Determination of antioxidative properties of Morinda citrifolia using near supercritical fluid extraction

Limited knowledge is available regarding the hydrophobic antioxidants present in the Morinda citrifolia L (Noni). Moreover, supercritical fluid carbon dioxide (SF-CO₂) extraction technique is well known with many superior extraction properties. The purpose of this study was to investigate the antioxidative properties of crude extracts from the leaves, green and brown stems, and fruit of Noni plant obtained by near SF-CO₂ extraction. Extracts from brown stems by near SF-CO2 extraction under high pressure and low temperature conditions afforded the highest total phenolic content (23.14 ± 1.83 mg/g) and the best reducing power (59.82 ± 6.28 ascorbic acid equivalents mg/g). It also possessed the greatest antioxidative capacities, including Trolox equivalent antioxidant capacity assay (564.52 ± 41.58 μmol/g), scavenging of 2,2-diphenyl-1-picrylhydrazyl (effective concentration : EC₅₀ = 6.87 ± 0.14 mg/L), and superoxide radical scavenging activity (505.12 ± 26.68 SOD unit/g), which indicated that the antioxidative activity is not only due to phenolic compounds but also due to non-polar antioxidants. Extracts from the brown stems of M. citrifolia could be a significant source of antioxidants when isolated by near SF-CO₂ extraction.