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J Agric Food Chem. 2018 May 9;66(18):4621-4629. doi: 10.1021/acs.jafc.8b00650. Epub 2018 Apr 25.

Novel Flavoalkaloids from White Tea with Inhibitory Activity against the Formation of Advanced Glycation End Products.

Author information

1
Natural Products Laboratory, International Joint Laboratory of Tea Chemistry and Health Effects, State Key Laboratory of Tea Plant Biology and Utilization , Anhui Agricultural University , Hefei , Anhui 230036 , People's Republic of China.

Abstract

Two novel flavoalkaloids, (-)-6-(5'''- S)- N-ethyl-2-pyrrolidinone-epigallocatechin- O-gallate (ester-type catechin pyrrolidinone A, etc-pyrrolidinone A, 1), (-)-6-(5'''- R)- N-ethyl-2-pyrrolidinone-epigallocatechin- O-gallate (etc-pyrrolidinone B, 2), and new naturally occurring flavoalkaloids, (-)-8- N-ethyl-2-pyrrolidinone-epigallocatechin- O-gallate (etc-pyrrolidinone C, 3a, and etc- pyrrolidinone D, 3b), were isolated from white tea ( Camellia sinensis). Their structures were identified by extensive nuclear magnetic resonance spectra. The absolute configuration of compounds 1 and 2 was decided by comprehensive circular dichroism spectroscopic analyses. The isolated flavoalkaloids together with (-)-epigallocatechin- O-gallate (EGCG) were evaluated for their inhibition against the formation of advanced glycation end products, with IC50 values ranging from 10.3 to 25.3 μM. Ultra performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry detected these flavoalkaloids in both white tea and fresh tea leaves, which demonstrated the existence of a corresponding biosynthetic pathway in tea plants. Therefore, a possible pathway was proposed to involve deamination, decarboxylation, and spontaneously cyclization of l-theanine and then attachment of the product to EGCG to form the flavoalkaloids.

KEYWORDS:

Camellia sinensis; absolute configuration; advanced glycation end products (AGEs); epigallocatechin-O-gallate (EGCG); l-theanine; pyrrolidinone

PMID:
29669412
DOI:
10.1021/acs.jafc.8b00650
[Indexed for MEDLINE]

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