Enzymatic Extracts from Wine Industry Waste May Provide Cardiovascular Benefits in the Rat Model

Wine industry wastes are a topic we’ve covered a few times before on The Academic Wino.  We’ve discussed papers on how water waste from the wine industry may be used as an alternative biofuel or biogas as well papers discussing how grape seed extract could be used as a meat preservative.  Grape pomace has also been investigated as a potential protein supplement for Tilapia fish, and in humans, grape pomace has been investigated as a potential supplement to help those suffering from diabetes.

Grape pomace, or marc, can be problematic in the environment when it is accumulated in large quantities.  Recycling grape pomace may provide the winery with economic gains by creating new products from it, in addition to protecting the environment from further damage or industrial pollution.  Grape pomace is full of bioactive polyphenolic compounds which could be beneficial for products aimed at providing some sort of health benefits for animals or humans.  Since the vast majority of these polyphenolic nutrients are located in the skins and seeds of the grapes, the grape pomace; which is basically pressed

Photo by Klearchos Kapoutsis; http://farm7.staticflickr.com/6182/6077347562_94e958e71f.jpg

skins and seeds left after the winemaking process is complete; is a huge source of nutrition that could be utilized in a sort of functional food or “nutraceutical” (think ‘vitamin’ or ‘supplement’).

Polyphenolic compounds have previously been extracted from grape pomace by way of organic solvents, which themselves may be a health risk and also concerning for environmental contamination.  One alternative that has been designed for this purpose is enzymatic extraction.  This method results in a more environmentally-friendly water-soluble by-product which is nontoxic.

These polyphenolic compounds that are found in wine are well documented to be beneficial to human health, including (but not limited to) cardiovascular benefits, antioxidant properties, and anticarcinogenic benefits.  Studies have shown that grape seed extracts also possess similar health benefits as wine, and have been shown to have cardiovascular and vasodilator benefits in the rat model.  Specifically, grape seed (and skin) extracts improve vascular function by increasing nitric oxide (NO), a vasodilator and antiplatelet factor, to the vessels endothelial cells.

Though grape seed extracts and grape skin extracts have been frequently studied for their potential health benefits, no studies have actually examined entire grape pomace extract to determine its ability to provide health benefits to animals or humans.  The goal of the study presented today was to chemically characterize grape pomace extract using enzymatic extraction methods, and to test its effects on the vascular system of rats.  The results could provide information regarding the usability of grape pomace as a functional food or dietary supplement for protecting against cardiovascular diseases.

Methods

Grape pomace consisted of pressed Verdejo grapes from Yllera wineries in Rueda, Valladolid, Spain, which contained the skins, pulp, seeds, and stems.  Polyphenolic compounds were extracted using an enzymatic extraction process then completely dried.  The extract was then lyophilized to a fine red powder.  For every 100 grams of wet pomace, 12 grams of lyophilized extract was made.

The grape pomace extract was analyzed for the following: total protein, crude fat, phytochemical content (kaempferol, quercetin, procyanidin and catechin), oxygen radical absorbance capacity (ORAC), and DPPH radical scavenging activity.

Photo by Nick Savchenko: http://farm8.staticflickr.com/7160/6495446227_33a3f9dfe1.jpg

Male rats were used and were fed a normal laboratory diet.  For the testing vascular function, the thoracic aorta, and second- or third-order branches of small mesenteric arteries were isolated.

For vascular function, the following for measured/analyzed: mechanical activity, relaxation and contraction, NO involvement, and O2- production in arterial sections.

Results

  • The enzymatic extraction process increased the carbohydrate and protein content of the pomace extract.
    • The insoluble fibers, cellulose, hemicellulose, and lignine, all decreased after extraction.
    • Pectin concentrations increased after extraction.
    • There was an overall reduction in fat content after extraction.
  • Polyphenolic compounds present in the extract included kaempferol, catechin, quercetin, and procyanidins B1 and B2.
    • Only trace amounts of resveratrol, gallocatechin, and anthocyanidins were found.
  • The antioxidant activity (ORAC) of the grape pomace extract was 4238.9 +/- 731.0 nmol TE/mg.
  • Addition of grape pomace extract elicited relaxation in the endothelium-intact vasculature of rats.
    • After removing the endothelial layer, this relaxation (a.k.a. vasodilation) was no longer observed.
  • When exposed to nitric oxide synthase inhibitors, vasodilation of the arteries was significantly reduced.
    • The NO synthase inhibitors prevented the synethsis (production) of NO, which had a negative effect on the vasodilatory properties of the blood vessels.
      • After adding grape pomace extract, this inhibitory effect was reversed.
    • After adding the α-adrenergic agonist Phe, concentration-dependent contractions were induced.
      • Exposure to grape pomace extract reduced the maximum concentration elicited by Phe.
  • ET-1 and DETCA, both of which are known to promote the vascular production of O2-, elicited and sustained a contraction in the rat aortas.
    • By exposing the aortas to grape pomace extract, these vascular contractions elicited by the ET-1 and DETCA were reduced.
  • After 3 hours, there was a significant increase in O2- production brought on by ET-1.
    • Grape pomace extract prevented this significant increase in O2- production.

Conclusions

First and foremost, this paper showed that processing grape pomace using an enzymatic extraction process may serve as a good mechanism for extracting the beneficial polyphenols from grape pomace and potentially other foodstuffs which may be recycled into functional foods, dietary supplements, or other

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uses.  The antioxidant activity of the grape pomace extracted in this manner was at similar levels to pomaces extracted using more traditional chemical methods.

Exposure of rat vasculature to grape pomace extract resulted in a reduction in superoxide anion elicited by ET-1.  At the same time, the vascular contraction caused by ET-1 was reduced due to grape pomace exposure.  Exposure to grape pomace also prevented O2- production in the vasculature of the rats.

What do these results suggest?

The authors of the study state that these results are the first of their kind showing the vascular vasodilatory properties of grape pomace extract.  According to the authors, it appears as though grape pomace extract (processed by enzymatic extraction) induces endothelium-dependent vasodilation and reduces vascular constriction brought on by NO-dependent mechanisms.

In plain English, it seems as though like grape seed and grape skin extract, grape pomace extracts also possess significant health benefits, in particular cardiovascular benefits.  Of course, this study focused on the rat model, therefore to be certain similar results will be seen in humans, clinical research trials would need to be performed.

I would also like to see a study that directly compares the vasodilatory properties of blood vessels after exposure by grape pomace extracts produced from traditional organic solvent methods with extract produced from enzymatic extraction methods.  Does one extraction method result in an extract with superior health benefits to the other?  Or is this simply a matter of environmental soundness (which is extremely important in and of itself).

Using the information gathered from this study, what sorts of studies would you like to see performed in the future?  What is the next step?  Do you have any other ideas for using grape pomace that have not been investigated yet in the scientific literature?

Please leave your comments!

Source: Rodriguez-Rodriguez, R., Justo, M.L., Claro, C.M., Vila, E., Parrado, J., Herrera, M.D., and de Sotomayor, M.A. 2012. Endothelium-dependent vasodilator and antioxidant properties of a novel enzymatic extract of grape pomace from wine industrial waste. Food Chemistry 135: 1044-1051.

2 comments for “Enzymatic Extracts from Wine Industry Waste May Provide Cardiovascular Benefits in the Rat Model

  1. WineKnurd
    October 18, 2012 at 7:28 pm

    What ever happened to the old fashioned way of treating marc, make grappa out of it :)

    I agree with your assessment Becca, repeat the study in the rat model using both solvent extracted marc and enzyme extracted marc, with some chemical analysis in order to compare levels antioxidants and polyphenols between the two.

    I do have to wonder, how well any of these extracts behave after digestion. It’s one thing to study the effects when applied directly to the target organ/area, but another to deliver these extracts to their target when they are subject to normal bio-system processing. Rereading the post, it is unclear how these were administered, though it looks like these extracts were not actually fed to the rats.

    • Becca
      October 21, 2012 at 10:05 am

      Apparently making grappa is taking the easy way out! ;)

      You are correct in assuming based on what I wrote in the methods section that they did not actually feed the extract to the rats. The rats received a normal laboratory diet and were then sacrificed when the experiment was ready to take place. After removal of the aorta and other vessels of study, these pieces were then “soaked” (or not) in the grape extract.

      I would think the next step would be to actually feed the extract to the rats in their daily meals, as it’s not like applying extract directly to one’s vessels is an option in real life! :)

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