Chemical investigation of Hyptis suaveolens seed, a potential antihyperuricemic nutraceutical, with assistance of HPLC-SPE-NMR

The seed of Hyptis suaveolens, commonly known as wild flour ball (san fen yuan) in Taiwan, serves as a main refreshing drink substance in several regions. This study investigated firstly its secondary metabolites, leading to the isolation of five major caffeoylquinic acid derivatives (1e5) from the ethanol extract. In addition, ten minors, including three caffeoylquinic acid derivatives (12e14), were characterized via assistance of HPLC-SPE-NMR. Of these isolates, sodium 4,5-dicaffeoylquinate (2) and methyl 3,5-dicaffeoylquinate (4) showed moderate inhibitory activity against xanthine oxidase with the respective IC50 values of 69.4 mM and 92.1 mM (c.f. allopurinol IC50 28.4 mM). Quantitative HPLC analysis of the EtOH extract indicates the content of sodium 3,5-dicaffeoylquinate (1) and sodium 4,5- dicaffeoylquinate (2) to be 0.1% and 0.08% (w/w, dry seed), respectively. This study not only discloses the bioactive constituents, but also demonstrates the potential of H. suaveolens seed as an antihyperuricemic nutraceutical.