Antioxidant activity of Myristica malabarica extracts and their constituents

The 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay of the ether, methanol, and aqueous extracts of the spice Myristica malabarica (rampatri) revealed the methanol extract to possess the best antioxidant activity. Column chromatography of the methanol extract led to the isolation of a new 2-acylresorcinol and four known diarylnonanoids of which the diarylnonanoid, malabaricone C, showed the maximum DPPH scavenging activity. Malabaricone C could prevent both Fe(II)- and 2,2'-azobis(2-amidinopropane)dihydrochloride-induced lipid peroxidation (LPO) of rat liver mitochondria more efficiently than curcumin. The anti-LPO activity of malabaricone C was attributed to its better radical scavenging and Fe(II) chelation capacities. The superior activity of malabaricone C was rationalized by a systematic structure-activity correlation of the results obtained with the structurally related diarylnonanoids and curcumin. Malabaricone C also prevented the gamma-ray-induced damage of pBR322 plasmid DNA in a concentration-dependent manner. The radioprotective activity was found to correlate with its (*)OH radical scavenging property, which matched well with that of d-mannitol.