Bioassay-Based Isolation and Identification of Phenolics from Sweet Cherry That Promote Active Glucose Consumption by HepG2 Cells

A Prunus avium L. Infusion Inhibits Sugar Uptake and Counteracts Oxidative Stress-Induced Stimulation of Glucose Uptake by Intestinal Epithelial (Caco-2) Cells

Sweet cherry (Prunus avium L.) is among the most valued fruits due to its organoleptic properties and nutritional worth. Cherry stems are rich in bioactive compounds, known for their anti-inflammatory and antioxidant properties. Innumerable studies have indicated that some bioactive compounds can modulate sugar absorption in the small intestine. In this study, the phenolic profile of a cherry stem infusion was investigated, as well as its capacity to modulate intestinal glucose and fructose transport in Caco-2 cells. Long-term (24 h) exposure to cherry stem infusion (25%, v/v) significantly reduced glucose (3H-DG) and fructose (14C-FRU) apical uptake, reduced the apical-to-basolateral Papp to 3H-DG, and decreased mRNA expression levels of the sugar transporters SGLT1, GLUT2 and GLUT5. Oxidative stress (induced by tert-butyl hydroperoxide) caused an increase in 3H-DG uptake, which was abolished by the cherry stem infusion. These findings suggest that cherry stem infusion can reduce the intestinal absorption of both glucose and fructose by decreasing the gene expression of their membrane transporters. Moreover, this infusion also appears to be able to counteract the stimulatory effect of oxidative stress upon glucose intestinal uptake. Therefore, it can be a potentially useful compound for controlling hyperglycemia, especially in the presence of increased intestinal oxidative stress levels.

Global Plus Local Jointly Regularized Support Vector Data Description for Novelty Detection

In many practice application, the cost for acquiring abnormal data is quite expensive, thus the one-class classification (OCC) problem attracts great attention. As one of the solutions, support vector data description (SVDD) gains a continuous focus in outlier detection since it is based on the data description. For the sphere obtained by SVDD, both the center and the volume (or radius) strongly depend on the support vectors, while the support vectors are sensitive to the tradeoff parameter C . Hence, how to select this parameter is a rather challenging problem. In order to address this problem, we define several distance metrics relative to the image region in Gaussian kernel space. With the distance metrics, two probability densities relative to the global region and the local region are designed, respectively. Then, the information quantity and the information entropy are developed for regularizing the tradeoff parameter. This novel SVDD is called global plus local jointly regularized support vector data description (GL-SVDD), in which both the global region information and the local image region information jointly penalize the images as possible outliers. Finally, we use the UCI dataset and the hyperspectral data of cherry fruit to evaluate the performance of several OCC approaches. Experimental results show that GL-SVDD is encouraging.

Quercetin: A Molecule of Great Biochemical and Clinical Value and Its Beneficial Effect on Diabetes and Cancer

Quercetin belongs to the broader category of polyphenols. It is found, in particular, among the flavonols, and along with kaempferol, myricetin and isorhamnetin, it is recognized as a foreign substance after ingestion in contrast to vitamins. Quercetin occurs mainly linked to sugars with the most common compounds being quercetin-3-O-glucoside or as an aglycone, especially in the plant population. The aim of this review is to present a recent bibliography on the mechanisms of quercetin absorption and metabolism, bioavailability, and antioxidant and the clinical effects in diabetes and cancer. The literature reports a positive effect of quercetin on oxidative stress, cancer, and the regulation of blood sugar levels. Moreover, research-administered drug dosages of up to 2000 mg per day showed mild to no symptoms of overdose. It should be noted that quercetin is no longer considered a carcinogenic substance. The daily intake of quercetin in the diet ranges 10 mg-500 mg, depending on the type of products consumed. This review highlights that quercetin is a valuable dietary antioxidant, although a specific daily recommended intake for this substance has not yet been determined and further studies are required to decide a beneficial concentration threshold.

Cherries and Blueberries-Based Beverages: Functional Foods with Antidiabetic and Immune Booster Properties

Nowadays, it is largely accepted that the daily intake of fruits, vegetables, herbal products and derivatives is an added value in promoting human health, given their capacity to counteract oxidative stress markers and suppress uncontrolled pro-inflammatory responses. Given that, natural-based products seem to be a promising strategy to attenuate, or even mitigate, the development of chronic diseases, such as diabetes, and to boost the immune system. Among fruits, cherries and blueberries are nutrient-dense fruits that have been a target of many studies and interest given their richness in phenolic compounds and notable biological potential. In fact, research has already demonstrated that these fruits can be considered functional foods, and hence, their use in functional beverages, whose popularity is increasing worldwide, is not surprising and seem to be a promising and useful strategy. Therefore, the present review reinforces the idea that cherries and blueberries can be incorporated into new pharmaceutical products, smart foods, functional beverages, and nutraceuticals and be effective in preventing and/or treating diseases mediated by inflammatory mediators, reactive species, and free radicals.

Prunus avium L. (Sweet Cherry) By-Products: A Source of Phenolic Compounds with Antioxidant and Anti-Hyperglycemic Properties—A Review

Prunus avium L. (sweet cherry) is one of the most appreciated fruit due to its organoleptic and nutritional value. Interestingly, cherry leaves, stems, and flowers are agri-food by-products rich in bioactive compounds that are mostly still unexploited. Stems and leaves have been used in folk medicine since ancient times. Recently, cherry flowers have also proved to be an interesting source of compounds with therapeutic properties. Phenolic compounds, namely hydroxycinnamic acids and flavonoids, are the most present phytochemicals in P. avium fruits and their by-products. These compounds have shown a good antioxidant potential to prevent oxidative stress-related diseases and glycemic control, fundamental in preventing and controlling diabetes mellitus. The present review summarizes the main phenolics found in P. avium stems, leaves, and flowers as compared to their fruits and describes their antioxidant and anti-hyperglycemic properties. Thus, these by-products are an accessible and low-cost source of bioactive constituents with interesting health-promoting properties, making their use promising in diabetes therapy.

Fruit quality trait discovery and metabolic profiling in sweet cherry genebank collection in Greece

The current study characterizes the physicochemical, sensory and bioactive compound traits of twenty-two sweet cherry accessions, namely breeding lines, landraces and modern cultivars, embodying the majority of Greek germplasm. The evaluated accessions differ in several quality traits including colour parameters and textural properties as well as sensory attributes, such as taste intensity and overall acceptance. Significant differences in primary metabolites, including fructose, glucose, sorbitol, malic acid were recorded among tested accessions. All genotypes were rich in polyphenols, primarily in quercetin-3,4-O-diglucoside, esculetin, rutin and neochlorogenic acid. An anthocyanins-related discrimination among accessions was also obtained based on cyanidin-3-O-rutinoside and peonidin glycosides content. Overall, the cultivars 'Tsolakeika' and 'Bakirtzeika' exhibited the higher consumer acceptance while the cultivars 'Vasiliadi' and 'Tragana Edessis-Naousis' and especially the breeding line 'TxAg33' contained high polyphenol levels. These results represent a valuable resource for future breeding efforts for sweet cherry cultivars with improved nutritional quality traits.

Novel insights in health-promoting properties of sweet cherries

Sweet cherry (Prunus avium L.) is one of the most popular and appreciated temperate fruit not only for its sensory and nutritional properties, but also for its content in bioactive compounds. Consumption of sweet cherries brings beneficial effects on to health, which include prevention and modulatory effects in several chronic diseases such as (diabetes mellitus, cancer, cardiovascular and other inflammatory diseases). The presence of natural polyphenolic compounds with high antioxidant potential might drive and partly explain such beneficial effects, but more translational and clinical studies should address this topic. Here, we review the health-promoting properties of cherries and their bioactive compounds against human diseases.

Determination of the bruise degree for cherry using Vis-NIR reflection spectroscopy coupled with multivariate analysis

Determination and classification of the bruise degree for cherry can improve consumer satisfaction with cherry quality and enhance the industry's competiveness and profitability. In this study, visible and near infrared (Vis-NIR) reflection spectroscopy was used for identifying bruise degree of cherry in 350-2500 nm. Sampling spectral data were extracted from normal, slight and severe bruise samples. Principal component analysis (PCA) was implemented to determine the first few principal components (PCs) for cluster analysis among samples. Optimal wavelengths were selected by loadings of PCs from PCA and successive projection algorithm (SPA) method, respectively. Afterwards, these optimal wavelengths were empolyed to establish the classification models as inputs of least square-support vector machine (LS-SVM). Better performance for qualitative discrimination of the bruise degree for cherry was emerged in LS-SVM model based on five optimal wavelengths (603, 633, 679, 1083, and 1803 nm) selected directly by SPA, which showed acceptable results with the classification accuracy of 93.3%. Confusion matrix illustrated misclassification generally occurred in normal and slight bruise samples. Furthermore, the latent relation between spectral property of cherries in varying bruise degree and its firmness and soluble solids content (SSC) was analyzed. The result showed both colour, firmness and SSC were consistent with the Vis-NIR reflectance of cherries. Overall, this study revealed that Vis-NIR reflection spectroscopy integrated with multivariate analysis can be used as a rapid, intact method to determine the bruise degree of cherry, laying a foundation for cherry sorting and postharvest quality control.

Nutrients, Bioactive Compounds and Bioactivity: The Health Benefits of Sweet Cherries (Prunus avium L.)

Background:

Sweet cherries are one of the most appreciated fruits worldwide as well as one of the great sources of several active substances, as phytochemical compounds (carotenoids, serotonin, melatonin and phenolic compounds) as well as in nutritive compounds (sugars and organic acids). Accumulating research demonstrate that their supplementation in our daily diet can contradict oxidative stress, mitigating or even attenuating chronic diseases, as cancerous processes, antiinflammatory- related disorders, diabetes, and neurological and cardiovascular pathologies. Therefore, the aims of this review are to present an overview on the effects of sweet cherries as health promotors, giving emphasis to the health benefits of their bioactive compounds, particularly their antimicrobial, antioxidant, antidiabetic, anticancer, anti-neurodegeneration, anti-inflammatory and cardiovascular effects.

Methods:

Research and online content about sweet cherry fruits is reviewed. The information available has been read several times to avoid inconsistencies. In addition, according what we read, original figures were done and added to facilitate understanding and to enrich the paper.

Results:

In this review, a total of 202 original reports were used. In respect to health benefits, it is possible to confirm by several studies that, in fact, the consumption of sweet cherries has positive impacts in human health, owing to their wealthy and vast constitution, particularly in phenolic compounds, vitamins and carotenoids whose health properties were already documented.

Conclusion:

The findings of this review support the evidence that sweet cherries can be applied in pharmaceutical and food formulations, since they are able to diminish free radical species and proinflammatory markers, preventing and/ or ameliorating oxidative-stress disorders.

Antioxidant Status, Antidiabetic Properties and Effects on Caco-2 Cells of Colored and Non-Colored Enriched Extracts of Sweet Cherry Fruits

This study aimed to compare three different extracts of Saco sweet cherry, namely the non-colored fraction, colored fraction, and total extract concerning phenolic composition, antioxidant and antidiabetic potential, and erythrocytes’ protection and effects on Caco-2 cells. Twenty-two phenolic compounds were identified using high-performance liquid chromatography with diode-array detection. Hydroxycinnamic acids were the most predominant in both the non-colored fraction and total extract, while cyanidin-3-O-rutinoside was the main anthocyanin found in the colored fraction. The total extract was the most effective against 1,1-diphenyl-2-picrylhydrazyl, nitric oxide, and superoxide radicals, and in the inhibition of α-glucosidase enzyme. The colored fraction revealed the best activity against hemoglobin oxidation and hemolysis. Regarding to Caco-2 cells, the colored extract exhibited the highest cytotoxic effects, while the total extract was the most efficient in protecting these cells against oxidative damage induced by tert-butyl hydroperoxide.

Resveratrol metabolites ameliorate insulin resistance in HepG2 hepatocytes by modulating IRS-1/AMPK

Resveratrol (trans-3,5,4′-trihydroxystilbene, RSV), a naturally occurring biologically active polyphenol has been observed to induce numerous beneficial effects in diabetic animals and humans. However, its protective effects are somewhat controversial due to low bioavailability and rapid clearance rate. Therefore, we in this study have tried to investigate if its main metabolites, RSV-3-O-glucuronide (R3G) and RSV-4-O-glucuronide (R4G) could ameliorate insulin resistance, similar to RSV in insulin-resistant HepG2 cells. Herein, we first established an insulin-resistant cell model by treating HepG2 cells with 1 × 10⁻⁶ mol L⁻¹ insulin for 24 h. Subsequently, the effects of R3G and R4G on insulin resistance inhibition were evaluated in HepG2 cells. Interestingly, our data indicated that R3G and R4G treatment improved cellular glucose uptake and glycogen synthesis contents, and blocked generation of intracellular reactive oxygen species (ROS). Additionally, R3G and R4G also modulated insulin signaling and improved insulin sensitivity by modulating the IRS-1/AMPK signaling pathway. Taken together, our data provided a significant new insight into the effects and molecular mechanism of R3G and R4G on ameliorating insulin resistance in HepG2 cells. Overall, our data supported the hypothesis that despite low bioavailability in vivo, RSV biological effects could be mediated through its metabolites.

RSV metabolites R3G and R4G protected HepG2 cell from insulin resistance by improving glucose uptake and glycogen synthesis, along with inhibiting ROS generation and modulating the RS-1/AMPK signaling pathway.

Exploring the phenolic profile, antioxidant, antidiabetic and anti-hemolytic potential of Prunus avium vegetal parts

The aim of the present work was to evaluate the phenolic profile of leaves, stems and flowers of P. avium and their biological potential. For this purpose, two extracts of each matrix (hydroethanolic and infusion) were prepared. A total of twenty-six phenolics were identified by LC-DAD, including 1 hydroxybenzoic acid, 9 hydroxycinnamic acids, 7 flavonols, 3 isoflavones, 3 flavanones and 3 flavan-3-ols, being the hydroethanolic leaves extract the richest one. 5-O-caffeoylquinic acid, hydroxycinnamic derivative 1 and sakuranetin derivative were the major compounds found in leaves, flowers and stems, respectively. The hydroethanolic extracts of stems and leaves proved to be the most active against DPPH^• and O₂^•- (IC₅₀ = 22.37 ± 0.29 μg/mL and IC₅₀ = 9.11 ± 0.16 μg/mL, respectively). On the other hand, the infusion extract of stems showed the highest antioxidant activity against ^•NO (IC₅₀ = 99.99 ± 1.89 μg/mL). The antidiabetic potential was tested using the α-glucosidase enzyme, being the infusion extract of stems the most active, with an IC₅₀ = 3.18 ± 0.23 μg/mL. Finally, the protective effect of the extracts towards human erythrocytes against oxidative damage was also evaluated. The hydroethanolic extract of stems was the most active against lipid peroxidation and hemolysis with an IC₅₀ = 26.20 ± 0.38 μg/mL and IC₅₀ = 1.58 ± 0.18 μg/mL, respectively. On the other hand, the hydroethanolic extract of flowers showed the greater protective effect against hemoglobin oxidation (IC₅₀ = 12.85 ± 0.61 μg/mL). Considering the results obtained in this work, we can consider that leaves, stems and flowers of P. avium are a promising source of bioactive compounds and present health-promoting properties.

Casein glycomacropeptide-derived peptide IPPKKNQDKTE ameliorates high glucose-induced insulin resistance in HepG2 cells via activation of AMPK signaling

SCOPE

Recently, casein glycomacropeptide (GMP)-derived peptide was found to possess potent antioxidant and anti-inflammatory activities. In this study, the improvement effects and underlying molecular mechanisms of GMP-derived peptide on hepatic insulin resistance were investigated.

METHODS AND RESULTS

The peptide IPPKKNQDKTE was identified from GMP papain hydrolysates by LC-ESI-MS/MS. Effects of IPPKKNQDKTE on glucose metabolism and expression levels of the hepatic insulin signaling proteins in high glucose-induced insulin-resistant HepG2 cells were evaluated. Results showed that IPPKKNQDKTE dose-dependently increased glucose uptake and intracellular glycogen in insulin-resistant HepG2 cells without affecting cell viability. IPPKKNQDKTE increased the phosphorylation of Akt and GSK3β and decreased the expression levels of p-GS, G6Pase and PEPCK. These IPPKKNQDKTE-mediated protection effects were reversed by PI3K/Akt inhibitor LY294002, showing the mediatory role of PI3K/Akt. Moreover, treatment with IPPKKNQDKTE reduced IRS-1 Ser307 phosphorylation and increased phosphorylation of AMPK. Knockdown AMPK using siRNA in HepG2 cells increased Ser307 phosphorylation of IRS-1 and reduced Akt phosphorylation in IPPKKNQDKTE-treated insulin-resistant cells.

CONCLUSION

IPPKKNQDKTE prevents high glucose-induced insulin resistance in HepG2 cells by modulating the IRS-1/PI3K/Akt signaling pathway through AMPK activation, indicating that IPPKKNQDKTE plays a potential role in the prevention and treatment of hepatic insulin resistance and type 2 diabetes.