ent-Kaurane Diterpenoids with Neuroprotective Properties from Corn Silk (Zea mays)

Thirteen new ent -kaurane diterpenoids, stigmaydenes A–M ( 1 - 13 ), together with two known compounds ( 14, 15 ), were isolated from the crude extract of corn silk ( Zea mays ). The structures of the compounds were confirmed by comprehensive spectroscopic analyses. The absolute configuration of compound 1 was defined by single-crystal X-ray diffraction. The absolute configurations of the compounds were also confirmed by comparison of experimental and calculated specific rotations. The compounds were evaluated for their neuroprotective effects against H 2 O 2 -induced SH-SY5Y cell injury, and compound 8 was active at 100 μM, as determined by flow cytometry (annexin V-FITC/PI staining) and Hoechst 33258 staining. The results suggested that compound 8 could protect neuronal cells from H 2 O 2 -induced injury by inhibiting apoptosis in SH-SY5Y cells.