In Vitro Potential of Ascophyllum nodosum Phenolic Antioxidant-Mediated α-Glucosidase and α-Amylase Inhibition

ABSTRACT: Ascophyllum nodosum is a brown seaweed that grows abundantly in the Northeast coastal region. In this study, the potential of A. nodosum for type 2 diabetes management through antioxidant-mediated α-glucosidase and α-amylase inhibition was investigated. After the initial screening of 4 locally harvested seaweeds, A. nodosum was chosen for its highest phenolic content and was subjected to water extraction. Among extraction ratios of 50 g to 100 to 1000 mL at room temperature, 50 g/400 mL yielded the highest phenolic content of 4.5 mg/g wet weight. For evaluation of extraction temperature ranging from 20 to 80 °C, 50 g/400 mL was chosen as a minimum amount of extractant. Among temperatures studied, extraction at 80 °C resulted in the highest total phenolic contents (4.2 mg/g wet weight). All extracts had similar levels of antioxidant activity in the range of 60% to 70% in terms of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. The 80 °C extract had the highest α-glucosidase and α-amylase inhibitory activity with IC₅₀ of 0.24 and 1.34 μg phenolics, respectively, compared to the IC₅₀ of acarbose, reference inhibitor, being 0.37 and 0.68 μg. The results show that fresh A. nodosum has strong α-glucosidase and mild α-amylase inhibitory activities that correlated with phenolic contents. This study suggests a nutraceutical potential of A. nodosum based on phytochemical antioxidant and antihyperglycemia activities.     

EVALUATION OF RED CURRANTS (RIBES RUBRUM L.), BLACK CURRANTS (RIBES NIGRUM L.), RED AND GREEN GOOSEBERRIES (RIBES UVA-CRISPA) FOR POTENTIAL MANAGEMENT OF TYPE 2 DIABETES AND HYPERTENSION USING IN VITRO MODELS

Red currants (Ribes rubrum L.), black currants (Ribes nigrum L.), red and green gooseberries (Ribes uva-crispa) were evaluated for the total phenolics, antioxidant capacity based on 2, 2-diphenyl-1-picrylhydrazyl radical scavenging assay and functionality such as in vitro inhibition of α-amylase, α-glucosidase and angiotensin I-converting enzyme (ACE) relevant for potential management of hyperglycemia and hypertension. The total phenolics content ranged from 3.2 (green gooseberries) to 13.5 (black currants) mg/g fruit fresh weight. No correlation was found between total phenolics and antioxidant activity. The major phenolic compounds were quercetin derivatives (black currants and green gooseberries) and chlorogenic acid (red currants and red gooseberries). Red currants had the highest α-glucosidase, α-amylase and ACE inhibitory activities. Therefore red currants could be good dietary sources with potential antidiabetes and antihypertension functionality to compliment overall dietary management of early stages of type 2 diabetes.     

Phenolic composition and functional properties of wild mint (Mentha longifolia var. calliantha (Stapf) Briq.)

Mints (Mentha species) are widely used as food, medicine, spice, and flavoring agents. At the present work, phenolics profile of infusion and ethanol extract of Mentha longifolia was determined using an RP–HPLC–DAD system. Total bioactive contents, radical scavenging, reducing power, metal chelating, and enzyme inhibitory activities relevant to Alzheimer’s disease, diabetes mellitus, and skin disorders were evaluated. Sixteen phenolic compounds (ten phenolic acids and six flavonoids) were identified in the extracts in which sinapic acid (7132 µg/g extract) and rosmarinic acid (6260 µg/g extract) were the most abundant compounds. Strong antioxidant effects were observed in 1,1-diphenyl-2-picrylhydrazyl radical, 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), cupric ion reducing activity, ferric reducing antioxidant power, phosphomolybdenum, and metal chelating assays. Results indicated selective acetylcholinesterase inhibitory activity and high α-amylase and α-glucosidase inhibitory potential. Findings showed that M. longifolia has promising health benefits due to its high concentration of useful phenolic compounds and has great potential for possible applications in the preparation of functional ingredients.     

Metabolite profiling,antioxidant activity,and glycosidase inhibition property of the mesocarp tissue extracts of sugar date palm [Phoenix sylvestris (L.) Roxb.] fruits

Phoenix sylvestris is an underutilized seasonal fruit in West Bengal, India. Methanol extract and extracts after alkaline hydrolysis of the mesocarp tissue of full-mature edible fruits of P. sylvestris were analyzed by GC-MS following a metabolomics approach. The fractions were tested for their antioxidant and inhibitory properties against the two key enzymes involved in diabetes, α-amylase, and α-glucosidase. Total 71 metabolites belonging to organic acids, amino acids, sugars, sugar alcohols, fatty acids, and phenols were identified in the methanol extract and in fractions after saponification. All the extracts and fractions showed high antioxidant, α-glucosidase, and α-amylase inhibitory activities. Sugars like raffinose (IC₅₀ = 0.36 μM), sucrose (IC₅₀ = 0.51 μM), trehalose (IC₅₀ = 0.85 μM), and phenols like taxifolin (IC₅₀ = 0.31 μM), benzoic acid (IC₅₀ = 2.74 μM) inhibited only the enzyme α-amylase. Phenolic components which inhibited both the enzymes were caffeic acid (IC₅₀ = 1.42 μM for α-amylase and IC₅₀ = 1.8 μM for α-glucosidase), 3, 4-dihydroxy benzoic acid (IC₅₀ = 0.23 μM for α-amylase and IC₅₀ = 2.58 μM for α-glucosidase), and quinic acid (IC₅₀ = 4.91 μM for α-amylase and IC₅₀ = 4.95 μM for α-glucosidase). Ferulic acid (IC₅₀ = 0.52 μM) and 4-hydroxycinnamic acid (IC₅₀ = 0.23 μM) inhibited only α-glucosidase. This study suggested that the metabolites present in the fruit mesocarp tissue showed the potential antioxidant activity and properties to inhibit the enzymes α-amylase and α-glucosidase. Further in vivo study is to be carried out to prove the efficacy of the fruits.

Abbreviations: FM: crude methanol extract; SI: ethyl acetate extract after alkaline hydrolysis step I; SII: ethyl acetate extract after alkaline hydrolysis step II     

Seasonal influence on phenolic-mediated antihyperglycemic properties of Canadian sugar and red maple leaves using in vitro assay models

Red and sugar maple leaves collected in the summer and fall from Canada, were evaluated for phenolic content, antioxidant, α-glucosidase, and α-amylase inhibitory activities variation. The phenolic contents of summer red maple leaves (RML-S) and summer sugar maple leaves (SML-S) were higher than red and sugar maple leaves collected in fall (RML-F and SML-F, respectively). HPLC analyses showed differences in phenolic compounds present in the SML samples compared to the RML samples. The extracts were assayed for yeast and rat α-glucosidase inhibitory activities. Both results showed that SML-S extracts had the highest inhibitory activity which could possibly be attributed to the unique phenolics present therein. Milder effects were observed in terms of α-amylase inhibitory activity, with RML-F having the highest inhibitory activity. These results suggest that maple tree leaf extracts may have potential for phenolic-mediated α-glucosidase inhibition, relevant to type 2 diabetes management, with SML-S extract having the highest bioactivity.     

Screening of Possible In Vitro Neuroprotective,Skin Care,Antihyperglycemic, and Antioxidative Effects of Anchusa undulata L. subsp. hybrida (Ten.) Coutinho from Turkey and Its Fatty Acid Profile

The aim of this work was to determine antioxidant capacities, neuroprotective, skin care, antidiabetic effects, and fatty acid composition of Anchusa undulata subsp. hybrida. The antioxidant activity was screened by four different test systems including total antioxidant, antiradical, reducing power, and metal chelating activities. Neuroprotective potential was determined by anticholinesterase inhibitor assay. Tyrosinase inhibitory activity was tested to detect skin care effect. Antidiabetic effects were evaluated with α-amylase and α-glucosidase inhibitory assays. Inhibitory activities on acetycholinesterase, butyrylcholinesterase, tyrosinase, α-amylase, and α-glucosidase enzymes were observed as 2.238 and 1.239 μmol GALAEs/g, 0.339 mmol KAEs/g, 0.193, and 0.219 mmol ACEs/g extract, respectively. Amount of total phenolics and flavonoids were found as 80.34 μg GAEs/mg and 25.09 μg QEs/mg in the extract, respectively. Twenty-three fatty acids were found in the aerial parts, being oleic acid (24.30 g/100 g of total fatty acids) the most abundant, followed by linoleic (21.19 g/100 g of total fatty acids) and palmitic acids (17.50 g/100 g of total fatty acids).     

Inhibitory effect of raspberries on starch digestive enzyme and their antioxidant properties and phenolic composition

Seven primocane fall-bearing raspberry (Rubus idaeus L.) cultivars, Nova (red), Dinkum (red), Heritage (red), Autumn Britten (red), Josephine, Anne (yellow), Fall Gold (yellow) were analysed for potential health promoting properties including their inhibitory effect on starch and fat digestive enzymes, antioxidant activities, and phenolic composition. The tested raspberry extracts showed no detectable inhibition of pancreatic α-amylase and lipase. However, all the extracts exhibited potent inhibition of α-glucosidase with IC₅₀ from 16.8 to 34.2 μg/mL. Four phenolic compounds, ellagic acid, cyanidin-diglucoside, pelargonidin-3-rutinoside, and catechin were identified as the active α-glucosidase inhibitors. The raspberry extracts also possessed significant antioxidant activities with oxygen radical absorbance capacities (ORAC) ranging from 136.7 to 205.2 μmol Trolox equivalents (TE)/g dry weight fruit and DPPH radical scavenging activities from 305 to 351 μmol TE/g. The total phenolic content of raspberry cultivars varied significantly from 40.9 to 98.5 mg of gallic acid equivalents/g dry weight. The anthocyanin content varied widely from 0.1 to 9.5 mg cyanidin 3-glucoside equivalents/g. Nine phenolic acids were quantified in raspberries and their total amounts varied from 157.3 to 713.5 μg/g. The enzyme inhibition and antioxidant properties of raspberry cultivars were not correlated with their total phenolic, anthocyanin, and phenolic acid content. Overall, ‘Dinkum’ and ‘Josephine’ raspberry varieties possess higher total phenolic content, ORAC, DPPH radical scavenging activity, and α-glucosidase inhibitory activity than other five cultivars.     

Functional components,antidiabetic, anti-Alzheimer’s disease,and antioxidant activities of Salvia syriaca L.

Antidiabetic, anti-Alzheimer, general toxicity, and antioxidant activities of Salvia syriaca were evaluated. Phytochemical composition of the essential oil and methanolic extract of the plant were identified using gas chromatography-mass spectrometry and reverse-phase high-performance liquid chromatography-diode array detector techniques, respectively. Essential oil of S. syriaca exhibited strong cytotoxicity, antioxidant, α-amylase, and α-glucosidase inhibitory activities. Gas chromatography-mass spectrometry analysis showed that spathulenol (87.4%), isospathulenol (7.6%), and bornyl acetate (2.7%) are the major compounds in essential oil. High-performance liquid chromatography analysis indicated that rutin, quercetin, apigenin, rosmarinic acid, and ferulic acid are the most abundant phenolic components. S. syriaca could be considered as a valuable source of bioactive natural compounds for functional foods, medical, and pharmaceutical applications.     

Inhibitory potential of herb,fruit, and fungal-enriched cheese against key enzymes linked to type 2 diabetes and hypertension

In the current study, three different types of cheese, cheddar, feta, and Roquefort, were screened to determine the variations in phenolic-linked antioxidant activity and the potential to inhibit key enzymes relevant to type 2 diabetes and related hypertension. The cheese samples were assayed for total phenolic content, related antioxidant activity, and inhibition of α-glucosidase, pancreatic α-amylase inhibitory activity, and the angiotensin-converting enzyme (ACE)-I inhibitory activity. The three fungal-enriched Roquefort cheese samples had the highest total phenolic content. The phenolic content in the herb cheese was slightly but not significantly higher compared to plain cheese. Roquefort cheese samples had the highest antioxidant-linked DPPH (free radical) scavenging activity and as expected DPPH radical scavenging activity was higher in the herb cheese compared to plain cheese. All samples had some α-glucosidase and α-amylase inhibitory activities, with cranberry-enriched cheese having the highest activities. However, no correlation to soluble phenolic content was observed. All the cheese samples had very high anti-ACE-I inhibitory activity, indicating no correlation to phenolic content and activity was even high in 10× diluted samples. The highest ACE-I inhibitory activity was observed in plain and herb-enriched cheddar cheese as well as cranberry-enriched cheese. These studies indicate that cranberry-enriched cheese had the best potential for inhibition of α-glucosidase and α-amylase relevant for type 2 diabetes management, whereas any cheese product had potential for ACE-I inhibition linked to hypertension management, indicating likely the role of other factors such as peptides from cheese fermentation.Industrial relevanceThis research is focused on screening of different types of commercial plain, herbal, fruit, and fungal-enriched to provide a strong biochemical rationale for further design of functional cheese products for anti-type 2 diabetic and relevant hypertension management. A better understanding of these functional attributes provides a strong biochemical rationale for design in vivo and clinical studies from which right design of functional food can be established.     

LC–MS/MS characterization,antidiabetic, antioxidative,and antibacterial effects of different solvent extracts of Anamur banana (Musa Cavendishii)

The main objective of this study was to examine the phenolic compounds and the antibacterial, antioxidant, anti-α-glucosidase and anti-α-amylase activities of the different extracts (methanol, ethanol and hexane) of Musa cavendishii collected from the Anamur district in Turkey. LC–MS/MS was used to identify phenolic compounds. Quinic acid, acotinic acid, hesperidin and amentoflavone were identified in methanol extract. These phenolic compounds, excluding hesperidin, were also identified in the ethanol extract. Methanolic extract appeared the most active in all enzyme inhibition, antibacterial and antioxidative activity assays which is mainly due to its rich phenolic content. The methanol extract of banana showed the highest anti-α-glucosidase and anti-α-amylase activities with IC50 values of 5.45 ± 0.39 mg/mL, 9.70 ± 0.29 mg/mL, respectively. This study showed that methanol and ethanol extract, especially the methanol extract, have potential for use in the development of functional foods for reducing the diabetes and bacterial risks.     

In vitro screening of phenolic compounds, potential inhibition against α-amylase and α-glucosidase of culinary herbs in Thailand

Herbs that are commonly used in Thai dishes were selected for evaluation in order to determine their phenolic compounds, antioxidant activity, and in vitro potential inhibition against α-amylase and α-glucosidase. The total phenolic content ranged from 2.89 to 75.26 mg GAE/g dw. The three aqueous herb extracts with the highest total phenolic content were yellow-berried nightshade (Solanum xanthocarpum), holy basil (Ocimum sanctum) and acacia (Acacia pennata). The antioxidant activity was expressed as percent inhibition of DPPH, ranging from a high of 85% in bitter gourd (Monordica charantia) to a low of 0% in garlic (Allium sativum) and shallot (Allium cepa). A high correlation (r = 0.70, p < 0.05) was observed between total phenolic content and antioxidant activity for the herb extracts in the Solanaceae family while, an insignificant high and negatively correlation (r = −1.00, p > 0.05) for the herb extracts in the Cucurbitaceae and Umbelliferae families was observed. All of the herbs had caffeic content, varying from 0.00 to 23.93 mg/g dw. Peppermint (Mentha canalenisa), galangal (Languas galangal) and holy basil (O. sanctum) had a significant p-coumaric acid content. The first and second obtained principal component represented 60% of the total variation. The potential inhibition against α-amylase for the herbs extracts ranged from 0% to 58%, while the highest percentage was observed in the acacia (A. pennata) extract. The potential inhibition against α-glucosidase varied from 7% to 100%. A high correlation (r = 0.68, p < 0.05) was observed between α-amylase inhibition and caffeic acid content for aqueous extracts in the Alliaceae, Cucurbitaceae, and Leguminosae families, while a high correlation (r = 0.49, p < 0.05) was observed between α-glucosidase inhibition and total phenolic content for the aqueous extracts of all herbs. Therefore, specific culinary herbs showed to have a potential use for dietary management during the early stages of hyperglycaemia.     

Biological activity of rice extract and the inhibition potential of rice extract,rice volatile compounds and their combination against α-glucosidase, α-amylase and tyrosinase

Rice is produced for consumption and traditional medicine. Rice is also used as an ingredient in cosmetic products. In this study, the author investigated the biological activity and inhibition potential against α-glucosidase, α-amylase and tyrosinase activity of rice extract (black rice [BR], red rice [RR] and white rice [WR]), rice volatile compounds, rice extract combined with volatile compounds, rice extract combined with standard inhibitors and volatile compounds combined with standard inhibitors. The results revealed that the free-radical scavenging capacity of rice extract is related to the phenolic content and flavonoids. BR showed the highest potential to inhibit α-glucosidase and α-amylase activity, whereas WR showed the highest potential to inhibit tyrosinase activity. Among rice volatile compounds, vanillin and vanillyl alcohol had the highest inhibition potential against α-glucosidase and α-amylase, respectively, whereas guaiacol had the highest inhibitory activity against tyrosinase. Molecular docking supported by the high binding efficiency was also obtained from vanillin and guaiacol when located at the active site of these enzymes. The combination of RR with acarbose (AB) had the highest inhibition potential and showed a synergic effect on both α-glucosidase and α-amylase. Interestingly, the combination of rice extract (BR, RR and WR) and vanillin and vanillyl alcohol had a synergic effect on α-amylase. Moreover, the combination of WR and vanillyl alcohol had the highest inhibition potential and showed a synergic effect on tyrosinase, whereas rice volatile compounds had a synergic effect on tyrosinase obtained from 2-pentylfuran/kojic acid (KA), vanillin/KA and vanillyl alcohol/KA.     

In vitro antioxidant potential and inhibitory effect of seaweed on enzymes relevant for hyperglycemia

Hizikia fusiforme, Capsosiphon fulvescens, Undaria pinnatifida sporophyll, and Undaria pinnatifida blade extracts were evaluated for in vitro antioxidant and antihyperglycemic activities. Seaweed extracts contained high levels of phenolic compounds (12.44 to 39.01 mg of gallic acid equivalents/g of extract) and exhibited multiple antioxidant activities. Extracts showed weak inhibition of α-amylase. However, all extracts showed pronounced inhibition of α-glucosidase with EC₅₀ values from 2.56 to 18.81 mg/mL. U. pinnatifida sporophyll and U. pinnatifida blade extracts both contained protocatechuic and syringic acids. p-Coumaric and ferulic acids were detected only in the H. fusiforme extract. Caffeic acid and epicatechin were the dominant phenoilc acids found in C. fulvescens extracts. A basis for further research is provided to establish the capability of seaweed extracts as hypoglycemic agents or functional food ingredients.     

Role of Carbohydrate-Cleaving Enzymes in Phenolic Antioxidant Mobilization from Whole Soybean Fermented with Rhizopus oligosporus

Previous research has suggested a relationship between free phenolic content and β-glucosidase activity in solid-state fermented food substrates and to amylase activity in germinating soybeans. This study was undertaken to examine the role of a number of carbohydrate-cleaving enzymes in phenolic antioxidant mobilization from whole soybean during solid-state fermentation. In addition to total soluble phenolic content, α- and β-glucosidase, α-amylase, and β-glucuronidase activities were measured in extracts of soybean fermented with a food-grade fungus, Rhizopus oligosporus. Antioxidant activity of the extracts was determined as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. Our results demonstrate that while total soluble phenolic content increased 120–135% in the extracts, increased antioxidant activity (+61%) was limited to the early fermentation period, with activity decreasing with increased culture time. Higher antioxidant activity was linked to increased glucosidase and glucuronidase activities, while high total phenolic content partly linked to increased amylase activity. The overall results (enzymatic activities and phenolic antioxidant contents) suggest the possible involvement of lignin remobilization and/or degradation activities, as well as phenolic detoxification activities, by Rhizopus oligosporus in phenolic antioxidant mobilization from fermented whole soybean.     

In vitro inhibitory effect of oriental melon (Cucumis melo L. var. makuwa Makino) seed on key enzyme linked to type 2 diabetes: Assessment of anti-diabetic potential of functional food

As the world’s population continues to increase, the agricultural discards of plant origin have attracted considerable attention for various purposes in the pharmaceutical and food industry. The objective of present study was to evaluate the potential of oriental melon (Cucumis melo L. var. makuwa Makino) seed for management of hyperglycaemia-linked to type 2 diabetes. Ethanol and hexane extracts from oriental melon seed were used to evaluate their inhibitory activities against α-glucosidase and α-amylase. Low phenolic-containing hexane extract exhibited much higher inhibitory activities against α-glucosidase and α-amylase than ethanol extract. The GC–MS result revealed that hexane extract constituted linoleic acid (29.6%), oleic acid (17.3%), and palmitic acid (6.5%). At high concentration, hexane extract exhibited strong inhibitory activities against α-glucosidase (35.3%) and α-amylase (61.8%). These in vitro studies indicated that hexane extract of oriental melon seed could be used as a potent alternative for controlling type 2 diabetes.     

Total phenolic content,antioxidant activity,and type II diabetes related functionality of traditionally processed ox-eye bean [Mucuna gigantea (Willd) DC.] seeds: An Indian underutilized food legume

The methanolic extract of ox-eye bean [Mucuna gigantea (Willd) DC.] contained total free phenolic content of 14.80±1.28 g catechin equivalent/100 g extract dry matter. Encouraging levels of ferric reducing/antioxidant power (FRAP, 1,023 mmol Fe[II]/mg extract), inhibition of β-carotene degradation (59.35%) and radical scavenging activity against DPPH (72.12%) and superoxide (43.11%) were exhibited by the raw samples. Further, it also recorded 82.17% of α-amylase and 91.26% of α-glucosidase enzyme inhibition characteristics. Sprouting+oil-frying caused a apparent increase on the total free phenolic content and also significant improvement on the antioxidant and free radical scavenging capacity of methanolic extract, while soaking+cooking as well as open-pan roasting treatments showed diminishing effects. Moreover, inhibition of α-amylase and α-glucosidase enzyme activities was declined to 22.82 and 45.47%, respectively during sprouting+oilfrying treatment, which are more desirable for the dietary management of type II diabetic patients.     

In vitro evaluation of digestive enzyme inhibition and antioxidant effects of naked oat phenolic acid compound (OPC)

This research was focused on digestive enzyme inhibition and antioxidant properties of naked oat phenolic acid compound (OPC). Free and bound phenolic acid were separated from ethyl acetate fraction, n-butanol fraction and aqueous fraction. The interactions between OPC and main digestive enzymes (α-amylase, α-glucosidase, pepsin and trypsin) were studied. It was shown that the semi-purified bound phenolic acid (semi-purified by AB-8 column) has a competitive alpha-glucosidase inhibitor, while OPC of the organic extract fraction exhibited the characteristics of a mixed inhibitor. Bound phenolic-n-butanol fraction (IC₅₀ = 98.39 ± 0.89 µg mL⁻¹) had the strongest ability to scavenge the 1,1-diphenyl-2-picrylhydrazyl (DPPH). Additionally, the starch hydrolysis degree of n-butanol extraction naked oat phenolic compound was significantly lower than other fractions in vitro. The integrated results suggested that OPC could be considered as potential healthy factor to control postprandial blood glucose, and the mechanism maybe via anti-digestion, antioxidation and interaction with diabetes-related starch.     

三种食用菌提取物体外抗氧化与降血糖活性研究

目的:为评价三种食用菌体外抗氧化与降血糖作用。方法:采用水杨酸显色法、DPPH·显色法、铁氰化钾显色法测定三种食用菌及副产物(竹荪、竹荪菌托、茶树菇、松乳菇)提取物的抗氧化能力,再通过α-淀粉酶和α-葡萄糖苷酶活性抑制作用分析提取物的降血糖活性。结果:在实验浓度(0.5~5 mg/mL)范围内三种食用菌及副产物的提取物具有一定的抗氧化和降血糖作用,且存在明显的量效关系。抗氧化以V_C作为阳性对照,降血糖组间进行对照。当浓度达到5 mg/mL时,茶树菇提取物对·OH和DPPH·的清除率最高可达89.45%和87.81%,对Fe3+的还原能力与V_C相近,IC₅₀均为1.04 mg/mL;而竹荪和竹荪菌托提取物对·OH(45.19%和36.04%)、DPPH·(44.30%和36.81%)的清除率和对Fe3+的还原能力(46.61%和48.09%)均较弱,且IC₅₀值均超出实验浓度。当浓度达到5 mg/mL时,茶树菇提取物对α-淀粉酶和α-葡萄糖苷酶活性的抑制率分别62.15%和57.08%,IC₅₀值为3.82和4.10 mg/mL;松乳菇提取物对两种酶的抑制率分别为83.52%和75.43%,IC₅₀值为2.22和2.53 mg/mL;而竹荪和竹荪菌托提取物对α-淀粉酶(15.15%和24.56%)和α-葡萄糖苷酶(26.20%和23.41%)活性的抑制率均较低,且IC₅₀值均超出实验浓度。结论:茶树菇提取物降血糖和抗氧化作用均较强,而松乳菇提取物的降血糖作用较强而抗氧化作用较弱,竹荪和竹荪菌托提取物的抗氧化活性和降血糖活性均较弱。     

Antioxidant and type II diabetes related enzyme inhibition properties of methanolic extract of an underutilized food legume,Canavalia ensiformis (L.) DC: Effect of traditional processing methods

The methanolic extract of Canavalia ensiformis (L.) DC (Jack bean) seed, an underutilized food legume collected from India was analyzed for antioxidant and health relevant functional properties. The raw seeds contained total free phenolic content of 12.98 ± 1.63 g catechin equivalent/100 g extract DM. The raw seed extract exhibited ferric reducing/antioxidant power (FRAP, 1218 mmol Fe[II]/mg extract), inhibition of β-carotene degradation (49.81%), radical scavenging activity against DPPH (56.78%) and superoxide (35.89%). In addition, 77.56% of α-amylase and 75.45% of α-glucosidase enzyme inhibition characteristics were found under in vitro starch digestion bioassay. Sprouting + oil-frying caused an apparent increase on the total free phenolic content with significant improvement on antioxidant and free-radical scavenging capacity, while soaking + cooking as well as open-pan roasting treatments showed diminishing effects. Inhibition of α-amylase and α-glucosidase enzyme activities were declined to 22.69 and 42.69%, respectively during sprouting + oil-frying treatment is more desirable for the dietary management of type II diabetic patients.     

Total phenolic content,antioxidant and antidiabetic properties of methanolic extract of raw and traditionally processed Kenyan indigenous food ingredients

Certain indigenous foods commonly consumed by Kenyan vulnerable groups (the malnourished; children under 5 years of age; pregnant and lactating women; malnourished adults in cases of vitamin or mineral deficiencies, TB, diabetes, cancer, AIDS; refugees; orphans the elderly and the disabled) are not yet evaluated for phenolic content and health relevant functionality. The present study was therefore designed to analyze the phenolic content, antioxidant and antidiabetic properties of methanolic extract of raw and traditionally processed food ingredients. The total phenolic contents of the cereals, legumes, oil seeds and vegetables were ranged from 0.41 to 3.00 g/100 g DM. Amaranth grain (Amaranthus cruentus) and drumstick leaves (Moringa oleifera) exhibited significantly higher phenolic content than the other samples. The methanolic extract of the investigated samples showed promising levels of DPPH radical scavenging activity (81–89%); ferric reducing/antioxidant power (FRAP, 44–744 mmolL^?1 Fe[II]/g extract DM); α-amylase (10–45%) and α-glucosidase (13–80%) inhibition activities. The food ingredients with high phenolic content exhibited relatively higher antioxidant and antidiabetic activities. The results indicate that soaking + cooking is the mild processing method to preserve the phenolic compounds and their health relevant functionality in the presently investigated cereal, legume and oil grains, while cooking is suitable treatment for vegetables.