O-methylation of phenolic natural products: translational insights from resveratrol.

O-Methylation is a rational optimisation strategy for resveratrol in which phenolic hydroxyl groups are replaced with methoxy groups to increase lipophilicity, metabolic stability, membrane permeability, and systemic exposure. The resulting pharmacokinetic (PK) improvements may contribute to enhanced pharmacodynamic (PD) effects, as exemplified by methoxylated stilbenes such as pterostilbene, which generally retain the core biological activities of resveratrol while mostly exhibiting greater in vivo efficacy. However, extending this concept to other phenolic natural products shows that improved PK does not uniformly translate into improved PD. Examples from flavonoids, phenolic acids, lignans, ellagitannins, and classical pharmacological analogues illustrate that, although O-methylation frequently enhances metabolic stability and bioavailability, PD outcomes depend on intrinsic target interactions, therapeutic mechanisms, and, in some cases, microbiota-dependent bioactivation. In some examples, O-methylation may even improve PK while reducing intrinsic pharmacodynamic potency. Increased lipophilicity also presents formulation challenges, particularly in aqueous nutraceutical and functional beverage systems, highlighting the need for advanced delivery strategies such as nanoemulsions, nanoliposomes, micellar systems, and cyclodextrin inclusion complexes. Using resveratrol as a model, this review critically evaluates the available, predominantly preclinical, evidence on the relationship between O-methylation, PK, and PD, identifies important exceptions to this relationship, and discusses the implications for pharmaceutical, nutraceutical, and functional beverage development.