Protective Effects of Hypericum orientale L. Extracts Against Cigarette Smoke-Induced Bronchial Cytotoxicity and Respiratory Pathogens.

The ethnomedicinal relevance of Hypericum orientale L. suggests notable pharmacological potential; however, its organ-specific phytochemical composition and biological activities remain insufficiently characterized. This study investigated the phytochemical profiles, cytoprotective activity, and antimicrobial properties of methanolic extracts obtained from the aerial parts and roots of H. orientale. Phytochemical analyses revealed distinct organ-dependent profiles. Hyperoside was the major constituent in both extracts, while the aerial extract was particularly rich in flavonols and flavones, including hyperoside, myricetin, acacetin, and quercetin. In contrast, the root extract was characterized by higher levels of catechin-type phenolics, especially (-)-epicatechin and (+)-catechin. Hypericin, pseudohypericin, and hyperforin were not detected. The main contribution of this study is the integrated evaluation of organ-specific phytochemical variation together with respiratory-relevant cytoprotective and antimicrobial screening. In a cigarette smoke extract-induced bronchial cytotoxicity model, 10% cigarette smoke extract reduced BEAS-2B cell viability to 38.32% ± 2.46%, whereas pre-treatment with the aerial extract significantly attenuated this cytotoxicity. Antimicrobial evaluation showed notable activity against ATCC reference strains (MIC = 7.8 µg/mL); however, efficacy was markedly reduced against multidrug-resistant clinical isolates (MIC > 250 µg/mL), limiting direct antimicrobial relevance. Overall, H. orientale appears to be a promising source of phenolic constituents with cytoprotective potential.