Our research group has interests in the areas of bio-organic chemistry, natural products chemistry and toxicology. Mass spectrometry is an important technique in our laboratory for studying small organic molecules in complex biological matrices such as blood plasma, cell lysates, tissue homogenates and plant extracts.
Bioconjugation of oxidized lipids
This research project aims to determine how vitamin C interacts with lipid peroxidation products and how vitamin C prevents cellular damage to proteins caused by oxidized lipids. We are interested in these interactions because lipid peroxidation contributes to the development and progression of chronic inflammatory and age-related diseases, such as atherosclerosis. Our laboratory has identified vitamin C (ascorbic acid) as a biological nucleophile able to form Michael adducts with lipid-derived 2-alkenals. This reaction may be of interest as a detoxification pathway for 2-alkenals. The tools that we use for our research include liquid chromatography coupled to mass spectrometry for analysis of lipid conjugates in complex biological matrices, synthesis of (labeled) lipids and their conjugates, cell culture for investigating the biological properties of oxidized lipids and their conjugates and animal models for studying the in vivo formation, metabolism and excretion of oxidized lipids.
In collaboration with Professor Claudia Maier of OSU’s Chemistry Department, we are developing quantitative methods based on isotope dilution mass spectrometry to examine the nature and the extent of protein modifications by lipid peroxidation products in cultured cells and animal models of oxidative stress. One of our main findings is that vitamin C, at physiologically relevant concentrations, prevents adduct formation of oxidized lipids with cellular proteins. The significance of this finding is that vitamin C may help maintain proper function of metabolizing and transporter proteins, thus mitigating the deleterious effects of oxidized lipids.
Structure elucidation and biological activity of natural products
Our laboratory has also interests in the field of natural products isolation and structure elucidation. We have explored the chemistry and biology of prenylated flavonoids of the hop plant (Humulus lupulus) since 1995. We were the first to report that the principal prenylated flavonoid in hops, xanthohumol, exerts anti-inflammatory and cancer chemopreventive activities. Our current aim is to determine whether and how xanthohumol improves dysfunctional lipid and glucose metabolism in humans diagnosed with metabolic syndrome.
Another research project in our laboratory is focused on the chemistry and biology of natural products from the oilseed crop, meadowfoam (Limnanthes alba). The Oregon oilseed industry produces a high-quality oil from meadowfoam seeds that is used in personal care products. Considered useless in the past, the seed waste may prove of value as a natural herbicide in organic farming. We have developed a fermentation procedure for enhancing the herbicidal activity of the seed waste by converting inactive seedmeal glucosinolates into degradation products with herbicidal activity.