Research Projects

In our laboratory, experimental work is being conducted in the area of mass spectrometry. We develop mass spectrometry-based methods to determine the bioactive components from dietary botanical supplements. We are also interested in biological systems at the protein level, as well as, quantitatively measuring directed metabolites in a variety of matrices. A number of these projects involve active collaborations with biochemistry, animal sciences and bioinformatic research groups.

1. 4-hydroxy hexenal and 4-hydroxy nonenal

Recent studies have demonstrated the ability of docosahexaenoic acid (DHA) to mediate oxidative stress. A proposed mechanism for these neuroprotective effects of DHA involves induced-peroxidation of DHA to produce 4-hydroxy hexenal (4-HHE), and this compound in turn, is believed to be responsible for triggering an antioxidant pathway. In our first studies, an increase of 4-HHE was marked by a decreased level of 4-hydroxy nonenal (4-HNE), the peroxidative products of arachidonic acid (AA). We have developed a UHPLC-ESI-MS/MS method to selectively analyze for the presence of 4-HHE and 4-HNE, after in-situ derivatization, in several biological matrices including, plasma, serum, and brain tissue. By optimizing the experimental conditions, multiple reaction monitoring (MRM) enables us to quantitatively detect the levels of these analytes. Our method provides a robust and sensitive measure of 4-HHE as a biomarker for assessing the effects of DHA. We have extended these studies to look at these peroxidation products as biomarkers of inflammation in mouse and rat models.

2. Elderberry

Our work examines the small molecules present in elderberry fruit, flowers, and pomace. We have focused initially on the polyphenols present in elderberry juice. Elderberries are provided by Dr. Andrew Thomas at the MU Southwest Research Farm. Dr. Thomas has cultivated a plot of specific genotypes of elderberry in a controlled field environment. This project has several aspects that involves us. One aspect was to develop a method to determine the anthocyanin and total phenol content of elderberry juice. The total phenol content was determined by established methods. The anthocyanin content determination involved adapting a solid phase extraction method, optimizing the UHPLC separation, and quantification by mass spectrometry. We are also characterizing by mass spectrometry the compounds present in aqueous and alcoholic extracts of elder flower and have looked for the presence of cyanogenic glycosides in different parts of elder plants.

Characterization of elderberry is important for the dietary supplement industry and helps to standardize experiments using these compounds, a major concern in this area of research. We will also be able to advise growers the best genotypes based on the intended use of the fruit.

3. Food adulteration by NMR and mass spectrometry

Adulteration of food products for economic benefit has evolved into multiple forms over the last 30 years. We are using NMR and mass spectrometry to examine a number of different food products. We are also developing methods to detect adulteration in a variety of food products such as honey, olive oil, and coffee.

4. Label-free quantitative proteomics

In this project, a global proteomic approach is used. Data are acquired using the parallel accumulation serial fragmentation (PASEF) method in a hybrid trapped ion mobility-quadrupole time-of-flight mass spectrometer (tims-ToF). Using label-free quantitative proteomics, protein groups are identified and quantified. The methodology is now being explored in a number of biological systems of interest.

5. Polyphenols

We are interested in measuring the polyphenol content in a variety of samples including elderberry and honey. This project uses a combination of LC/MS methods and UV/Vis spectrophotometry.