Gad G. Yousef

Hypoglycemic activity of a novel anthocyanin-rich formulation from lowbush blueberry, Vaccinium angustifolium Aiton

Blueberry fruits are known as a rich source of anthocyanin components. In this study we demonstrate that anthocyanins from blueberry have the potency to alleviate symptoms of hyperglycemia in diabetic C57b1/6J mice. The anti-diabetic activity of different anthocyanin-related extracts was evaluated using the pharmaceutically acceptable self-microemulsifying drug delivery system: Labrasol. Treatment by gavage (500 mg/kg body wt) with a phenolic-rich extract and an anthocyanin-enriched fraction formulated with Labrasol lowered elevated blood glucose levels by 33 and 51%, respectively. The hypoglycemic activities of these formulae were comparable to that of the known anti-diabetic drug metformin (27% at 300 mg/kg). The extracts were not significantly hypoglycemic when administered without Labrasol, demonstrating its bio-enhancing effect, most likely due to increasing the bioavailability of the administered preparations. The phenolic-rich extract contained 287.0+/-9.7 mg/g anthocyanins, while the anthocyanin-enriched fraction contained 595+/-20.0 mg/g (cyanidin-3-glucoside equivalents), as measured by HPLC and pH differential analysis methods. The greater hypoglycemic activity of the anthocyanin-enriched fraction compared to the initial phenolic-rich extract suggested that the activity was due to the anthocyanin components. Treatment by gavage (300 mg/kg) with the pure anthocyanins, delphinidin-3-O-glucoside and malvidin-3-O-glucoside, formulated with Labrasol, showed that malvidin-3-O-glucoside was significantly hypoglycemic while delphinidin-3-O-glucoside was not.

Antioxidant Capacity and in Vitro Inhibition of Adipogenesis and Inflammation by Phenolic Extracts of Vaccinium floribundum and Aristotelia chilensis

Interest in berries from South America has increased due to their potential health benefits. The objective of this study was to characterize the anthocyanins and proanthocyanidins of Vaccinium floribundum and Aristotelia chilensis , total phenolics, and antioxidant capacity and to evaluate, in vitro, the ability of their phenolic extracts to reduce adipogenesis and lipid accumulation in 3T3-L1 adipocytes. The anti-inflammatory property of these extracts on RAW 264.7 macrophages was also investigated. Antioxidant capacity, measured as oxygen radical scavenging capacity and expressed as Trolox equivalents, was higher in the berries of A. chilensis. Phenolic extracts inhibited lipid accumulation by 4.0-10.8% when adipocytes were treated at maturity and by 5.9-37.9% when treated throughout differentiation. Furthermore, a proanthocyanidin-enriched fraction from V. floribundum significantly increased Pref-1 expression in preadipocytes. Phenolic extracts decreased the production of nitric oxide (3.7-25.5%) and prostaglandin E2 (9.1-89.1%) and the expression of inducible nitric oxide synthase (9.8-61.8%) and cycloxygenase-2 (16.6-62.0%) in lipopolysaccharide-stimulated RAW 264.7 macrophages. V. floribundum and A. chilensis phytochemicals limit adipogenesis and inflammatory pathways in vitro, warranting further in vivo studies.

Characterization of Anthocyanins and Proanthocyanidins in Wild and Domesticated Mexican Blackberries (Rubus spp.)

This study was designed to characterize and compare wild, commercial, and noncommercial cultivated blackberry genotypes grown in Michoacan, Mexico. Six genotypes, including WB-3, WB-7, WB-10, and WB-11 (all wild blackberry types), Tupy (a commercial cultivar), and UM-601 (a cultivated breeding line), were selected and profiled for anthocyanins and proanthocyanidins by separating extracts over Amberlite XAD-7 resin and Sephadex LH-20 columns. Subsequent high-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analyses revealed that the major anthocyanin for all genotypes was cyanidin 3-O-glucoside. The proanthocyanidins (condensed tannins) were present in mono- to hexamer forms. Also, hydrolyzable tannins, ellagitannins, were characterized in the blackberry fruits. The average anthocyanin concentration in Sephadex LH-20 fractions was 49.2 mg/g in the commercial cultivar Tupy, while in the wild genotypes and the breeding line, the range was 361.3-494.9 mg/g (cyanidin 3-O-glucoside equivalent). The proanthocyanidin concentration varied widely among wild genotypes (417.5-1343.6 mg/g, catechin equivalent). This study demonstrated that the use of Amberlite XAD-7 followed by Sephadex LH-20 chromatography, with subsequent HPLC and LC-ESI-MS analyses, was able to effectively separate and characterize the diverse polyphenolics in blackberry genotypes. These results suggest that recommendations for dietary intake of blackberries for human health benefits need to take into account the source, because of the wide inherent variation in bioactive polyphenolic content in different blackberry genotypes.

Neuroprotective effects of anthocyanin- and proanthocyanidin-rich extracts in cellular models of Parkinson׳s disease.

Neuropathological evidence indicates that dopaminergic cell death in Parkinson׳s disease (PD) involves impairment of mitochondrial complex I, oxidative stress, microglial activation, and the formation of Lewy bodies. Epidemiological findings suggest that the consumption of berries rich in anthocyanins and proanthocyanidins may reduce PD risk. In this study, we investigated whether extracts rich in anthocyanins, proanthocyanidins, or other polyphenols suppress the neurotoxic effects of rotenone in a primary cell culture model of PD. Dopaminergic cell death elicited by rotenone was suppressed by extracts prepared from blueberries, grape seed, hibiscus, blackcurrant, and Chinese mulberry. Extracts rich in anthocyanins and proanthocyanidins exhibited greater neuroprotective activity than extracts rich in other polyphenols, and a number of individual anthocyanins interfered with rotenone neurotoxicity. The blueberry and grape seed extracts rescued rotenone-induced defects in mitochondrial respiration in a dopaminergic cell line, and a purple basal extract attenuated nitrite release from microglial cells stimulated by lipopolysaccharide. These findings suggest that anthocyanin- and proanthocyanidin-rich botanical extracts may alleviate neurodegeneration in PD via enhancement of mitochondrial function.

Pharmacokinetics and Tissue Distribution of 14C-Labeled Grape Polyphenols in the Periphery and the Central Nervous System Following Oral Administration

Grape polyphenols confer potential health benefits, including prevention of neurodegenerative diseases. To determine the absorption and tissue distribution of the complex grape polyphenol mixture, (14)C-labeled polyphenols were biosynthesized by grape cell suspension cultures, during co-incubation with radioisotopically labeled sucrose, and fractionated into polyphenolic subfractions. The pharmacokinetics and distribution of grape polyphenols into blood, brain, and peripheral interstitial fluid were determined by tracking the (14)C label. The blood peak (14)C concentration of the fractions ranged from 15 minutes to 4 hours. Absorption and tissue distribution varied greatly between fractions. Concentrations in interstitial fluid were lower than in blood. The amount of residual label in the brain at 24 hours ranged from 0.1% to 1.7% of the dose, depending on the fraction. (14)C label found in the brain tissue and brain microdialysate indicated that grape polyphenols or their metabolites are able to cross the blood-brain barrier. Using (14)C-labeled plant polyphenols it is possible to track the compounds or their metabolic products into any tissue and determine distribution patterns in spite of low concentrations. A central question regarding the potential role of dietary polyphenolics in neurodegenerative research is whether they are bioavailable in the brain. Our observations indicate that some grape-derived polyphenolics do reach the brain, which suggests their potential value for applications in neurodegenerative disorders.

Anthocyanins and proanthocyanidins from blueberry-blackberry fermented beverages inhibit markers of inflammation in macrophages and carbohydrate-utilizing enzymes in vitro

SCOPE Berries are an excellent source of dietary flavonoids which have several health benefits. METHODS AND RESULTS We evaluated well-characterized anthocyanins (ANCs) and proanthocyanidins (PACs) from fermented blueberry-blackberry beverages. Wines were produced from highbush blueberries and blackberries grown in Illinois and blended to create ratios ranging from 100% blueberry to 100% blackberry. Total ANCs of the wine were strongly correlated to total phenolics (r = 0.99, p < 0.05) and to antioxidant capacity (r = 0.77, p < 0.05). ANC- and PAC-enriched fractions were purified from each wine blend and a phenolic profile was generated. ANCs increased with more blackberries from 1114 to 1550 mg cyanidin-3-O-glucoside (C3G) equivalents/L. Hydrolysable tannins were identified in the PAC-enriched fraction. Both ANC- and PAC-enriched fractions inhibited starch-degrading enzyme α-glucosidase and dipeptidyl peptidase-IV activity. Computational docking demonstrated that delphinidin-3-arabinoside effectively inactivated dipeptidyl peptidase-IV by binding with the lowest interaction energy (-3228 kcal/mol). ANC and PAC (100 μM C3G and epicatechin equivalents, respectively) from blueberry-blackberry blends reduced LPS-induced inflammatory response in mouse macrophages via the nuclear factor kappa B-mediated pathway. CONCLUSION ANC- and PAC- (including hydrolysable tannins in blackberry) enriched fractions from blueberry and blackberry fermented beverages are beneficial sources of antioxidants, inhibitors of carbohydrate-utilizing enzymes, and potential inhibitors of inflammation.

Phytochemical changes in phenolics, anthocyanins, ascorbic acid, and carotenoids associated with sweetpotato storage and impacts on bioactive properties

Sweetpotato phytochemical content was evaluated in four genotypes (NCPUR06-020, Covington, Yellow Covington, and NC07-847) at harvest and after curing/storage for 4 or 8 months. Curing and storage for up to 8 months did not significantly affect total phenolic content in Covington, Yellow Covington, and NC07-847, however for NCPUR06-020, a purple-fleshed selection, total phenolic content declined mainly due to anthocyanin degradation during storage. Covington had the highest carotenoid content at harvest time (281.9 μg/g DM), followed by NC07-847 (26.2 μg/g DM), and after 8 months, total carotenoids had increased by 25% and 50%, respectively. Antioxidant activity gradually declined during storage, and freshly harvested sweetpotatoes also demonstrated higher anti-inflammatory capacity as gauged by inhibition of lipopolysaccharide-induced reactive oxygen species (ROS) in SH-SY5Y cells. Gradual changes in sweetpotato phytochemical content and antioxidant and anti-inflammatory capacity were noted during normal long-term storage, but the specific effects were genotype-dependent.

Inhibition of Pro-inflammatory Responses and Antioxidant Capacity of Mexican Blackberry (Rubus spp.) Extracts

Total polyphenolic and anthocyanin- and proanthocyanidin-rich fractions from wild blackberry genotypes (WB-3, WB-7, WB-10, and WB-11), a domesticated noncommercial breeding line (UM-601), and a commercial cultivar (Tupy) were evaluated for inhibition of pro-inflammatory responses [nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression, cyclooxygenase-2 (COX-2) expression, and prostaglandin E2 (PGE2)] in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS). At 50 microM [cyanidin-3-O-glucoside (C3G) or catechin equivalent], most fractions significantly (P<0.05) inhibited all markers. The anthocyanin-rich fraction from WB-10 and the proanthocyanidin-rich fraction from UM-601 exhibited the highest NO inhibitory activities (IC50=16.1 and 15.1 microM, respectively). Proanthocyanidin-rich fractions from the wild WB-10 showed the highest inhibition of iNOS expression (IC50=8.3 microM). Polyphenolic-rich fractions from WB-7 and UM-601 were potent inhibitors of COX-2 expression (IC50=19.1 and 19.3 microM C3G equivalent, respectively). For most of the extracts, antioxidant capacity was significantly correlated with NO inhibition. Wild genotypes of Mexican blackberries, as rich sources of polyphenolics that have both antioxidant and anti-inflammatory properties, showed particular promise for inclusion in plant improvement programs designed to develop new varieties with nutraceutical potential.

Efficient Quantification of the Health-Relevant Anthocyanin and Phenolic Acid Profiles in Commercial Cultivars and Breeding Selections of Blueberries (Vaccinium spp.)

Anthocyanins and phenolic acids are major secondary metabolites in blueberry with important implications for human health maintenance. An improved protocol was developed for the accurate, efficient, and rapid comparative screening for large blueberry sample sets. Triplicates of six commercial cultivars and four breeding selections were analyzed using the new method. The compound recoveries ranged from 94.2 to 97.5 ± 5.3% when samples were spiked with commercial standards prior to extraction. Eighteen anthocyanins and 4 phenolic acids were quantified in frozen and freeze-dried fruits. Large variations for individual and total anthocyanins, ranging from 201.4 to 402.8 mg/100 g, were assayed in frozen fruits. The total phenolic acid content ranged from 23.6 to 61.7 mg/100 g in frozen fruits. Across all genotypes, freeze-drying resulted in minor reductions in anthocyanin concentration (3.9%) compared to anthocyanins in frozen fruits. However, phenolic acids increased by an average of 1.9-fold (±0.3) in the freeze-dried fruit. Different genotypes frequently had comparable overall levels of total anthocyanins and phenolic acids, but differed dramatically in individual profiles of compounds. Three of the genotypes contained markedly higher concentrations of delphinidin 3-O-glucoside, cyanidin 3-O-glucoside, and malvidin 3-O-glucoside, which have previously been implicated as bioactive principles in this fruit. The implications of these findings for human health benefits are discussed.

Berry and Citrus Phenolic Compounds Inhibit Dipeptidyl Peptidase IV: Implications in Diabetes Management

Beneficial health effects of fruits and vegetables in the diet have been attributed to their high flavonoid content. Dipeptidyl peptidase IV (DPP-IV) is a serine aminopeptidase that is a novel target for type 2 diabetes therapy due to its incretin hormone regulatory effects. In this study, well-characterized anthocyanins (ANC) isolated from berry wine blends and twenty-seven other phenolic compounds commonly present in citrus, berry, grape, and soybean, were individually investigated for their inhibitory effects on DPP-IV by using a luminescence assay and computational modeling. ANC from blueberry-blackberry wine blends strongly inhibited DPP-IV activity (IC50, 0.07 ± 0.02 to >300 μM). Of the twenty-seven phenolics tested, the most potent DPP-IV inhibitors were resveratrol (IC50, 0.6 ± 0.4 nM), luteolin (0.12 ± 0.01 μM), apigenin (0.14 ± 0.02 μM), and flavone (0.17 ± 0.01 μM), with IC50 values lower than diprotin A (4.21 ± 2.01 μM), a reference standard inhibitory compound. Analyses of computational modeling showed that resveratrol and flavone were competitive inhibitors which could dock directly into all three active sites of DPP-IV, while luteolin and apigenin docked in a noncompetitive manner. Hydrogen bonding was the main binding mode of all tested phenolic compounds with DPP-IV. These results indicate that flavonoids, particularly luteolin, apigenin, and flavone, and the stilbenoid resveratrol can act as naturally occurring DPP-IV inhibitors.