General description of Perilla frutescencs

Perilla frutescens, is a member of the Lamiaceae/Labiatae family and commonly called perilla. The crop is annual and is native to India and China. Major producing countries of perilla are China, India, Japan, Korea, Thailand, other East Asian countries. The herb is about 1 m high with small flowers, a gray-brown fruit, and glossy, downy-haired leaves. Cultivation of the crop is grown from seed and sown in May. Harvesting is usually between the end of September and beginning of October. The applicable parts of perilla plants are the leaves and seeds. There are two main types: red and green perilla. Perilla seeds, also called EBARA seed. This oil is a kind of light yellow clear and transparent liquid, with aromatic odor and slight soluble in ethanol. Major fatty acids of the oil are unsaturated fatty acids like Oleic acid 14–23%, linoleic acid 11–16%, linolenic acid 54–64% (Graph 1). This oil also contains saturated fatty acids 6.7–7.6%. Perilla seeds contain different polyphenols or flavones (rosemarinic acid, luteolin, chrysoeriol, quercetin, catcehin, apegenin and shishonin). Perilla seed oil is used as cooking oil, fuel. It is dry oil used as in paint, varnish and ink manufacturing or as a substitute for linseed oil. The seed cakes are used as animals and birds feed (Gediminas et al. 2008; Talbott and Hughes 2006; Longvah et al. 2000; Borchers et al. 1997; Narisawa et al. 1994).

Graph 1

Gas Chromatography report of perilla frutescens seeds oil

Source and uses of omega fatty acids

Perilla is used for oil production as a rich source of omega-3 polyunsaturated fatty acids (PUFAs), specifically alpha-linolenic acid (ALA). It also contains omega 6 and omega 9 fatty acids. Omega fatty acids are the essential for our health, so the omega-3s and 6s must be obtained through our diet or by supplementation. It is the best resources for additional human omega-3 polyunsaturated fatty acids (PUFAs). ALA (omega-3 fatty acid), is found in some other plant oils sources such as flaxseed (linseed), with lower amounts in walnut, canola, soy and animal sources like fish oil (cold water fish as salmon, cod and mackerel).

Perilla oil suppresses the production of chemical mediator in the allergy and inflammatory responses. These essential fatty acids have been associated with benefits in a wide range of inflammatory conditions, heart diseases, colitis/Crohn’s disease, asthma, allergies, antimicrobial, anticancer etc. Perilla is also used for nausea, sunstroke, to induce sweating and as an antispasmodic. In vivo metabolism of polyunsaturated omega-3 fatty acids, it mainly exists in the form of DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). These two specific omega-3 fatty acids metabolites are inserted in cell membranes throughout the body, where cellular machinery converts them into substances which prevent abnormal clotting, reduce inflammation, and relax blood vessels and improved ventilatory parameters (Lewis 2008; Talbott and Hughes 2006; Calder 2004; James et al. 2000; Chin et al. 1992; Mattson and Grundy 1985).

Other dietary sources of omega-3 fatty acidsBotanical sources

Flax seeds produce linseed oil, which has a very high omega−3 fatty acid content Six times richer than most fish oils in n−3, flax (or linseed) (Linum usitatissimum) and its oil are perhaps the most widely available botanical source of n−3. Flaxseed oil consists of approximately 55% ALA (alpha-linolenic acid). Flax, like chia, contains approximately three times as much n−3 as n−6. 15 g of flaxseed oil provides 8 g of ALA, which is converted in the body to EPA and then DHA at efficiency of 5–10% and 2–5%, respectively (Azcona et al. 2008; Lewis 2008; Albert et al. 2002; Schacky and Dyerberg 2001; James et al. 2000; Mattson and Grundy 1985) (Tables 1 and 2).

Table 1 Omega−3 content as the percentage of ALA in the seed oil (From Wikipedia, the free encyclopedia report) Table 2 Omega−3 content as the percentage of ALA in the whole food (Wikipedia, the free encyclopedia) Animal sources Fish

The most widely available source of EPA and DHA is cold water oily fish such as salmon, herring, mackerel, anchovies and sardines. Oils from these fish have a profile of around seven times as much omega−3 as omega−6. Other oily fish such as tuna also contain omega−3 in somewhat lesser amounts. Consumers of oily fish should be aware of the potential presence of heavy metals and fat-soluble pollutants like PCBs and dioxin which may accumulate up the food chain. Although fish is a dietary source of n−3 fatty acids, fish do not synthesize them; they obtain them from the algae or plankton in their diet (James et al. 2000; Renaud 2002; Chin et al. 1992).

Eggs

Eggs produced by chickens fed a diet of greens and insects produce higher levels of n−3 fatty acids (mostly ALA) than chickens fed corn or soybeans. In addition to feeding chickens insects and greens, fish oils may be added to their diet to increase the amount of fatty acid concentrations in eggs. The addition of flax and canola seeds to the diet of chickens, both good sources of alpha-linolenic acid, increases the omega-3 content of the eggs (Azcona et al. 2008; Trebunová et al. 2007).

Meat

The n−6 to n−3 ratio of grass-fed beef is about 2:1, making it a more useful source of n−3 than grain-fed beef, which usually has a ratio of 4:1. In most countries, commercially available lamb is typically grass-fed, and thus higher in n−3 than other grain-fed or grain-finished meat sources. The omega-3 content of chicken meat may be enhanced by increasing the animals’ dietary intake of grains that are high in n−3, such as flax, chia, and canola (Azcona et al. 2008; Trebunová et al. 2007).

Seal oil

Seal oil is a source of EPA, DPH, and DPA. According to Health Canada, it helps to support the development of the brain, eyes and nerves in children up to 12 years of age (Azcona et al. 2008; Trebunová et al. 2007).

Other sources

Milk and cheese from grass-fed cows may also be good sources of n−3. The microalgae Crypthecodinium cohnii and Schizochytrium are rich sources of DHA (22:6 n−3) and can be produced commercially in bioreactors. This is the only source of DHA acceptable to vegans. Oil from brown algae (kelp) is a source of EPA. Walnuts are one of few nuts that contain appreciable n−3 fat, with approximately a 1:4 ratio of n−3 to n−6. Acai palm fruit also contains n−3 fatty acids. Omega-3 is also found in soft gels in pharmacies and nowadays it is also found in combination with omega-6, omega-9 and shark liver oil(Azcona et al. 2008; Trebunová et al. 2007).

Chemistry of fatty acids

Perilla is an alternative source of fatty acids that contains both saturated and unsaturated (monosaturated and polyunsaturated) fatty acids. Fatty acids having more than one double bonds are termed as PUFAs. It contains saturated fatty acids mainly palmitic acid 5–7%, stearic acid 1–3%, monosaturated oleic acid 12–22%, and poly saturated fatty acids linoleic acid 13–20%, γ-linolenic acid 0–1%, α-linolenic acid 52–64%, icosanoic acid 0–1%. Increase in the number of double bonds progressively decreases the melting point. Unsaturated fatty acids are lower melting point than saturated fatty acids. Plant triglycerides have a large portion of unsaturated fatty acids such as oleic, lenoleic and linolenic acids. Animal triglycerides have high proportion of saturated fatty acids such as palmitic and stearic acids (Tables 3 and 4).

Table 3 Major saturated and saturated fatty acids Table 4 Gas chromatography report of different components present in perilla oil

The carbon chain of saturated fatty acids posses zigzag configuration with the bond between carbon-carbon being 109°. The stearic acid (18 C) depicted as fallows (Fig. 1).

Fig. 1

Zigzag configuration of unsaturated stearic acid (18 C)

Introduction of double bonds in oleic acid between carbon-9 and carbon 10, causes bend in the molecule (Fig. 2).

Fig. 2

Configuration of monosaturated oleic acid (C 18)

Introduction of two double bonds (e.g. Linoleic acid) causes further bending of the hydrocarbon chain.

Geometrical isomerism occurs in fatty acids whose hydrocarbon has double bonds. Most unsaturated fatty acids occur in the relatively less stable isomeric form rather than more stable trans form (Fig. 3, Tables 3 and 4).

Fig. 3

Geometrical isomerism of unsaturated fatty acids

Nomenclature of fatty acids

The systemic nomenclature of fatty acids is derived from the name of its parent hydrocarbon by replacing its final e by oleic acid. Thus the names of saturated fatty acids end with the suffix anoic acid and those of unsaturated fatty acids with the suffix enoic acid. The numbering of carbon atoms in fatty acids is started at the carboxyl terminus and end methyl carbon is known as omega carbon atom (Figs. 4 and 5).

Fig 4

Numbering of carbon atoms in fatty acids

Various conventions are adopted for indicating the position of the double bonds. The most widely used are involve the use of the symbol Δ fallowed by superscript number. For example Δ9 means that there is a double bound between carbon 9 and carbon 10. Alternatively the position of the double bond is indicated by the numerals as in case simple alkenes. Lastly note that total number of carbon atoms and number of position(s) of double bond(s) is again indicated by convention. Examples, the symbol 18;0 denote a C18 fatty acid with no double bonds, the symbol 18: 1; 9 denote a C 18 fatty acid with a double bond between carbon 9 and carbon 10 and the symbol 18: 2; 9,12 denote a C 18 fatty acid with two double bonds between C9 and C10 and between C12 and 13 (Renaud 2002; Mattson and Grundy 1985) (Table 5).

Table 5 List of several different names for the most common n−3 fatty acids Definition of omega fatty acids

The names “omega 3” or “omega 6” or “omega 9” fatty acids refer to where a double bond occurs in the fatty acid molecule. The terms “omega” or “n minus” refer to the position of the double bond of the fatty acid closest to the methyl end of the molecule. Thus, oleic acid, which has its double bond 9 carbons from the methyl end, is considered an omega-9 (or an n–9) fatty acid. Similarly, linoleic acid, common in vegetable oils, is an omega-6 (n–6) fatty acid because its second double bond is 6 carbons from the methyl end of the molecule (i.e., between carbons 12 and 13 from the carboxyl end). Omega 3 and omega 6 fatty acids are “essential fatty acids”, meaning that these fatty acids cannot synthesized by body itself. Instead, we must include them in our diet or through supplements to meet our body demands. Omega 9 fatty acids are “conditionally essential”, which means that if we have the other fatty acids in our diet, then our body can manufacture omega 9 fatty acids. Otherwise, omega 9 fatty acids must be consumed or supplemented as well. DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) are the two specific omega 3 fatty acids found in fish oil such as cold water fish as salmon, cod and mackerel (Green et al. 2007; Calder 2004; Renaud 2002; Chin et al. 1992; Ip et al. 1996; Mattson and Grundy 1985).

Importance of omega fatty acids

Among plant oils, the balance between omega-3, omega-6 and omega 9 fatty acids must dictate which oil is chosen. Oils which predominate in omega-3 component would be most likely to promote health, only perilla and flax seed (vegetable) oil predominate in omega-3 fatty acid. Most would actually contribute to the imbalance of omega-6 fatty acids because they contain more omega-6 than omega-3. Any amount of omega-9 is beneficial, but in balancing these fatty acids, the omega-3 component is the most important.

The most common omega 6 fatty acid is linoleic acid. When omega 6 fatty acids are consumed in the diet, they are inserted in the cell membranes, where the same cellular machinery converts them into substances which promote abnormal clotting and increase inflammation. While Omega-3 fatty acids are beneficial to improved cardiovascular health, and certain types of cancers, as well as enhancing the immune system (Lewis 2008; Reisman et al. 2006; Talbott and Hughes 2006; Calder 2004; Albert et al. 2002; James et al. 2000; Longvah et al. 2000; Lee et al. 1994; Narisawa et al. 1994; Thompson et al. 1997; Chin et al. 1992; Kromann and Green 1980).

Balance of omega-3 & 6 is key for normal immune function

Many health issues depend on a proper balance of omega 3 and omega 6 fatty acids. While omega 6 fatty acids are necessary for normal immune function and clotting, too much omega 6 fatty acid may promote abnormal clotting and an overactive immune system. It is believed that our ancestors evolved on a diet where these two omega fatty acids were approximately equal. However, modern diets usually have up to 20 times more omega 6 fatty acids than omega 3 fatty acids. Many of the chronic degenerative diseases we experience today are believed to have their origins in an imbalance of omega 3 and omega 6 fatty acids in our diet. This necessitates that n−3 and n−6 be consumed in a balanced proportion; healthy ratios of n−6: n−3 range from 1:1 to 4:1. (Renaud 2002; Mattson and Grundy 1985).

Cardio-vascular benefits

Heart disease is the one of the most common diseases nowadays due to current life style and eating habits. Certain population studies have shown that a diet high in omega-3 fatty acids, specifically EPA and DHA found in fish oil or metabolized product of ALA (perilla oil) can help to prevent heart disease. Omega-3 fatty acid (ALA), through the body’s metabolic pathway, can be converted into EPA and DHA at a rate of roughly 7–10%. The research proved that when using omega-3 rich perilla oil instead of soybean oil, the subjects increased omega-3 levels in their blood, which may lead to prevention of coronary heart disease and decrease blood clotting (Lewis 2008; Calder 2004; Schacky and Dyerberg 2001).

In different cells of the body, the cellular machinery makes different things. In platelets, the cell products in the blood which aid in clotting, omega 6 fatty acids are converted to thromboxane A2 (TXA2). This makes the platelets more likely to burst (degranulate), releasing their clotting substances and cell messengers. These cell messengers constrict blood vessels and tell other platelets to burst—causing a clotting cascade. On the other hand, when omega 3 fatty acids are used in the same machinery in platelets, thromboxane A3 (TXA3) is made, which is inactive. If you have been cut or injured, you want the bleeding to stop with the help of platelets. However, if you have not been cut or injured, clotting is abnormal and may block flow to areas which need it—causing a heart attack or stroke. In white blood cells (WBC’s), the infection fighting cells of the body, omega 6 fatty acids make more inflammatory substances. These substances include leukotriene B4, (LTB4), which is a cell messenger responsible for inflammation throughout the body. It is a “call to arms” for other WBC’s. LTB4 even tells certain WBC’s to get into the wall of the blood vessel. LTB4 actually causes these WBC’s to absorb oxidized LDL cholesterol (cholesterol plaque is formed). In contrast, when omega 3 fatty acids are used in the same cellular machinery, leukotriene B5 (LTB5) is made. LTB5 is anti-inflammatory. Health demands normal functioning of both systems (Bemelmans et al. 2002; de Lorgeril et al. 1999; Thompson et al. 1997; Lee et al. 1994).

Anti-inflammatory and rheumatoid arthritis benefits

Perilla oil is rich in the omega-3 fatty acids, on metabolism gives eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which can displace arachidonic acid (AA) from cell membranes. These omega-3 fatty acids are also released with AA by phospholipases and act as substrate inhibitors of conversion of AA by cyclo-oxygenases (COX) and the terminal synthases to the pro-inflammatory oxygenated inflammatory mediators known as eicosanoids. EPA is structurally identical to AA with the exception of its additional n−3 double bond and can be converted to eicosanoids that resemble eicosanoids. In addition to these effects on inflammatory eicosanoid synthesis, perilla oils have been shown to reduce the production of the inflammatory cytokines IL-1β and TNFα by monocytes stimulated in vitro. These cytokines are important effector molecules in inflammatory responses and TNFα blocking agents are now used widely to treat rheumatoid disease that has proven refractory to less expensive therapies. In vitro studies have also shown inhibition of release of the metalloproteinases that are implicated in the tissue damage that is the hallmark of rheumatoid arthritis and other inflammatory diseases (Osakabe et al. 2005, 2004; Banno et al. 2004; James et al. 2000).

It has been reported that conversion of ALA to EPA and further to DHA in humans is limited, but varies with individuals. Women have higher ALA conversion efficiency than men, probably due to the lower rate of utilization of dietary ALA for beta-oxidation.

Fig. 5

Structure of alfa linolenic acid (ALA) arachidonic acid (AA), Docosahexaenoic acid (DHA) prostaglandin (PGE) and eicosapentaenoic acid (EPA)

Perilla oil reduces recourse to NSAIDs for analgesia in rheumatoid arthritis and thereby reduces risk for upper GI haemorrhage. Perilla oil contrasts with the highly selective COX-2 inhibitor rofecoxib, which has been associated with increased serious cardiovascular events, by reducing risk for these events. The result is fewer AA derived eicosanoids with production of homologous metabolites products such as PGE1 (one less double bond than AA derived PGE2). ALA rich oils appear to reduce symptoms in rheumatoid arthritis but available evidence is far less than that for perilla oil in rheumatoid arthritis (Osakabe et al. 2005; Banno et al. 2004; Calder 2004; James et al. 2000; Borchers et al. 1997).

Cancer benefits

Similarly, studies in animals have found that omega-3 fatty acids suppress cancer formation, but at this time there is no direct evidence for protective effects in humans. A group of isomers of the essential fatty acid linoleic acid, “conjugated linoleic acid” (CLA), appear to have both anticarcinogenic and antiatherogenic properties and may affect body composition. CLA differs from linoleic acid by the position and geometric configuration of one of its double bonds (Chin et al. 1992). Animal studies have indicated that CLA reduces the incidence of tumors induced by carcinogens (Ip et al. 1996; Thompson et al. 1997). In addition to its anticarcinogenic properties, CLA appears to be antiatherogenic as well (Lee et al. 1994). Saturated fatty acids have not been found to have any specific effects on carcinogenesis. On a positive note, recent studies have shown that conjugated linoleic acid, appears to be unique among fatty acids because low levels in the diet produce significant cancer protection (Banno et al. 2004; Osakabe et al. 2004; Caughey et al. 1996; Narisawa et al. 1994; Chin et al.