Nutraceuticals and functional foods for diabetes and obesity control

The aim of this work was to study the anti-diabetic potential of different berry-producing plants. Their mineral and phytochemical composition was studied by inductively coupled plasma - mass spectrometry and high-performance liquid chromatography/electrospray ionization tandem mass spectrometry analysis, respectively. A static model to simulate gastrointestinal digestion was employed to analyse the stability of phenolic compounds from targeted species. The mechanism of hypoglycaemic activity was evaluated in terms of in vitro inhibitory action on key digestive enzymes linked to type-2 diabetes (α-,β-glucosidases and α-amylase) and obesity (pancreatic lipase). Additionally, the inhibitory effect towards human aldose reductase and protein glycation, associated with long-term diabetic complications, was determined. The antioxidant activity of methanolic extracts was investigated using four different free radicals (ABTS•+, DPPH•, NO• and O2•-). Finally, the cytotoxicity of analysed species was assessed in Caco-2 cells by the resazurin reduction fluorescence method. Berry species proved to be good sources of essential minerals, some of which, are known to possess hypoglycaemic effects. Analysed extracts showed diverse phytochemical profiles, anthocyanins, hydroxycinnamic acids, flavonols, flavan-3-ols and ellagitannins being the dominant compounds. Extracts showed a stronger inhibition towards glucosidases and were moderate inhibitors of α-amylase and pancreatic lipase. Potent inhibitory effects were observed in aldose reductase assay and towards formation of advanced glycation end-products. Additionally, good antioxidant activities were observed. Preliminary cytotoxicity measurements revealed that plant extracts can be considered safe for human consumption. The phenolic content and biological activities were substantially affected by the simulated in vitro digestion. Still, positive health effects were verified for digested samples. The generated data about these berry-producing plants and their potential effect on the management/control of type-2 diabetes and prevention of associated complications may be useful in designing future dietary/nutraceutical strategies aimed at alleviating hyperglycaemia.O objectivo deste trabalho foi estudar o potencial antidiabético de diferentes plantas produtoras de bagas. A composição mineral e fitoquímica foi estudada recorrendo, respectivmente, a plasma indutivamente acoplado a espectrometria de massa e cromatografia líquida de alta eficiência com espectrometria de massa. Um modelo estático para simular a digestão gastrointestinal foi utilizado para analisar a estabilidade dos compostos fenólicos das espécies alvo. A actividade hipoglicémica foi avaliada in vitro em enzimas digestivas ligadas à diabetes tipo-2 (α, β-glucosidases e α-amilase) e à obesidade (lípase pancreática). O efeito inibitório sob a actividade da aldose reductase e a glicação de proteínas, associadas a complicações diabéticas, foi também determinado. A actividade antioxidante dos extratos foi investigada usando quatro radicais livres diferentes (ABTS•+, DPPH•, NO• e O2•-). Finalmente, a citotoxicidade das espécies analisadas foi avaliada em células Caco-2 pelo método da redução da resasurina. As bagas mostraram ser boas fontes de minerais essenciais, alguns com atribuídas capacidades hipoglicémicas. Os extratos analisados apresentaram perfis fitoquímicos diversos, sendo as antocianinas, os ácidos hidroxicinâmicos, os flavonóis, os flavan-3-oís, e os elagitaninos os compostos dominantes. Os extratos demostraram fortes inibições para as glucosidases e foram inibidores moderados da α-amilase e da lipase pancreática. Foram observados potentes efeitos inibitórios no ensaio da aldose reductase e na glicação de proteínas. Adicionalmente, observaramse boas actividades antioxidantes. A avaliação preliminar da citotoxicidade dos extractos, revelou que são seguros para o consumo humano. O conteúdo fenólico e as atividades biológicas foram substancialmente afectados pela simulação in vitro do processo de digestão. Contudo, foram verificados efeitos positivos para a saúde nas amostras sujeitas à digestão. Os dados gerados sobre as plantas produtoras de bagas analisadas relativamente ao potencial controlo da diabetes tipo-2 e prevenção de complicações associadas podem ser úteis no desenvolvimento de futuras estratégias dietéticas/nutracêuticas destinadas a aliviar a hiperglicemia

Phytochemical Profile, Chemotaxonomic Studies, andIn VitroAntioxidant Activities of Two Endemisms from Madeira Archipelago:Melanoselinum decipiensandMonizia edulis(Apiaceae)

Melanoselinum decipiens and Monizia edulis (Apiaceae) are two endemic plants from Madeira archipelago, phytochemical compositions of which remains little explored, despite their use in folk medicine. Using liquid chromatography with diode array and electrospray ionization/mass spectrometry analysis, their polyphenolic profile was established for the first time. Fifty-six compounds were identified with 5-O-caffeoylquinic acid, quercetin-O-(malonyl)hexoside, luteolin diacetyl, and quercetin-O-hexoside being the major constituents in the leaves of both plant species (≥ 0.76 mg/g of dry extract). Principal component analysis provided a suitable tool to differentiate targeted plants. Naringenin-6,8-di-C-glucoside, quercetin 3-O-pentosylhexoside, and 1,5-O-dicaffeoylquinic acid can be used as discriminatory taxonomic/geographical markers for M. edulis subspecies from Madeira and Porto Santo populations. This methodology of using polyphenols as chemotaxonomic markers proved to be useful for identification of plant species since the results are consistent with previous taxonomical data. The free-radical scavenging activities of the M. decipiens extracts proved to be higher than those of M. edulis, which correlated well with their phenolic content (R2  > 0.906).info:eu-repo/semantics/publishedVersio

Madeira moneywort (Sibthorpia peregrina L.) as a new source of verbascoside and its derivatives with potential phyto-pharmaceutical applications

The qualitative and quantitative characterization of Madeira moneywort (Sibthorpia peregrina L.) compounds was investigated for the first time. The antioxidant activity and the effect of the methanolic extract on digestive enzymes activity linked to type-2 diabetes and obesity were also determined by in vitro assays. A total of 56 components were characterized in S. peregrina. Phenylethanoids glycosides (PhEGs) represented the main classes of compounds (95.23 mg g-1 of dry extract), almost all verbascoside and its derivatives (up to 98.85% of the total individual phenolic content). The analysed sample was active against ABTS, DPPH, nitric oxide and superoxide radicals, suggesting a potential beneficial effect against oxidative stress. In addition, the methanolic extract was able to inhibit the catalytic activity of α-, β-glucosidases, α-amylase and pancreatic lipase. Overall, S. peregrina showed good perspectives to be explored as a rich source of verbascoside and its derivatives for nutraceutical/pharmaceutical products.This work was supported by Fundação para a Ciência e a Tecnologia (FCT, Portugal) [grant number SFRH/ BD/84672/2012] with funds from the Portuguese Government (Project PEst-OE/QUI/UI0674/2013) and the Portuguese National Mass Spectrometry Network (Contract RNEMREDE/1508/REM/2005). Funding through the project M1420-01-0145-FEDER-000005 – Centro de Química da Madeira – CQM+(Madeira 14-20).info:eu-repo/semantics/publishedVersio

Novas metodologias para a determinação do conteúdo de ácido ascórbico em alimentos frescos

A vitamina C é uma das vitaminas mais importantes para a nutrição humana e destacase pela sua eficiente acção antioxidante e participação em inúmeras reacções metabólicas como cofactor enzimático. A vitamina C inclui vários compostos que têm actividade biológica semelhante ao ácido L-ascórbico (L-AA), incluindo o produto da sua oxidação, ácido desidroascórbico (DHAA), e as formas sintéticas. Os seres humanos não são capazes de sintetizar a vitamina C, sendo necessário obter este nutriente através da alimentação. As frutas e vegetais são alimentos ricos em vitamina C, ao contrário das carnes e cereais. Existem diversos métodos analíticos disponíveis para quantificação dos teores de vitamina C nos alimentos, sendo os métodos cromatográficos os mais utilizados devido à sua capacidade de separação e elevada sensibilidade e precisão. Neste trabalho, foi desenvolvido e validado um método de cromatografia líquida de ultra-eficiência (UHPLC) para determinar o conteúdo de vitamina C total (L-AA + DHAA) em várias frutas e vegetais com proveniências diferentes. A produção de produtos hortofrutícolas na ilha da Madeira não é auto-suficiente, sendo necessário importar alguns alimentos. Realizou-se um pequeno estudo comparativo do teor total de vitamina C e a sua degradação nos produtos locais e importados. O DHAA foi medido indirectamente através da reacção com o redutor DL-1,4-ditiotreitol (DTT), antes da injecção cromatográfica. Os resultados obtidos foram comparados com a titulação iodométrica. As amostras foram extraídas durante 5 dias consecutivos sendo os extractos resultantes armazenados a -80ºC imediatamente após a extracção até ao dia de análise. A estabilidade do L-AA nos extractos conservados a diferentes temperaturas e os efeitos do cozimento dos alimentos sobre esta molécula foram avaliados. A actividade antioxidante dos produtos hortofrutícolas foi também medida pelo método ABTS (2,2-azino-bis(3-etilbenzotiazolina- 6-sulfonato). O estudo da validação do método apresentou resultados bastante satisfatórios, demonstrando uma boa repetibilidade e sensibilidade elevada. Além disso, o método proposto revelou ser uma abordagem melhorada, simples e rápida para a determinação do conteúdo de vitamina C total em diversos produtos alimentares.Universidade da Madeir

Evaluation of Asteraceae herbal extracts in the management of diabetes and obesity. Contribution of caffeoylquinic acids on the inhibition of digestive enzymes activity and formation of advanced glycation end-products (in vitro)

The study was performed to assess, for the first time, the in vitro anti-diabetic potential of ten Asteraceae plant extracts to inhibit the activity of digestive enzymes (α-amylase, α-, β-glucosidases and lipase) responsible for hydrolysis/digestion of sugar and lipids. Prevention of advanced glycation end-products (AGEs) formation was evaluated in bovine serum albumin/ribose glycation reaction model. The phytochemical profiles and caffeoylquinic acids (CQAs) contents were determined for the methanolic extract of each plant. Analyzed plant extracts exhibited significant inhibitory activity against key digestive enzymes linked to type II diabetes and obesity. A strong inhibition was observed for glucosidases and mild activity towards amylase and lipase (compared to reference compounds). Moreover, some extracts exhibited potent ability to prevent formation of AGEs, implicated in some diabetic complications. Caffeoylquinic acids were dominant in all plant extracts and findings demonstrate that these compounds are the most relevant hypoglycemic and anti-glycation agents. From the obtained results, Argyranthemum pinnatifidum, Helichrysum melaleucum, and Phagnalon lowei are good candidates for further development of phyto-pharmaceutical preparations as complementary therapy for diabetes and obesity control.The authors are grateful to Francisco Fernandes and Jose Carvalho from Madeira Botanical Garden and to Funchal Ecological Park for the supply and identification of plant material.info:eu-repo/semantics/publishedVersio

Assessing the In Vitro Inhibitory Effects on Key Enzymes Linked to Type-2 Diabetes and Obesity and Protein Glycation by Phenolic Compounds of Lauraceae Plant Species Endemic to the Laurisilva Forest

Methanolic leaf extracts of four Lauraceae species endemic to Laurisilva forest (Apollonias barbujana, Laurus novocanariensis, Ocotea foetens and Persea indica) were investigated for the first time for their potential to inhibit key enzymes linked to type-2 diabetes (α-amylase, α-glucosidase, aldose reductase) and obesity (pancreatic lipase), and protein glycation. Lauraceae extracts revealed significant inhibitory activities in all assays, altough with different ability between species. In general, P. indica showed the most promissing results. In the protein glycation assay, all analysed extracts displayed a stronger effect than a reference compound: aminoguanidine (AMG). The in vitro anti diabetic, anti-obesity and anti-glycation activities of analysed extracts showed correlation with their flavonols and flavan-3-ols (in particular, proanthocyanins) contents. These Lauraceae species have the capacity to assist in adjuvant therapy of type-2 diabetes and associated complications, through modulation of the activity of key metabolic enzymes and prevention of advanced glycation end-products (AGEs) formation.info:eu-repo/semantics/publishedVersio

Hypoglycemic, anti-glycation and antioxidant in vitro properties of two Vaccinium species from Macaronesia: A relation to their phenolic composition

Vaccinium cylindraceaeum (Azores blueberry) and V. padifolium (Madeira blueberry) are two Portuguese endemic species, which phytochemical composition and beneficial properties lack scientific validation. In this work, their potential in vitro inhibitory effects against key enzymes linked to type 2 diabetes and obesity and glycation of proteins were evaluated. Anthocyanins were predominant in fruits, while hydroxycinnamic acids (in particular 5-O-caffeoylquinic acid) and flavonoids were the main compounds in leaves. Vaccinium extracts showed effective inhibitions of glucosidases and glycation of proteins and mild activity towards α-amylase and pancreatic lipase (by comparison with reference compounds). Phenolic composition was strongly correlated with reported bioactivities. In fact, 5-O-caffeoylquinic can be considered one of the main hypoglycemic and anti-glycation agents of analysed extracts. Consumption of both Vaccinium species should be encouraged since berries could offer a dietary option in the prevention and control of diabetes and obesity, while leaves are good candidates for development of nutraceuticals.The authors are grateful to Cândida Dias from Flores Island (Azores archipelago), to Francisco Fernandes and José Carvalho from Madeira Botanical Garden and to Funchal Ecological Park for the supply and identification of plant material.info:eu-repo/semantics/publishedVersio

Identification and quantification of phenolic compounds of selected fruits from Madeira Island by HPLC-DAD–ESI-MSn and screening for their antioxidant activity

Five fruits species commonly cultivated and consumed in Madeira Island (Portugal) were investigated for their phenolic profile by means of reversed phase high-performance liquid chromatography coupled to diode array detection and electrospray ionisation mass spectrometry (HPLC-DAD-ESI/MS(n)) and antioxidant potential. A large number of compounds were characterised, flavonoids and phenolic acids being the major components found in target samples, 39 compounds (flavonoids, phenolic acids, terpenoids, cyanogenic glycosides and organic acids) were identified in cherimoyas, lemons, papayas, passion-fruits and strawberries for the first time. Furthermore, all samples were systematically analysed for their total phenolic and flavonoid contents along with two radical scavenging methods (ABTS and ORAC) for antioxidant activity measurement. Target fruits presented high phenolic contents which is responsible for most of the antioxidant activity against radical reactive species (R(2)>0.80). Quantitative data showed that anthocyanins, in particular pelargonidin-3-O-hexoside (>300 mg/100 mL), present only in strawberries were the compounds in largest amounts but are the ones which contribute less to the antioxidant activity.info:eu-repo/semantics/publishedVersio

In vitro studies on the effect of watercress juice on digestive enzymes relevant to type 2 diabetes and obesity and antioxidant activity

Inhibition of enzymes involved in carbohydrate and lipids metabolism is an important strategy against type 2 diabetes and obesity, by suppressing dietary sugar and fat absorption. This work reports, for the first time, the in vitro inhibition of a-glucosidase, a-amylase and lipase by water cress juice (WJ). Juice was analyzed for qualitative and quantitative composition and in vitro antioxidant activities. Several components were identified, namely hydroxycinnamic acids, flavo nols, and other minor water-soluble phytochemicals. Quantitative data revealed a dimer of caffeoylmalic acid (0.73 mg mL21 of juice), disinapoylgentibiose (0.64 mg mL21 ), ferulic acid (0.56 mg mL21 ), and isorhamnetin-O-sophoroside-O-malonyl(hexoside) (0.38 mg mL21 ) as the pre dominant polyphenols. The results showed that WJ had dose-dependent inhibitory potential against targeted enzymes, displaying a more potent inhibitory effect against a-glucosidase relative to a-amylase and lipase. WJ can be considered a potential complementary dietary approach to control hyperglycaemia and hyperlipidaemia, through inhibition of digestive enzymes. Practical applications Currently, raw watercress is widely consumed in liquid form, alone or together with other fresh vege tables, as an ingredient of the “detox juices.” Studies on watercress phenolic composition and antidiabetic properties have been performed on extracts, but not on juice, which is closer to the edi ble form. The present study supports consumption of watercress juice as source of phytochemicals potentially capable of inhibiting digestive enzymes linked to diabetes and obesity prevention/control.info:eu-repo/semantics/publishedVersio

Release of adsorbed ferulic acid in simulated gastrointestinal conditions

Ferulic acid (FA) is a natural antioxidant with limited absorption when conjugated with biomolecules but whose free form is readily absorbed in the stomach and, to a lesser extent, in the ileum. The latter sufers from infammation and oxidative stress, so a novel strategy for the delivery of FA in this compartment of the gastrointestinal tract was developed. Using the neutral un-functionalized resin Lewatit® VP OC 1064 MD PH, under optimized conditions, a loading of 144 mg FA/g of dry resin was obtained. By means of an in vitro simulated digestion, an average release of 32 mg FA/g of dry loaded resin (recovery of 22%) was observed in intestinal conditions. The incorporation/release of FA onto/from the resin was confrmed by ATR-FTIR spectroscopy and by HPLC-DAD. This work showed that the free form of FA can efectively be delivered in the small intestine, after immobilization in solid matrices.info:eu-repo/semantics/publishedVersio