Non-enzymatic cyclization of creatine ethyl ester to creatinine
Abstract
Creatine ethyl ester was incubated at 37 degrees C in both water and phosphate-buffered saline and the diagnostic methylene resonances in the (1)H NMR spectrum were used to identify the resultant products. It was found that mild aqueous conditions result in the cyclization of creatine ethyl ester to provide inactive creatinine as the exclusive product, and this transformation becomes nearly instantaneous as the pH approaches 7.4. This study demonstrates that mild non-enzymatic conditions are sufficient for the cyclization of creatine ethyl ester into creatinine, and together with previous results obtained under enzymatic conditions suggests that there are no physiological conditions that would result in the production of creatine. It is concluded that creatine ethyl ester is a pronutrient for creatinine rather than creatine under all physiological conditions encountered during transit through the various tissues, thus no ergogenic effect is to be expected from supplementation.
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There are no peer-reviewed published papers showing that ingestion of equal amounts of creatine salts or other forms of creatine (effervescent creatine, creatine ethyl ester, buffered creatine, creatine nitrate, creatine dipeptides, or micro amounts in creatine serum and beverages) increases creatine storage in muscle to a greater degree than creatine monohydrate.
“there are no peer-reviewed published papers showing that the ingestion of equal amounts of creatine salts [188–191] or other forms of creatine like effervescent creatine [128], creatine ethyl ester [43, 192, 193], buffered creatine [41], creatine nitrate [194, 195], creatine dipeptides, or the micro amounts of creatine contained in creatine serum [196] and beverages (e.g., 25–50 mg) increases cre”
From Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? (2021) · cites this paper as [193]
Prior studies have shown that CEE degrades rather quickly to creatinine when exposed to low pH levels as would be found in the stomach.
“However, prior studies have shown that it degrades rather quickly to creatinine when exposed to low pH levels as would be found in the stomach (Giese and Lecher 2009a; Katseres et al. 2009).”
From Analysis of the efficacy, safety, and regulatory status of novel forms of creatine (2011) · cites this paper as Giese and Lecher 2009a
CEE rapidly degrades to creatinine when exposed to stomach acid; under physiological conditions, CEE non-enzymatically converts to creatinine with no measurable conversion to creatine; and the half-life of CEE is about one minute, suggesting it may hydrolyze too quickly to reach muscle cells in its ester form.
“Childs and Tallon reported that CEE rapidly degrades to creatinine when exposed to stomach acid [34].”
From Bioavailability, Efficacy, Safety, and Regulatory Status of Creatine and Related Compounds: A Critical Review (2022) · cites this paper as [35]
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References 22 · Cited by 27
- Authors
- Giese, M. W., & Lecher, C. S.
- Affiliations
- Marian University - Indiana (US)
- Corresponding author
- Giese, Matthew W.
- ORCID
- Giese, Matthew W.
- Venue
- Biochemical and Biophysical Research Communications
- Publisher
- Elsevier BV
- Published
- 2009-10
- Volume
- 388
- Issue
- 2
- Pages
- 252-255
- ISSN
- 0006-291X (ISSN-L)
- OpenAlex
- W1991687611
- Cited by
- 27
- References
- 22
- Citations by year
- 2025: 2 · 2023: 1 · 2022: 1 · 2021: 2 · 2019: 1 · 2018: 1 · 2016: 1 · 2015: 4 · 2014: 1 · 2013: 3 · 2012: 2
- FWCI
- 1.33
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Biochemical and Biophysical Research Communications (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Butler University
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
- Health Sciences › Medicine › Physiology › Biochemical effects in animals
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Biochemistry › Amino Acid Enzymes and Metabolism
- Keywords
- creatinine, creatine, ergogenic aids, creatine supplementation, pH dependence, creatine metabolism
- MeSH terms
- Creatine, Creatinine, Cyclization, Magnetic Resonance Spectroscopy
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