Extracts of Maqui ( Aristotelia chilensis ) and Murta ( Ugni molinae Turcz.): sources of antioxidant compounds and α-Glucosidase/α-Amylase inhibitors

α-Glucosidase inhibitors: consistency of in silico docking data with in vitro inhibitory data and inhibitory effect prediction of quercetin derivatives

The relationship between in silico and in vitro experiments regarding the inhibitory effects of polyphenols on α-glucosidase was investigated.

Analytical Profiling of Proanthocyanidins from Acacia mearnsii Bark and In Vitro Assessment of Antioxidant and Antidiabetic Potential

The proanthocyanidins from ethanol extracts (80%, v/v) of Acacia mearnsii (A. mearnsii) bark on chemical-based and cellular antioxidant activity assays as well as carbolytic enzyme inhibitory activities were studied. About 77% of oligomeric proanthocyanidins in ethanol extracts of A. mearnsii bark were found by using normal-phase HPLC. In addition, HPLC-ESI-TOF/MS and MALDI-TOF/TOF MS analyses indicated that proanthocyanidins from A. mearnsii bark exhibited with a degree of polymerization ranging from 1 to 11. These results of combined antioxidant activity assays, as well as carbolytic enzyme inhibitory activities of proanthocyanidins from A. mearnsii bark, indicated an encouraging antioxidant capacity for the high polyphenol content and a potential for use as alternative drugs for lowering the glycemic response.

Effects of In Vitro Digestion on the Content and Biological Activity of Polyphenols from Acacia mearnsii Bark

The stability and bioaccessibility of polyphenol from Acacia mearnsii bark were measured at various stages during in vitro simulated digestion. Subsequently, the changes in the total polyphenol content (TPC) and biological activity were studied. The results showed that the phenolic compounds from A. mearnsii remained stable, and TPC underwent few changes during gastric digestion. Nonetheless, intestinal digestion led to the degradation of proanthocyanidins (PAs) and a significant decrease in TPC (26%). Degradation was determined by normal-phase HPLC and gel permeation chromatography. Only monomers, dimers, and trimers of flavan-3-ols were identified in the serum-accessible fraction for characterization of their bioaccessibility. The results also indicated the obvious antioxidant capacity of PAs from A. mearnsii bark, and ~53% of the α-glucosidase⁻inhibitory effect was preserved. All these findings show that PAs from A. mearnsii bark as a native plant source may be particularly beneficial for human health as a natural nutritional supplement.

Novel Natural Products for Healthy Ageing from the Mediterranean Diet and Food Plants of Other Global Sources-The MediHealth Project

There is a rapid increase in the percentage of elderly people in Europe. Consequently, the prevalence of age-related diseases will also significantly increase. Therefore, the main goal of MediHealth, an international research project, is to introduce a novel approach for the discovery of active agents of food plants from the Mediterranean diet and other global sources that promote healthy ageing. To achieve this goal, a series of plants from the Mediterranean diet and food plants from other origins are carefully selected and subjected to in silico, cell-based, in vivo (fly and mouse models), and metabolism analyses. Advanced analytical techniques complement the bio-evaluation process for the efficient isolation and identification of the bioactive plant constituents. Furthermore, pharmacological profiling of bioactive natural products, as well as the identification and synthesis of their metabolites, is carried out. Finally, optimization studies are performed in order to proceed to the development of innovative nutraceuticals, dietary supplements or herbal medicinal products. The project is based on an exchange of researchers between nine universities and four companies from European and non-European countries, exploiting the existing complementary multidisciplinary expertise. Herein, the unique and novel approach of this interdisciplinary project is presented.

Inhibition of α-glucosidase, α-amylase, and aldose reductase by potato polyphenolic compounds

Diabetes mellitus is a chronic disease that is becoming a serious global health problem. Diabetes has been considered to be one of the major risks of cataract and retinopathy. Synthetic and natural product inhibitors of carbohydrate degrading enzymes are able to reduce type 2 diabetes and its complications. For a long time, potatoes have been portrayed as unhealthy for diabetic patients by some nutritionist due to their high starch content. However, purple and red potato cultivars have received considerable attention from consumers because they have high levels of polyphenolic compounds that have potent antioxidant activities. In this study, we screened the total phenolics (TP) and total anthocyanins (TA) and analyzed the phenolic and anthocyanin compounds in selected potato cultivars and advanced selections with distinct flesh colors (purple, red, yellow and white). Purple and red potato cultivars had higher levels of TP and TA than tubers with other flesh colors. Chlorogenic acid is the predominant phenolic acid, and major anthocyanin is composed of the derivatives of petunidin, peonidin, malvidin and pelargonidin. We tested the potential inhibitory effect of potato extracts on the activities of α-amylase and α-glucosidase, which were targeted to develop antidiabetic therapeutic agents. We also measured inhibitory effect of potato extracts on aldose reductase (AR) which is a key enzyme that has been a major drug target for the development of therapies to treat diabetic complications. Purple flesh tubers extract showed the most effective inhibition of α-amylase, α-glucosidase, and aldose reductase with IC50 values 25, 42, and 32 μg/ml, respectively. Kinetic studies showed that anthocyanins are noncompetitive inhibitors of these enzymes, whereas phenolic acids behaved as mixed inhibitors for α-amylase and α-glucosidase and noncompetitive inhibitors for AR. This study supports the development of a positive and healthful image of potatoes, which is an important issue for consumers.

Changes in polyphenol composition and bioactivity of the native Chilean white strawberry (Fragaria chiloensis spp. chiloensis f. chiloensis) after in vitro gastrointestinal digestion

The Chilean white strawberry (Fragaria chiloensis spp. chiloensis f. chiloensis) is a semi-domesticated strawberry with high polyphenol content and antioxidant activity occurring in southern Chile. The aim of this work was to compare the composition and bioactivity of the polyphenol-enriched fruit extract (PEE) before and after simulated gastrointestinal digestion (GID). Results show a decrease by >50% in the total phenolic (TP) content at the end of the GID, compared to the non-digested PEE. A reduction in the antioxidant capacity of the PEEs was observed after GID by means of DPPH, FRAP, TEAC and anion superoxide assays. After simulated GID the PEE significantly inhibited α-glucosidase with an IC₅₀ value of 3.13μg/mL. The inhibition of pancreatic lipase was reduced by 95% after GID. All the PEEs did not show inhibitory effect towards α-amylase throughout the GID. In the same way, the PEEs did not significantly protect human gastric adenocarcinoma (AGS) cells against H₂O₂-induced stress. Thirty eight compounds were tentatively identified in the non-digested PEE. The compounds that were more affected by the simulated GID were simple phenolics. After the GID, only 33 and 25 compounds were detected, in the gastric and intestinal steps, respectively. These results evidence the changes elicited by GID on the bioactivity and polyphenolic composition of the white strawberry.

Plant Flavonoid Content Modified by Domestication

Plant domestication can modify and weaken defensive chemical traits, reducing chemical defenses in plants and consequently their resistance against pests. We characterized and quantified the major defensive flavonols and isoflavonoids present in both wild and cultivated murtilla plants (Ugni molinae Turcz), established in a common garden. We examined their effects on the larvae of Chilesia rudis (Butler) (Lepidoptera: Arctiidae). Insect community and diversity indices were also evaluated. We hypothesized that domestication reduces flavonoid contents and modifies C. rudis preference, the insect community, and diversity. Methanolic extracts were obtained from leaves of U. molinae plants and analyzed by high performance liquid chromatography. Results showed higher insect numbers (86.48%) and damage index (1.72 ± 0.16) in cultivated plants. Four new first records of insects were found associated with U. molinae. Diversity indices, such as Simpson, Shannon, and Margalef, were higher in cultivated plants than in wild plants. Furthermore, eight isoflavonoids were identified in U. molinae leaves for the first time. The five flavonols showed higher concentrations in wild U. molinae leaves (89.8 µg/g) than in cultivated plants (75.2 µg/g); however, no differences were found in isoflavonoids between wild and cultivated plants. The larvae of C. rudis consumed more leaf material of cultivated plants than wild plants in choice (3.8 vs. 0.8 mm2) and no-choice (7.5 vs. 3.0 mm2) assays. Our study demonstrates that domestication in U. molinae reduces the amount of flavonoids in leaves, increasing the preference of C. rudis and the insect community.

Chilean berry Ugni molinae Turcz. fruit and leaves extracts with interesting antioxidant, antimicrobial and tyrosinase inhibitory properties

The knowledge of the biological properties of fruits and leaves of murta (Ugni molinae Turcz.) has been owned by native Chilean culture. The present study investigated the phenolic content, the antioxidant, antimicrobial and anti-tyrosinase activities of different murta fruit and leaves extracts to approach their uses on future food, pharmaceutical and cosmetic applications. Extractions of murta fruit and leaves were carried out under water, ethanol and ethanol 50%. Phenolic content of these extracts was measured through Folin Ciocalteu test and the antioxidant power by four different antioxidant systems (ORAC, FRAP, DPPH and TEAC assays) owing to elucidate the main mechanism of antioxidant. Some flavonoids, such as rutin, isoquercitrin and quercitrin hydrate were identified and quantified through HPLC analysis. Antimicrobial activity was determined measuring minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values against Escherichia coli and Listeria monocytogenes, and the effect of these extracts on L. monocytogenes was confirmed by flow cytometry. Highest contents of polyphenol compounds were obtained in hydroalcoholic extracts (28±1mggallicacid/g dry fruit, and 128±6mggallicacid/g dry leaves). The same trend was found for the values of biological properties: hydroalcoholic extracts showed the strongest activities. Leaves presented higher antioxidant, antimicrobial and anti-tyrosinase properties than murta fruit. Highest antioxidant activity values according to ORAC, FRAP, TEAC and DPPH were 80±8mgTrolox/g, 70±2mgTrolox/g, 87±8mgTrolox/g and 110±12mgTrolox/g, respectively, for murta fruit samples, and 280±10mgTrolox/g, 192±4mgTrolox/g, 286±13mgTrolox/g and 361±13mgTrolox/g, respectively, for murta leaves. These activities were confirmed by HPLC analysis that revealed highest presence of analyzed compounds on leaves hydroalcoholic extract. Regarding to antimicrobial analysis, hydroalcoholic leaves extract presented the highest activity presenting the lowest MIC value for L. monocytogenes (0.07mg/mL). This extract also performed the highest anti-tyrosinase activity (CE₅₀ values of 1.6±0.3 (g/L) and 8.9±1.2 (g/L) for leaves and fruit, respectively).

Radish (Raphanus sativus) and Diabetes

For more than three decades, various in vitro and in vivo studies have linked radishes with diabetes, though this link has not been discussed. This review systematically addresses and summarizes the effect of radishes on diabetes. We searched the Web of Science, PubMed, and EMBASE databases for English language articles from June 1987 through May 2017 using the key words "radish" and "diabetes," and the references from particular reports were also considered if relevant. In summary, radish has been identified as having antidiabetic effects, making it favorable for those with diabetic conditions. This may be due to its ability to enhance the antioxidant defense mechanism and reduce the accumulation of free radicals, affect hormonal-induced glucose hemostasis, promote glucose uptake and energy metabolism, and reduce glucose absorption in the intestine. However, this summary requires further confirmation in research in vivo studies and clinical trials.

Qualitative and quantitative changes in polyphenol composition and bioactivity of Ribes magellanicum and R. punctatum after in vitro gastrointestinal digestion

The wild Chilean currants Ribes magellanicum and R. punctatum are a good source of polyphenolic compounds. The effect of simulated gastrointestinal digestion (GID) on phenolic content, composition and antioxidant capacity was determined. The inhibitory activity of the non-digested and digested samples towards metabolic syndrome-associated enzymes (α-amylase, α-glucosidase and lipase) was evaluated. The total phenolic (TP) and flavonoid contents (TF) decreased by about 50% at the end of the in vitro GID. Main anthocyanins and hydroxycinnamic acids were strongly affected by this process, with a loss of about 80%. A decrease in the antioxidant activity was observed throughout the digestion steps, which was correlated with the reduction in the TP and TF content. After the in vitro GID of the samples, only the inhibition of α-glucosidase was preserved. Our results show that the simulated GID modified the health-promoting properties of the studied currants.

Phenolic composition and antioxidant capacity of Ugni molinae Turcz. leaves of different genotypes

Ugni molinae Turcz. is a native shrub of Chile, known for its edible berries and its leaves, which have been the focus of recent attention, as a good source of phenolic compounds to be used in cosmetics and food products. The aim of this study was to assess the differences in the phenolic composition and antioxidant capacity of the ethanolic extracts from the leaves of 10 genotypes of U. molinae, that were cultivated under the same soil, climate and agronomical management. Antioxidant activity was assessed by complementary methods (ORAC-Fl, FRAP and DPPH assay), phenolic composition of each extract was analyzed by LC-MS. Phenolic and flavonoid total contents were determined by Folin-Ciocalteu and AlCl3 methods. Significative differences were found by these methods, and ellagitannins, gallic acid derivatives and flavonols were identified as responsible for these differences, showing the influence of the genotype on the phenolic composition of U. molinae leaves.

Metabolic Activity of Radish Sprouts Derived Isothiocyanates in Drosophila melanogaster

We used Drosophila melanogaster as a model system to study the absorption, metabolism and potential health benefits of plant bioactives derived from radish sprouts (Raphanus sativus cv. Rambo), a Brassicaceae species rich in glucosinolates and other phytochemicals. Flies were subjected to a diet supplemented with lyophilized radish sprouts (10.6 g/L) for 10 days, containing high amounts of glucoraphenin and glucoraphasatin, which can be hydrolyzed by myrosinase to the isothiocyanates sulforaphene and raphasatin, respectively. We demonstrate that Drosophila melanogaster takes up and metabolizes isothiocyanates from radish sprouts through the detection of the metabolite sulforaphane-cysteine in fly homogenates. Moreover, we report a decrease in the glucose content of flies, an upregulation of spargel expression, the Drosophila homolog of the mammalian PPARγ-coactivator 1 α, as well as the inhibition of α-amylase and α-glucosidase in vitro. Overall, we show that the consumption of radish sprouts affects energy metabolism in Drosophila melanogaster which is reflected by lower glucose levels and an increased expression of spargel, a central player in mitochondrial biogenesis. These processes are often affected in chronic diseases associated with aging, including type II diabetes mellitus.

Domestication in Murtilla (Ugni molinae) Reduced Defensive Flavonol Levels but Increased Resistance Against a Native Herbivorous Insect

Plant domestication can have negative consequences for defensive traits against herbivores, potentially reducing the levels of chemical defenses in plants and consequently their resistance against herbivores. We characterized and quantified the defensive flavonols from multiple cultivated ecotypes with wild ancestors of murtilla, Ugni molinae Turcz, an endemic plant from Chile, at different times of the year, and examined their effects on a native insect herbivore, Chilesia rudis Butler (Lepidoptera: Arctiidae). We hypothesized that domestication results in a decrease in flavonol levels in U. molinae plants, and that this negatively affected C. rudis performance and preference. Ethanolic extracts were made from leaves, stems, and fruit of murtilla plants for flavonol analysis. Flavonols identified were kaempferol, quercetin, rutin, and quercetin 3-D-β-glucoside, the last two being the most abundant. More interestingly, we showed differences in flavonol composition between wild and cultivated U. molinae that persisted for most of the year. Relative amounts of all four flavonols were higher in wild U. molinae leaves; however, no differences were found in the stem and fruit between wild and cultivated plants. In choice and no-choice assays, C. rudis larvae gained more mass on, and consumed more leaf material of, wild as compared with cultivated U. molinae plants. Moreover, when applied to leaves, larvae ate more leaf material with increasing concentrations of each flavonol compound. Our study demonstrates that domestication in U. molinae reduced the amount of flavonols in leaves as well as the performance and preference of C. rudis, indicating that these compounds stimulate feeding of C. rudis.

Isolation and characterization of phenolic compounds and anthocyanins from Murta (Ugni molinae Turcz.) fruits. Assessment of antioxidant and antibacterial activity

Berry fruit consumption has become important in the promotion of human health, mainly due to their phenolic compounds, which have been associated with protection against different pathologies, as well as antimicrobial and other biological activities. Consequently, there has been a growing interest in identifying natural antioxidants and antimicrobials from these plants. This study aimed to characterize the phenolic chemical composition and anthocyanin profile of murta (Ugni molinae Turcz.) fruit, and to evaluate the antioxidant and antimicrobial activity of its extracts (ethanolic and methanolic). LC/MS of the ethanolic extracts showed the presence of three major compounds: caffeic acid 3-glu, quercetin-3-glu and quercetin, while in the methanolic acid extract they were cyanidin-3-glucoside, pelargonidin-3-arabinose and delphinidin-3-glucoside. The antioxidant activity of ethanolic extracts (DPPH· and ORAC assays) was higher than that of methanol acid extracts or purified anthocynins. Furthermore, the methanol acid extract showed an inhibitory activity against the bacteria E. coli and S. typhi similar to that of standard antibiotics. The results suggest that the antioxidant activity of the ethanolic extract is regulated by the high content of phenolic compounds and the fruit's characteristic color is due to the content of pelargonidin-3-arabinose and delphinidin-3-glucoside. The obtained results demonstrated the appreciable antioxidant and antibacterial activities, providing opportunities to explore murta extracts as biopreservatives.

Separation and characterization of polyphenolics from underutilized byproducts of fruit production (Choerospondias axillaris peels): inhibitory activity of proanthocyanidins against glycolysis enzymes

Bioactive proanthocyanidins were isolated from the peel ofChoerospondias axillarisfruit, which is a waste product of the food processing industry.

Maqui berry vs Sloe berry – Liquor-based Beverage for New Development

“Pacharán” is an aniseed liquor-based beverage made with sloe berry ( Prunus spinosa L.) that has been produced in northern Spain. On the other hand, maqui berry ( Aristotelia chilensis) is a common edible berry from Chile, and currently under study because of its multiple beneficial effects on health. The aim of this work was to design a new aniseed liquor-based beverage with maqui berry, as an industrial alternative to a traditional alcoholic product with bioactive berries. The characterization of its composition, compared with the traditional “Pacharán”, and its evolution during maceration (6 and 12 months) showed that the new maqui liquor had significantly-higher anthocyanin retention over time. More studies on the organoleptic properties and bioactivity are underway.

Phytochemistry and biological activity of Spanish Citrus fruits

The evaluation of the potential inhibitory activity on α-glucosidase and pancreatic lipase by Citrus spp. fruits of Spanish origin (lemon, orange, grapefruit, lime, and mandarin) together with the evaluation of their phytochemical content and antioxidant capacity (DPPH˙, ORACFL, ABTS(+), FRAP and O2˙(-)) aiming for new applications of the fruits in nutrition and health was carried out. As far as we are aware, the presence of 3-O-caffeoylferuoylquinic acid and two hydrated feruloylquinic acids in orange and the presence of 3,5-diferuoylquinic acid in grapefruit have been reported for the first time. Although grapefruit showed higher contents of phytochemicals such as flavanones and vitamin C, lemon and lime showed higher potential for inhibitory effects on lipase, and lime also showed the best results for in vitro α-glucosidase inhibition. On the other hand, higher antioxidant capacity was reported for grapefruit, lemon and lime, which correlated well with their phytochemical composition. Based on the results, it could be concluded that Citrus fruits are of great value for nutrition and treatment of diet-related diseases such as obesity and diabetes, and consequently, a new field of interest in the food industry regarding new bioactive ingredients would be considered.

Chilean native fruit extracts inhibit inflammation linked to the pathogenic interaction between adipocytes and macrophages

Obesity is characterized by an increase in the infiltration of monocytes into the adipose tissue, causing an inflammatory condition associated with, for example, the development of insulin resistance. Thus, anti-inflammatory-based treatments could emerge as a novel and interesting approach. It has been reported that Chilean native fruits maqui (Aristotelia chilensis) and calafate (Berberis microphylla) present high contents of polyphenols, which are known for their antioxidant and anti-inflammatory properties. The aim of this study was to evaluate the ability of extracts of these fruits to block the pathogenic interaction between adipocytes and macrophages in vitro and to compare its effect with blueberry (Vaccinium corymbosum) extract treatment, which has been already described to possess several biomedical benefits. RAW264.7 macrophages were treated with 5 μg/mL lipopolysaccharides (LPS), with conditioned media (CM) from fully differentiated 3T3-L1 adipocytes, or in a coculture (CC) with 3T3-L1 adipocytes, in the presence or absence of 100 μM [total polyphenolic content] of each extract for 24 h. The gene expression and secretion profile of several inflammatory markers were evaluated. Nitric oxide secretion induced by LPS, CM, and CC was reduced by the presence of maqui (-12.2%, -45.6%, and -14.7%, respectively) and calafate (-27.6%, -43.9%, and -11.8%, respectively) extracts. Gene expression of inducible nitric oxide synthase and TNF-α was inhibited and of IL-10 was induced by maqui and calafate extract incubation. In conclusion, the extracts of these fruits present important inhibitory-like features over the inflammatory response of the interaction between adipocytes and macrophages, comprising a potential therapeutic tool against comorbidities associated with obesity development.

Microwave and micronization treatments affect dehulling characteristics and bioactive contents of dry beans (Phaseolus vulgaris L.)

BACKGROUND

Heat pretreatment is considered the first step in grain milling. This study therefore evaluated microwave and micronization heat treatments in improving the dehulling characteristics, phenolic composition and antioxidant and α-amylase activities of bean cultivars from three market classes.

RESULTS

Heat treatments improved dehulling characteristics (hull yield, rate coefficient and reduced abrasive hardness index) depending on bean cultivar, whereas treatment effects increased with dehulling time. Micronization increased minor phenolic components (tartaric esters, flavonols and anthocyanins) of all beans but had variable effects on total phenolic content depending on market class. Microwave treatment increased α-amylase inhibitor concentration, activity and potency, which were strongly correlated (r²  = 0.71, P < 0.0001) with the flavonol content of beans. Heat treatment had variable effects on the phenolic composition of bean hulls obtained by abrasive dehulling without significantly altering the antioxidant activity of black and pinto bean hulls. Principal component analysis on 22 constituents analyzed in this study demonstrated the differences in dehulling characteristics and phenolic components of beans and hulls as major factors in segregating the beneficial heat treatment effects.

CONCLUSION

Heat treatment may be useful in developing novel dietary fibers from beans with variable composition and bioactivity with a considerable range of applications as functional food ingredients.

Evaluation of sensorial, phytochemical and biological properties of new isotonic beverages enriched with lemon and berries during shelf life

BACKGROUND

The aim of this work was to design new isotonic drinks with lemon juice and berries: maqui (Aristotelia chilensis (Molina) Stuntz), açaí (Euterpe oleracea Mart.) and blackthorn (Prunus spinosa L.), following previous research. Quality parameters, sensorial attributes, antioxidant activities (ABTS(+), DPPH(•) and O2(•-) assays) and biological capacities (α-glucosidase and lipase inhibitory assays) were evaluated over 70 days of shelf-life period.

RESULTS

Maqui isotonic blends were the most active in all antioxidant assays (8.35 and 3.07 mmol L(-1) Trolox for ABTS(+) and DPPH(•)), in the lipase inhibitory assay (43.19 U L(-1)), and showed the highest total phenol content by the Folin-Ciocalteu test (80.97 mg 100 mL(-1) gallic acid), as a result of its higher content of total anthocyanins (42.42 mg 100 mL(-1)). Berry mixtures were also the most potent inhibitors of α-glucosidase between all samples, and displayed an attractive red colour and good sensorial attributes.

CONCLUSIONS

All the studied parameters remained quite stable during preservation, in general, and the new isotonic drinks can be useful to equilibrate redox balance in acute and intense exercise, and support weight loss programmes, avoiding triglyceride absorption and hyperglycaemia involved in obesity and diabetes mellitus, respectively. Further research in vivo is necessary to verify their beneficial effects for sports, nutrition and health.

Helichrysum and grapefruit extracts inhibit carbohydrate digestion and absorption, improving postprandial glucose levels and hyperinsulinemia in rats

Several plant extracts rich in flavonoids have been reported to improve hyperglycemia by inhibiting digestive enzyme activities and SGLT1-mediated glucose uptake. In this study, helichrysum ( Helichrysum italicum ) and grapefruit ( Citrus × paradisi ) extracts inhibited in vitro enzyme activities. The helichrysum extract showed higher inhibitory activity of α-glucosidase (IC50 = 0.19 mg/mL) than α-amylase (IC50 = 0.83 mg/mL), whereas the grapefruit extract presented similar α-amylase and α-glucosidase inhibitory activities (IC50 = 0.42 mg/mL and IC50 = 0.41 mg/mL, respectively). Both extracts reduced maltose digestion in noneverted intestinal sacs (57% with helichrysum and 46% with grapefruit). Likewise, both extracts inhibited SGLT1-mediated methylglucoside uptake in Caco-2 cells in the presence of Na(+) (56% of inhibition with helichrysum and 54% with grapefruit). In vivo studies demonstrated that helichrysum decreased blood glucose levels after an oral maltose tolerance test (OMTT), and both extracts reduced postprandial glucose levels after the oral starch tolerance test (OSTT). Finally, both extracts improved hyperinsulinemia (31% with helichrysum and 50% with grapefruit) and HOMA index (47% with helichrysum and 54% with grapefruit) in a dietary model of insulin resistance in rats. In summary, helichrysum and grapefruit extracts improve postprandial glycemic control in rats, possibly by inhibiting α-glucosidase and α-amylase enzyme activities and decreasing SGLT1-mediated glucose uptake.

The association between dietary flavonoid and lignan intakes and incident type 2 diabetes in European populations: the EPIC-InterAct study

OBJECTIVE

To study the association between dietary flavonoid and lignan intakes, and the risk of development of type 2 diabetes among European populations.

RESEARCH DESIGN AND METHODS

The European Prospective Investigation into Cancer and Nutrition-InterAct case-cohort study included 12,403 incident type 2 diabetes cases and a stratified subcohort of 16,154 participants from among 340,234 participants with 3.99 million person-years of follow-up in eight European countries. At baseline, country-specific validated dietary questionnaires were used. A flavonoid and lignan food composition database was developed from the Phenol-Explorer, the U.K. Food Standards Agency, and the U.S. Department of Agriculture databases. Hazard ratios (HRs) from country-specific Prentice-weighted Cox regression models were pooled using random-effects meta-analysis.

RESULTS

In multivariable models, a trend for an inverse association between total flavonoid intake and type 2 diabetes was observed (HR for the highest vs. the lowest quintile, 0.90 [95% CI 0.77-1.04]; P value trend = 0.040), but not with lignans (HR 0.88 [95% CI 0.72-1.07]; P value trend = 0.119). Among flavonoid subclasses, flavonols (HR 0.81 [95% CI 0.69-0.95]; P value trend = 0.020) and flavanols (HR 0.82 [95% CI 0.68-0.99]; P value trend = 0.012), including flavan-3-ol monomers (HR 0.73 [95% CI 0.57-0.93]; P value trend = 0.029), were associated with a significantly reduced hazard of diabetes.

CONCLUSIONS

Prospective findings in this large European cohort demonstrate inverse associations between flavonoids, particularly flavanols and flavonols, and incident type 2 diabetes. This suggests a potential protective role of eating a diet rich in flavonoids, a dietary pattern based on plant-based foods, in the prevention of type 2 diabetes.

New isotonic drinks with antioxidant and biological capacities from berries (maqui, açaí and blackthorn) and lemon juice

The aim of the study was to design new isotonic drinks with lemon juice and berries: maqui [Aristotelia chilensis (Molina) Stuntz], açaí (Euterpe oleracea Mart.) and blackthorn (Prunus spinosa L.), following on from previous research. Quality parameters - including colour (CIELab parameters), minerals, phytochemical identification and quantification by high-performance liquid chromatography with diode array detector, total phenolic content by the Folin-Ciocalteu reagent, the antioxidant capacity (ABTS(+), DPPH• and [Formula: see text] assays) and biological activities (in vitro alpha-glucosidase and lipase inhibitory effects) - were tested in the samples and compared to commercially available isotonic drinks. The new isotonic blends with lemon and anthocyanins-rich berries showed an attractive colour, especially in maqui samples, which is essential for consumer acceptance. Significantly higher antioxidant and biological effects were determined in the new blends, in comparison with the commercial isotonic beverages.

New beverages of lemon juice enriched with the exotic berries maqui, açaı́, and blackthorn: bioactive components and in vitro biological properties

Following previous research on lemon juice enriched with berries, the aim of this work was to design new blends based on lemon juice mixed with different edible berries of exotic and national origin: maqui ( Aristotelia chilensis (Molina) Stuntz), açaı́ ( Euterpe oleracea Mart.), and blackthorn ( Prunus spinosa L.). The phytochemical characterization of controls and blends was performed by HPLC-DAD-ESI/MS(n). Their antioxidant capacity against DPPH, superoxide, and hydroxyl radicals and hypochlorous acid and their potential to inhibit cholinesterases were also assessed. The profiling of the red fruits and lemon revealed a wide range of bioactive phenolics. The novel beverage based on lemon juice and maqui berry (LM) was the most interesting blend in terms of antioxidant capacity. Berry control samples displayed reduced effects on acetylcholinesterase and butyrylcholinesterase, the lemon juice control being always the most active. This activity was also remarkable for lemon-blackthorn (LB) and lemon-açaı́ (LA) blends, the last being the most effective inhibitor of cholinesterases among all samples. The results suggested that lemon juice enriched with berries could be of potential interest in the design of new drinks with a nutritive related function on health for chronic diseases.

Antidiabetic effects of natural plant extracts via inhibition of carbohydrate hydrolysis enzymes with emphasis on pancreatic alpha amylase

INTRODUCTION

The increasing prevalence of type 2 diabetes mellitus and the negative clinical outcomes observed with the commercially available anti-diabetic drugs have led to the investigation of new therapeutic approaches focused on controlling postprandrial glucose levels. The use of carbohydrate digestive enzyme inhibitors from natural resources could be a possible strategy to block dietary carbohydrate absorption with less adverse effects than synthetic drugs.

AREAS COVERED

This review covers the latest evidence regarding in vitro and in vivo studies in relation to pancreatic alpha-amylase inhibitors of plant origin, and presents bioactive compounds of phenolic nature that exhibit anti-amylase activity.

EXPERT OPINION

Pancreatic alpha-amylase inhibitors from traditional plant extracts are a promising tool for diabetes treatment. Many studies have confirmed the alpha-amylase inhibitory activity of plants and their bioactive compounds in vitro, but few studies corroborate these findings in rodents and very few in humans. Thus, despite some encouraging results, more research is required for developing a valuable anti-diabetic therapy using pancreatic alpha-amylase inhibitors of plant origin.