Role of Glucoraphanin
Role of glucoraphanin/sulfurophane from broccoli and broccoli sprouts in protection against cancer and other oxidative and degenerative diseases
2005 IFT Annual Meeting, July 15-20 – New Orleans, Louisiana
Session 45, Health benefits of fruits and vegetables: Biological activity of phytonutrients
J. W. FAHEY, Dept. of Pharmacology & Molecular Sciences, Johns Hopkins Univ. School of Medicine, Brassica Chemoprotection Lab., 725 N. Wolfe St., 406 WBSB, Baltimore, MD 21205
The cancer protective effects of broccoli and other cruciferous vegetables have been well documented in the epidemiologic literature over the past 25 years. Glucosinolates, (e.g. “glucoraphanin” in broccoli), are maintained stably in tissues of cruciferous plants and converted to reactive isothiocyanates, (e.g. “sulforaphane” in broccoli), by an enzyme (myrosinase) which is physically segregated from its substrate. Myrosinase is thus only released upon chewing or other damage to that plant tissue but it is also present in the gastrointestinal microflora of healthy human beings. When broccoli and broccoli sprouts are consumed, glucoraphanin is converted to sulforaphane, rapidly absorbed, transported systemically in the blood, metabolized, conjugated, and excreted in the urine. In the process of uptake and elimination from the cells, it induces the formation of a variety of detoxifying and antioxidant peptides and proteins. Additionally, it exerts a direct antibiotic effect on some microbes such as Helicobacter pylori, which infects at least 50% of human beings worldwide, is the causative agent of ulcers and gastritis, and is a major risk factor for the development of gastric cancer. Broccoli and broccoli sprouts have thus been hypothesized to play a role in the amelioration of gastritis, peptic ulcer disease, and stomach cancer as well as a variety of oxidative and degenerative conditions including cancers at a variety of organ sites, age-related macular degeneration, and hypertension. Understanding precisely how glucoraphanin/sulforaphane fits into this preventive spectrum requires a thorough knowledge of its pharmacodynamics, pharmacokinetics and the possible confounding effects of other substances in the diet. Complete appreciation of the effects of dietary delivery of these compounds on health-span is even more complicated, as it requires an understanding of their bioavailability from a complex food matrix.