Diffusosides C and D, two new iridoid glucosides from Oldenlandia diffusa

During our continual investigations on Oldenlandia diffusa (Willd.) Roxb., two new iridoid glucosides, diffusosides C (1) and D (2), were isolated and their structures were elucidated through cumulative analysis of NMR and HRESIMS spectroscopic data as well as computational studies. Both isolated compounds displayed no obvious neuroprotective activity on H2O2-induced injury PC12 cells at 50 μM in vitro.