Chemical compostion and biological activities of Oenothera biennis L. and Oenothera paradoxa Hudziok aerial parts' extracts

Oenothera biennis L. and Oenothera paradoxa Hudziok, commonly known as evening primrose, are two perennial herbs cultivated in Europe and North America as a source of seeds used for the production of oil rich in unsaturated fatty acids. There are no studies concerning the polyphenol composition of O.paradoxa herb, and those concerning aerial parts of O. biennis are limited. The aqueous-methanol extracts were prepared and analyzed by HPLC-MS³ and then anti-oxidative properties of extracts towards different reactive oxygen species were checked using both cellular and non-cellular models. Anti-hialuronidase activity was also evaluated. The HPLC analyses allowed for identification of 40 compounds in both extracts belonging to different classes of polyphenols, including tannins, phenolic acids and flavonoids. Both extracts (examined at a concentration between 2 and 50µg/mL) performed scavenging properties towards reactive oxygen species, especially against H₂O₂ (SC₅₀ =2.7 and 2.8µg/mL). Anti-hialuronidase assays have shown that extracts of evening primrose exhibit inhibitory activity on the pro-inflamatory enzyme (IC₅₀ ˜ 20µg/mL). The study conducted showed that both plant materials may be considered as a source of extracts rich in polyphenols, exhibiting reactive oxygen species scavenging activity and anti-inflammatory activity.