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J Agric Food Chem. 2019 Oct 2;67(39):10853-10862. doi: 10.1021/acs.jafc.9b03894. Epub 2019 Sep 20.

Dynamics of the Cellular Metabolism of Leptosperin Found in Manuka Honey.

Author information

1
Faculty of Life and Environmental Science , Shimane University , Matsue , Shimane 690-8504 , Japan.
2
Graduate School of Environmental and Life Science , Okayama University , Okayama 700-0082 , Japan.
3
Department of Biotechnology , Toyama Prefectural University , Imizu , Toyama 939-0398 , Japan.

Abstract

Leptosperin (methyl syringate β-d-gentiobioside) is abundantly found in manuka honey, which is widely used because of its antibacterial and possible anti-inflammatory activities. The aim of this study was to examine the molecular mechanism underlying the metabolism of leptosperin. Five phytochemicals (leptosperin, methyl syringate (MSYR), glucuronate conjugate of MSYR (MSYR-GA), sulfonate conjugate of MSYR (MSYR-S), and syringic acid (SYR)) were separately incubated with HepG2 and Caco-2 cells. After incubation, we found that the concentration of MSYR decreased, whereas the concentrations of SYR, MSYR-GA, and MSYR-S increased. By profiling with inhibitors and carboxylesterases (CES1, 2), we found that the conversion from MSYR to SYR was mediated by CES1. Lipopolysaccharide-stimulated RAW264.7 cells restored MSYR-GA to MSYR possibly by the secreted β-glucuronidase. All of the mice administered with leptosperin, MSYR, or manuka honey showed higher MSYR (13.84 ± 11.51, 14.29 ± 9.19, or 6.66 ± 2.30 nM) and SYR (1.85 ± 0.66, 6.01 ± 1.20, or 8.16 ± 3.10 nM) levels in the plasma compared with that of the vehicle controls (3.33 ± 1.45 (MSYR) and 1.85 ± 0.66 (SYR) nM). The findings of our study indicate that the unique metabolic pathways of these compounds may account for possible functionalities of manuka honey.

KEYWORDS:

carboxylesterase; leptosperin; metabolism; methyl syringate; syringic acid

PMID:
31496237
DOI:
10.1021/acs.jafc.9b03894
[Indexed for MEDLINE]

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