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.
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.
This 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.
National Diabetes Education Program of NIH, Mayo Clinic and American Diabetes Association recommend eggplant-based diet as a choice for management of type 2 diabetes. The rationale for this ...suggestion is the high fiber and low soluble carbohydrate content of eggplant. We propose that a more physiologically relevant explanation lies in the phenolic-linked antioxidant activity and α-glucosidase inhibitory potential of eggplant which could reduce hyperglycemia-induced pathogenesis. Results from this study indicate that phenolic-enriched extracts of eggplant with moderate free radical scavenging-linked antioxidant activity had high α-glucosidase inhibitory activity and in specific cases moderate to high angiotensin I-converting enzyme (ACE) inhibitory activity. Inhibition of these enzymes provide a strong biochemical basis for management of type 2 diabetes by controlling glucose absorption and reducing associated hypertension, respectively. This phenolic antioxidant-enriched dietary strategy also has the potential to reduce hyperglycemia-induced pathogenesis linked to cellular oxidation stress. These results provide strong rationale for further animal and clinical studies.
Levels of obesity-linked non-insulin-dependent diabetes mellitus (NIDDM) and hypertension are highest among indigenous communities in North America. This is linked to changes in dietary pattern ...towards high calorie foods such as sugar, refined grain flour, and sweetened beverages. Therefore, a return to traditional dietary patterns may help to reduce these disease problems because of better balance of calories and beneficial nutrients. Further protective non-nutrient phenolic phytochemicals against NIDDM and hypertension are potentially high in these foods but less understood. In this study antidiabetic- and antihypertension-relevant potentials of phenolic phytochemicals were confirmed in select important traditional plant foods of indigenous communities such as pumpkin, beans, and maize using in vitro enzyme assays for -glucosidase, alpha-amylase, and angiotensin I-converting enzyme (ACE) inhibitory activities. In vitro inhibitory activities of these enzymes provide a strong biochemical rationale for further in vivo studies and dietary management strategy for NIDDM through the control of glucose absorption and reduction of associated hypertension. These enzyme inhibitory activities were further compared to total soluble phenolic content and antioxidant activity of the above-targeted plant foods. Pumpkin showed the best overall potential. Among the varieties of pumpkin extracts P5 (round orange) and P6 (spotted orange green) had high content of total phenolics and moderate antioxidant activity coupled to moderate to high alpha-glucosidase and ACE inhibitory activities. Therefore this phenolic antioxidant-enriched dietary strategy using specific traditional plant food combinations can generate a whole food profile that has the potential to reduce hyperglycemia-induced pathogenesis and also associated complications linked to cellular oxidation stress and hypertension.
Listeria monocytogenes is a food safety challenge in various food systems including fresh and frozen meat and poultry. Natural antimicrobials from plant sources in combination with salts of organic ...acids have the potential to control
L. monocytogenes. In this research the efficiency of water soluble phenolic extracts of oregano and cranberry in combination with sodium lactate was evaluated for control of
L .monocytogenes. In both broth and cooked meat studies, the results indicated that the combination of water soluble extracts of oregano and cranberry, at a ratio of 50:50 and a concentration of 750 ppm, with 2% sodium lactate had the best inhibitory effect in the tested strain. Based on the rationale that phenolics in oregano and cranberry behave as proline analogs, the potential recovery of pathogen growth in medium with the best inhibitor concentration and supplemented with 1 mM proline was evaluated. The results indicated that there was a proline-induced growth recovery, pointing to a possible mechanism of action of inhibitors, involving proline metabolism. These results confirm the potential of plant extracts to be antimicrobial, and when combined with sodium lactate, can be used as a nature constituent of multiple-barrier food preservation systems.
The rationale of this study was to enhance the nutritional quality of dry barley seeds. In this study we are evaluating the effect of germination on barley seeds relevant to total phenolic contents, ...antioxidant activity (in terms of DPPH free-radical scavenging) and the
in vitro
α-glucosidase inhibitory activities. Barley seeds were germinated for 18.5, 24, 30, 48, and 67 h and then extracted in water. The total phenolic contents, antioxidant activities and α-glucosidase inhibitory activities changed with germination time. More specifically, within the first 48 h of germination the total phenolic content increased from 1.1 mg/g fresh weight (0 h) to 3.4 mg/g fresh weight (48 h) and then slightly reduced by 67 h. Similarly, α-glucosidase inhibitory activity was significantly increased from an IC
50
128.82 mg/mL (0 h) to an IC
50
18.88 mg/mL (48 h) and then slightly reduced by 67 h. Significant maltase inhibitory activity was observed only with 48 h-germinated extract. Antioxidant activities increased continuously from an IC
50
15.72 mg/mL at 0 h to and IC
50
5.72 mg/mL after 48 h of germination. Based on our observations, barley seed germination was over after 48 h. During the progress of germination phenolic compounds are becoming available and are more easily extracted. After 48 h, lignification is initiated resulting to the decreased total phenolic content and observed antioxidant and carbohydrate hydrolyzing enzyme inhibition activities. The above results indicate the positive effect of germination in barley seeds for enhanced antioxidant and α-glucosidase inhibitory activities.
Cinnamomum cassia
(cinnamon) proanthocyanidins (PACs) are believed to have anti-hyperglycemic potential
via
stimulation of insulin sensitivity. The present study investigates the carbohydrate ...hydrolyzing enzyme inhibition of cinnamon PACs. Five grams of cinnamon bark powder were extracted in 100 mL acetone solution (CAE) (acetone: water: hydrochloric acid, 70:29.9:0.01) for 2 h at room temperature and in 100 mL deionized water for 30 min at 90 °C (CWE). PACs were purified from CAE using LH-20 (CAE-PAC) to be further evaluated. PAC contents were evaluated by 4-Dimethylaminocinnamaldehyde (DMAC) assay and yielded 795, 177 and 123 mg/g, for CAE-PAC, CAE and CWE respectively. The total phenolic contents of CAE and CWE were determined to be 152 and 134 mg/g respectively. All extracts were adjusted to the same PAC content (180, 90, 45 and 20 μg) and the inhibitory activity against rat α-glucosidase was determined. The CAE-PAC fraction had very low rat α-glucosidase inhibitory activity, CAE had the highest (IC
50
0.474 mg/mL total phenolic (TP) basis) followed by CWE (IC
50
0.697 mg/mL TP basis). The specific maltase and sucrase inhibitory activities were determined and CAE (IC
50
0.38 and 0.10 mg/mL TP basis) had higher inhibition than CWE (IC
50
0.74 and 0.37 mg/mL TP basis). Results suggest that the observed bioactivity is not PAC dependent and that CAE has a higher anti-hyperglycemic potential than CWE
via
inhibition of carbohydrate hydrolyzing enzymes.
ABSTRACT
An increasing number of studies indicate that regular intake of fruits and vegetables have clear links to reduced risk of chronic diseases like diabetes and cardiovascular disease. The ...beneficial effects in many cases have been attributed to the phenolic and antioxidant content of the fruits and vegetables. Apples are a major source of fiber and contain good dietary phenolics with antioxidant function. Previous epidemiological studies have indicated that intake of apples reduces the risk of developing type 2 diabetes. Our studies indicate that this reduced risk is potentially because of the modulation of postprandial glucose increase by phenolics present in apples via inhibition ofα‐glucosidase. Phenolic content was evaluated during 3 months of postharvest storage of four varieties of apples and results indicated positive linkage to enhanced postharvest preservation andα‐glucosidase inhibition. These in vitro results along with existing epidemiological studies provide strong biochemical rationale for further animal or human clinical studies.
PRACTICAL APPLICATIONS
The understanding of phenolic‐linked antioxidant enzyme responses during postharvest storage of apples has implications for using the same phenolic functional ingredients toward health benefits such as α‐glucosidase inhibition linked to glycemic index control associated with type 2 diabetes. Therefore strategies to understand phenolic‐linked postharvest preservation and natural treatments to extend this preservation in selected varieties, such as McIntosh and Cortland in this study, can be basis for food ingredient design for health benefits. These strategies can then be extended to prolong postharvest preservation and enhance phenolic linked human health benefits of a wide variety of fruits and vegetables.
Theobroma cacao (cocoa) contains a wide variety of phenolic phytochemicals, including proanthocyanidins (PACs), and their bioactivities have been reported in various reports. The present study ...investigates the carbohydrate hydrolyzing enzyme inhibitory activity of cocoa. Defatted cocoa powder was extracted in 100 mL acetone solution (acetone: water: hydrochloric acid, 70:29.9:0.01) for 2 h at room temperature. The acetone extract was subjected to LH‐20 column chromatography using two different methods to recover fractions of different polarities. The extract and resulting fractions were evaluated for the total phenolic content, PAC content and in vitro inhibitory activity against carbohydrate hydrolyzing enzymes. COAE‐PAC had higher total phenolic content and PACs than COAE‐LMW; however, COAE‐LMW resulted to higher inhibitory activity against carbohydrate hydrolyzing enzymes. Our findings suggest that cocoa acetone extracts have potential to manage post‐prandial hyperglycemia via inhibition of carbohydrate hydrolysis enzymes and that this effect is not PAC dependent.
Practical Applciation
Type 2 diabetes prevention is a major hurdle of our society. Various research findings suggest that natural product ingredients in combination with lifestyle changes can prevent the progression of prediabetes to type 2 diabetes. To effectively design natural product ingredients for the prevention of prediabetes progression to type 2 diabetes requires thorough evaluation of the mechanism of action and potential bioactives. Proanthocyanidins (PACs) present in cocoa have been linked to various health benefits of cocoa. Recent findings suggest that cocoa can potentially prevent type 2 diabetes via inhibition of carbohydrate hydrolyzing enzymes. This work identifies whether this inhibitory activity is PAC or lower molecular weight phenolic dependent. Ultimately, this work contributes a small piece in the deeper evaluation of cocoa for the management of type 2 diabetes.
The health-relevant functional benefits of Lactobacillus bulgaricus and Lactobacillus acidophilus fermented milk and soymilk were investigated and targeted for management of hyperglycemia and related ...complication of hypertension using in vitro models. Free radical scavenging-linked antioxidant activity and enzyme inhibitory activities linked to hyperglycemia (α - amylase and α−glucosidase) and hypertension (angiotensin - I converting enzyme, ACE) of fermented substrates were evaluated using in vitro assays. These activities were correlated to phenolic and lactic acid contents. In spite of total phenolic content decreasing over 24 h, the free radical scavenging-linked antioxidant activity increased. α−Glucosidase inhibitory activity increased with fermentation, with higher activity in soymilk substrate. α-Amylase inhibitory activity was high in milk substrate throughout the fermentation and in soymilk it increased from a lower initial activity. Initial ACE inhibitory activity was high in soymilk and was maintained following fermentation. In milk, initial ACE inhibitory activity was low, which increased following fermentation, especially for L. bulgaricus fermentation. The enhancement of ACE inhibitory activity in milk was correlated to the lactic acid contents with the range of 0.5-1% having the highest activity. This study provides insights that fermentation of milk and soymilk with specific lactic acid bacterial strains can potentially enhance functional properties relevant for hyperglycemia management linked to type 2 diabetes and related complication of hypertension.
