In this study, Dendropanax morbifera, a plant species native to Southeast Asia and Jeju Island in Korea, was examined for several biological activities. Four different fractions of Dendropanax morbifera extracts were used, and the extracts were named DPLS 1, DPLS 4, DPLS 5 and DPLW 4 according to solvent polarity and extraction parts of the plant. For anti-oxidant activity six different anti-oxidant tests were performed using trolox, an analog substance of vitamin E, as a standard material. The results revealed that DPLS 4 and DPLW 4 were the most effective anti-oxidant fractions. The overall anti-oxidant capacity of DPLS 1 was very low, but the hydroxyl radical scavenging activity and inhibition of lipid peroxidation were very high.
The anti-inflammatory effects of the four extracts were examined by treating each extract to RAW264.7 cells simultaneously with the treatment of LPS to induce inflammatory responses. DPLS 1 showed the highest inhibitory activity against Nitric Oxide(NO) secretion, and the other three extracts also significantly inhibited NO secretion. The activity of blocking the NF-κB signaling pathway was further analyzed for DPLS 1. The results confirmed that the expression of iNOS and COX 2 was very effectively reduced in LPS-stimulated RAW264.7. DPLS 1 also reduced the translocation of NF-κB from the cytoplasm to the nucleus and inhibited the phosphorylation of IκB.
In addition, the ability of the extracts to inhibit NLRP3 inflammasome formation was also investigated. First, the amount of intracellular ROS, one of the major causes of inflammasome formation, was analyzed. DPLS 1, a fraction that was the most effective in inhibiting the NF-κB signaling pathway, and DPLW 4, the most anti-oxidative fraction, were chosen for this analysis. DPLS 1 significantly reduced intracellular ROS, whereas DPLW 4 reduced extracellular ROS but did not decrease intracellular ROS. It is assumed that the polarity difference of the two extracts may be the reason for this result. Changes in the amount of NLRP3 protein following DPLS 1 treatment were also confirmed by western blot analysis, and as a result, DPLS 1 markedly decreased the amount of NLRP3 protein.
Therefore, DPLS 4, DPLS 5 and DPLW 4, which had high anti-oxidative activities, are likely to be developed as a skin-whitening or anti-aging agent. DPLS 1 has the potential to be developed as a natural drug that can prevent diseases caused by excessive inflammation.