Structural identification and physiological function evaluation of A new natural non-protein amino acid in Camellia...

Camellia ptilophylla, a precious tea variant, has an inferior flavor, possibly related to the specificity of its amino acid composition. In this study, significantly different compositions of amino acids were revealed through systematic analysis of C. ptilophylla and conventional tea, with low theanine but high levels of an unknown amino acid-like substance found in the above-ground parts of C. ptilophylla. Through isolation and structural analysis, the unknown substance was identified for the first time as 4-amino-5-hydroxyvaleric acid (named camptinine). Structural and content correlation analysis suggested that it might be a metabolic product diverted from glutamate, which is related to the decomposition of theanine. Function evaluation showed camptinine had anti-anxiety effect by increasing brain 5-hydroxytryptamine, similar to the positive control of theanine and estazolam, with milder organ impact in mice. This study offers novel insights into tea plant amino acid metabolism, and offers theoretical support for C. ptilophylla product development.