Although phytochemicals have a long history of use in the treatment of diseases, only recently have a number of phytochemical been identified that may prevent certain diseases in humans. The long-term objective of this proposal is to discovery new phytochemicals, especially from dietary sources, that have the potential to prevent coronary heart disease. In this proposal, phytochemicals from tropical fruits and vegetables will be examined for their potential to prevent heart disease. Tropical fruits and vegetables will be used in this study due to their anticipated low toxicity, as well as for the diversity of phyto produced by tropical plant species. Tropical fruits and vegetables will be obtained from US suppliers, as well as from Asian collaborators. Plants will be extracted and tested in an in vitro assay to detect potential cardioprotective agents. The assay described in this proposal is a fast, simple, and reliable test for the inhibition in the scientific literature, and is a method that detects oxidation products using head-space gas chromatography. Extracts that display significant activity in this assay will be subjected to bioactivity- directed isolation. Active phytochemicals will be identified using modern spectroscopic techniques, including one- and two-dimensional nuclear magnetic resonance. Attempts will be made to prevent re-isolation of known inhibitors of LDL-oxidation through literature searches, and by the use of a LC/MS dereplication system. It is expected that this research will lead to the discovery of novel phytochemicals that prevent the oxidation of LDL in vitro. These compounds may also serve as models for potential new therapeutic agents for the treatment of hypercholesterolemia. This is a pilot project for a new investigator.