Steroidal saponins and homoisoflavonoids from the fibrous roots of ophiopogon japonicus and their anti-pulmonary fibrosis activities

The chemical investigation of the fibrous roots of Ophiopogon japonicus afforded two new steroidal saponins, named ophiojaponin F (1) and ophiojaponin G (2), together with twelve known steroidal saponins (3–14) and ten known homoisoflavonoids (15–24). The structures of the isolated compounds were established unambiguously via spectroscopic analyses (NMR and HR-ESI-MS). Ophiojaponin F (1) is a 23-hydroxylated spirostanol saponin, and this type of steroidal saponin rarely been reported in liriopogons. All isolates were evaluated for their anti-pulmonary fibrosis activities on TGF-β1-actived NIH3T3 cells for the first time. Among them, compounds 3, 4, 11–13, 15–19, 21 and 24 showed potential anti-pulmonary fibrosis effects with IC50 values ranging from 3.61 ± 0.86 μM to 21.33 ± 1.82 μM, and the main component ophiopogonin D (4) displayed the best activity with an IC50 value of 3.61 ± 0.86 μM. Thus, ophiopogonin D may be a potent candidate for the treatment of pulmonary fibrosis.