%0 PDF %T Metabolomic Profiling of Natural Products. %A Kowalsick, Amanda. %8 2017-04-20 %R http://localhost/files/hd76sb084 %X Abstract: Plant-based diets have been used for therapeutic purposes, including the prevention and treatment of disease dating back to early times. The upsurge in consumer demand for health-enhancing, biologically active products can be attributed to the growing awareness that diets rich in plant-based materials may help to combat chronic diseases. Plants produce a diverse array of secondary metabolites which assist in the protection and reproduction of the plant. Variation in secondary metabolites produced by plants in response to abiotic and biotic stresses is a key factor that dictates the nutritional, functional and sensory quality of plant-based products. The chemical content of plant volatile extract varies with regards to plant species, geographical origin, cultivar, plant organ, maturity, and environmental factors, making identification of individual constituents difficult. The complex nature of plant-based products makes it difficult to identify all of the constituents by gas chromatography/mass spectrometry (GC/MS) alone. The work described herein employs automated sequential, multidimensional gas chromatography/mass spectrometry (GC-GC/MS) to obtain matrix-specific, retention time/index and mass spectrometry libraries for natural products. Once targeted metabolite libraries are produced, spectral deconvolution of GC/MS data provides a reliable, unambiguous means to identify constituents in various natural products. Specifically, juniper berry essential oil constituents were tracked from starting materials through the manufacturing process to final gin product as a means to determine product and manufacturing quality. Differences in gin products from several manufacturers were observed based on juniper berry content. Matrix-specific citrus metabolites were used to identify individual oil content in citrus oil mixtures and gin products to determine product authenticity. Finally, metabolites were used to track seasonal variations in teas harvested before and after the onset of the East Asian Monsoon in SW China. Volatile extracts were prepared using two different sample preparation techniques to produce a more comprehensive investigation into the effects extreme weather events have on plant physiology. Striking differences in concentration were observed within and among chemical families in as little as five-days after the monsoon rains began.; Thesis (Ph.D.)--Tufts University, 2015.; Submitted to the Dept. of Chemistry.; Advisor: Albert Robbat, Jr..; Committee: Samuel Thomas, Jonathan Kenny, and Jessalin Howell.; Keywords: Analytical chemistry, and Plant sciences. %[ 2022-10-11 %9 Text %~ Tufts Digital Library %W Institution