Grape Seed Extract (2016, 2017) & Diabetic Retinopathy
Diabetic retinopathy has long been considered to be a vascular condition, that is, caused by damage to microcapillaries in the eyes due to elevated glucose. It is also considered to be a neurodegenerative condition in that damaged photoreceptor cells may contribute to damaged microcapillaries.
In this study researchers investigated the underlying molecular mechanism of damaged photoreceptors. They used grape seed proanthocyanidin extract to improve functioning of thioredoxin (a protein that acts as an antioxidant and is important for cell-to-cell communication). Doing so would help prevent and treat neurodegenerative diseases. An in vitro test found that grape seed extract upregulated thiordoxin and decreased cell death. In vivo, in lab animals, damage to photoreceptor cells was inhibited by grape seed extract treatment.
Ren, X., Lu, H., Wang, N., Zhang, C., Ji, Y., et al. (2017). Thioredoxin is implicated in the anti apoptotic effects of grapeseed proanthocyanidin extract during hyperglycemia. Mol Med Rep, Nov;16(5):7731-7737.
This study investigated whether grape seed extract could protect the retina in diabetics. Animals with diabetes were divided into three groups, healthy, diabetic, and diabetic animals treated with grape seed extract. The retinas of the diabetic animals became damaged, but the retinal structure of those treated with grape seed extract improved. The researchers concluded that grape seed extract may protect the retina against hyperglycemic damage. This result may be due to activating the Nrf2 pathway (a gene encoding that regulates antioxidant proteins).
Sun, Y., Xiu, C., Liu, W., tao, Y., Wang, J., Qu, Y.I. (2016). Grape seed proanthocyanidin extract protects the retina against early diabetic injury by activating the Nrf2 pathway. Exp Ther Med, Apr;11(4):1253-1258.