The overall goals are to develop plant-derived glucosinolates (GS) for long-term human use as dietary chemoprotectors against cancer and other chronic diseases. GS are a large family of thioglucoside N-hydroxysulfates synthesized by plants from several classes of amino acids. They are very abundant in crucifers (broccoli, cabbage, cauliflower) and are likely to provide the main phytochemical contribution to the chemoprotective properties of these plants. GS are the stable, biologically inactive storage forms of isothiocyanates which are potent inhibitors of tumor development and growth. Bioactivation (conversion) of GS to isothiocyanates is catalyzed by plant cell myrosinase and by the gastrointestinal microflora. Mechanistic understanding of the mode of action of these phytochemicals has advanced greatly. The principal obstacles to progress are now lack of adequate quantities of pure GS for evaluation in cells, animals, and humans, and to control and improve bioavailability.
Aim 1 is concerned with developing more efficient methods for isolating and purifying new and already known GS on a progressively larger scale from milligrams to kilograms. With support of this grant, a major advance has been our development of highly efficient continuous, centrifugal, counter-current partition chromatography methods which are easily scalable, and have made possible the production of almost 1 kg of glucoraphanin (the precursor of sulforaphane) and its submission to the NCI RAPID program for clinical development.
This aim seeks to expand this novel and highly efficient separation technology for isolation of additional new glucosinolates guided by their biological activities.
Aim 2 will evaluate the biological activities of a small number of the most promising candidate GS. Activity testing will include evaluating phase 2 enzyme induction, antioxidant, and anti-inflammatory potencies in cell lines;prevention of mouse skin tumors;and protection of human skin against UV. Proposed studies will also assay the antibiotic activity of GS hydrolysates against Helicobacter pylori (a major causative agent of gastric cancer).
Aim 3 will identify individuals with high and low GS to isothiocyanate conversion phenotypes and attempt to discern the factors contributing to these characteristics. Cohorts with stable low conversion phenotypes will be subjected to a variety of dietary modifications, including prebiotic and probiotic interventions, in order to increase conversions and improve the bioavailability of isothiocyanates from GS, and enhance their protective efficacy. This information will advance our development of GS as chemoprotectors and could lead to major health benefits.
The goals of this project are to identify plant components that block the development of cancer and other chronic diseases by boosting our cellular defenses against oxidants, DNA-damaging chemicals, inflammation and radiation. We will isolate these components in adequate quantities for evaluation in animals and humans, and formulate appropriate recommendations to achieve disease risk reduction in humans.
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