Key Flavanone Glucoside Associated With Sweet Taste of Hawk Tea

ABSTRACT Hawk tea ( Litsea coreana ) has been consumed as a unique beverage in southwest China for centuries, but the key components responsible for its sweet taste have not been known clearly. In this study, a taste sensory evaluation‐guided isolation of its water extract led to the identification of a key sweet compound (2 S )‐eriodictyol‐3′‐O‐ β ‐D‐glucopyranoside ( 1 ). Notably, no 13 C‐NMR, two dimensional NMR data, or absolute configuration determinations have been previously reported. The structure of 1 was elucidated using high‐resolution electrospray ionization mass spectrometry (HRESIMS), heteronuclear singular quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC), while its absolute configuration was unambiguously confirmed through single‐crystal X‐ray diffraction analysis. Taste sensory evaluation suggested the relative sweetness of 1 was 2.5 in reference to 5% sucrose solution, and a distinctive fruity taste was revealed. Molecular docking indicated a strong binding energy of −8.5 kcal/mol for ligand 1 with TAS1R2/TAS1R3 receptor. The primary interaction sites were identified as conventional hydrogen bond donors (SER‐A‐105, ASN‐A‐106, ASN‐A‐107, and SER‐B‐158) and π‐alkyl bond interaction sites (VAL‐A‐56 and PRO‐B‐181). This compound was revealed as one of the key sweet components due to the high content in the range of 5.155%–6.525% and the knockout and recombination experiments. This is the first report about revealing the key sweet compound of hawk tea and determining the flavour characteristics of this flavanone glucoside.