Grapefruit Seed Extract , also known as GSE, is a naturally potent antioxidant derived from the seeds and vibrant pulp of the grapefruit. GSE is particularly rich in phytochemicals such as Flavonoids, Ascorbic acid (Vitamin C), and Tocopherols (Vitamin E) that contribute to its preservative and disinfecting actions. It is used as a natural preservative in a wide range of cosmetic and skincare products to help stop the growth of harmful microorganisms such as fungus or bacteria and extend its shelf life. In water-based formulations, GSE must be supplemented by a full-spectrum commercial preservative.