Neuroprotective potential of phytochemicals isolated from Paeonia ostii ‘Feng Dan’ stamen

Paeonia ostii ‘Feng Dan’, traditionally known as an important medicinal and ornamental plant, is an emerging oilseed crop widely cultivated in China. As a byproduct, its stamens showed promising anti-neuroinflammation potential in our previous study. In this work, an in-depth phytochemical investigation was firstly conducted through comprehensive spectra to elucidate the neuroprotective components. Two new compounds (+)-oxylactiflorin (1), (+)-3′′-methoxy-oxylactiflorin (2), and twenty-two known compounds were isolated and identified. In lipopolysaccharides-induced BV-2 cells, compound 2 exhibited excellent inhibitory property in inhibiting nitric oxide (NO) production with the lowest EC50 value of 3.02 ± 1.60 µM among all tested compounds. Western blotting and molecular docking results demonstrated the feasible mechanism that 2 exerted anti-inflammatory activity mainly by binding with the key protein cyclooxygenase-2 (COX-2). Additionally, compound 2 showed potent protective effects on the oxidative damages of H2O2 or 6-Hydroxydopamine (6-OHDA)-treated PC12 cells. This work provides a theoretical basis of P. ostii stamens for developing into a promising functional tea or neuroprotective drug.