Antioxidant, antimicrobial, and antiproliferative potential of hydroethanolic bark and nutshell extracts

This study aimed to comparatively evaluate the phenolic composition and biological activities (antioxidant, antimicrobial, and antiproliferative) of hydroethanolic extracts obtained from the barks of Fraxinus ornus and Quercus vulcanica, and the nutshells of Pinus pinea. Extraction yields of barks (F. ornus, 24.9%, Q. vulcanica, 10.2%) were markedly higher than those of nutshells (1.2%). Chemical profiling revealed distinctive extract patterns: F. ornus extract was enriched in coumarins (esculin, fraxin), whereas Q. vulcanica and P. pinea extracts contained catechin and protocatechuic acid as predominant compounds. Both bark extracts exhibited strong antioxidant activity in the oxidative haemolysis inhibition assay (OxHLIA), with F. ornus exceeding Trolox and Q. vulcanica showing comparable activity. Antimicrobial assays demonstrated moderate inhibition of Gram-positive and Gram-negative bacteria and weak antifungal activity. Cytotoxicity testing indicated limited antiproliferative effects, most pronounced against colon cancer cells. In contrast, the nutshell extracts displayed negligible bioactivity.