Grapes (Vitis vinifera) belong to the Vitaceae family and are native to central Europe and Southwestern Asia. Many varieties of grapes can be classified based on their usage, like raisin grapes, wine grapes, etc. Seeds from wine-making industries are collected as by-products and used for Grape Seed Extract (GSE) production. Grape seed extract is rich in polyphenols, flavonoids, and polyunsaturated fatty acids (PUFAs). Polyphenols and flavonoids in grape seed extract are attributed to its excellent antioxidant properties. Due to the presence of PUFAs, grape seed extract exerts cardioprotective effects. Besides having antioxidant and cardioprotective properties, GSE has anti-cancer, anti-apoptotic, and anti-ageing effects1. In this article, we will focus on the antioxidant and anti-hypertensive effects of GSE.
In our body, there is a balance between oxidants (free radicals) and antioxidants; when this balance is lost, it results in impaired redox signalling and molecular damage2. There are various reports on the antioxidant potential of grape seed extract. A study observed that administering GSE to diabetic Wistar rats significantly reduced plasma lipid peroxides and carbonylated protein levels and improved overall antioxidant activity3. Another study observed an increased lipid peroxidation in the nervous system of aged rats, which was restored to a normal level after administering GSE. Additionally, the level of antioxidant enzymes (catalase, superoxide dismutase and glutathione peroxidase) decreased in aged rats were restored to normal levels, thereby improving the overall antioxidant status of aged rats4. In another study, researchers identified catechin, gallic acid, chlorogenic acid, ellagic acid and cyanidin in GSE. They observed that cyanidin in GSE imparted maximum prevention of DNA oxidation than other metabolites5.
Grape seed extract is rich in phenolic compounds. It is reported to regulate blood pressure via the activation of nitric oxide synthase (eNOS) in blood vessels, which causes relaxation of blood vessels. Various clinical studies support the fact that GSE exerts antihypertensive effects. Clinical research observed that GSE supplementation (150 mg and 300 mg OD) lowered systolic and diastolic blood pressure in patients with metabolic syndrome. No significant difference in the two doses was observed6. Another 16-week, double-blind, placebo-controlled, randomized clinical trial observed that GSE supplementation (300 mg/day) significantly reduced systolic and diastolic blood pressure in the interventional group compared to placebo. They also observed eNOS activation and reduced endothelin-1, sICAM, and sVCAM secretion in HUVEC cells in vitro7.
Overall, it can be inferred that grape seed extract exerts an antioxidant effect by modulating the levels of antioxidant enzymes and an antihypertensive effect via eNOS production. GSE supplementation is key to managing blood pressure.
References
(1) Gupta, M.; Dey, S.; Marbaniang, D.; Pal, P.; Ray, S.; Mazumder, B. Grape Seed Extract: Having a Potential Health Benefits. Journal of Food Science and Technology. Springer April 1, 2020, pp 1205–1215. https://doi.org/10.1007/s13197-019-04113-w.
(2) Sies, H. Oxidative Stress: Concept and Some Practical Aspects. Antioxidants 2020, 9 (9), 1–6. https://doi.org/10.3390/antiox9090852.
(3) Chis, I. C.; Ungureanu, M. I.; Marton, A.; Simedrea, R.; Muresan, A.; Postescu, I.-D.; Decea, N. Antioxidant Effects of a Grape Seed Extract in a Rat Model of Diabetes Mellitus. Diab Vasc Dis Res 2009, 6 (3), 200–204. https://doi.org/10.1177/1479164109336692.
(4) Balu, M.; Sangeetha, P.; Haripriya, D.; Panneerselvam, C. Rejuvenation of Antioxidant System in Central Nervous System of Aged Rats by Grape Seed Extract. Neurosci Lett 2005, 383 (3), 295–300. https://doi.org/10.1016/j.neulet.2005.04.042.
(5) Aybastıer, Ö.; Dawbaa, S.; Demir, C. Investigation of Antioxidant Ability of Grape Seeds Extract to Prevent Oxidatively Induced DNA Damage by Gas Chromatography-Tandem Mass Spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2018, 1072, 328–335. https://doi.org/10.1016/j.jchromb.2017.11.044.
(6) Sivaprakasapillai, B.; Edirisinghe, I.; Randolph, J.; Steinberg, F.; Kappagoda, T. Effect of Grape Seed Extract on Blood Pressure in Subjects with the Metabolic Syndrome. Metabolism 2009, 58 (12), 1743–1746. https://doi.org/10.1016/j.metabol.2009.05.030.
(7) Schön, C.; Allegrini, P.; Engelhart-Jentzsch, K.; Riva, A.; Petrangolini, G. Grape Seed Extract Positively Modulates Blood Pressure and Perceived Stress: A Randomized, Double-Blind, Placebo-Controlled Study in Healthy Volunteers. Nutrients 2021, 13 (2), 1–18. https://doi.org/10.3390/nu13020654.
