The antioxidant property and α-amylase inhibition activity of young apple polyphenols are related with apple varieties

Structural characteristics of lotus seed starch-chlorogenic acid complexes during dynamic in vitro digestion and prebiotic activities

The functional properties of starch-polyphenol complexes closely related to the digestion process. Here, dynamic in vitro digestion properties and prebiotic activities of lotus seed starch-chlorogenic acid complexes under autoclaving treatment (A-LS-CA) were investigated. The results showed that the ordered structure, thermal stability and molecular weight of the A-LS-CA complexes significantly altered during dynamic in vitro digestion. Remarkably, the ordered structure of digestive products significantly decreased in oral-gastric phase, while the ordered structure was increased in oral-gastric-small intestinal phase. The molecular weight of A-LS-CA complexes decreased gradually in oral, oral-gastric and oral-gastric-small intestinal phase, which were 7.40 ± 0.57, 2.23 ± 0.98 and 0.46 ± 0.10 × 107 g/mol, respectively. In addition, chlorogenic acid was attached to the surface of starch by hydrogen bonding during dynamic in vitro digestion, improving the bioavailability of chlorogenic acid. Interestingly, the dynamically digested A-LS-CA complexes stimulated the proliferation of Bifidobacterium longum subsp. infantis, Bifidobacterium adolescentis, Lacticaseibacillus rhamnosus and Lacticaseibacillus casei, and promoted to produce acetic acid, which was 1.07-1.49 folds that of the controls. In summary, this study provided a new insight for the structural and functional properties of starch-polyphenol complexes.

The inhibitory effects of free and bound phenolics from Phyllanthus emblica Linn. on α-amylase: a comparison study

BACKGROUND

Phyllanthus emblica Linn. (PE) is rich in polyphenols, which can be categorized into free and bound phenolics (PEFP and PEBP). This study evaluated the inhibitory effect of PEFB and PEBP on α-amylase for the first time. The mechanism of the inhibition effect of PEFP and PEBP on α-amylase was investigated by enzyme inhibition kinetics, multispectral analysis, thermodynamics, and molecular docking.

RESULTS

Free and bound phenolics inhibited α-amylase activity effectively in a mixed type of inhibition. Fluorescence quenching and thermodynamic analyses showed that the binding of PEFP and PEBP to α-amylase occurred through a static quenching process (Kq = 6.94 × 10¹² and 5.74 × 10¹² L mol-1 s-1), which was accompanied by a redshift (λem from 343 to 347 nm), leading to a change in the microenvironment. This process was found to be a spontaneous exothermic reaction (ΔG < 0). Circular dichroism (CD) analysis confirms that the secondary structure of α-amylase was altered, in particular a decrease in α-helixes and an increase in random coils. Molecular docking studies showed that PEFP and PEBP interacted with α-amylase through hydrogen bonding and hydrophobic interactions.

CONCLUSION

The present study provides valuable insights into the mechanism of action of PEFP and PEBP on α-amylase, which will provide a theoretical basis for their possible use as novel natural α-amylase inhibitors. © 2024 Society of Chemical Industry.

The Heating Under Micro Variable Pressure (HUMVP) Process to Decrease the Level of Saponin in Quinoa: Evidence of the Antioxidation and the Inhibitory Activity of α-Amylase and α-Glucosidase

To reduce the level of saponin while preserving essential nutrients and antioxidative properties in quinoa (Chenopodium quinoa), this study delves into the optimization of the HUMVP process and thoroughly examines its effects on antioxidation as well as its inhibitory influence on α-amylase and α-glucosidase. The optimal HUMVP conditions involved wetting quinoa grains with 6% water (pH = 6.0) and subjecting them to a 4 min treatment under 0.35 MPa pressure. The values of •OH, DPPH, and ABTS•+ scavenging rate of the extracts from the quinoa sample (named Q2HUMVP) treated under the optimum HUMVP process were 70.02, 87.13, and 50.95%, respectively. Furthermore, the treatment preserved 95.20% of polyphenols and 73.06% of flavonoids, while the saponin content was reduced to 23.13% of that in raw quinoa. Notably, Q2HUMVP extracts demonstrated superior inhibitory activity against α-amylase and α-glucosidase compared to dehulled quinoa samples. The inhibition exhibited by the quinoa sample extracts on α-amylase and α-glucosidase was found to be reversible.

Interactions between corn starch and lingonberry polyphenols and their effects on starch digestion and glucose transport

This study investigated the interaction mechanism between corn starch (CS) and lingonberry polyphenols (LBP) during starch gelatinization, focusing on their effects on starch structure and physicochemical properties. Moreover, it explored the effect of this interaction on starch digestion and glucose transport. The results indicated that LBP interacted non-covalently with CS during starch gelatinization, disrupted the short-range ordered structure of starch, decreased gelatinization enthalpy of starch, and formed a dense network structure. Furthermore, the incorporation of LBP remarkably reduced the digestibility of CS. In particular, the addition of 10 % LBP decreased the terminal digestibility (C∞) from 77.87 % to 60.43 % and increased the amount of resistant starch (RS) by 21.63 %. LBP was found to inhibit α-amylase and α-glucosidase in a mixed manner. Additionally, LBP inhibited glucose transport in Caco-2 cells following starch digestion. When 10 % LBP was added, there was a 34.17 % decrease in glucose transport compared with starch digestion without LBP. This study helps establish the foundation for the development of LBP-containing starch or starch-based healthy foods and provides new insights into the mechanism by which LBP lowers blood glucose.

The Behavior of Phenolic Compounds from Apples during Simulated Gastrointestinal Digestion with Focus on Chlorogenic Acid

The fate of phenolic compounds during digestion is important for their bioactive effects in the digestive tract. The aim was to study the various phenolic compounds occurring in the peel and flesh of apples in in vitro simulated gastrointestinal digestion, focusing on the behavior of chlorogenic acids. Additionally, the behavior of individual chlorogenic acids (chlorogenic, neochlorogenic, and cryptochlorogenic) was studied in models of simulated salivary, gastric, and intestinal fluid electrolyte solutions (SSF, SGF, SIF). At the end of the intestinal phase of the digestion of peel and flesh, the amount of recovered dihydrochalcones and flavonols increased or was similar to the amount in the gastric phase, which showed their stability. Anthocyanins and flavan-3-ols decreased, which suggests their biotransformation. Chlorogenic acid isomerized into neochlorogenic and cryptochlorogenic acid: chlorogenic acid from the peel into 22% and 41% of the isomers in the salivary and intestinal phases, respectively; chlorogenic acid from the flesh into 12% of the isomers in the intestinal phase. Similarly, chlorogenic acid isomerized in model solutions (20% and 26% of the isomers in SSF and SIF, respectively). Neochlorogenic and cryptochlorogenic acid isomerized in SSF and SIF into other two forms. They were all stable in SGF. For bioactive effects in the digestive tract, the biotransformation of chlorogenic acids should be considered.

In vitro inhibitory effect of five natural sweeteners on α-glucosidase and α-amylase

A promising and efficacious approach to manage diabetes is inhibiting α-glucosidase and α-amylase activity. Therefore, the inhibitory activities of five natural sweeteners (mogrosides (Mog), stevioside (Ste), glycyrrhizinic acid (GA), crude trilobatin (CT), and crude rubusoside (CR)) against α-glucosidase and α-amylase and their interactions were evaluated in vitro using enzyme kinetics, fluorescence spectroscopy, Fourier infrared spectroscopy, and molecular docking. The inhibitor sequence was CT > GA > Ste, as GA competitively inhibited α-glycosidase activity while CT and Ste exhibited mixed inhibitory effects. Compared to a positive control acarbose, the inhibitory activity of CT was higher. For α-amylase, the mixed inhibitors CT, CR, and Mog and the competitive inhibitor Ste effectively inhibited the enzyme, with the following order: CT > CR > Ste > Mog; nevertheless, the inhibitors were slightly inferior to acarbose. Three-dimensional fluorescence spectra depicted that GA, CT, and CR bound to the hydrophobic cavity of α-glucosidase or α-amylase and changed the polarity of the hydrophobic amino acid-based microenvironment and structure of the polypeptide chain backbone. Infrared spectroscopy revealed that GA, CT, and CR could disrupt the secondary structure of α-glucosidase or α-amylase, which decreased enzyme activity. GA, trilobatin and rubusoside bound to amino acid residues through hydrogen bonds and hydrophobic interactions, changing the conformation of enzyme molecules to decrease the enzymatic activity. Thus, CT, CR and GA exhibit promising inhibitory effects against α-glucosidase and α-amylase.

Phenolic Compounds from Apples: From Natural Fruits to the Beneficial Effects in the Digestive System

Conditions in the gastrointestinal tract and microbial metabolism lead to biotransformation of parent, native phenolic compounds from apples into different chemical forms. The aim of this work was to review current knowledge about the forms of phenolic compounds from apples in the gastrointestinal tract and to connect it to their potential beneficial effects, including the mitigation of health problems of the digestive tract. Phenolic compounds from apples are found in the gastrointestinal tract in a variety of forms: native (flavan-3-ols, phenolic acids, flavonols, dihydrochalcones, and anthocyanins), degradation products, various metabolites, and catabolites. Native forms can show beneficial effects in the stomach and small intestine and during the beginning phase of digestion in the colon. Different products of degradation and phase II metabolites can be found in the small intestine and colon, while catabolites might be important for bioactivities in the colon. Most studies connect beneficial effects for different described health problems to the whole apple or to the amount of all phenolic compounds from apples. This expresses the influence of all native polyphenols from apples on beneficial effects. However, further studies of the peculiar compounds resulting from native phenols and their effects on the various parts of the digestive tract could provide a better understanding of the specific derivatives with bioactivity in humans.

Beneficial effects of phenolic compounds: native phenolic compounds vs metabolites and catabolites

In the human body, the positive effects of phenolic compounds are increasingly observed through their presence in tissues and organs in their native form or in the form of metabolites or catabolites formed during digestion, microbial metabolism, and host biotransformation. The full extent of these effects is still unclear. The aim of this paper is to review the current knowledge of beneficial effects of native phenolic compounds or their metabolites and catabolites focusing on their role in the health of the digestive system, including disorders of the gastrointestinal and urinary tracts and liver. Studies are mostly connecting beneficial effects in the gastrointestinal and urinary tract to the whole food rich in phenolics, or to the amount of phenolic compounds/antioxidants in food. Indeed, the bioactivity of parent phenolic compounds should not be ignored due to their presence in the digestive tract, and the impact on the gut microbiota. However, the influence of their metabolites and catabolites might be more important for the liver and urinary tract. Distinguishing between the effects of parent phenolics vs metabolites and catabolites at the site of action are important for novel areas of food industry, nutrition and medicine.

Functional components profile and glycemic index of kidney beans

Low glycemic index (GI) diet has been considered as a strategy for type II diabetes patients. In the present study, the phenolics profile, α-amylase inhibitor activities, starch composition as well as the glycemic index of seven varieties of kidney beans were studied. An enzymatic inhibitory reaction model was employed to determine the α-amylase inhibitor activity, and the in vitro digestion model coupled with the 3, 5-dinitrosalicylic acid colorimetry method was adopted to evaluate the starch composition and glycemic index. The results showed that gallic acid was dominant in kidney beans, and the colored beans contained more phenolics than the white ones. In addition, the α-amylase inhibitor activities of kidney beans ranged from 1.659 ± 0.050 to 4.162 ± 0.049 U/g DW, among which the Y2 variety was the top-ranked. Furthermore, kidney beans starch demonstrated brilliant resistance to digestion with the contribution of resistant starch to total starch between 70.90 ± 0.39% and 83.12 ± 0.42%. Eventually, these kidney beans were categorized as low GI foods, which ranged from 32.47 ± 0.13 to 52.99 ± 0.56, the resistant starch makes dominant contribution to the low GI. These results indicate that kidney beans can be served as ingredients in functional low GI foods.

Phytochemical Properties and In Vitro Biological Activities of Phenolic Compounds from Flower of Clitoria ternatea L

Phenolic compounds from the flower of Clitoria ternatea L. (PCFCTL) were extracted using a high-speed shearing extraction technique and purified by AB-8 macroporous resins, and the phytochemical composition of the purified phenolic compounds from the flower of Clitoria ternatea L. (PPCFCTL) was then analyzed. Subsequently, its bioactivities including antioxidant properties, enzyme inhibitory activities, and antiproliferative activities against several tumor cell lines were evaluated. Results indicated that the contents of total phenolics, flavonoids, flavonols, flavanols, and phenolic acids in PPCFCTL were increased by 3.29, 4.11, 2.74, 2.43, and 2.96-fold, respectively, compared with those before being purified by AB-8 macroporous resins. The results showed PPCFCTL have significant antioxidant ability (measured by reducing power, RP, and ferric reducing antioxidant power method, FRAP) and good DPPH, ABTS+, and superoxide anion radical scavenging activities. They can also significantly inhibit lipase, α-amylase, and α-glucosidase. In addition, morphological changes of HeLa, HepG2, and NCI-H460 tumor cells demonstrated the superior antitumor performance of PPCFCTL. However, the acetylcholinesterase inhibitory activity was relatively weak. These findings suggest that PPCFCTL have important potential as natural antioxidant, antilipidemic, anti-glycemic and antineoplastic agents in health-promoting foods.

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.

"An apple a day keeps the doctor away": The potentials of apple bioactive constituents for chronic disease prevention

Apples are rich sources of selected micronutrients (e.g., iron, zinc, vitamins C and E) and polyphenols (e.g., procyanidins, phloridzin, 5′‐caffeoylquinic acid) that can help in mitigating micronutrient deficiencies (MNDs) and chronic diseases. This review provides an up‐to‐date overview of the significant bioactive compounds in apples together with their reported pharmacological actions against chronic diseases such as diabetes, cancer, and cardiovascular diseases. For consumers to fully gain these health benefits, it is important to ensure an all‐year‐round supply of highly nutritious and good‐quality apples. Therefore, after harvest, the physicochemical and nutritional quality attributes of apples are maintained by applying various postharvest treatments and hurdle techniques. The impact of these postharvest practices on the safety of apples during storage is also highlighted. This review emphasizes that advancements in postharvest management strategies that extend the storage life of apples should be optimized to better preserve the bioactive components crucial to daily dietary needs and this can help improve the overall health of consumers.

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.

Antioxidant Activity and Discrimination of Organic Apples (Malus domestica Borkh.) Cultivated in the Western Region of Romania: A DPPH· Kinetics-PCA Approach

Apple (Malus domestica Borkh.) is one of the most used fruit for beverages in Romania. The goal of the study was to evaluate the antioxidant activity and discrimination of various parts of organic and non-organic apple varieties cultivated in the western region of Romania using the DPPH· kinetics–PCA (principal component analysis) approach. Organic and non-organic apples were subjected to solid–liquid ethanol extraction. Core and shell extracts were mixed with DPPH· and spectrophotometrically monitored at 517 nm. Antioxidant activity and mean DPPH· reaction rate at various time ranges reveal significant differences between organic and non-organic samples, as well as apple parts. Organic core and shell extracts had higher antioxidant activities than the corresponding non-organic samples (74.5–96.9% and 61.9–97.2%, respectively, 23.5–94.3% and 59.5–95.5%). Significant differences were observed for the DPPH· reaction rate for the first ½ min, especially in the presence of organic core extracts (3.7–4.8 μM/s). The organic samples were well discriminated by DPPH· kinetics–PCA, the most important variables being the DPPH· reaction rate for the first time range. This is the first DPPH· kinetics–PCA approach applied for discriminating between organic and non-organic fruits and can be useful for evaluating the quality of such type of fruits.

Phenolic Profiling of Five Different Australian Grown Apples

Apples (Malus domestica) are one of the most widely grown and consumed fruits in the world that contain abundant phenolic compounds that possess remarkable antioxidant potential. The current study characterised phenolic compounds from five different varieties of Australian grown apples (Royal Gala, Pink Lady, Red Delicious, Fuji and Smitten) using LC-ESI-QTOF-MS/MS and quantified through HPLC-PDA. The phenolic content and antioxidant potential were determined using various assays. Red Delicious had the highest total phenolic (121.78 ± 3.45 mg/g fw) and total flavonoid content (101.23 ± 3.75 mg/g fw) among the five apple samples. In LC-ESI-QTOF-MS/MS analysis, a total of 97 different phenolic compounds were characterised in five apple samples, including Royal Gala (37), Pink Lady (54), Red Delicious (17), Fuji (67) and Smitten (46). In the HPLC quantification, phenolic acid (chlorogenic acid, 15.69 ± 0.09 mg/g fw) and flavonoid (quercetin, 18.96 ± 0.08 mg/g fw) were most abundant in Royal Gala. The obtained results highlight the importance of Australian apple varieties as a rich source of functional compounds with potential bioactivity.

Systematic Review of Phenolic Compounds in Apple Fruits: Compositions, Distribution, Absorption, Metabolism, and Processing Stability

As the most widely consumed fruit in the world, apple (Malus domestica Borkh.) fruits provide a high level of phenolics and have many beneficial effects on human health. The composition and content of phenolic compounds in natural apples differs according to the tissue types and cultivar varieties. The bioavailability of apple-derived phenolics, depending on the absorption and metabolism of phenolics during digestion, is the key determinant of their positive biological effects. Meanwhile, various processing technologies affect the composition and content of phenolic compounds in apple products, further affecting the bioavailability of apple phenolics. This review summarizes current understanding on the compositions, distribution, absorption, and metabolism of phenolic compounds in apple and their stability when subjected to common technologies during processing. We intend to provide an updated overview on apple phenolics and also suggest some perspectives for future research of apple phenolics.

Traditional, Indigenous Apple Varieties, a Fruit with Potential for Beneficial Effects: Their Quality Traits and Bioactive Polyphenol Contents

Earlier studies suggested that traditional apple varieties have quality traits well accepted by consumers and beneficial effects on human health. The aim was to collect 25 traditional apple varieties grown in Croatia and to determine, for the first time in so many details, their external (weight, height, width, shape, color), internal quality traits (firmness, starch decomposition index, maturity index, soluble solid concentration, total acids, soluble solid/total acids ratio, pH), and seed characteristics. In addition, individual polyphenols were determined in the flesh and peel, by using RP-HPLC. All was compared to the commercial variety ‘Idared’. Quality parameters of these varieties were similar to those of the commercial variety. The flesh and peel contained flavan-3-ols, dihydrochalcones, phenolic acids, and flavonols, while anthocyanins were additionally found in the peel. Total polyphenols in the peel (536–3801 mg kg⁻¹ fresh weight (FW)) and in the flesh (79–1294 mg kg⁻¹ FW) of the majority of varieties were higher than in the commercial variety. Principal component analysis showed possible clustering according to polyphenol amounts. According to the observed diversity of quality traits and bioactive polyphenol contents, the traditional varieties have potential for consumer acceptance and increased cultivation.