Keracyanin (chloride) is a polyphenolic anthocyanin found naturally in many plants. It has high antioxidant activity, protecting erythrocytes from apoptosis. [1] [2] However, keracyanin (chloride) impairs growth and induces apoptosis in the highly tumorigenic RE-149 DHD cell line. [3] It inhibits a range of mammalian and bacterial proteases, including neutrophil elastase, matrix metalloproteinase-1 (MMP-1), and MMP-9 at concentrations of 6.25-50 &#181g/ml. [4] When added to food, keracyanin (chloride) significantly reduces body weight gain, resistance to insulin, and lipid accumulation in mice fed a high-fat diet. [5]

Reference:
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[2]. Zhang, J., Hou, X., Ahmad, H., et al. Assessment of free radicals scavenging activity of seven natural pigments and protective effects in AAPH-challenged chicken erythrocytes. Food Chemistry 145, 57-65 (2014).
[3]. Zikri, N.N., Riedl, K.M., Wang, L.S., et al. Black raspberry components inhibit proliferation, induce apoptosis, and modulate gene expression in rat esophageal epithelial cells. Nutrition and Cancer 61(6), 816-826 (2009).
[4]. Santos, J., La, V.D., Bergeron, C., et al. Inhibition of host- and bacteria-derived proteinases by natural anthocyanins. J.Periodontal.Res. 46(5), 550-557 (2011).
[5]. Wu, T., Qi, X., Liu, Y., et al. Dietary supplementation with purified mulberry (Morus australis Poir) anthocyanins suppresses body weight gain in high-fat diet fed C57BL/6 mice. Food Chemistry 141(1), 482-487 (2013).