Pycnogenol Cytotoxicity in Pancreatic INS-1E β cells Induced by Calcium Dysregulation.

Natural standardized flavonoid extract from the bark of Pinus pinaster, Pycnogenol (Pyc), was recently found to decrease intensively the activity of sarcoplasmic reticulum Ca2+ -ATPase of rabbit skeletal muscle (SERCA1). On the basis of this inhibitory effect in a cell-free system and similarities of SERCA1 to its other isoforms, proapoptotic properties of Pyc may be expected in cellular systems. Pycnogenol (40-100 μg/mL) induced a concentration-dependent decrease of the viability of pancreatic INS-1E β cells associated with induction of apoptosis. In addition, intracellular Ca2+ level increase was found along with reduction of protein expression level of SERCA2b and impairment of insulin secretion by β cells. These facts indicate that Pyc may induce apoptosis by impairment of calcium homeostasis.