Mass Spectrometry-Based Pharmacometabolomics for Understanding Natural Product and Drug Metabolism Restricted; Files & ToC
Crandall, William J. (Spring 2026)
Abstract
Natural products are an important source of pharmacologically active drug scaffolds, yet their chemical complexity presents significant analytical challenges. Slight differences in stereochemistry can have a large effect in terms of biological activity, while biotransformation in the body can further modify pharmacological outcomes through the formation of active or toxic metabolites. Traditional analytical workflows are limited in their ability to study complex natural product mixtures and their biotransformation due to their reliance on isolation intensive workflows, and reductionist approaches toward studying drug metabolism. This dissertation develops and applies advanced tandem mass spectrometry–based methods to integrate molecular networking, stereochemical differentiation, and pharmacometabolomic analysis to provide a unified analytical framework for studying natural product mixtures.
In this dissertation, I first assist in the development of new tools for the querying of mass spectrometry datasets, which are information rich and underutilized. I specifically apply this methodology towards identifying metabolites of the natural product mitragynine, formed through an in vitro model using pooled human liver s9 fractions.
Secondly, I use Kratom (Mitragyna speciosa, Korth, Rubiaceae) as a model for understanding the metabolism of complex natural product mixtures. An in vitro human liver biotransformation system was combined with high-resolution liquid chromatography coupled with tandem mass spectrometry (LC-HRMS/MS) to characterize metabolic products from both individual alkaloids and multiple chemotypes of whole-leaf kratom extracts. A multi-layer molecular networking workflow was established enabling the semi-targeted propagation of metabolic relationships across the entire mixture. Importantly, the precursors exhibited distinct metabolic profiles when metabolized within the full extract compared to individual compounds, highlighting the influence of chemotype and chemical complexity of the mixture on biotransformation pathways.
Lastly, in combination with computational modeling, I applied energy resolved mass spectrometry (ERMS) and ion mobility spectrometry (IMS) to elucidate the stereochemical differences and gas-phase structural dynamics of mitragynine and its three diastereomers. I show for the first time the collision induced rearrangement (CIR) of precursor ions measured by IMS, providing advanced mechanistic insight into the energetics and pathways of dissociation through a 10-member ring opening intermediate.
Collectively, this work bridges analytical chemistry and pharmacology of natural products, providing new approaches for structural characterization, metabolite ID, and metabolism of complex natural product mixtures.
Table of Contents
This table of contents is under embargo until 27 May 2028
About this Dissertation
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File download under embargo until 27 May 2028 | 2026-04-03 16:08:04 -0400 | File download under embargo until 27 May 2028 |
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