Onagraceae - syn. Oenothera graveolens Gilib., Oenothera communis Leveille, Onagra biennis Scop.; evening primrose, tree primrose, broad-leafed oenothera, Gemeine Nachtkerze
Erect biennial, native to North America, naturalized in Eurasia, New Zealand, South Africa, South America, 0.50-2.50 high; inflorescence erect, flowers yellow, with 8 stamens, opening in the evening.
„In addition to the fleshy tap roots, the leaves, flowers and seeds are also edible. The roots are boiled like salsify or parsnips in broth; occasionally also sliced and dressed with oil and vinegar. The roots are harvested in autumn of the first year (rosette stage) until spring. In modern kitchen, the petals are sometimes used as edible decoration.“ http://de.wikipedia.org/wiki/Gemeine_Nachtkerze
Linalool was found to be the main constitutent of floral volatiles.
[Pollination Biology of Oenothera (Onagraceae). The Interplay between Floral UV‐Absorbancy Patterns and Floral Volatiles as Signals to Nocturnal Insects. Kawaano, S., Odaki, M., Yamaoka, R., Oda‐Tanabe, M., Takeuchi, M., & Kawano, N., Plant Species Biology, Vol.10(1), 1995, 31-38]
The seed oil is used for the treatment of eczema internally and externally (ointment), but: „Oral borage oil and evening primrose oil lack effect on eczema; improvement was similar to respective placebos used in trials. Oral BO and EPO are not effective treatments for eczema. In these studies, along with the placebos, EPO and BO have the same, fairly common, mild, transient adverse effects, which are mainly gastrointestinal. The short-term studies included here do not examine possible adverse effects of long-term use of EPO or BO. A case report warned that if EPO is taken for a prolonged period of time (more than one year), there is a potential risk of inflammation, thrombosis, and immunosuppression; another study found that EPO may increase bleeding for people on Coumadin® (warfarin) medication.“ [Bamford JTM, Ray S, Musekiwa A, van Gool C, Humphreys R, Ernst E. Oral evening primrose oil and borage oil for eczema. Cochrane Database of Systematic Reviews 2013, Issue 4. Art. No.: CD004416. DOI: 10.1002/14651858.CD004416.pub2. ] http://summaries.cochrane.org/CD004416/oral-evening-primrose-oil-and-borage-oil-for-eczema
In a Korean study, atopic dermatitis patients showed clinical improvement after gamma-linolenic acid supplementation (160/320mg daily, 8 weeks) with no side effects and with statistical significance. [Dose-Dependent Effects of Evening Primrose Oil in Children and Adolescents with Atopic Dermatitis. Bo Young Chung, Jin Hye Kim, Soo Ick Cho, In Su Ahn, Hye One Kim, Chun Wook Park, and Cheol Heon Lee, Ann Dermatol. 2013 Aug;25(3):285-291] http://synapse.koreamed.org/search.php?where=aview&id=10.5021/ad.2013.25.3.285&code=0140AD&vmode=FULL
„Evening primrose (Oenothera spp.) seed contains ca. 15% protein, 24% oil, and 43% cellulose plus lignin. The protein is unusually rich in sulphur-containing amino acids and in tryptophan. The component fatty acids of the oil are 65–80% linoleic and 7–14% of γ-linolenic, but no α-linolenic acid. The 1.5–2% unsaponifiable matter has a composition very similar to that of cottonseed oil. The sterol fraction contains 90% β-sitosterol and the 4-methyl sterol fraction contains 48% citrostadienol; γ-tocopherol dominates its class, with some α- but no other tocopherols.“ [Evening primrose (Oenothera spp.) oil and seed. B. J. F. Hudson, Journal of the American Oil Chemists’ Society, Vol.61 (3), 1984, 540-543]
„The yields obtained are very similar to those resulting from the conventional extraction process using hexane as solvent (26.0 wt.%); however, the quality of oil extracted by supercritical fluid is higher (acidity, 11.0; unsaponifiables, 1.8). The fatty acid composition of the borage seed oil extracted by SFE is particularly rich in unsaturated fatty acids, especially the γ-linolenic acid (21.7%). For these reasons, the borage seed oil extracted using carbon dioxide could be competitive with the conventional process, since it simplifies considerably the oil refinement stages and completely eliminates the solvent distillation stage, which are the most costly processing stages in terms of energy consumption.“ [Quality of borage seed oil extracted by liquid and supercritical carbon dioxide. A Molero Gómez, E Martı́nez de la Ossa, Chemical Engineering Journal, Vol.88 (1–3), 2002, 103–109]
Oenothera biennis flowers, CC BY-SA 3.0, Author: Andreas Kraska