From the viewpoint of the structure-property (electron donating) relationship of RsvH3, the position of OH mainly contributes to the activity, due to its higher degree of conjugation with 4'OH and the capability to delocalize the -electrons characterized by stilbene-double-bond with its resonance structure. The resonance effect with -conjugation is considered to thermodynamically stabilize the radical product. Furthermore, the coplanar molecular-structure of the trans-stilbene skeleton may expand the -conjugation into two phenolic rings and the meta-OH groups, resulting in enhanced ROS-scavenging ability of RsvH3. However, it is difficult to observe the reaction of isolated HO2 • and HO • from the experimental protic (aqueous) solution because of their high reactivity and interference by solvent-derived protons, thus, the structure-activity relationship for ROS scavenging characterized by the stilbene-double-bond, the meta-OHs, and the para-OH, has not been elucidated. Hence, conclusive evidence for the ROS-scavenging mechanism of RsvH3 is lacking in the literature.