Phytochemical Analysis of Lipid Composition and Biological Activities in the Seeds of Evening Primrose from Bulgaria

<b>Background/Objectives:</b> The present study is aimed at evaluating the chemical profile and biological activity of the widespread species <i>Oenothera biennis</i> L. in Bulgaria, collected from its natural habitat. <b>Methods:</b> The seeds of the species were collected in 2023 and 2024, and the fatty acid and unsaponified (sterols, tocopherols, phospholipids) profile of the glyceride oil was investigated using standard chromatographic methods. The oil's antimicrobial activity was evaluated using MBC/MFC assays, while its antioxidant capacity was assessed using the ORAC method. The proliferative effects of the oil were investigated using an MTT assay in human cell lines BJ, HaCaT, and MCF-12F. <b>Results:</b> The oil content of the seeds remained stable during the two years studied (16.7-16.9%). Variations were observed in the oil's unsaponified fraction, including sterols, phospholipids, tocopherols, and several fatty acids. The primary fatty acid (linoleic acid) remained at almost the same value (~70%) during both periods, while γ-linolenic acid varied from 7.1% to 13.7%. β-sitosterol and phosphatidylcholine were the leading sterol and phospholipid components, while γ-tocopherol predominated among the tocopherols. The oil exhibited antimicrobial activity only against <i>S. epidermidis</i> and <i>S. pyogenes</i> and showed strong antioxidant capacity. MTT assays present sustained viability in BJ and MCF-12F cells and significantly increased proliferation in HaCaT cells. <b>Conclusions:</b> The oil demonstrated promising antioxidant potential, selective antimicrobial effects, and keratinocyte-stimulating activity, supporting its potential for diverse applications. However, to further confirm these findings, in vivo studies of the oil are needed.