Structural Modification of Resveratrol: Biological Activities and Anticancer Potential of Emerging Methoxylated Analogs

Resveratrol remains one of the most extensively studied plant-derived polyphenols because of its broad antioxidant, anti-inflammatory, cardioprotective, neuroprotective, and anticancer activities. However, its clinical translation has been substantially limited by its poor aqueous solubility, rapid phase II metabolism, and low systemic bioavailability, despite decades of intensive investigation. Structural modification through methoxylation has emerged as a promising strategy to overcome these pharmacokinetic limitations by enhancing metabolic stability, lipophilicity, membrane permeability, and biological activity. While considerable attention has focused on resveratrol and a limited number of established analogs, emerging methoxylated derivatives remain comparatively underexplored. This review highlights the structural characteristics, biological activities, and molecular mechanisms of two such derivatives, 4,4-(ethane-1,2-diyl)bis(2-methoxyphenol) (EG) and (Z)-3,5,4′-trimethoxystilbene (Z-TMS), and discusses evidence from structurally similar, better-characterized compounds that may aid in understanding their activities. Despite promising experimental findings, the therapeutic relevance of EG and Z-TMS remains insufficiently characterized because the available evidence is predominantly derived from in vitro studies, while data on toxicity, therapeutic index, long-term safety, pharmacodynamics, and clinically relevant systemic exposure remain limited. This review emphasizes the anticancer potential of these emerging methoxylated derivatives, identifies current knowledge gaps, and provides a basis for considering them as lead compounds for anticancer drug development.