Neuroprotective and Antioxidant Constituents from Curcuma zedoaria Rhizomes

This study investigates the effect of phytochemical constituents from medicinally important plant Curcuma zedoaria (Christm.) Rosc., on hydrogen peroxide induced oxidative stress in mouse neuroblastoma-rat glioma hybridoma cells NG108-15. Phytochemical investigation of C. zedoaria rhizomes resulted in the isolation of nine sesquiterpenes (germacrone 1, dehydrocurdione 2, curcumenol 3, isoprocurcumenol 5, curcumenone 6, procurcumenol 7, zerumbone epoxide 8, zederone 9 and gweicurculactone 10) and one labdane diterpene (zerumin A 4). Curcumenol (3) and dehydrocurdione (2) showed 100% protection of the NG108-15 cells at the concentrations of 4 and 10 µM, respectively. Procurcumenol (7), isoprocurcumenol (5), zerumbone epoxide (8), zerumin A (4) and germacrone (1) showed moderate activity (80-90% protection). In the oxygen radical antioxidant capacity (ORAC) assay, all the test compounds showed strong antioxidant activity except curcumenol (3) which showed moderate antioxidant activity, as compared to the reference standard quercetin.