Quantification of coumarin derivatives in Noni (Morinda citrifolia) and their contribution of quenching effect on reactive oxygen species

The quantification of coumarin derivatives such as scopoletin, 7-hydroxycoumarin (7-HC) and 4-hydroxycoumarin (4-HC) in Noni (Morinda citrifolia) was described. The coumarin derivatives were determined by HPLC-UV or -fluorescence detection. More than 95% of peak purity for coumarin derivatives in Noni sample was confirmed by a multi-wavelength fluorescence detector. Amounts of scopoletin and 7-HC in Noni juices (A–H) were ranging 5.1–231 μg/ml and 0.04–0.45 μg/ml, respectively (n = 12). No 4-HC was detected in any Noni samples examined.Furthermore, the quenching effects of Noni products and coumarin derivatives on reactive oxygen species (ROS) were evaluated by a luminol chemiluminescent assay. Both Noni samples and coumarin derivatives dose-dependently quenched ROS such as superoxide (O2-), singlet oxygen (1O2), hydroxyl radical (OH) and peroxynitrite (ONOO−). The EC50 of scopoletin for O2-, 1O2, OH and ONOO− were 1.27 ± 0.22 mg/ml, 0.68 ± 0.04 mg/ml, >4.00 mg/ml, and 0.042±0.002 mg/ml, respectively. The contribution ratio of scopoletin for ROS in Noni juices was also evaluated.