Anthocyanins, derived from the Greek words "anthos" meaning flower and "kyanos" meaning blue,  are water-soluble flavonoid pigments that appear red to blue, according to pH. They are created by plants and provide color in leaves, stems, roots, flowers, and fruits.

Richly concentrated in berries, anthocyanins were the topic of research presented at a 2007 symposium on the health benefits of berries. Researchers presented anthocyanins potential health effects against:

• Cancer
• Aging
• Neurological diseases
• Inflammation
• Diabetes
• Bacterial infections

As of 2003 more than 400 anthocyanins had been reported while more recent literature (early 2006), puts the number at more than 550.

Anthocyanins are found in fresh and frozen berries, but not in processed foods.

References

Wang SY, Jiao H. Scavenging capacity of berry crops on superoxide radicals, hydrogen peroxide, hydroxyl radicals, and singlet oxygen. J Agric Food Chem 2000 Nov;48(11):5677-84.Igarashi K, et al. Preventive effects of dietary cabbage acylated anthocyanins on paraquat-induced oxidative stress in rats. Biosci Biotechnol Biochem 2000 Aug;64(8):1600-7. Tsuda T. The role of anthocyanins as an antioxidant under oxidative stress in rats. Biofactors 2000;13(1-4):133-9.Zadok D. The effect of anthocyanosides in a multiple oral dose on night vision. Eye 1999 Dec;13(Pt 6):734-6.Meiers S. The anthocyanidins cyanidin and delphinidin are potent inhibitors of the epidermal growth-factor receptor. J Ag Food Chem 2001 Feb 19;49(2):958-62.Kong J. M., Chia L. S., Goh N. K., Chia T. F., Brouillard R. (2003). "Analysis and biological activities of anthocyanins.". Phytochemistry 64 (5): 923-33. doi:10.1016/S0031-9422(03)00438-2.?