Imitation of biologically relevant oxidation reactions by titanium dioxide photocatalysis: Advances in understanding the mimicking of drug metabolism and the oxidation of phosphopeptides

Miina Maarit Hennikki Ruokolainen

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

Redox reactions play an important role in human physiology and pathophysiology. For example, oxidative stress and free radical-mediated oxidation of proteins and lipids are implicated in several diseases such as Alzheimer’s and Parkinson’s disease. Oxidation reactions belong also to the most important phase I metabolism pathways of drugs, which can give rise to pharmacologically active or toxic metabolites. The established methods for in vitro drug metabolism studies, e.g. methods using hepatocytes, human liver microsomes (HLMs), and recombinant enzymes, are relatively time-consuming and expensive. Thus, the potential of several nonenzymatic oxidation methods, such as those based on metalloporphyrins, electrochemistry (EC), and Fenton reaction, have been explored for metabolism studies. However, new methods need to be developed to enable rapid production of drug metabolite standards and since none of the above nonenzymatic methods allow comprehensive prediction of phase I drug metabolism. The titanium dioxide (TiO2) photocatalysis method was developed and applied to evaluate the effect of phosphorylation of tyrosine on the oxidation of (phospho)peptides with the same sequence but different phosphorylation states. The results obtained using ultra-high-performance liquid chromatography – mass spectrometry (UHPLC-MS) show that nonphosphorylated tyrosine was the amino acid most susceptible to hydroxyl radical-initiated oxidation, but oxidation of tyrosine was in most cases inhibited by its phosphorylation. The feasibility of TiO2 photocatalysis for imitation of in vitro phase I HLM metabolism of small drug molecules was studied using UHPLC-MS and compared with the electrochemically assisted Fenton reaction (EC-Fenton) and EC. TiO2 photocatalysis, EC-Fenton, and EC imitated 44%, 31%, and 11%, respectively, of the in vitro phase I HLM metabolites of four model compounds. As TiO2 photocatalysis proved most feasible for the imitation of in vitro phase I HLM metabolism, its feasibility for imitation of in vitro phase I HLM metabolism of five anabolic steroids was also examined. TiO2 photocatalysis was able to imitate over half of the hydroxylation and dehydrogenation metabolites, but its imitation of the metabolites resulting from combinations of these reactions was considerably poorer. To enable even more rapid experiments to study biologically relevant oxidation reactions, TiO2-photocatalysis was simply integrated with desorption electrospray ionization (DESI)-MS by using the same TiO2-coated glass wafer for photocatalytic reactions and DESI-MS analysis. This new method enabled high-throughput investigation of photocatalytic oxidation reactions, as demonstrated using 12 model compounds, and imitation of several drug metabolism reactions of three model compounds studied in more detail. In conclusion, TiO2 photocatalysis proved a feasible method for oxidation of compounds with different polarities. TiO2 photocatalysis cannot predict drug metabolism comprehensively, but offers a potential method for rapid, simple, and inexpensive study of oxidation reactions of biomolecules and imitation of several drug metabolism reactions. Preparative scale synthesis of oxidation products by TiO2 photocatalysis is likely an alternative application of the method, but this remains to be demonstrated.
Original languageEnglish
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Kostiainen, Risto, Supervisor
  • Kotiaho, Tapio, Supervisor
  • Sikanen, Tiina, Supervisor
Award date27 Oct 2017
Place of PublicationHelsinki
Publisher
Print ISBNs978-951-51-3713-5
Electronic ISBNs978-951-51-3714-2
Publication statusPublished - 27 Oct 2017
MoE publication typeG5 Doctoral dissertation (article)

Fields of Science

  • 317 Pharmacy

Cite this

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title = "Imitation of biologically relevant oxidation reactions by titanium dioxide photocatalysis: Advances in understanding the mimicking of drug metabolism and the oxidation of phosphopeptides",
abstract = "Redox reactions play an important role in human physiology and pathophysiology. For example, oxidative stress and free radical-mediated oxidation of proteins and lipids are implicated in several diseases such as Alzheimer’s and Parkinson’s disease. Oxidation reactions belong also to the most important phase I metabolism pathways of drugs, which can give rise to pharmacologically active or toxic metabolites. The established methods for in vitro drug metabolism studies, e.g. methods using hepatocytes, human liver microsomes (HLMs), and recombinant enzymes, are relatively time-consuming and expensive. Thus, the potential of several nonenzymatic oxidation methods, such as those based on metalloporphyrins, electrochemistry (EC), and Fenton reaction, have been explored for metabolism studies. However, new methods need to be developed to enable rapid production of drug metabolite standards and since none of the above nonenzymatic methods allow comprehensive prediction of phase I drug metabolism. The titanium dioxide (TiO2) photocatalysis method was developed and applied to evaluate the effect of phosphorylation of tyrosine on the oxidation of (phospho)peptides with the same sequence but different phosphorylation states. The results obtained using ultra-high-performance liquid chromatography – mass spectrometry (UHPLC-MS) show that nonphosphorylated tyrosine was the amino acid most susceptible to hydroxyl radical-initiated oxidation, but oxidation of tyrosine was in most cases inhibited by its phosphorylation. The feasibility of TiO2 photocatalysis for imitation of in vitro phase I HLM metabolism of small drug molecules was studied using UHPLC-MS and compared with the electrochemically assisted Fenton reaction (EC-Fenton) and EC. TiO2 photocatalysis, EC-Fenton, and EC imitated 44{\%}, 31{\%}, and 11{\%}, respectively, of the in vitro phase I HLM metabolites of four model compounds. As TiO2 photocatalysis proved most feasible for the imitation of in vitro phase I HLM metabolism, its feasibility for imitation of in vitro phase I HLM metabolism of five anabolic steroids was also examined. TiO2 photocatalysis was able to imitate over half of the hydroxylation and dehydrogenation metabolites, but its imitation of the metabolites resulting from combinations of these reactions was considerably poorer. To enable even more rapid experiments to study biologically relevant oxidation reactions, TiO2-photocatalysis was simply integrated with desorption electrospray ionization (DESI)-MS by using the same TiO2-coated glass wafer for photocatalytic reactions and DESI-MS analysis. This new method enabled high-throughput investigation of photocatalytic oxidation reactions, as demonstrated using 12 model compounds, and imitation of several drug metabolism reactions of three model compounds studied in more detail. In conclusion, TiO2 photocatalysis proved a feasible method for oxidation of compounds with different polarities. TiO2 photocatalysis cannot predict drug metabolism comprehensively, but offers a potential method for rapid, simple, and inexpensive study of oxidation reactions of biomolecules and imitation of several drug metabolism reactions. Preparative scale synthesis of oxidation products by TiO2 photocatalysis is likely an alternative application of the method, but this remains to be demonstrated.",
keywords = "317 Pharmacy",
author = "Ruokolainen, {Miina Maarit Hennikki}",
year = "2017",
month = "10",
day = "27",
language = "English",
isbn = "978-951-51-3713-5",
series = "Dissertationes scholae doctoralis ad sanitatem investigandam Universitatis Helsinkiensis",
publisher = "University of Helsinki",
number = "57/2017",
address = "Finland",
school = "University of Helsinki",

}

Imitation of biologically relevant oxidation reactions by titanium dioxide photocatalysis : Advances in understanding the mimicking of drug metabolism and the oxidation of phosphopeptides. / Ruokolainen, Miina Maarit Hennikki.

Helsinki : University of Helsinki, 2017. 130 p.

Research output: ThesisDoctoral ThesisCollection of Articles

TY - THES

T1 - Imitation of biologically relevant oxidation reactions by titanium dioxide photocatalysis

T2 - Advances in understanding the mimicking of drug metabolism and the oxidation of phosphopeptides

AU - Ruokolainen, Miina Maarit Hennikki

PY - 2017/10/27

Y1 - 2017/10/27

N2 - Redox reactions play an important role in human physiology and pathophysiology. For example, oxidative stress and free radical-mediated oxidation of proteins and lipids are implicated in several diseases such as Alzheimer’s and Parkinson’s disease. Oxidation reactions belong also to the most important phase I metabolism pathways of drugs, which can give rise to pharmacologically active or toxic metabolites. The established methods for in vitro drug metabolism studies, e.g. methods using hepatocytes, human liver microsomes (HLMs), and recombinant enzymes, are relatively time-consuming and expensive. Thus, the potential of several nonenzymatic oxidation methods, such as those based on metalloporphyrins, electrochemistry (EC), and Fenton reaction, have been explored for metabolism studies. However, new methods need to be developed to enable rapid production of drug metabolite standards and since none of the above nonenzymatic methods allow comprehensive prediction of phase I drug metabolism. The titanium dioxide (TiO2) photocatalysis method was developed and applied to evaluate the effect of phosphorylation of tyrosine on the oxidation of (phospho)peptides with the same sequence but different phosphorylation states. The results obtained using ultra-high-performance liquid chromatography – mass spectrometry (UHPLC-MS) show that nonphosphorylated tyrosine was the amino acid most susceptible to hydroxyl radical-initiated oxidation, but oxidation of tyrosine was in most cases inhibited by its phosphorylation. The feasibility of TiO2 photocatalysis for imitation of in vitro phase I HLM metabolism of small drug molecules was studied using UHPLC-MS and compared with the electrochemically assisted Fenton reaction (EC-Fenton) and EC. TiO2 photocatalysis, EC-Fenton, and EC imitated 44%, 31%, and 11%, respectively, of the in vitro phase I HLM metabolites of four model compounds. As TiO2 photocatalysis proved most feasible for the imitation of in vitro phase I HLM metabolism, its feasibility for imitation of in vitro phase I HLM metabolism of five anabolic steroids was also examined. TiO2 photocatalysis was able to imitate over half of the hydroxylation and dehydrogenation metabolites, but its imitation of the metabolites resulting from combinations of these reactions was considerably poorer. To enable even more rapid experiments to study biologically relevant oxidation reactions, TiO2-photocatalysis was simply integrated with desorption electrospray ionization (DESI)-MS by using the same TiO2-coated glass wafer for photocatalytic reactions and DESI-MS analysis. This new method enabled high-throughput investigation of photocatalytic oxidation reactions, as demonstrated using 12 model compounds, and imitation of several drug metabolism reactions of three model compounds studied in more detail. In conclusion, TiO2 photocatalysis proved a feasible method for oxidation of compounds with different polarities. TiO2 photocatalysis cannot predict drug metabolism comprehensively, but offers a potential method for rapid, simple, and inexpensive study of oxidation reactions of biomolecules and imitation of several drug metabolism reactions. Preparative scale synthesis of oxidation products by TiO2 photocatalysis is likely an alternative application of the method, but this remains to be demonstrated.

AB - Redox reactions play an important role in human physiology and pathophysiology. For example, oxidative stress and free radical-mediated oxidation of proteins and lipids are implicated in several diseases such as Alzheimer’s and Parkinson’s disease. Oxidation reactions belong also to the most important phase I metabolism pathways of drugs, which can give rise to pharmacologically active or toxic metabolites. The established methods for in vitro drug metabolism studies, e.g. methods using hepatocytes, human liver microsomes (HLMs), and recombinant enzymes, are relatively time-consuming and expensive. Thus, the potential of several nonenzymatic oxidation methods, such as those based on metalloporphyrins, electrochemistry (EC), and Fenton reaction, have been explored for metabolism studies. However, new methods need to be developed to enable rapid production of drug metabolite standards and since none of the above nonenzymatic methods allow comprehensive prediction of phase I drug metabolism. The titanium dioxide (TiO2) photocatalysis method was developed and applied to evaluate the effect of phosphorylation of tyrosine on the oxidation of (phospho)peptides with the same sequence but different phosphorylation states. The results obtained using ultra-high-performance liquid chromatography – mass spectrometry (UHPLC-MS) show that nonphosphorylated tyrosine was the amino acid most susceptible to hydroxyl radical-initiated oxidation, but oxidation of tyrosine was in most cases inhibited by its phosphorylation. The feasibility of TiO2 photocatalysis for imitation of in vitro phase I HLM metabolism of small drug molecules was studied using UHPLC-MS and compared with the electrochemically assisted Fenton reaction (EC-Fenton) and EC. TiO2 photocatalysis, EC-Fenton, and EC imitated 44%, 31%, and 11%, respectively, of the in vitro phase I HLM metabolites of four model compounds. As TiO2 photocatalysis proved most feasible for the imitation of in vitro phase I HLM metabolism, its feasibility for imitation of in vitro phase I HLM metabolism of five anabolic steroids was also examined. TiO2 photocatalysis was able to imitate over half of the hydroxylation and dehydrogenation metabolites, but its imitation of the metabolites resulting from combinations of these reactions was considerably poorer. To enable even more rapid experiments to study biologically relevant oxidation reactions, TiO2-photocatalysis was simply integrated with desorption electrospray ionization (DESI)-MS by using the same TiO2-coated glass wafer for photocatalytic reactions and DESI-MS analysis. This new method enabled high-throughput investigation of photocatalytic oxidation reactions, as demonstrated using 12 model compounds, and imitation of several drug metabolism reactions of three model compounds studied in more detail. In conclusion, TiO2 photocatalysis proved a feasible method for oxidation of compounds with different polarities. TiO2 photocatalysis cannot predict drug metabolism comprehensively, but offers a potential method for rapid, simple, and inexpensive study of oxidation reactions of biomolecules and imitation of several drug metabolism reactions. Preparative scale synthesis of oxidation products by TiO2 photocatalysis is likely an alternative application of the method, but this remains to be demonstrated.

KW - 317 Pharmacy

M3 - Doctoral Thesis

SN - 978-951-51-3713-5

T3 - Dissertationes scholae doctoralis ad sanitatem investigandam Universitatis Helsinkiensis

PB - University of Helsinki

CY - Helsinki

ER -

Ruokolainen MMH. Imitation of biologically relevant oxidation reactions by titanium dioxide photocatalysis: Advances in understanding the mimicking of drug metabolism and the oxidation of phosphopeptides. Helsinki: University of Helsinki, 2017. 130 p. (Dissertationes scholae doctoralis ad sanitatem investigandam Universitatis Helsinkiensis; 57/2017).