Evening primrose - A plant of nutritional and pharmacological importance
Zahoor Ahmad and Peter Lapinskas (1998)
Presented at: Novel Crops Sympsium, Islamabad, November 1998

Evening primrose (Oenothera biennis) is a proven source of Gamma Linolenic Acid (GLA). The deficiency of GLA is well established in human population particularly in developing countries. The deficiency of GLA leads to many diseases like coronary, eczema, arthritis, diabetes, immunological disorders etc. After the discovery of evening primrose in 1970 as a rich source of GLA the various pharmaceutical companies in Europe became interested in the extraction of evening primrose oil (EPO). Scotia Pharmaceuticals Limited has marketed the EPO as "Efamol" and it is being imported in Pakistan. The import of Efamol has started in Pakistan very recently. Due to importance of this plant, the Plant Introduction Centre of Pakistan Agricultural Research Council conducted the adaptability studies on this plant species at Murree, Kaghan, Quetta, and Islamabad. The plant growth studies and seed yield data indicated that it can be grown successfully in Islamabad and other cooler areas of Pakistan. The oil content of seeds harvested from Islamabad was estimated as 19.6% and GLA 5.8%.

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Evening primroses have been considered only wild flowers since 1970 when research on these species began in Germany, Netherlands, and England. The main reason of interest in these species was the discovery of high quantities of Gamma Linolenic Acid (GLA) in their oil which is present up to 20-25% in seeds. The other known source of GLA at that time was human milk. Now some other sources of GLA have also been discovered.

The modern human populations are characterized by deficiency of GLA because of less tendency of breast feeding. This deficiency leads to many diseases like eczema, arthritis, disease of arteries, diabetes, cancer, allergies, gynaecological disorders, neurological disorders, immunological disorders etc. (Bamford et al. 1985, Biagi et al. 1988, Chaudhry et al. 1991, Belch et al. 1986, William and Broughton 1992, Williams and Casper 1994, Oxholm et al. 1986). Most of the above mentioned diseases are considered to be mysterious in origin and are resistant to therapy. It is proved now that GLA is the most active of all essential fatty acids in correcting these deficiencies. GLA is a polyunsaturated essential fatty acid which forms part of the membranes that surrounds the cell of the body; they are essential for the proper functioning of the membranes. They are also precursors of prostaglandin which are hormones that are produced by every organ of the body and control the second-by-second regulation of organ functions.

Keeping in view the importance of evening primrose oil in human health, efforts were made to introduce Oenothera biennis in Pakistan and to develop production technology for obtaining optimum yields.

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The seeds of evening primrose (Oenothera biennis) an exotic plant species was selected for research as it is reported to have higher oil and GLA contents. The seeds were sown in raised nursery beds in the month of November at Islamabad and seedlings with 4-5 small leaves were transplanted in field in mid February with a plant to plant and row to row distance of 35 and 80 inches respectively. At the time of transplanting, the field was irrigated and after that it rarely needed irrigation as there are enough rains and the plant is also resistant to drought. The plants were harvested at maturity which was in June. After threshing the seed yield data were recorded. For the determination of seed oil contents and fatty acid profile, the seed samples were sent to Scotia Pharmaceuticals Limited, England.


The plant growth behaviour from transplantation to maturity indicated that evening primrose has no problem in first establishment of plant stand in climatic conditions of Islamabad. The plant growth was recorded quite satisfactory and no disease problem was observed during the vegetative or maturity stage. The seed yield data varied from 760 - 850 kg per hectare in three different years. It was further noted that if the seedlings are transplanted in February, the plants start flowering in May, and mature by the end of June or early July. But if the seedlings are transplanted in March, the flowering and maturity are also delayed suggesting photoperiod insensitivity. The associated weed was identified as crab grass (Digitaria sanguinalis).

As regards the seed analysis data, the oil contents in the seeds were found to be 19.6 percent. The GLA in oil was estimated to be 5.8 percent. The oil contents and GLA were relatively low which are due to very high temperature (37 - 42 C) at flowering and maturity time. The optimum temperature during flowing and maturity should be between 25 - 30 °C (Sheidow and Roy 1990 and personal communications with Lapinskas). The various areas in Baluchistan and Northern Pakistan may be best suited for evening primrose cultivation from where higher oil and GLA contents can be obtained.

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Bamford JTM; Gibson RW; Renier CM (1985)
Atopic eczema unresponsive to evening primrose oil ( Linolenic acid and gamma Linolenic acids).
J Am Acad Dermatol. 13(4) :959- 965.

Belch JJF; Shaw B; O'Dowd, A; Curran, L; Forbes CD; Sturrok RD (1986)
Evening primrose oil (Efamol) as a treatment for cold induced vasospasm (Raynauds phenomenon)
Prog Lipid Res. 25: 335 -340.

Biagi PL; Bordoni A ; Masi M ; Ricci G ; Fanelli C; Patrizi A; Coccolini E (1988)
A long term study in the use of evening primrose oil (Efamol) in atopic children.
Drugs Exp Clin Res 14 (4) : 285-290

Chaudhry AA; McClinton S; Moffat LEF; Wahie KWJ (1991)
Essential fatty acid distribution in the plasma and tissue phospholipids of patients with begin and malignant protatic disease.
Br J Cancer: 1157 - 1160.

Oxholm, P; Manthrope, R; Prause. JU; Horrobin DF ( 1986)
Patients with primary Sjogren's syndrome treated for two months with evening primrose oil.
Scand Rheumatol 15 : 103 - 108

Sheidow NW; Roy RC; (1990)
Evening Primrose Factsheet, April, 1990
Ministry of Agriculture & Food, Ontario, Canada

Williams K; Casper R (1994)
Primrose oil in the treatment of premenstrual disphoric disorder: is the bloom off the rose?
Psych Ann. 24(5): 255-258

Williams R; Broughton M (1992)
A pilot study of gamma linolenic acid in diabetic retinopathy
In: Horrobin, DF (ed) Treatment of diabetic neuropathy : A new approach. London, UK., Churchill livingstone 131 - 134.

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© Peter Lapinskas 1999-2012 Email Peter Lapinskas Last updated: 3 July 2012

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