A gamma-glutamyl peptide isolated from onion (Allium cepa L.) by bioassay-guided fractionation inhibits resorption activity of osteoclasts

Wetli, Herbert A; Brenneisen, Rudolf; Tschudi, Ingrid; Langos, Manuela; Bigler, Peter; Sprang, Thomas; Schürch, Stefan; Mühlbauer, Roman C (2005). A gamma-glutamyl peptide isolated from onion (Allium cepa L.) by bioassay-guided fractionation inhibits resorption activity of osteoclasts. Journal of agricultural and food chemistry, 53(9), pp. 3408-14. Columbus, Ohio: American Chemical Society 10.1021/jf040457i

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One gram of onion added to the food of rats inhibits significantly (p < 0.05) bone resorption as assessed by the urinary excretion of tritium released from bone of 9-week-old rats prelabeled with tritiated tetracycline from weeks 1 to 6. To isolate and identify the bone resorption inhibiting compound from onion, onion powder was extracted and the extract fractionated by column chromatography and medium-pressure liquid chromatography. A single active peak was finally obtained by semipreparative high-performance liquid chromatography. The biological activity of the various fractions was tested in vitro on the activity of osteoclasts to form resorption pits on a mineralized substrate. Medium, containing the various fractions or the pure compound, was added to osteoclasts of new-born rats settled on ivory slices. After 24 h of incubation, the tartrate-resistant acid phosphatase positive multinucleated cells, that is, osteoclasts, were counted. Subsequently, the number of resorption pits was determined. Activity was calculated as the ratio of resorption pits/osteoclasts and was compared to a negative control, that is, medium containing 10% fetal bovine serum only and to calcitonin (10(-12) M) as a positive control. Finally, a single peak inhibited osteoclast activity significantly (p < 0.05). The structure of this compound was elucidated with high-performance liquid chromatography-electrospray ionization-mass spectrometry, time-of-flight electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy. The single peak was identified as gamma-L-glutamyl-trans-S-1-propenyl-L-cysteine sulfoxide (GPCS). It has a molecular mass of 306 Da and inhibits dose-dependently the resorption activity of osteoclasts, the minimal effective dose being approximately 2 mM. As no other peak displayed inhibitory activity, it likely is responsible for the effect of onion on bone resorption.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR)
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DBMR Forschung Mu35 > Forschungsgruppe Phytopharmakologie, Bioanalytik & Pharmakokinetik (discontinued)
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DBMR Forschung Mu35 > Forschungsgruppe Phytopharmakologie, Bioanalytik & Pharmakokinetik (discontinued)

04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DBMR Forschung Mu35 > Forschungsgruppe Knochenbiologie & Orthopädische Forschung
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DBMR Forschung Mu35 > Forschungsgruppe Knochenbiologie & Orthopädische Forschung

UniBE Contributor:

Wetli, Herbert; Brenneisen, Rudolf Max; Tschudi, Ingrid; Langos, Manuela and Mühlbauer, Roman C.

ISSN:

0021-8561

Publisher:

American Chemical Society

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 15:12

Last Modified:

13 Dec 2017 08:33

Publisher DOI:

10.1021/jf040457i

PubMed ID:

15853380

Web of Science ID:

000228810200023

URI:

https://boris.unibe.ch/id/eprint/31652 (FactScience: 196299)

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