An animal study conducted by Tsuda et al. (2004), demonstrated that cyanidin-3-glucoside from purple corn functions as an anti-obesity and an anti-diabetic agent. Weight gain was apparent in over-fed control mice, but not in over-fed mice that were administered purple corn cyanidin-3-glucoside. The researchers also reported that adipocytokine production increased when cyanidin-3-glucoside was administered in animal models. Adipocytokines, such as adiponectin and leptin, are proteins in the plasma that are valuable markers in glucose homeostasis. It was also discussed by Ryan et al. (2003) that adiponectin levels are substantially lower in obese or diabetic human subjects. When weight loss occurs, adiponectin levels are increased and restored to normal levels. Hyperglycemia is also a key marker tied to diabetes and obesity. When weight gain occurs, it is generally followed by excessive glucose levels in the plasma leading to hyperglycemia. Excess glucose is converted to fats/triglycerides and stored in adipose tissue. Tsuda’s team investigated purple corn’s role in fat metabolism and found that mice consuming the purple corn anthocyanins had reduced triglyceride accumulation in adipocytes (fat cells), and hyperglycemia (excessive glucose in the plasma) was reversed. This suggests that purple corn may have a significant role in controlling weight and hyperglycemia.
Hagiwara et al. (2001) illustrated the ability of purple corn to suppress colorectal cancer in an animal study. When purple corn was administered to mice with colorectal carcinomas, the lesions significantly decreased. To further understand the structure-function relationships of anthocyanins and chemoprotection, a group of researchers from Ohio State University (Jing et al., 2008) investigated a number of high-anthocyanin extracts and their effect on a colon cancer cell line. Purple corn was the most inhibitory, even over chokeberry, purple carrot, bilberry, and others. It was determined that the anthocyanin chemical structure affected chemoprotection, with nonacylated monoglycosylated anthocyanins having greater inhibitory effect on the cancer cell proliferation. These exciting preliminary findings suggest that the ability of purple corn anthocyanins to suppress cancer growth is an area that should be further explored.
In the vascular system, endothelial nitric oxide synthase (eNOS) produces nitric oxide. Higher nitric oxide levels aid in relaxing the blood vessels and can be a good indicator of overall vascular integrity. Xu et al. (2004) have shown that cyanidin-3-glucoside increases eNOS production, which then relaxes vascular endothelial cells and indirectly has a positive effect on blood pressure. An animal study conducted by Shindo et al. (2007) showed a reduction in the blood pressure and heart rate of hypertensive rats after their diets were supplemented with purple corn anthocyanins. Oxidative stress and inflammation are also considered to play a pivotal role in vascular endothelial dysfunction by triggering activation of certain transcription factors. A study by Speciale et al. (2010) discusses how the predominant anthocyanin in purple corn, cyanidin-3-glucoside, appears to act as a modulator of gene regulation and signal transduction pathways. This helps us to understand the underlying the role of this and other anthocyanins in the prevention of diseases associated with inflammation and oxidative stress.