Grapefruit seed extract (GSE) contains mainly polyphenolic compounds, including quercetin, hesperidin, campherol glycoside, neohesperidin, naringin, apigenin, rutinoside, poncirin, etc. The polyphenols themselves are unstable, but are chemically converted into more stable substances that belong to a diverse class of products, called quaternary ammonium compounds. Some quaternary compounds—benzethonium chloride and benzalkonium chloride, for example—are used industrially as antimicrobials, but are toxic to animal life; hence, we don’t find them in detectable amounts in our GSE. The B vitamin choline is also a quaternary compound, but is nontoxic and even essential for maintaining healthy neurological function and fat metabolism. GSE features the best of both worlds: the quaternary compounds derived from grapefruit exhibit broad-spectrum antimicrobial activity, while evidencing none of the toxic side effects of chemically derived quaternaries. According to an independent laboratory testing “Acute Oral Toxicity,” it would take at least 4 000 times the normal dose of GSE to produce a 50% chance of poisoning (called LD50). Each drop contains: Grapefruit seed extract Other ingredient: Vegetable glycerin.Shake well. Adults: Mix 12–15 drops in a glass of water or juice, one to three times daily, with or without meals, or as directed by your health-care practitioner.