Poppyseed oil

Poppyseed oil (also poppy seed oil, poppy oil, and oleum papaveris seminis) is an edible oil from poppy seeds (seeds of Papaver somniferum, the opium poppy). The oil has culinary and pharmaceutical uses, as well as long established uses in the making of paints, varnishes, and soaps.

Poppy seeds yield 45–50% oil.^[1] Like poppy seeds, poppyseed oil is highly palatable, high in vitamin E, and contains opium alkaloids such as morphine and codeine in quantities of up to 400 mg/L.^[2]

Chemistry

Poppy seeds are notable for being especially high in tocopherols other than vitamin E (alpha-tocopherol). Poppyseed oil from one source has been reported to contain 30.9 mg gamma-tocopherol per 100 g.^[3] It also contains alpha and gamma tocotrienols, but not others.^[3] Compared to other vegetable oils, poppyseed oil has a moderate amount of phytosterols: higher than soybean oil and peanut oil, lower than safflower oil, sesame oil, wheat germ oil, corn oil, and rice bran oil.^[4] Sterols in poppyseed oil consist almost entirely of campesterol, stigmasterol, sitosterol and delta 5-avenasterol.^[5] Poppyseed oil is high in linoleic acid. Although not generally higher than safflower oil, it can be as high as 74.5%.^[3] Other triglycerides present in notable quantities are oleic acid and palmitic acid.^[6]

It is less likely than some other oils to become rancid.^[1] It is more stable than safflower oil and linseed oil.^[3]

Poppyseed oil is a carrier oil, having little or no odor and a pleasant taste. The primary aroma compound responsible for its flavor is 2-pentylfuran;^[7] also present are the volatile compounds 1-pentanol, 1-hexanal, 1-hexanol, and caproic acid.^[6]

Uses

In the 19th century poppy seed oil was used as cooking oil, lamp oil, and varnish, and was used to make paints and soaps. Today, all of these uses continue, and poppyseed oil has additional culinary and pharmaceutical uses.^[6] Particularly notable are its uses as a carrier for oil paints and as a pharmaceutical grade carrier for medicinal iodine and drugs.

Poppyseed oil was sometimes added to olive and almond oils (see Adulterant).^[8] In industrialized countries its most important culinary use these days is as a salad or dipping oil.^[9]

Oil painting

Poppyseed oil is a drying oil. In oil painting, it is a popular oil for binding pigment, thinning paint, and varnishing finished paintings. Some users consider "sun-thickened" poppyseed oil to be the best painting medium.^[10]

Poppyseed oil has been used for painting for at least 1500 years—one of the oldest known oil paintings, found in caves of Afghanistan and dated to AD 650, was likely drawn using poppyseed oil.^[11] It is most often found in white paints,^[1] and as a varnish. Painters prepared poppyseed oil by hand until the late 19th century, when oil paints became available prepared in tubes. While poppyseed oil does not cause as much yellowish tinting of paints as linseed oil, it dries slower and is less durable than linseed oil because the fat responsible for the yellowing also provides durability.^[10] Perilla oil, which causes yellow tinting even more than linseed, is even more durable than linseed.

Contrast agent

Example of iodine-based contrast in cerebral angiography

Iodized poppyseed oil (oil with iodine added) has several kinds of pharmaceutical uses. The first of these uses was as a radiocontrast agent used in medical radiology. The origin of this use is attributed to Jean-Athanase Sicard and Jacques Forestier. Two brand name formulations are ethiodol and lipiodol. These are sterile formulations for medical use that commonly are injected.

These two formulations, and other similarly iodized poppyseed oils, also have multiple applications in the treatment of cancers and iodine deficiencies.

Prevention of iodine deficiency

In some regions where iodized salt is not available, iodized poppyseed oil is the standard for preventing iodine deficiency and its complications including goiter. It may be given by mouth or by injection, injection being markedly more effective.^[12] The origin of this use is attributed to Paulo Campos. Usually it is given to adults and children by intramuscular injection, one injection delivering enough iodine to last 2 or 3 years. Poppyseed oil is used because it is already manufactured and it very rarely causes an allergic reaction. Also, injections are more expensive and more difficult to administer than oral medications, thus there is interest in giving iodized oil by mouth. Use by mouth requires only food grade, not medical grade, quality control. A randomized, placebo-controlled clinical trial on giving infants iodized poppyseed oil together with an oral polio vaccine had good results.^[13] A randomized, double-blind, fully controlled trial in which lipiodol was given by mouth to children had disappointing results.^[14] A recent clinical trial in which iodized oil was given by mouth found that the amount of iodine taken up (see bioavailability) varied with the amount of oleic acid in the oil.^[15] Poppyseed oil has relatively little oleic acid. Peanut oil and rapeseed oil have far more oleic acid and are less expensive, and may be superior to poppyseed oil for giving iodine by mouth.^[15][16]

Cancer therapies

Poppyseed oil had long been used as a carrier for embolizing agents to treat tumors. In the 1980s, in order to better understand the action of these agents, poppyseed oil was replaced with lipiodol, to use its properties as a contrast agent.^[17] It soon became apparent that the lipiodol was selectively taken up by tumors. Whether this is true also of poppyseed oil is unknown.

Iodized poppy-seed oil has an especially high rate of uptake into the cells of hepatocellular carcinoma (HCC). This property was soon recognized as an opportunity to deliver to HCC a variety of highly toxic chemotherapy and radiotherapy agents,^[18] and formed the basis of several therapies for HCC not treatable by surgery alone.^[19][20] Injected emulsions of epirubicin in lipiodol are popular, but greater stability is needed.^{[21] [22]}

Lipiodol is under investigation as an adjuvant and carrier for use in chemotherapy to treat hepatocellular carcinoma (HCC). It increases the uptake and hence the cytotoxicity of doxorubicin in HCC cells^[23] (and also in hepatoblastoma cells^[24]). As a carrier, it is under investigation in conjunction with a lipophilic compound of platinum,^[25] and in conjunction with a complex derivative of neocarzinostatin.^[26] It also is being investigated as a radiation therapy against hepatocellular carcinoma, by being loaded with an isotope of iodine, iodine-131.^[27]

Similarly, lipiodol has been used with the chemotherapy agent epirubicin, but with less success than with doxorubicin. Epirubicin is less lipophilic than doxorubicin. However, a "water/oil/water" microemulsion, in which epirubicin was dissolved in droplets of water, and the droplets were suspended in lipiodol, significantly increased uptake of epirubicin by HCC cells.^[28]

Lipiodol is often used in transarterial embolization (TAE), a treatment for HCC, with and without an additional chemotherapy agent. A systematic review of cohort and randomized studies found that TAE improves survival, but found no evidence of additional benefit for using either chemotherapy agents or lipiodol in TAE.^[29]

History

Opium poppy seed pod

An early 20th century industry manual states that while the opium poppy was grown extensively in Eurasia, most of the world production of poppyseed oil occurred in France and Germany, from poppy seeds imported from other countries. From 1900 to 1911, France and Germany together produced on the order of 60,000,000 kilograms per year. At that time, poppyseed oil was used primarily to dress salads and frequently was adulterated with sesame oil and hazelnut oil to improve the taste of oil from stored (rancid) seeds. Poppyseed oil was used to adulterate olive oil and peach kernel oil.^[1] Poor quality poppyseed oil was valuable in the soap industry.

Some pharmaceutical uses of the other major product of Papaver somniferum, opium, were recognized thousands of years ago. In contrast, pharmaceutical uses of poppyseed oil began in the 20th century. Iodized poppyseed oil was the subject of a 1959 article in a pharmaceutical research journal.^[30] Various formulations were tried.^[31] In 1976 a contrast agent for imaging the liver and spleen using computed tomography was proposed: AG 60.99, an emulsion of poppyseed oil.^[32] A 1979 article reports on a new formulation, "improved" over ethiodol: "an emulsion of triglycerides of iodinated poppy seed oil".^[33] After a series of experiments in animals, by 1981 iodized poppy seed oil was in use as a contrast agent for computed tomography in humans.^[34]

See also

• Essential oil
• Fat over lean
• Guerbet

References