Chemical Composition, Antioxidant and Anti-AGEs Activities of a French Poplar Type Propolis

Accumulation in tissues and serum of advanced glycation end-products (AGEs) plays an important role in pathologies such as Alzheimer’s disease or, in the event of complications of diabetes, atherosclerosis or renal failure. Therefore, there is a potential therapeutic interest in compounds able to lower intra and extracellular levels of AGEs. Among them, natural antioxidants (AO) with true anti-AGEs capabilities would represent good candidates for development. The purpose of this study was to evaluate the AO and anti-AGEs potential of a propolis batch and then to identify the main compounds responsible for these effects. In vivo, protein glycation and oxidative stress are closely related. Thus, AO and antiglycation activities were evaluated using both DPPH and ORAC assays, respectively, as well as a newly developed automated anti-AGEs test. Several propolis extracts exhibited very good AO and anti-AGEs activities, and a bioguided fractionation allowed us to identify pinobanksin-3-acetate as the most active component

Additional Insights into <i>Hypericum perforatum</i> Content: Isolation, Total Synthesis, and Absolute Configuration of Hyperbiphenyls A and B from Immunomodulatory Root Extracts

Phytochemical investigation of the root extracts of <i>Hypericum perforatum</i> led to the isolation of two biphenyl derivatives named hyperbiphenyls A and B (<b>1</b> and <b>2</b>) and four known xanthones (<b>3</b>–<b>6</b>). These structures were elucidated by spectroscopic and spectrometric methods including UV, NMR, and HRMS. The absolute configuration of the biphenyl derivatives was defined by two different approaches: biomimetic total synthesis of racemic hyperbiphenyl A followed by ¹H and ¹⁹F NMR Mosher’s esters analysis and stereoselective total synthesis of hyperbiphenyl B, permitting assignment of the <i>S</i> absolute configuration for both compounds. The bioactivity of compounds <b>1</b>–<b>6</b> toward a set of biomolecules, including major histocompatibility complex (MHC) molecules expressed on vascular endothelial cells, was measured. The results showed that the major xanthone, i.e., 5-<i>O</i>-methyl-2-deprenylrheediaxanthone B (<b>3</b>), is a potent inhibitor of MHC that efficiently reduces HLA-E, MHC-II, and MICA biomolecules on cell surfaces