Skin Care Hyaluronic Acid Sea Buckthorn Oil Ferulic Acid Plant Stem Cells Not Tested on Animals. Our Vitamin C serum is packed with nutrients to brighten the skin and prevent common signs of aging. To enhance the antioxidant benefits of Vitamin C, our serum includes Ferulic Acid to defend against environmental aggressors, as well as Hyaluronic Acid and Sea Buckthorn Oil to support the skin's protective barrier.