**4.2 Anti-dementia effects of anthocyanins**

A large number of studies have shown that the oxidative stress response is involved in the pathophysiologic process of Alzheimer's disease (AD) and a large amount of free radicals produced in AD patients' brain. If the large amount free radicals cannot be removed immediately, they will cause the lipid peroxidation of protein, nucleic acid, and other biomolecules and result in the neuronal apoptosis and aggravate the disease development of AD. *Lycium barbarum* L. anthocyanins can improve the mimic AD model rat memory impairment, increase the activity of antioxidant enzymes (SOD and CAT) and GSH content, and reduce MDA and protein carbonyl levels of serum and brain tissues [21]. Other experimental studies have confirmed that grape seed proanthocyanidins can prevent excessive production of β-amyloid protein (Aβ) in the brain and reduce cognitive decline with AD model rats and *Solanum tuberosum* anthocyanins ameliorate domoic acidinduced cognitive dysfunction, which may be used to the treatment of cognitive impairment caused by excitotoxicity and other brain diseases. *Solanum tuberosum* anthocyanins can also inhibit the nerve inflammation by blocking ERK, JNK, and NF-KB signals and show therapeutic effect on the acute encephalitis induced by lipopolysaccharide (LPS) in rats [22, 23].

### **4.3 Effects of anthocyanins in treatment of diabetes**

Diabetes is a lifelong disease, and its incidence rate increases with the age, which seriously disturbs the quality of life to people. Studies have shown that the occurrence and development of diabetes are closely related to the abnormal metabolism

of free radicals in the body. Oxidative stress, deposition of glycosylated end products, and changes of vascular structure and function are all contributed to the increase of free radicals. Anthocyanins have antioxidant activity and can prevent and treat diabetes. Many studies showed that grape seed proanthocyanidin extract (GSPE) could significantly lower the blood glucose and glucose tolerance, increase the body quality, decrease the serum MDA level and increase the SOD activity to the mimic diabetic mice, inhibit fat deposition, and lower blood lipid to the fatty mice. Proanthocyanidins regulate fatty metabolism in mice by commonly influencing the expression of lipid metabolism-related genes, glucose, and insulin tolerance [24–26]. A series of studies by Bao et al. found that GSPE could improve renal function injury caused by diabetes and could improve the symptoms of diabetic nephropathy by antioxidative stress and inhibiting inflammation [27]. These studies suggest that GSPE have a strong hypoglycemic effect, and its hypoglycemic mechanism may be associated to its antioxidant capacity.
