Black Goji Berry (Lycium ruthenicum) Juice Fermented with Lactobacillus rhamnosus GG Enhances Inhibitory Activity against Dipeptidyl Peptidase-IV and Key Steps of Lipid Digestion and Absorption.

With the global increase in hyperglycemia and hyperlipidemia, there is an urgent need to explore dietary interventions targeting the inhibition of dipeptidyl peptidase-IV (DPP-IV) and lipid digestion and absorption. This study investigated how Lactobacillus rhamnosus GG (LGG) affects various aspects of black goji berry (BGB) (Lycium ruthenicum Murr.) juice, including changes in physicochemical and functional properties, as well as microbiological and sensory attributes. Throughout the fermentation process with 2.5-10% (w/v) BGB, significantly improved probiotic viability, lactic acid production, and decreased sugar content. While total flavonoids increase, anthocyanins decrease, with no discernible change in antioxidant activities. Metabolite profiling reveals elevated phenolic compounds post-fermentation. Regarding the inhibition of lipid digestion and absorption, fermented BGB exhibits improved bile acid binding, and disrupted cholesterol micellization by approximately threefold compared to non-fermented BGB, while also increasing pancreatic lipase inhibitory activity. Furthermore, a decrease in cholesterol uptake was observed in Caco-2 cells treated with fermented BGB (0.5 mg/mL), with a maximum reduction of 16.94%. Fermented BGB also shows more potent DPP-IV inhibition. Sensory attributes are significantly improved in fermented BGB samples. These findings highlight the potential of BGB as a bioactive resource and a promising non-dairy carrier for LGG, enhancing its anti-hyperglycemic and anti-hyperlipidemic properties.

Modulation of the gut microbiota and short-chain fatty acid production by gac fruit juice and its fermentation in in vitro colonic fermentation.

This study aimed to investigate the effects of gac fruit juice and its probiotic fermentation (FGJ) utilizing Lactobacillus paracasei on the modulation of the gut microbiota and the production of short-chain fatty acids (SCFAs). We conducted a comparison between FGJ, non-fermented gac juice (GJ), and control samples through in vitro digestion and colonic fermentation using the human gut microbiota derived from fecal inoculum. Our findings revealed that both GJ and FGJ led to an increase in the viability of Lactobacilli, with FGJ exhibiting even higher levels compared to the control. The results from the 16S rDNA amplicon sequencing technique showed that both GJ and FGJ exerted positive impact on the gut microbiota by promoting beneficial bacteria, notably Lactobacillus mucosae and Bacteroides vulgatus. Additionally, both GJ and FGJ significantly elevated the levels of SCFAs, particularly acetic, propionic, and n-butyric acids, as well as lactic acid, in comparison to the control. Notably, FGJ exhibited a more pronounced effect on the gut microbiota compared to GJ. This was evident in its ability to enhance species richness, reduce the Firmicutes to Bacteroidetes (F/B) ratio, promote Akkermansia, and inhibit pathogenic Escherichia coli. Moreover, FGJ displayed enhanced production of SCFAs, especially acetic and lactic acids, in contrast to GJ. Our findings suggest that the probiotic fermentation of gac fruit enhances its functional attributes in promoting a balanced gut microbiota. This beverage demonstrates potential as a functional food with potential advantages for sustaining intestinal health.

Analysis of Lutein Content in Microencapsulated Marigold Flower Extract (Tagetes erecta L.) Using UHPLC-Q-Orbitrap-HRMS and Its Cytotoxicity in ARPE-19 Cells.

Organic solvents are commonly used to extract lutein. However, they are toxic and are not environmental-friendly. There are only a few reports on the quantification of lutein. Therefore, this study aimed to determine a suitable extraction method by which to obtain lutein from marigold flower (Tagetes erecta L.), using coconut oil to evaluate the cytotoxicity of extract in ARPE-19 cells, to optimize the encapsulation process for the development of microencapsulated marigold flower extract, and to develop the method for analysis of lutein by using UHPLC-Q-Orbitrap-HRMS. Coconut oil was used for the extraction of marigold flowers with two different extraction methods: ultrasonication and microwave-assisted extraction. The UHPLC-Q-Orbitrap-HRMS condition for the analysis of lutein was successfully developed and validated. Marigold flower extract obtained using the microwave method had the highest lutein content of 27.22 ± 1.17 mg/g. A cytotoxicity study revealed that 16 µM of lutein from marigold extract was non-toxic to ARPE-19 cells. For the development of microencapsulated marigold extract, the ratio of oil to wall at 1:5 had the highest encapsulation efficiency and the highest lutein content. Extraction of lutein using coconut oil and the microwave method was the suitable method. The microencapsulated marigold extract can be applied for the development of functional ingredients.

Dragon Fruit Peel Waste (Hylocereus undatus) as a Potential Ingredient for Reducing Lipid Peroxidation, Dietary Advanced Glycation End Products, and Starch Digestibility in Cookies.

Excessive consumption of cookies has been linked to harmful health outcomes owing to the presence of refined carbohydrates and heat-induced toxicants including end products of lipid peroxidation and dietary advanced glycation end products (dAGEs). To address this issue, this study explores the addition of dragon fruit peel powder (DFP), which is rich in phytochemicals and dietary fibers, to cookies as a potential solution to mitigate their adverse effects. The results indicate that adding DFP at 1%, 2%, and 5% w/w of raw cookie dough significantly improves the total phenolic and betacyanin contents and antioxidant activity, as evidenced by increased ferric-reducing antioxidant power. DFP incorporation also led to reductions in malondialdehyde and dAGEs (p < 0.05). Furthermore, the starch digestibility, hydrolysis index, and predicted glycemic index were all reduced in the presence of DFP, with the latter estimate being due to the higher content of undigested starch. Incorporating DFP in cookies resulted in significant changes in their physical properties, including texture and color. However, sensory evaluation indicates that the overall acceptability of the cookies was not negatively impacted by the addition of up to 2% DFP, suggesting that it is a viable option for enhancing the nutritional value of cookies without compromising their palatability. These findings suggest that DFP is a sustainable and healthier ingredient that can improve the antioxidant capacity of cookies while also mitigating the harmful effects of heat-induced toxins.

Antihyperglycemic effects of Lysiphyllum strychnifolium leaf extract in vitro and in vivo.

CONTEXT: Lysiphyllum strychnifolium (Craib) A. Schmitz (LS) (Fabaceae) has traditionally been used to treat diabetes mellitus. OBJECTIVE: This study demonstrates the antidiabetic and antioxidant effects of aqueous extract of LS leaves in vivo and in vitro. MATERIALS AND METHODS: The effects of aqueous LS leaf extract on glucose uptake, sodium-dependent glucose cotransporter 1 (SGLT1) and glucose transporter 2 (GLUT2) mRNA expression in Caco-2 cells, α-glucosidase, and lipid peroxidation were evaluated in vitro. The antidiabetic effects were evaluated using an oral glucose tolerance test (OGTT) and a 28-day consecutive administration to streptozotocin (STZ)-nicotinamide (NA)-induced type 2 diabetic mice. RESULTS: The extract significantly inhibited glucose uptake (IC50: 236.2 ± 36.05 µg/mL) and downregulated SGLT1 and GLUT2 mRNA expression by approximately 90% in Caco-2 cells. Furthermore, it non-competitively inhibited α-glucosidase in a concentration-dependent manner with the IC50 and Ki of 6.52 ± 0.42 and 1.32 µg/mL, respectively. The extract at 1000 mg/kg significantly reduced fasting blood glucose levels in both the OGTT and 28-day consecutive administration models as compared with untreated STZ-NA-induced diabetic mice (p < 0.05). Significant improvements of serum insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and GLUT4 levels were observed. Furthermore, the extract markedly decreased oxidative stress markers by 37-53% reduction of superoxide dismutase 1 (SOD1) in muscle and malondialdehyde (MDA) in muscle and pancreas, which correlated with the reduction of MDA production in vitro (IC50: 24.80 ± 7.24 µg/mL). CONCLUSION: The LS extract has potent antihyperglycemic activity to be used as alternative medicine to treat diabetes mellitus.

Dietary anthocyanins inhibit insulin fibril formation and cytotoxicity in 3T3-L1 preadipocytes.

Insulin fibril formation decreases the effectiveness of insulin therapy and causes amyloidosis in diabetes. Studies suggest that phytochemicals are capable of inhibiting fibril formation. Herein, we investigated the inhibitory effects of anthocyanins, including cyanidin, cyanidin-3-glucoside (C3G), cyanidin-3-rutinoside (C3R), malvidin, and malvidin-3-glucoside (M3G) on fibril formation. Our results revealed that anthocyanins (50-200 µM) significantly reduced the formation of insulin fibrils by increasing lag times and decreasing ThT fluorescence at the plateau phase. These findings were confirmed by TEM images, which showed reduced fibril length and number. Furthermore, FTIR analysis indicated that anthocyanins reduced the secondary structure transition of insulin from α-helix to ß-sheet. Anthocyanins interacted with monomeric insulin (residues B8-B30) via H-bonds, van der Waals, and hydrophobic interactions, covering the fibril-prone segments of insulin (residues B12-B17). Based on the structure-activity analysis, the presence of glycosides and hydroxyl groups on phenyl rings increased intermolecular interaction, mediating the inhibitory effect of anthocyanins on fibril formation in the order of malvidin < cyanidin < M3G < C3G < C3R. Moreover, anthocyanins formed H-bonds with preformed insulin fibrils, except for malvidin. In preadipocytes, C3R, C3G, and cyanidin attenuated insulin fibril-induced cytotoxicity. In conclusion, anthocyanins are effective inhibitors of insulin fibril formation and cytotoxicity.

Encapsulation of Mesona chinensis Benth Extract in Alginate Beads Enhances the Stability and Antioxidant Activity of Polyphenols under Simulated Gastrointestinal Digestion.

The aim of this study was to investigate the stability and antioxidant activity of the polyphenols from Mesona chinensis Benth extract (MCE) and its alginate-based encapsulation by extrusion technique during simulated gastrointestinal digestion. The encapsulation efficacy ranged from 41.1 ± 4.7 to 56.7 ± 3.4% with different concentrations of MCE (50-75% v/v), sodium alginate (1.2-1.8% w/v), and CaCl2 solution (3-5% w/v). The optimal condition for MCE-loaded alginate beads (MCB) was composed of 75% MCE, 1.5% alginate, and 3% CaCl2 solution, which provided the highest encapsulation efficiency with a spherical structure and a mean particle diameter of 1516.67 ± 40.96 µm. Fourier transform infrared spectroscopy (FT-IR) reported no chemical interaction between alginate and MCE. The release of total phenolic content (TPC) was only 8.9% after placing MCB in water for 4 h. After simulated digestion, changes in TPC and ferric reducing antioxidant power (FRAP) of MCE significantly decreased by 25.0% and 29.7%, respectively. Interestingly, the incorporation of MCB significantly increased TPC and FRAP in the digesta compared to those of MCE during gastrointestinal tract conditions. The findings suggest that the encapsulation of MCE with alginate as a carrier helps to improve the bioaccessibility and biological activity of M. chinensis polyphenols.

Investigating the Impact of Dragon Fruit Peel Waste on Starch Digestibility, Pasting, and Thermal Properties of Flours Used in Asia.

As a by-product of dragon fruit consumption, dragon fruit peel (DFP) was developed into powder as a natural ingredient. Nevertheless, the effect of DFP on the physicochemical properties of flours used in Asian food processing and cooking remains unknown. In this study, starch digestibility, thermal, pasting, and physicochemical properties of DFP and flours (potato, rice, glutinous rice, and wheat) were characterized. It was found that DFP contained 65.2% dietary fiber together with phenolic compounds, betacyanins, and antioxidant activity. The results demonstrated that DFP (from 125 to 500 mg) reduced starch digestibility of flours, rapidly digestible starch, and slowly digestible starch, along with an increased proportion of undigested starch. A marked increase in phenolic compounds, betacyanins, and antioxidant activity occurred when DFP and flour were incubated for 180 min under simulated gastrointestinal digestion. The results indicate that bioactive compounds in DFP were highly bioaccessible and remained intact after digestion. Moreover, DFP exerted a significantly lower gelatinization enthalpy of flours with increasing peak viscosity and setback with decreasing pasting temperature. FTIR confirmed the decreased ratio at 1047/1022 cm-1, indicating the disruption of short-range orders of starch and DFP. These findings would expand the scope of DFP food applications and provide a knowledge basis for developing DFP flour-based products.

Cyanidin-3-rutinoside stimulated insulin secretion through activation of L-type voltage-dependent Ca2+ channels and the PLC-IP3 pathway in pancreatic ß-cells.

Cyanidin-3-rutinoside (C3R) is an anthocyanin with anti-diabetic properties found in red-purple fruits. However, the molecular mechanisms of C3R on Ca2+-dependent insulin secretion remains unknown. This study aimed to identify C3R's mechanisms of action in pancreatic ß-cells. Rat INS-1 cells were used to elucidate the effects of C3R on insulin secretion, intracellular Ca2+ signaling, and gene expression. The results showed that C3R at 60, 100, and 300 µM concentrations significantly increased insulin secretion via intracellular Ca2+ signaling. The exposure of cells with C3R concentrations up to 100 µM did not affect cell viability. Pretreatment of cells with nimodipine (voltage-dependent Ca2+ channel (VDCC) blocker), U73122 (PLC inhibitor), and 2-APB (IP3 receptor blocker) inhibited the intracellular Ca2+ signals by C3R. Interestingly, C3R increased intracellular Ca2+ signals and insulin secretion after depletion of endoplasmic reticulum Ca2+ stores by thapsigargin. However, insulin secretion was abolished under extracellular Ca2+-free conditions. Moreover, C3R upregulated mRNA expression for Glut2 and Kir6.2 genes. These findings indicate that C3R stimulated insulin secretion by promoting Ca2+ influx via VDCCs and activating the PLC-IP3 pathway. C3R also upregulates the expression of genes necessary for glucose-induced insulin secretion. This is the first study describing the molecular mechanisms by which C3R stimulates Ca2+-dependent insulin secretion from pancreatic ß-cells. These findings contribute to our understanding on how anthocyanins improve hyperglycemia in diabetic patients.

Clitoria ternatea Flower Extract Attenuates Postprandial Lipemia and Increases Plasma Antioxidant Status Responses to a High-Fat Meal Challenge in Overweight and Obese Participants.

High-fat (HF) meal-induced postprandial lipemia, oxidative stress and low-grade inflammation is exacerbated in overweight and obese individuals. This postprandial dysmetabolism contributes to an increased risk of cardiovascular disease and metabolic disorders. Clitoria ternatea flower extract (CTE) possesses antioxidant potential and carbohydrate and fat digestive enzyme inhibitory activity in vitro. However, no evidence supporting a favorable role of CTE in the modulation of postprandial lipemia, antioxidant status and inflammation in humans presently exists. In the present study, we determine the effect of CTE on changes in postprandial glycemic and lipemic response, antioxidant status and pro-inflammatory markers in overweight and obese men after consumption of an HF meal. Following a randomized design, sixteen participants (age, 23.5 ± 0.6 years, and BMI, 25.7 ± 0.7 kg/m2) were assigned to three groups that consumed the HF meal, or HF meal supplemented by 1 g and 2 g of CTE. Blood samples were collected at fasting state and then at 30, 60, 90, 120, 180, 240, 300 and 360 min after the meal consumption. No significant differences were observed in the incremental area under the curve (iAUC) for postprandial glucose among the three groups. Furthermore, 2 g of CTE decreased the iAUC for serum triglyceride and attenuated postprandial serum free fatty acids at 360 min after consuming the HF meal. In addition, 2 g of CTE significantly improved the iAUC for plasma antioxidant status, as characterized by increased postprandial plasma FRAP and thiol levels. Postprandial plasma glutathione peroxidase activity was significantly higher at 180 min after the consumption of HF meal with 2 g of CTE. No significant differences in the level of pro-inflammatory cytokines (interleukin-6, interleukin-1ß and tumor necrosis factor-α) were observed at 360 min among the three groups. These findings suggest that CTE can be used as a natural ingredient for reducing postprandial lipemia and improving the antioxidant status in overweight and obese men after consuming HF meals.

Phytochemical Composition, Antiglycation, Antioxidant Activity and Methylglyoxal-Trapping Action of Brassica Vegetables.

Brassica vegetables are common in cuisines worldwide. The aim of this study was to investigate the antiglycation, methylglyoxal (MG)-trapping action and antioxidant activity of Brassica vegetable extract (BVE) from cabbage, cauliflower and Chinese cabbage. The results showed that cauliflower had the highest phenolic content with the strongest DPPH radical scavenging activity, ferric reducing antioxidant power and oxygen radical absorbance capacity. Seven phenolic acids and three flavonoids were identified by ESI-Q-TOF-MS analysis. The common phenolic compounds in all BVE were sinapic acid and p-hydroxybenzoic acid. The BVE (0.5 mg/mL) showed significant inhibitory activity against glucose-induced fluorescent advanced glycation end products (AGEs) formation (34 - 67%) and preserved the amount of protein thiol group (30 - 35%). In addition, all extracts (0.125 - 4 mg/mL) also had the ability to trap MG, a reactive glycating agent. Total phenolic content of BVE exhibited a positive correlation with DPPH radical scavenging activity (r = 0.524) and % inhibition of AGE formation (r = 0.570) and % MG-trapping capacity (r = 0.786). These findings suggest that the BVE possesses antioxidant and antiglycating activity that may help to protect against protein glycation and oxidation mediated by glycation reaction.

Protective role of Clitoria ternatea L. flower extract on methylglyoxal-induced protein glycation and oxidative damage to DNA.

BACKGROUND: Methylglyoxal (MG) is a highly reactive dicarbonyl precursor for the formation of advanced glycation end products (AGEs) associated with age-related diseases, including diabetes and its complications. Clitoria ternatea L. flower has been reported to possess antioxidant and antiglycating properties. Evidence indicates that the extract of Clitoria ternatea L. flower inhibits fructose-induced protein glycation and oxidative damage to bovine serum albumin (BSA). However, there is no evidence to support the inhibitory effect of CTE against MG-mediated protein glycation and oxidative damage to protein and DNA. Therefore, the aim of the present study was to investigate whether C. ternatea flower extract (CTE) prevents MG-induced protein glycation and oxidative DNA damage. METHODS: The formation of fluorescent AGEs in BSA was evaluated using spectrofluorometer. The protein carbonyl and thiol group content were used for detecting protein oxidation. DNA strand breakage in a glycation model comprising of MG, lysine and Cu2+ or a free radical generator 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH) systems was investigated using gel electrophoresis. Generation of superoxide anions and hydroxyl radicals in the MG/lysine system was assessed by the cytochrome c reduction assay and thiobarbituric acid reactive substances assay, respectively. High performance liquid chromatography (HPLC) was used to measure the MG-trapping ability. RESULTS: In the BSA/MG system, CTE (0.25-1 mg/mL) significantly inhibited the formation of fluorescent AGEs and protein oxidation by reducing protein carbonyl content as well as preventing the protein thiol depletion. The concentration of CTE at 0.125-1 mg/mL prevented oxidative DNA cleavage in MG/lysine and AAPH systems associated with the inhibition of superoxide anion and hydroxyl radical formation. It also directly trapped MG in a concentration-dependent manner, ranging from 15 to 43%. CONCLUSIONS: The study findings suggest that the direct carbonyl trapping ability and the free radical scavenging activity of CTE are the underlying mechanisms responsible for the prevention of protein glycation and oxidative DNA damage.

Anthocyanin-rich fraction from Thai berries interferes with the key steps of lipid digestion and cholesterol absorption.

Several studies have documented the hypolipidemic effect of anthocyanin-rich plants in vitro and in vivo. The objective of this study was to elucidate the inhibitory activity of anthocyanin-rich fraction from Thai berries against fat digestive enzymes. The ability of Thai berries to bind bile acid, disrupt cholesterol micellization and the cholesterol uptake into Caco-2 cells was also determined. The content of total phenolics, flavonoid and anthocyanin in Prunus domestica L. (TPE), Antidesma bunius (L.) Spreng, Syzygium cumini (L.) Skeels, and Syzygium nervosum A. Cunn. Ex DC was 222.7-283.5 mg gallic acid equivalents, 91.2-184.3 mg catechin equivalents, and 37.9-49.5 mg cyanidin-3-glucoside equivalents/g extract, respectively. The anthocyanin-rich fraction of all extracts inhibited pancreatic lipase and cholesterol esterase with the IC50 values of 90.6-181.7 µg/mL and 288.7-455.0 µg/mL, respectively. Additionally, all extracts could bind primary and secondary bile acids (16.4-36.6%) and reduce the solubility of cholesterol in artificial micelles (53.0-67.6%). Interestingly, TPE was the most potent extract on interfering the key steps of lipid digestion among the tested extracts. In addition, TPE (0.10-0.50 mg/mL) significantly reduced the cholesterol uptake into Caco-2 cells in a concentration-dependent manner. These results demonstrate a new insight into the role of anthocyanin-rich Thai berry extract on interfering the key steps of lipid digestion and absorption.

Postprandial Effect of Yogurt Enriched with Anthocyanins from Riceberry Rice on Glycemic Response and Antioxidant Capacity in Healthy Adults.

The pigment of riceberry rice has been reported to contain anthocyanins which act as a free radical scavenger and inhibitor of carbohydrate digestive enzymes. Since the probiotic yogurt incorporated with the pigment of riceberry rice extract was previously developed, the present study was aimed to investigate the acute effect of riceberry rice yogurt consumption on postprandial glycemic response, antioxidant capacity, and subjective ratings in healthy adults. In a cross-over design, 19 healthy participants were randomized to consume 350 g of yogurt supplemented with 0.25% (w/w) riceberry rice extract or the control yogurt. Postprandial plasma glucose, antioxidant status, and subjective ratings were measured at fasting and intervals (0-3 h) after ingestion of yogurt. The primary outcome was glycemic response; the secondary outcomes were plasma antioxidant capacity. In comparison to the yogurt control, riceberry rice yogurt reduced plasma glucose concentration after 30 min of consumption. The incremental area under the curve (iAUC) was significantly lower after riceberry rice yogurt load than after the control yogurt load. The consumption of riceberry yogurt caused an acute increase in plasma ferric reducing ability of plasma (FRAP), Trolox equivalent antioxidant capacity (TEAC), and oxygen radical absorbance capacity (ORAC) from the baseline values after 60 min of 0.25 ± 0.06 mM FeSO4, 253.7 ± 35.5 mM Trolox equivalents, and 166.8 ± 28.9 mM Trolox equivalents, respectively. Furthermore, the iAUCs for FRAP, TEAC, ORAC, and protein thiol were higher in riceberry yogurt consumption compared with the control yogurt (1.6-, 1.6-, 2.9-, and 1.9-fold, respectively). A decrease in iAUC for plasma malondialdehyde (MDA) concentration was also observed in the riceberry yogurt group. However, consumption of riceberry rice yogurt and control yogurt showed similar subjective rating scores of hunger, desire to eat, fullness, and satiety. In conclusion, acute consumption of riceberry rice yogurt suppressed postprandial glucose level and improved plasma antioxidant capacity in healthy volunteers.

Anthocyanin-Enriched Riceberry Rice Extract Inhibits Cell Proliferation and Adipogenesis in 3T3-L1 Preadipocytes by Downregulating Adipogenic Transcription Factors and Their Targeting Genes.

Riceberry rice (Oryza sativa L.) is a new pigmented variety of rice from Thailand. Despite its high anthocyanin content, its effect on adipogenesis and adipocyte function remains unexplored. We investigated whether Riceberry rice extract (RBE) impacted cell proliferation by examining viability and cell cycle, using preadipocyte 3T3-L1 cells. To test RBE's effect on adipocyte formation, cells were cultured in adipogenic medium supplemented with extract and adipocyte number and triglyceride levels were quantified. Furthermore, Akt1 phosphorylation along with RT-qPCR and intracellular calcium imaging were performed to obtain an insight into its mechanism of action. The effect of RBE on adipocyte function was investigated using glucose uptake and lipolysis assays. Treatment of cells with RBE decreased preadipocyte number without cytotoxicity despite inducing cell cycle arrest (p < 0.05). During adipogenic differentiation, RBE supplementation reduced adipocyte number and triglyceride accumulation by downregulating transcription factors (e.g., PPARγ, C/EBPα, and C/EBPß) and their target genes (p < 0.05). The Akt1 phosphorylation was decreased by RBE but insignificance, however, the extract failed to increase intracellular calcium signals. Finally, the treatment of adipocytes with RBE reduced glucose uptake by downregulating Glut4 mRNA expression and enhanced isoproterenol-induced lipolysis (p < 0.05). These findings suggest that RBE could potentially be used in the treatment of obesity by inhibiting adipocyte formation and proliferation.

Cyanidin Attenuates Methylglyoxal-Induced Oxidative Stress and Apoptosis in INS-1 Pancreatic ß-Cells by Increasing Glyoxalase-1 Activity.

Recently, the mechanisms responsible for anti-glycation activity of cyanidin and its derivatives on the inhibition of methylglyoxal (MG)-induced protein glycation and advanced glycation-end products (AGEs) as well as oxidative DNA damage were reported. In this study, we investigated the protective effect of cyanidin against MG-induced oxidative stress and apoptosis in rat INS-1 pancreatic ß-cells. Exposure of cells to cytotoxic levels of MG (500 µM) for 12 h caused a significant reduction in cell viability. However, the pretreatment of cells with cyanidin alone (6.25-100 µM) for 12 h, or cotreatment of cells with cyanidin (3.13-100 µM) and MG, protected against cell cytotoxicity. In the cotreatment condition, cyanidin (33.3 and 100 µM) also decreased MG-induced apoptosis as determined by caspase-3 activity. Furthermore, INS-1 cells treated with MG increased the generation of reactive oxygen species (ROS) during a 6 h exposure. The MG-induced increase in ROS production was inhibited by cyanidin (33.3 and 100 µM) after 3 h stimulation. Furthermore, MG diminished the activity of glyoxalase 1 (Glo-1) and its gene expression as well as the level of total glutathione. In contrast, cyanidin reversed the inhibitory effect of MG on Glo-1 activity and glutathione levels. Interestingly, cyanidin alone was capable of increasing Glo-1 activity and glutathione levels without affecting Glo-1 mRNA expression. These findings suggest that cyanidin exerts a protective effect against MG-induced oxidative stress and apoptosis in pancreatic ß-cells by increasing the activity of Glo-1.

Inhibitory Effect of Antidesma bunius Fruit Extract on Carbohydrate Digestive Enzymes Activity and Protein Glycation In Vitro.

Antidesma bunius (L.) spreng (Mamao) is widely distributed in Northeastern Thailand. Antidesma bunius has been reported to contain anthocyanins, which possess antioxidant and antihypertensive actions. However, the antidiabetic and antiglycation activity of Antidesma bunius fruit extract has not yet been reported. In this study, we investigated the inhibitory activity of anthocyanin-enriched fraction of Antidesma bunius fruit extract (ABE) against pancreatic α-amylase, intestinal α-glucosidase (maltase and sucrase), protein glycation, as well as antioxidant activity. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) chromatogram revealed that ABE contained phytochemical compounds such as cyanidin-3-glucoside, delphinidin-3-glucoside, ellagic acid, and myricetin-3-galactoside. ABE inhibited intestinal maltase and sucrase activity with the IC50 values of 0.76 ± 0.02 mg/mL and 1.33 ± 0.03 mg/mL, respectively. Furthermore, ABE (0.25 mg/mL) reduced the formation of fluorescent AGEs and the level of Nε-carboxymethyllysine (Nε-CML) in fructose and glucose-induced protein glycation during four weeks of incubation. During the glycation process, the protein carbonyl and ß-amyloid cross structure were decreased by ABE (0.25 mg/mL). In addition, ABE exhibited antioxidant activity through DPPH radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) with the IC50 values 15.84 ± 0.06 µg/mL and 166.1 ± 2.40 µg/mL, respectively. Meanwhile, ferric reducing antioxidant power (FRAP) showed an EC50 value of 182.22 ± 0.64 µg/mL. The findings suggest that ABE may be a promising agent for inhibiting carbohydrate digestive enzyme activity, reducing monosaccharide-induced protein glycation, and antioxidant activity.

Cyanidin-3-rutinoside acts as a natural inhibitor of intestinal lipid digestion and absorption.

BACKGROUND: Cyanidin-3-rutinoside (C3R), a naturally occurring anthocyanin, possesses anti-oxidant, anti-hyperglycemic, anti-glycation and cardioprotective properties. However, its mechanisms responsible for anti-hyperlipidemic activity have not been fully identified. The aim of the study was to investigate the lipid-lowering mechanisms of C3R through inhibition of lipid digestion and absorption in vitro. METHODS: The inhibitory activity of C3R against pancreatic lipase and cholesterol esterase was evaluated using enzymatic fluorometric and enzymatic colorimetric assays, respectively. An enzyme kinetic study using Michaelis-Menten and the derived Lineweaver-Burk plot was performed to understand the possible types of inhibition. The formation of cholesterol micelles was determined using the cholesterol assay kit. The bile acid binding was measured using the colorimetric assay. The NBD cholesterol uptake in Caco-2 cells was determined using fluorometric assay. The mRNA expression of cholesterol transporter (Niemann-Pick C1-like 1) was determined by RT-PCR. RESULTS: The results showed that C3R was a mixed-type competitive inhibitor of pancreatic lipase with the IC50 value of 59.4 ± 1.41 µM. Furthermore, C3R (0.125-1 mM) inhibited pancreatic cholesterol esterase about 5-18%. In addition, C3R inhibited the formation of cholesterol micelles and bound to primary and secondary bile acid. In Caco-2 cells, C3R (12.5-100 µM) exhibited a significant reduction in cholesterol uptake in both free cholesterol (17-41%) and mixed micelles (20-30%). Finally, C3R (100 µM) was able to suppress mRNA expression of NPC1L1 in Caco-2 cells after 24 h incubation. CONCLUSIONS: The present findings suggest that C3R acts as a lipid-lowering agent through inhibition of lipid digestion and absorption.

Cyanidin-3-rutinoside reduces insulin fibrillation and attenuates insulin fibrils-induced oxidative hemolysis of human erythrocytes.

Insulin is able to form amyloid-like fibrils, a misfolding process by which insulin molecules interact with each other to form aggregates and pathological amyloid deposition. Inhibition of amyloid aggregation using natural products is proposed as a new strategy to prohibit the development of amyloid diseases. Herein, we demonstrated the inhibitory effect of cyanidin-3-rutinoside (C3R), a natural anthocyanin with multiple biological activities, against insulin amyloid fibrillation. The results showed that increased insulin concentration resulted in faster growth and higher amounts of insulin fibrils. C3R (10.6-170µM) concentration dependently decreased insulin fibril growth and increased the duration of lag time of insulin fibril formation. Moreover, C3R directly decreased the secondary structure transition from α-helix to ß-sheet structure. C3R (0.31-5µM) attenuated insulin fibrils-induced oxidative hemolysis of human erythrocytes in a concentration-dependent manner. Moreover, C3R reduced insulin fibrils-induced erythrocyte membrane disruption through the inhibition of reactive oxygen species (ROS) generation. The findings also suggest that C3R reduced fibrils-induced membrane lipid peroxidation by maintaining the catalase activity and oxidized/reduced glutathione content (GSH/GSSH) in erythrocytes. These findings suggest that C3R may serve as a potential inhibitory agent against amyloid fibril formation and insulin fibrils-induced oxidative hemolysis.

Acute effect of Clitoria ternatea flower beverage on glycemic response and antioxidant capacity in healthy subjects: a randomized crossover trial.

BACKGROUND: Clitoria ternatea L., a natural food-colorant containing anthocyanin, demonstrated antioxidant and antihyperglycemic activity. The aim of this study was to determine the effects of Clitoria ternatea flower extract (CTE) on postprandial plasma glycemia response and antioxidant status in healthy men. METHODS: In a randomized, crossover study, 15 healthy men (ages 22.53 ± 0.30 years; with body mass index of 21.57 ± 0.54 kg/m2) consumed five beverages: (1) 50 g sucrose in 400 mL water; (2) 1 g CTE in 400 mL of water; (3) 2 g CTE in 400 mL of water; (4) 50 g sucrose and 1 g CTE in 400 mL of water; and (5) 50 g sucrose and 2 g CTE in 400 mL of water. Incremental postprandial plasma glucose, insulin, uric acid, antioxidant capacities and lipid peroxidation were measured during 3 h of administration. RESULTS: After 30 min ingestion, the postprandial plasma glucose and insulin levels were suppressed when consuming sucrose plus 1 g and 2 g CTE. In addition, consumption of CTE alone did not alter plasma glucose and insulin concentration in the fasting state. The significant increase in plasma antioxidant capacity (ferric reducing ability of plasma (FRAP), oxygen radical absorbance capacity (ORAC), trolox equivalent antioxidant capacity (TEAC), and protein thiol) and the decrease in malondialdehyde (MDA) level were observed in the subjects who received 1 g and 2 g CTE. Furthermore, consumption of CTE protected sucrose-induced reduction in ORAC and TEAC and increase in plasma MDA. CONCLUSIONS: These findings suggest that an acute ingestion of CTE increases plasma antioxidant capacity without hypoglycemia in the fasting state. It also improves postprandial glucose, insulin and antioxidant status when consumed with sucrose. TRIAL REGISTRATION: Thai Clinical Trials Registry: TCTR20170609003 . Registered 09 September 2017. 'retrospectively registered'.