Three New Hydroxytetradecenals from Amomum tsao-ko with Protein Tyrosine Phosphatase 1B and Glycogen Phosphorylase Inhibitory Activity.

The fruits of Amomum tsao-ko (Cao-Guo) were documented in Chinese Pharmacopoeia for the treatment of abdominal pain, vomiting, and plague. In our previous study, a series of diarylheptanes and flavonoids with α-glucosidase and protein tyrosine phosphatase 1B (PTP1B) inhibitory activity have been reported from the middle-polarity part of A. tsao-ko, whereas the antidiabetic potency of the low-polarity constituents is still unclear. In this study, three new hydroxytetradecenals, (2E, 4E, 8Z, 11Z)-6R-hydroxytetradeca-2,4,8,11-tetraenal (1), (2E, 4E, 8Z)-6R-hydroxytetradeca-2,4,8-trienal (2) and (2E, 4E)-6R-hydroxytetradeca-2,4-dienal (3) were obtained from the volatile oils of A. tsao-ko. The structures of compounds 1–3 were determined using spectroscopic data involving 1D and 2D nuclear magnetic resonance (NMR), high-resolution mass spectra (HRMS), and specific rotation ([α]D). Their hypoglycemic activity was evaluated against glycogen phosphorylase (GPa) and PTP1B. Compounds 1 and 2 displayed moderate activity against PTP1B with inhibition rates of 33.8%−50.3% at 100 and 200 µM. Moreover, compound 1 exhibited an obvious inhibitory effect on GPa (IC₅₀ = 31.7 µM), whereas compound 2 was inactive. This study demonstrates hydroxytetradecenals as the characteristic components of A. tsao-ko with therapeutic potential in diabetes. [ABSTRACT FROM AUTHOR]