Zeaxanthin dipalmitate from Lycium chinense has hepatoprotective activity

We previously reported the isolation of zeaxanthin and zeaxanthin dipalmitate using bioactivity-guided fractionation to discover hepatoprotective components of Lycium chinense against carbon tetrachloride induced hepatotoxicity. The present study was designed to uncover the effects of zeaxanthin dipalmitate on hepatic parenchymal and nonparenchymal cells in vitro. Uptake of [3H]thymidine by cultured rat Ito cells in response to zeaxanthin dipalmitate was measured. Collagen synthesis was assessed by the collagenase digestion method. The effects of zeaxanthin dipalmitate on the formation of nitric oxide (NO) and the release of tumor necrosis factor-alpha (TNF-alpha) from Kupffer cells and peritoneal macrophages were also assayed. Zeaxanthin dipalmitate showed a significant hepatoprotective activity against carbon tetrachloride toxicity. Cellular malondialdehyde (MDA) levels declined significantly with the treatment of the compound in a concentration dependent manner. Zeaxanthin dipalmitate significantly inhibited the uptake of [3H]thymidine by Ito cells. Zeaxanthin dipalmitate also reduced collagen synthesis in Ito cells by 65.1% (p < 0.05) as compared to untreated controls. The formation of NO in either Kupffer cells or in peritoneal macrophages was significantly decreased by zeaxanthin dipalmitate in a concentration dependent manner. The release of TNF-alpha was somewhat less affected by the compound. From these results, we conclude that zeaxanthin dipalmitate exerts a potent hepatoprotective activity by inhibiting Ito cell proliferation, collagen synthesis and by inhibiting certain biochemical functions of Kupffer cells.