1.d.123. The Ganoderma Triterpenoid (GT) Family
The triterpenoid fraction of Ganoderma (Ganoderma triterpenoids, GTs) has been shown to provide effective antioxidant, neuroprotective or cardioprotective activities. These compounds are also capable of perturbing the transmembrane ionic currents, Ih, existing in electrically excitable cells. Chang et al. 2019 showed that GTs can modify hyperpolarization-activated cation currents in pituitary tumor cells and in atrial cardiomyocytes. In whole-cell current recordings, the addition of GTs produced a dose-dependent reduction in current in combination with a lengthening in activation time constants. GTs (10 μg/mL) also caused a shift in the steady-state activation curve. In current-clamp voltage recordings, GTs diminished the firing frequency of spontaneous action potentials and also decreased the amplitude of the sag potential in response to hyperpolarizing current stimuli. In murine HL-1 cardiomyocytes, GT addition also suppressed the amplitude of Ih. The inhibition of Ih caused by GTs is independent of its possible binding to adenosine receptors and might have profound influence in electrical behaviors of different types of electrically excitable cells (Chang et al. 2019).