AUTHOR=Huang Qianqian , Hu Tianming , Xu Zhongjun , Jin Long , McAllister Tim A. , Acharya Surya , Zeller Wayne E. , Mueller-Harvey Irene , Wang Yuxi 

TITLE=Composition and Protein Precipitation Capacity of Condensed Tannins in Purple Prairie Clover (Dalea purpurea Vent.)

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.715282

DOI=10.3389/fpls.2021.715282

ISSN=1664-462X

ABSTRACT=<p>This study aimed to determine the concentration and composition of condensed tannins (CT) in different tissues of purple prairie clover (PPC; <italic>Dalea purpurea</italic> Vent.) at different maturities and to determine their protein-precipitating capacity. The compositions of CT were elucidated after thiolysis with benzyl mercaptan followed by high-performance liquid-chromatography (HPLC) and <sup>1</sup>H–<sup>13</sup>C heteronuclear single quantum coherence (HSQC) NMR spectroscopy. The results indicated that PPC flowering heads contained the highest CT concentration. Purple prairie clover CT consisted mainly of epicatechin (EC) and epigallocatechin (EGC) subunits. CT in the leaves were composed of more EC and less EGC than CT in stems and flowering heads at both the early flowering (EF) and late flowering (LF) head stages. The mean degree of polymerization was the highest for CT in stems and increased with maturity. CT isolated from PPC leaves at the early flowering head stage exhibited the greatest biological activity in terms of protein precipitation. Overall, the CT in PPC were predominantly procyanidins and the concentration and composition varied among the plant tissues and with maturity.</p>