Quercus rotundifolia Bark as a Source of Polar Extracts: Structural and Chemical Characterization

Quercus rotundifolia bark was studied regarding anatomical, chemical, and antioxidant properties from trees in two sites southern Portugal are here reported for the first time. The general structure anatomy of Q. showed a rhytidome with sequential undulated anastomosed periderms small proportion cork, while phloem included broad rays strong cell sclerification, groups sclereids embed large prismatic crystals, abundant druses parenchyma cells. mean chemical composition 15.5% ash, 1.6% dichloromethane extractives, 6.4% ethanol 9.3% water 3.0% suberin, 30.5% total lignin, 33.8% carbohydrates. Carbohydrates mainly glucose (50.7% monomers) xylose (23.8%), uronic (3.0%) acetic acids (1.0%). Suberin composed ω-hydroxyacids (48.0% all compounds) α,ω-diacids (19.5%). main compounds found lipophilic extracts were triterpenes (43.6%–56.2% alkanoic (32.7%–41.7%). Phenolic content high especially extracts, ranging 219.5–572.9 mg GAE/g extract comprising 162.5–247.5 CE/g flavonoids 41.2–294.1 condensed tannins. revealed very good IC50 values 4.4 µg extract/mL 4.7 extract/mL. Similar characteristics both sites. phenolic excellent polar holm oak barks to be promising natural source antioxidants possible use industry pharmaceutical/medical areas.