, and their antioxidant activities and mechanisms of hypoglycemia were investigated. Compounds 1-7 were tested for DPPH, ABTS scavenging ability, and FRAP assay to evaluate the antioxidant activity. α-Amylase inhibition assay was introduced to assess the hypoglycemic activity, and the mechanism was investigated by kinetic analysis, CD spectrum, and molecular docking. Compound 6 showed the strongest antioxidant ability, while compound 1 exhibited the strongest inhibition of α-amylase by changing the secondary structure of α-amylase in a mixed competitive inhibition mode. Molecular docking test predicted that the tetrahydropyran part in compound 1 may contribute to its hypoglycemic effect. This study furnishes a new theoretical reference for the utilization and development of walnut diaphragm into a health food with antioxidant and hypoglycemic properties. PRACTICAL APPLICATIONS: The finding of this research may serve as a basis for the subsequent development of walnut diaphragm into instant tea-based health food or added to other food carriers to achieve auxiliary antioxidant and hypoglycemic effects. This study revealed that polyphenolic components were the material basis for the antioxidant and hypoglycemic effects of walnut diaphragm, which could be identified as landmark chemical components for controlling quality standards in the development of walnut diaphragm, thus accelerating the research process of quality standards for walnut diaphragm-related products. Furthermore, the studies on the mechanism of hypoglycemic activity supply more credible data to support the development of walnut diaphragm into a safe and consumer-friendly health food. With abundant resources and clear efficacy, walnut diaphragm has great development prospect and application value.

In vitro digestibility and fermentability profiles of wheat starch modified by chlorogenic acid

This study was designed to investigate the effect of chlorogenic acid (CA) on starch digestibility and fermentability in vitro. Compared with wheat starch (WS), WS-CA complexes exhibited a looser porous gel matrix, and higher solubility and swelling power with the addition of different proportion of CA. The WS-CA complexes significantly reduced the digestive rate of the gelatinized WS, and increased the proportion of resistant starch (RS) ranging from 31.70 % to 69.63 % much higher than that in the gelatinized WS (26.34 %). The residual WS-CA complexes after 24 h of fermentation with human feces induced the production of short-chain fatty acid, as well as the proliferation of gut microbiota such as genera Megamonas and Parabacteroides positively associated with the improvement of human health. The results suggest that complex of starch and CA could be a promising method for developing starchy foods with lower starch hydrolysis and promoting the growth of probiotics.

Screening of Aqueous Extract of Persea americana Seeds for Alpha-Glucosidase Inhibitors

Activity of α-glucosidase enzyme in the gastrointestinal tract has been implicated in postprandial hyperglycaemia. If not properly controlled, postprandial hyperglycaemia might progress to diabetes mellitus, a metabolic syndrome. Diabetes is associated with many complications such as retinopathy, heart attack, nephropathy, neuropathy, stroke, and lower limb amputation. Antidiabetic medications presently in use have little effect on postprandial glycaemic excursion and hence do not bring down the blood glucose level to baseline. This study extracted, fractionated, and screened the aqueous extract of Persea americana seeds for hypoglycaemic potential. Inhibitory effects of the fractions and subfractions of the extract on α-glucosidase activity were investigated. The most active subfraction was subjected to Fourier transform infrared (FTIR) and gas chromatography mass spectroscopy (GC-MS) analysis to elucidate the active components. The active subfraction showed a significant inhibition (p < 0.05) on α-glucosidase. The subfraction competitively inhibits α-glucosidase (with IC50 = 09.48 ± 0.58 μg/mL), though less potent than the standard drug, acarbose (IC50 = 06.45 ± 0.47 μg/mL). FTIR analysis of the subfraction showed the presence of carbonyl group, hydroxy group, carboxyl group, double bonds, methylene, and methyl groups. GC-MS analysis suggests the presence of cis-11,14-eicosadienoic acid, catechin, and chlorogenic acid as the active components. In conclusion, the components obtained from this study can be synthesised in the laboratory to further confirm their hypoglycaemic activity. The most active subfraction can be explored further to confirm its inhibitory activity against the enzyme and to determine its extent in the treatment of diabetes mellitus in vivo.

The inhibitory mechanism of chlorogenic acid and its acylated derivatives on α-amylase and α-glucosidase

Due to the poor lipophilicity of chlorogenic acid (CA), five CA derivatives (C2-CA, C4-CA, C6-CA, C8-CA, and C12-CA) with different lipophilicities were synthesized using acylation catalyzed by lipase in present study. The inhibitory activities and mechanisms of CA and its derivatives on α-amylase and α-glucosidase were then determined. Results showed that the inhibitory activities of CA derivatives on α-amylase and α-glucosidase were enhanced as lipophilicity increased, and the inhibitory activities of C12-CA were stronger than those of CA. IC₅₀ values of C12-CA were 13.30 ± 0.26 μmol/mL for α-amylase and 3.42 ± 0.10 μmol/mL for α-glucosidase. C12-CA possessed the smallest K_ic and K_iu values, and its inhibitory actions on α-amylase and α-glucosidase were stronger than those of CA and the other derivatives. Effects of C12-CA on microenvironments of amino acid residues and secondary structures of α-amylase and α-glucosidase were greater than those of CA and the other derivatives.

Caffeoyl substitution decreased the binding and inhibitory activity of quinic acid against α-amylase: The reason why chlorogenic acid is a relatively weak enzyme inhibitor

α-Amylase inhibition of chlorogenic acid (CHA) and its component moieties including quinic acid (QA) and caffeic acid (CA) were characterized by IC₅₀, inhibition kinetics, fluorescence quenching, isothermal titration calorimetry, differential scanning calorimetry and molecular docking. QA was found with the highest inhibitory activity in a competitive-mode, and caffeoyl substitution significantly decreased its inhibition but maintained inhibition type. Interestingly, QA hardly quenched α-amylase fluorescence, while CA quenched that significantly without inhibitory activity. This resulted from lack of aromatic ring in QA that can form π-conjugation with α-amylase fluorescent residues. Besides, the binding constant of QA with α-amylase was higher than CHA. Additionally, QA and CA decreased but CHA remained α-amylase thermal stability, indicating that change in α-amylase spatial structure was related with enzyme residue sites involved in interactions with inhibitors, instead of with inhibition effect. Conclusively, caffeoyl substitution decreased α-amylase inhibition of QA through reducing its binding affinity to the enzyme.

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.

Phytochemical Composition, Antibacterial Activity, and Antioxidant Properties of the Artocarpus altilis Fruits to Promote Their Consumption in the Comoros Islands as Potential Health-Promoting Food or a Source of Bioactive Molecules for the Food Industry

The present study aimed to evaluate the health-promoting potential of breadfruit (Artocarpus altilis (Parkinson) Fosberg, Moraceae family), a traditional Comorian food, considering the sample variability according to geographic localisation. Moreover, the main aims of this research were also to promote its consumption in the Comoros Islands as potential health-promoting food and evaluate it as a source of bioactive molecules for the food industry thanks to its antioxidant and antibacterial properties. Investigations on biologically active substances were carried out on the extracts obtained from breadfruit flours from five regions of Grande Comore (Ngazidja), the main island in Comoros. Phytochemical screening revealed the presence of tannins and polyphenols, flavonoids, leucoanthocyanins, steroids, and triterpenes. The considered secondary metabolites were phenolic compounds, vitamin C, monoterpenes, and organic acids. The contents of total phenolic compounds (mgGAE/100 g of dry weight—DW) in the extracts ranged from 29.69 ± 1.40 (breadfruit from Mbadjini—ExMBA) to 96.14 ± 2.07 (breadfruit from Itsandra—ExITS). These compounds included flavanols, flavonols, cinnamic acid and benzoic acid derivatives, and tannins which were detected at different levels in the different extracts. Chlorogenic acid presented the highest levels between 26.57 ± 0.31 mg/100 g DW (ExMIT) and 43.80 ± 5.43 mg/100 g DW (ExMBA). Quercetin was by far the most quantitatively important flavonol with levels ranging from 14.68 ± 0.19 mg/100 g DW (ExMIT) to 29.60 ± 0.28 mg/100 g DW (ExITS). The extracts were also rich in organic acids and monoterpenes. Quinic acid with contents ranging from 77.25 ± 6.04 mg/100 g DW (ExMBA) to 658.56 ± 0.25 mg/100 g DW of ExHAM was the most important organic acid in all the breadfruit extracts, while limonene was quantitatively the main monoterpene with contents between 85.86 ± 0.23 mg/100 g DW (ExMIT) and 565.45 ± 0.24 mg/100 g DW (ExITS). The antibacterial activity of the extracts was evaluated on twelve pathogens including six Gram (+) bacteria and six Gram (−) bacteria. By the solid medium disc method, except for Escherichia coli and Pseudomonas aeruginosa, all the bacteria were sensitive to one or more extracts. Inhibitory Halo Diameters (IHDs) ranged from 8 mm to 16 mm. Salmonella enterica, Clostridium perfringens, and Vibrio fischeri were the most sensitive with IHD > 14 mm for ExITS. By the liquid microdilution method, MICs ranged from 3.12 mg/mL to 50 mg/mL and varied depending on the extract. Bacillus megaterium was the most sensitive with MICs ≤ 12.5 mg/mL. Pseudomonas aeruginosa, Shigella flexneri, and Vibrio fischeri were the least sensitive with all MICs ≥ 12.5 mg/mL. ExHAM was most effective with a MIC of 3.12 mg/mL on Staphylococcus aureus and 6.25 mg/mL on Salmonella enterica. The antioxidant power of the extracts was evaluated by the FRAP method. The activity ranged from 5.44 ± 0.35 (ExMBA) to 14.83 ± 0.11 mmol Fe²⁺/kg DW (ExHAM). Breadfruit from different regions of Comoros contained different classes of secondary metabolites well known for their important pharmacological properties. The results of this study on phenolics, monoterpenes, and organic acids have provided new data on these fruits. The obtained results showed that breadfruit from the biggest island of the Union of Comoros also presented antimicrobial and antioxidant properties, even if some differences in effectiveness existed between fruits from different regions.

Comparison of quercetin and rutin inhibitory influence on Tartary buckwheat starch digestion in vitro and their differences in binding sites with the digestive enzyme

Inhibitory effects of flavonoids on starch digestibility were well known, but the structural mechanism was not clear. This study was focused on the diverse effect of quercetin and rutin on digestibility of Tartary buckwheat starch. Results showed that quercetin and rutin reduced the starch digestion by altering starch structure in bound forms and inhibiting digestive enzyme activity in free forms simultaneously, and quercetin showed a stronger effect than rutin. Molecular docking and saturation transfer difference-nuclear magnetic resonance (STD-NMR) revealed different binding site of rutin from quercetin was due to its hydroxyl and hydrogen on the glycoside structure. Rutin interacted with enzymes mainly by CH and OH on the glycoside structure which induced steric hindrance and restricted the inhibitory effect of quercetin fraction. The glycoside structure weakened inhibition of rutin on digestive enzymes in free forms rather than influence its anti-digestive effects in bound forms with starch.

Quantification of Major Bioactive Constituents, Antioxidant Activity, and Enzyme Inhibitory Effects of Whole Coffee Cherries (Coffea arabica) and Their Extracts

Coffee cherry is a rich source of chlorogenic acids (CGAs) and caffeine. In this study we examined the potential antioxidant activity and enzyme inhibitory effects of whole coffee cherries (WCC) and their two extracts on α-amylase, α-glucosidase and acetylcholinesterase (AChE) activities, which are targets for the control of diabetes and Alzheimer’s diseases. Whole coffee cherry extract 40% (WCCE1) is rich in chlorogenic acid compounds, consisting of a minimum of 40% major isomers, namely 3-caffeoylquinic acids, 4-caffeoylquinic acids, 5-caffeoylquinic acids, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, 4-feruloylquinc acid, and 5-feruloylquinc acid. Whole coffee cherry extract 70% (WCCE2) is rich in caffeine, with a minimum of 70%. WCCE1 inhibited the activities of digestive enzymes α-amylase and α-glucosidase, and WCCE2 inhibited acetylcholinesterase activities with their IC₅₀ values of 1.74, 2.42, and 0.09 mg/mL, respectively. Multiple antioxidant assays—including DPPH, ABTS, FRAP, ORAC, HORAC, NORAC, and SORAC—demonstrated that WCCE1 has strong antioxidant activity.

Glycoside Hydrolases and Non-Enzymatic Glycation Inhibitory Potential of Viburnum opulus L. Fruit-In Vitro Studies

Phytochemicals of various origins are of great interest for their antidiabetic potential. In the present study, the inhibitory effects against carbohydrate digestive enzymes and non-enzymatic glycation, antioxidant capacity, and phenolic compounds composition of Viburnum opulus L. fruits have been studied. Crude extract (CE), purified extract (PE), and ethyl acetate (PEAF) and water (PEWF) fractions of PE were used in enzymatic assays to evaluate their inhibitory potential against α-amylase with potato and rice starch as substrate, α-glucosidase using maltose and sucrose as substrate, the antioxidant capacity (ABTS, ORAC and FRAP assays), antiglycation (BSA-fructose and BSA-glucose model) properties. Among four tested samples, PEAF not only had the highest content of total phenolics, but also possessed the strongest α-glucosidase inhibition, antiglycation and antioxidant activities. UPLC analysis revealed that this fraction contained mainly chlorogenic acid, proanthocyanidin oligomers and flavalignans. Contrary, the anti-amylase activity of V. opulus fruits probably occurs due to the presence of proanthocyanidin polymers and chlorogenic acids, especially dicaffeoylquinic acids present in PEWF. All V. opulus samples have an uncompetitive and mixed type inhibition against α-amylase and α-glucosidase, respectively. Considering strong anti-glucosidase, antioxidant and antiglycation activities, V. opulus fruits may find promising applications in nutraceuticals and functional foods with antidiabetic activity.

Inhibition of in vitro enzymatic starch digestion by coffee extract

There is evidence that moderate coffee consumption is beneficial in the prevention of type 2 diabetes, however, the underlying mechanism is not understood. In this study, the effects of an extract of ground coffee on the in vitro enzymatic digestion of starch were investigated. The coffee extract decreased the rate and extent of starch digestion, with kinetic analysis showing that the extract reduced the binding affinity of the enzymes for the substrate and their catalytic turnover. Fluorescence quenching indicated that the coffee extract formed complexes with the digestive enzymes through a static quenching mechanism. Ultraviolet absorption and circular dichroism spectra of the digestive enzymes confirmed that the coffee extract decreased the proportion of β-sheet structures in the enzymes. Therefore, we conclude that compounds in the soluble coffee extract can interact with porcine pancreatic amylase and amyloglucosidase causing inhibition of the enzymes and decreasing in vitro starch digestion.

Improvement of Health-Promoting Functionality of Rye Bread by Fortification with Free and Microencapsulated Powders from Amelanchier alnifolia Nutt

This study established the appropriate amounts of a functional Saskatoon berry fruit powder in fortified rye bread acceptable to consumers and determined the potential relative bioaccesibility of bioactive compounds exhibiting antioxidant activity, and enzymatic in vitro inhibitory activity against lipoxygenase, cyclooxigenase-1, cyclooxigenase-2, acetylcholinesterase, pancreatic lipase α-glucosidase, and α-amylase, as well as the relative digestibility of nutrients. The content of polyphenolic compounds and antioxidant capability were strongly, positively correlated with the content of the functional additive. The highest phenolics content and antioxidant activity were determined in the products enriched with the powders microencapsulated with maltodextrin (an increase by 91% and 53%, respectively, compared with the control). The highest overall acceptability was shown for the products with 3% addition of the functional additive, regardless of its type. The simulated in vitro digestion released phenols (with the highest bioaccessibility shown for anthocyanins) and enhanced the antioxidant activity of rye bread. In turn, the microencapsulation contributed to the improvement in the relative bioaccesibility of antioxidant compounds. Bread fortification led to an increased inhibitory activity against α-amylase, α-glucosidase, and lipoxygenase. Furthermore, the additive microencapsulated with maltodextrin and inulin improved the capacity to inhibit the activities of pancreatic lipase and cyclooxigenase-2. The results presented allowed concluding that the powders from Saskatoon berry fruits, especially microencapsulated ones, may be a promising functional additive dedicated for the enrichment of rye bread.

Starch Digestion Enhances Bioaccessibility of Anti-Inflammatory Polyphenols from Borlotti Beans (Phaseolus vulgaris)

The consumption of beans has been associated with chronic disease prevention which may be attributed to the polyphenols present in the seed coat and endosperm. However, their bioaccessibility is likely to be limited by interactions with bean matrix components, including starch, protein and fibre. The aim of this project was to evaluate the effect of domestic processing and enzymatic digestion on the bioaccessibility of polyphenols from Borlotti beans (Phaseolus vulgaris) and to test their anti-inflammatory properties in a macrophage cell model. In vitro digestion of cooked beans released twenty times more polyphenols (40.4 ± 2.5 mg gallic acid equivalents (GAE)/g) than domestic processing (2.22 ± 0.1 mg GAE/g), with starch digestion contributing to the highest release (30.9 ± 0.75 mg GAE/g). Fluorescence microscopy visualization of isolated bean starch suggests that polyphenols are embedded within the granule structure. LC-MS analysis showed that cooked Borlotti bean contain flavonoids, flavones and hydroxycinnamic acids, and cooked bean extracts exerted moderate anti-inflammatory effects by decreasing mRNA levels of IL1β and iNOS by 25% and 40%, respectively. In conclusion, the bioaccessibility of bean polyphenols is strongly enhanced by starch digestion. These polyphenols may contribute to the health benefits associated with bean consumption.

Liquid state fermentation vinegar enriched with catechin as an antiglycative food product

Catechin, a natural antiglycative agent, was incorporated into fermented vinegar, and has high potential to lower the risk of diabetes. In this study, vinegar containing 5% catechin as a substrate for acetous fermentation significantly inhibited the formation of total fluorescent advanced glycation end-products (AGEs), as well as N^ε-(carboxymethyl)lysine (CML)/N^ε-(carboxyethyl)lysine (CEL), especially when added during acetic fermentation. Further study proved that catechin could not only significantly suppress the increase of blood glucose levels, but also inhibit α-amylase, α-glucosidase and β-glucosidase strongly with IC₅₀ values of 0.533 mg mL^-1, 0.307 mg mL^-1 and 0.413 mg mL^-1, respectively. Moreover, 32 volatile compounds were finally identified by headspace solid phase microextraction gas chromatography-mass spectrometry (HSPM-GC-MS) and electronic nose. The flavor of the catechin-vinegars, which possess relatively high ester and low acid contents, was superior to that of traditional vinegar. Therefore, it was helpful to use catechin as a functional food ingredient in vinegar to prevent AGE-associated diseases and alleviate postprandial hyperglycemia, through limiting the digestion of starch and inhibiting the uptake of glucose. Meanwhile, the pleasant flavor and safety of catechin-vinegar were better than traditional vinegar, which represents prominent value to attract consumers.

Starch digested product analysis by HPAEC reveals structural specificity of flavonoids in the inhibition of mammalian α-amylase and α-glucosidases

An accurate high-performance anion-exchange chromatography (HPAEC) method is presented to measure the inhibition property of flavonoids against mammalian starch digestive enzymes, because flavonoids interfere with commonly used 3,5-dinitrosalicylic acid (DNS) and glucose oxidase/peroxidase (GOPOD) methods. Eriodictyol, luteolin, and quercetin increased absorbance values (without substrate) in the DNS assay and, with substrate, either overestimated or underestimated values in the DNS and GOPOD assays. Using a direct HPAEC measurement method, flavonoids showed different inhibition properties against α-amylase and α-glucosidases, showing different inhibition constants (K_i) and mechanisms. The double bond between C2 and C3 on the C-ring of flavonoids appeared particularly important to inhibit α-amylase, while the hydroxyl group (OH) at C3 of the C-ring was related to inhibition of α-glucosidases. This study shows that direct measurement of starch digestion products by HPAEC should be used in inhibition studies, and provides insights into structure-function aspects of polyphenols in controlling starch digestion rate.

Monkey orange fruit juice improves the nutritional quality of a maize-based diet

This paper studied the nutritional impact of the use of juice from Strychnos cocculoides (monkey orange) in a maize-based porridge. Monkey orange juice is traditionally used to supplement maize porridge - a staple breakfast cereal especially for vulnerable groups. Monkey orange fruits contain high amounts of micronutrients and phenolic compounds and are widely distributed throughout sub-Saharan Africa. The valuable components can be efficiently extracted by traditional and pectinase maceration techniques. The bioaccessibility of minerals and main phenolic compounds in maize porridge (5 g maize meal) supplemented by monkey orange juice (100 ml) were assessed after in-vitro digestion together with the kinetics of starch degradation. Caffeic and protocatechuic acids exceeded 100%, and chlorogenic acid 81% bioaccessibility after simulated intestinal digestion. Rutin was undetected after the simulated intestinal phase due to precipitation in the pellet. In-vitro bioaccessibility of minerals ranged from 12 to 62% in monkey orange enriched porridge. A 50-70% decrease of starch hydrolysis was observed at the end of the simulated intestinal digestion of monkey orange maize porridge confirming the known potential of phenolic compounds to decrease the glycaemic index of starch-rich foods. Consequently monkey orange juice appeared a suitable ingredient to enrich staple maize porridge thanks to its micronutrients and health benefit potential. Similar relationships of other fruits and starchy foods warrant study as a means to improve the nutritional quality of the diets of malnourished populations.

Mechanism of binding interactions between young apple polyphenols and porcine pancreatic α-amylase

The binding interactions between young apple polyphenols and porcine pancreatic α-amylase were investigated through isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) and molecular docking. The results obtained were compared with those obtained through inhibition kinetics and fluorescence quenching. It was found that binding of tannic acid, chlorogenic acid, caffeic acid and epicatechin with α-amylase is an exothermal process, with the binding constants in the order of tannic acid > chlorogenic acid > caffeic acid > epicatechin. This is consistent with the orders of reciprocal of competitive inhibition constant and fluorescence quenching constant. The binding energy obtained through molecular docking showed the same order, except for epicatechin. These results are consistent with the inhibition of α-amylase being caused by the binding of the polyphenols with the enzyme. In addition, from the fluorescence quenching and DSC data, total polyphenols, tannic acid, chlorogenic acid and caffeic acid were found to partially unfold the enzyme structure.

Potato product form impacts in vitro starch digestibility and glucose transport but only modestly impacts 24 h blood glucose response in humans

Potatoes are rich in phenolic compounds which have been reported to impact starch digestion and intestinal glucose transport in model systems through phenolic–starch interactions.

Chlorogenic and phenolic acids are only very weak inhibitors of human salivary α-amylase and rat intestinal maltase activities

There is increasing evidence that consumption of polyphenol and phenolic-rich foods and beverages have the potential to reduce the risk of developing diabetes type 2, with coffee a dominant example according to epidemiological evidence. One of the proposed mechanisms of action is the inhibition of carbohydrate-digesting enzymes leading to attenuated post-prandial blood glucose concentrations, as exemplified by the anti-diabetic drug, acarbose. We determined if the phenolic, 5-caffeoylquinic acid, present in coffee, apples, potatoes, artichokes and prunes, for example, and also selected free phenolic acids (ferulic acid, caffeic acid and 3,4-dimethoxycinnamic acid), could inhibit human salivary α-amylase and rat intestinal maltase activities, digestive enzymes involved in the degradation of starch and malto-oligosaccharides. Using validated assays, we show that phenolic acids, both free and linked to quinic acid, are poor inhibitors of these enzymes, despite several publications that claim otherwise. 5-CQA inhibited human α-amylase only by <20% at 5 mM, with even less inhibition of rat intestinal maltase. The most effective inhibition was with 3,4-dimethoxycinnamic acid (plateau at maximum 32% inhibition of human α-amylase at 0.6 mM), but this compound is found in coffee in the free form only at very low concentrations. Espresso coffee contains the highest levels of 5-CQA among all commonly consumed foods and beverages with a typical concentration of ~5 mM, and much lower levels of free phenolic acids. We therefore conclude that inhibition of carbohydrate-digesting enzymes by chlorogenic or phenolic acids from any food or beverage is unlikely to be sufficient to modify post-prandial glycaemia, and so is unlikely to be the mechanism by which chlorogenic acid-rich foods and beverages such as coffee can reduce the risk of developing type 2 diabetes.

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Chlorogenic and phenolic acids weakly inhibit human α-amylase activity.

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Chlorogenic acids weakly inhibit rat maltase activity.

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Free phenolic acids exhibit no inhibition of rat maltase activity.

Smilax aristolochiifolia Root Extract and Its Compounds Chlorogenic Acid and Astilbin Inhibit the Activity of α-Amylase and α-Glucosidase Enzymes

Regulating activities of α-amylase and α-glucosidase through the use of specific inhibitors is a main strategy for controlling type 2 diabetes. Smilax aristolochiifolia root decoctions are traditionally used in Mexico as hypoglycemic and for weight loss, but the active principles and mechanisms underlying such putative metabolic effects are yet unknown. Here, we isolated the major bioactive compounds from a hydroethanolic extract of S. aristolochiifolia root by fast centrifugal partition chromatography and evaluated their effects against pancreatic α-amylase and yeast α-glucosidase. A chlorogenic acid-rich fraction (CAF) inhibited α-amylase activity with an IC₅₀ value of 59.28 μg/mL in an uncompetitive manner and α-glucosidase activity with an IC₅₀ value of 9.27 μg/mL in a noncompetitive mode. Also, an astilbin-rich fraction (ABF) inhibited α-glucosidase activity with an IC₅₀ value of 12.30 μg/mL, in a noncompetitive manner. CAF inhibition α-amylase was as active as acarbose while both CAF and ABF were 50-fold more potent inhibitors of α-glucosidase than acarbose. The molecular docking results of chlorogenic acid and astilbin with α-amylase and α-glucosidase enzymes correlated with the inhibition mechanisms suggested by enzymatic assays. Our results prove that S. aristolochiifolia roots contain chlorogenic acid and astilbin, which inhibit carbohydrates-hydrolyzing enzymes, suggesting a new mechanism for the hypoglycemic effect reported for this plant.

Bioactive Compounds, Nutritional Traits, and Antioxidant Properties of Artocarpus altilis (Parkinson) Fruits: Exploiting a Potential Functional Food for Food Security on the Comoros Islands

Comoros Union presents a considerable biodiversity of food resources that are neglected or still not valorised, as breadfruit. This study aimed to evaluating nutritional and nutraceutical traits of Artocarpus altilis (Parkinson) Fosberg by characterizing its main bioactive compounds, nutritional traits, and antioxidant properties in order to contribute to the development of traditional and innovative uses of this species as functional food (e.g., infant flour). Bioactive compound composition, antioxidant properties, protein and sugar content, lipids, fibre, and macro- and microelements were observed in these fruits after a specific drying process. Breadfruit showed positive nutritional traits. The main identified phenolic groups were cinnamic acids (with a maximum of 51.88 ± 2.63 mg/100 gDW for chlorogenic acid) and tannins. The highest value of antioxidant activity was 6.40 ± 1.02 mmol·Fe2+/kgDW. This preliminary phytochemical investigation may provide a contribution to the identification and quantification of lead compounds responsible for traditional nutritional and therapeutic claims.

Persimmon Tannin Decreased the Glycemic Response through Decreasing the Digestibility of Starch and Inhibiting α-Amylase, α-Glucosidase, and Intestinal Glucose Uptake

Regulation of postprandial blood glucose levels is an effective therapeutic proposal for type 2 diabetes treatment. In this study, the effect of persimmon tannin on starch digestion with different amylose levels was investigated both in vitro and in vivo. Oral administration of persimmon tannin-starch complexes significantly suppressed the increase of blood glucose levels and the area under the curve (AUC) in a dose-dependent manner compared with starch treatment alone in an in vivo rat model. Further study proved that persimmon tannin could not only interact with starch directly but also inhibit α-amylase and α-glucosidase strongly, with IC₅₀ values of 0.35 and 0.24 mg/mL, separately. In addition, 20 μg/mL of persimmon tannin significantly decreased glucose uptake and transport in Caco-2 cells model. Overall, our data suggested that persimmon tannin may alleviate postprandial hyperglycemia through limiting the digestion of starch as well as inhibiting the uptake and transport of glucose.