Application of high-performance liquid chromatography-solid phase extraction-nuclear magnetic resonance in the identification of bioactive constituents from Hyptis spicigera leaf and H. brevipes aerial part

Two Hyptis plants endemic to Taiwan, H. rhomboides and H. suaveolens, contained xanthine oxidase inhibitors. To chemically investigate more herbs of the same genus, this study aimed to explore bioactive constituents from Hyptis spicigera leaf and the aerial part of H. brevipes, which would also enrich the chemotaxonomic basis for the Hyptis plants. The EtOH extract of the plant materials was fractionated by liquid-liquid partitioning, followed by separation over various chromatography. High-performance liquid chromatography-solid phase extraction-nuclear magnetic resonance hyphenation, a sustainable and environmentally friendly instrument, was applied to accelerate the chemical investigation of each subfraction. Eighteen isolates from Hyptis spicigera leaf and 14 compounds from H. brevipes aerial part were characterized. Of these, 12 compounds are rosmarinic acid derivatives, of which 9′-O-methyl melitrate A (10) and sagecoumarin methyl ester (22) are tentatively identified as new compounds. In total, 25 compounds were separated and characterized from Hyptis spicigera leaf and H. brevipes aerial part. Of these, seven of them (2–4, 11, 12, 18, 20) are in common between these two species, and 17 isolates (2–4, 8-14, 22, 23, and 26-30) are phenylpropanoids which are commonly distributed in the Labiatae family.