myricitrin and myricanol

Three new diarylheptanoids, myricanol 11-sulfate (1), juglanin B 11-sulfate (2), and myricanone 5-O-(6'-O-galloyl)glucoside (3), were isolated from the bark of Myrica rubra. Compounds 1 and 2 were characterized as diarylheptanoid sulfates on the basis of spectroscopic analyses. The antioxidative activities of the fractionated extracts and isolated compounds were estimated by the oxygen radical absorbance capacity (ORAC) and superoxide dismutase (SOD)-like activity assays. The major isolate, myricitrin (4), displayed a high ORAC value and moderate SOD-like activity (13,198 μmol TE (Trolox equivalent)/g and IC₅₀ 127.5 μg/mL, respectively), which might explain the potent antioxidative activity of this material.

Topics: Antioxidants; Diarylheptanoids; Flavonoids; Glucosides; Japan; Molecular Structure; Myrica; Nuclear Magnetic Resonance, Biomolecular; Plant Bark; Sulfuric Acid Esters; Superoxide Dismutase

Target-based drug discovery for Alzheimer's disease (AD) centered on modulation of the amyloid β peptide has met with limited success. Therefore, recent efforts have focused on targeting the microtubule-associated protein tau. Tau pathologically accumulates in more than 15 neurodegenerative diseases and is most closely linked with postsymptomatic progression in AD. We endeavored to identify compounds that decrease tau stability rather than prevent its aggregation. An extract from Myrica cerifera (bayberry/southern wax myrtle) potently reduced both endogenous and overexpressed tau protein levels in cells and murine brain slices. The bayberry flavonoids myricetin and myricitrin were confirmed to contribute to this potency, but a diarylheptanoid, myricanol, was the most effective anti-tau component in the extract, with potency approaching the best targeted lead therapies. (+)-aR,11S-Myricanol, isolated from M. cerifera and reported here for the first time as the naturally occurring aglycone, was significantly more potent than commercially available (±)-myricanol. Myricanol may represent a novel scaffold for drug development efforts targeting tau turnover in AD.

Topics: Alzheimer Disease; Animals; Diarylheptanoids; Female; Flavonoids; HeLa Cells; Humans; Male; Mice; Models, Biological; Myrica; Plant Roots; Prosencephalon; tau Proteins