Diabetes affects at least 285 million people globally, and this number continues to increase. Clinical complications include impaired glucose metabolism, hyperglycemia, dyslipidemia, atherosclerosis and non-alcoholic fatty liver disease. Evidence has shown that natural phenolics play a protective effect on both the development and management of type 2 diabetes. This study evaluated effects of the extract from peanut skins containing polyphenols on induced- hyperglycemia using
in vivo
and
in vitro
methods. A human hepatocellular liver carcinoma cell line (HepG2) was used to investigate the effect of the peanut skin extract on cell viability after exposure to high glucose concentrations.
In vivo
, the effect of peanut skin extract on an oral glucose tolerance was investigated in human subjects. Fifteen participants aged 21–32 underwent an oral glucose tolerance test with five treatments: 1) 50-gram glucose solution (reference); 2). 50-gram glucose solution, followed by 12 mg of vegi-capsulated maltodextrin; 3) 50-gram glucose solution, followed by 120 mg of vegi-capsulated maltodextrin-encapsulated peanut skin extract; 4). 50-gram glucose solution, followed by 28 grams of unfortified coated peanuts; 5) 50-gram glucose solution, followed by 28 grams of chili lime coated peanuts fortified with encapsulated peanut skin extract. Glucose levels were measured using a continuous monitor. Peanut skin extract was found to attenuate the decrease in cell viability in high glucose treated HepG2 cells, showing a protective effect against hyperglycemia induced cell death. No difference in the glycemic response area under the curve between any treatments using the tolerance test, but the treatment of the peanut skin extract with the glucose reference resulted in a significantly lower peak blood glucose response at 45 minutes, indicating that it was effective at reducing the glycemic response. The present study shows that the phenolic extract of peanut skins has an antidiabetic effect, further confirming their value as a functional food ingredient.
The ability of polyphenols to act as antioxidants suggests that extracts of peanut skins containing polyphenols can be used as functional ingredients in new food products. The encapsulation of peanut skin extract in maltodextrin allowed for the incorporation of the extracts into flavored coatings for peanuts at levels high enough to increase the antioxidant activity without impacting sensory profiles. Utilization of this by-product of the peanut can create an economic opportunity for the peanut industry.
Muscadine wine has a unique polyphenol profile consisting of anthocyanins, ellagic acids, and flavonols. This study aims to compare the prevention, treatment, and combined activity (P+T) of dealcoholized muscadine wine...
Objectives
The aim of this study was to investigate the effect of concentrated muscadine grape polyphenols (MGP) and muscadine wine polyphenols (MWP) on the onset and progression of collagen induced arthritis (CIA) in mice.
Methods
MGP and MWP were concentrated using Amberlite XAD16N resin. Polyphenol composition was determined on HPLC. Male DBA/1 mice were divided into four treatment groups as (1) healthy control, (2) CIA control, (3) CIA + MWP, and (4) CIA + MGP. Arthritis was induced by intradermal injection of type II collagen on days 0 and day 21. Mice in groups 3 and 4 were gavaged with MWP and MGP using a dose of 400 mg/kg body weight for a total of 21 days. Severity of CIA was evaluated using clinical arthritic score and inflammation in the hind-paws. Plasma levels of cytokines, proteases, and anti-collagen antibody were measured using ELISA.
Results
MGP and MWP contained anthocyanin 3, 5-diglucosides, flavonols, and ellagic acid. Mice in the CIA control group had an onset of arthritis on day 18, which was delayed to day 22 and 24 by MWP and MGP, respectively (P < 0.05). Severity of arthritis was much lower in mice gavaged with muscadine polyphenols after the onset. On day 42, the average arthritic score of mice in the CIA control group progressed to 7.75 on a scale of 0–16, while MGP and MWP significantly reduced this score to 3.75 and 4.00, respectively (P < 0.01). In addition, MGP and MWP significantly reduced the plasma concentration of TNF-α, IL-6, anti-collagen antibodies, and matrix metalloproteinase-3 in CIA mice but not to the same level of healthy mice. The plasma concentration of IL-17 was drastically elevated in CIA mice, but it was not affected by MWP or MGP like other cytokines. This suggested that muscadine polyphenols had limited impact on the Th17 cells in the immune system. Mice gavaged with MPG and MWP had comparable plasma cytokine content, suggesting similar anti-inflammation activity.
Conclusions
Muscadine grape and wine polyphenols blunt the development of arthritis in mice by reducing the levels of key inflammatory cytokines, antibodies, and proteases, and may offer a promising dietary approach to manage arthritic symptoms.
Funding Sources
Florida Department of Agriculture and Consumer Service and Florida Viticulture Advisory Council.
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