Perilla Leaf, Seed, and Stem
Perilla is a mint plant (Laminaceae Family), Perilla frutescens, growing in the hills and mountains of East Asia (mainly India, China, Japan, and Korea). It has been spread around the globe during the previous century; initially it was desired as a decorative garden plant, but then it escaped cultivation; as an example, it now grows in spots throughout most of the Eastern and Midwestern United States, described as an invasive weed. The plant has long been used as a source of herb materials for Chinese medicine; it is known in China as zisu. The character zi refers to the distinctive purple color of the stem; in some varieties or under certain growing conditions, the leaves also display a red-purple coloration; green leaves are more commonly found, while some varieties have one side of the leaf being green and one side red-purple. The character su means comfort, and refers to the comforting effect of perilla leaves when taken as a tea. Two parts of the plant are commonly used in Chinese medicine: the leaf (ye) and the seed (zi), respectively called zisuye and zisuzi (or Zi Su Ye and Zi Su Zi); some herbalists use the stem separately or mixed with the leaves. Jiao Shude has a good description of the different plant parts (1):
Perilla leaf is used to resolve the exterior and dissipate cold; perilla stem (sugeng) has the effect of rectifying the qi and quieting the fetus and is often used for vomiting or for abdominal distention in pregnancy; perilla stem and leaf together is used to downbear qi and disperse phlegm. Perilla leaf, which has aromatic qi, aromatically repels foulness, dispels summerheat and transforms turbidity, and resolves the toxins of fish and crabs; therefore, it is often used for summerheat-damp foul turbidity or poisoning from fish and craps that results in oppression in the chest, vomiting, and abdominal pain. Perilla seed has a strong qi-precipitating and phlegm-dispersing action and is effective in treating panting counterflow and phlegm cough.
The references to foulness, summerheat, and turbidity, mainly refer to food poisoning or “stomach flu,” that is, the result of a food-borne infection that produces nausea, vomiting, diarrhea, and accompanying symptoms, such as headache. The fish and crab “toxins” mainly refers to the adverse effects of eating bacterially-contaminated seafood, though it also implies seafood-induced allergic reactions. In the treatment of nausea and vomiting of pregnancy, the leaf and/or stem can be used alone or with fresh ginger as a tea. Perilla leaf is included in the ancient formula Pinellia and Magnolia Combination (Banxia Houpu Tang) that has been applied to these symptoms of pregnancy as well as other conditions, especially those involving swallowing disorders and emotional distress; that formula, from the Jingui Yaolue, has fresh ginger, hoelen (fuling), and perilla leaves in addition to the two herbs of the formula name.
Perilla is also used as a food source (2). The crispa variety of perilla, which has “crisped” leaves (curled along the edges), is known in Japan as shiso leaf (or jiso; this is the Japanese version of the word zisu), used in preparing some sushi dishes and in making pickled plums (umeboshi). The leaves of perilla are used as a garnish or flavoring for some Vietnamese dishes. In China, Hunan cuisine may include perilla leaves in preparing fish. The seeds are used in Japan as a source of oil for cooking, and this oil has been developed as a specialty health product marketed internationally because it is rich in omega-3 fatty acids. Perilla seed is used in making some Indian curries. The seeds are a major food in Korea, used plain and roasted, as well as a source of cooking oil; annual production of perilla seeds in Korea is about 40,000 metric tons.
In the modern Chinese Materia Medica, perilla leaf is categorized as a surface-relieving herb used for common cold and similar types of acute disorders that might involve stuffy nose, cough, and headache; it is considered best for treating “wind-cold” type disorders, and is classified as pungent and warm. Perilla leaf (and especially the stem) is also considered valuable for dispersing stagnant qi and calming the mind. This dual use is also noted for bupleurum (chaihu), classified as a surface relieving herb but commonly employed for regulating qi and calming the mind; a combination of bupleurum, perilla leaf, curcuma, and acorus is used for treating depression. Other surface relieving herbs are sometimes used by Chinese doctors as qi-regulating herbs, such as siler (fangfeng) included in Tong Xie Yao Fang, and mentha (bohe) included in Xiao Yao San.
Perilla leaf is aromatic, with main active ingredients being volatile oils dominated by monoterpenes (3). Among these components are perillaldehyde (the major flavor and fragrance constituent; structure shown left), perillene, β-caryophyllene, thujopsene, β-farnesene, limonene, elsholtziaketone, perillaketone, furylketone, linalool, and trans-citral. The leaves also contain some larger molecules as active components, such as ursolic acid (a triterpene glycoside) and rosmarinic acid (structure shown right). The red-purple coloration of the stem (and leaves, when so-colored) has been attributed to anthocyanins and flavones, such as luteolin; a specially prepared perilla extract rich in these compounds is sold as a food color for beverages, jams, and candies; it is red in acid pH (but green at basic pH).
Perilla seed is classified among the herbs for alleviating cough. Like the leaf, it is pungent and warm in nature. Its effect on cough is attributed primarily to its ability to cause uprushing qi (also described as qi “counterflow”) to descend. Thus, as with the leaf and stem, the seed of perilla has important effects on qi circulation. Because of the mild nature of perilla seed, it is especially used in formulas for treating chronic cough in patients who are weak and for treating children’s respiratory disorders. The pungent aspect of perilla seed is attributed to essential oils as found in the leaf, though in different proportions; like many other seeds, perilla seed has fixed oils (fats), including unsaturated fatty acids, such as α-linolenic acid.
Both the leaf and seed of perilla can be used regularly and in significant quantity. For perilla leaf typical dosing in decoction formulas is 6 grams per daily dose, the range is 3 to 12 grams per day when combined with other herbs (often including other mint plants, such as mentha, schizonepeta, elscholtzia, or agastache, and/or combining with fresh ginger). To preserve the volatile oils of the leaves and stems, the herb is added at the end of the decoction process. A tea of perilla leaf can be made by simply steeping the herb; Perilla Tea (Zisuye Cha) is made this way, adding brown sugar to tea made from 16 grams of the herb and used for the initial stage of wind-cold (4). Perilla seed (sometimes referred to as perilla fruit) is also typically used in decoction dosage of 6 grams; the range is 3 to 15 grams per day. The seed is usually stir-fried and it is crushed before decocting to help release the components.
Adverse reactions to perilla can occur under unusual circumstances. Cattle and horses consuming large amounts (several kilograms) of perilla, by grazing on the herb or consuming hay cut from fields where this plant is prevalent, have suffered adverse pulmonary effects, attributed to perillaketone. In Japan and Korea, many workers in the perilla industry eventually develop an allergy to the herb (contact dermatitis) as a result of constant exposure to the essential oils, primarily a reaction to perillaldehyde (5). However, with normal use of the herb, toxicity is not reported.
Perilla in Traditional Formulas
Although perilla was used since the Han Dynasty period (e.g., a major ingredient in Pinellia and Magnolia Combination), perilla first became a popular herb during the Song Dynasty, and it was included in several formulas which come to us today, especially used in Kampo Medicine (Chinese medicine as practiced in Japan), first recorded in the famous Song Dynasty book Taiping Huimin Hejiju Fang (1110 A.D). Among the formulas with perilla leaf described in this text, and their indications, are (6):
Cyperus and Perilla Formula (Xiang Su Tang): common cold with digestive difficulties
And formulas with perilla seed from that text include:
Perilla Seed Combination (Zisu Jiangqi Tang): asthmatic breathing with weakness of lower body
These and other prescriptions from later Chinese texts were made available in the West just over 40 years ago with the introduction of granules (dried decoctions) from Taiwan and Japan, but some of them have become much less used recently due to limitations on ma-huang, unavailability of aquilaria (endangered tree species), and worries about the effects of ginseng. Of the formulas mentioned above, only Huoxiang Zhengqi San is widely utilized in western countries, and this was primarily because it was heavily promoted as a patent remedy from China during the 1990s. It is a “traveler’s remedy,” suitable for disorders associated with foods and for headaches and initial stage of common cold and bronchitis.
Perilla continues to be incorporated into modern prescriptions, sometimes in simplified versions of the traditional formulas (7). For example, a recipe for common cold is made of three herbs of the mint family (8), with 9 grams each mentha (bohe) and schizonepeta (jingjie) and 6 grams of perilla leaf; a recipe for neurogenic vomiting associated with stomach heat is made of 9 grams each of agastache (huoxiang) and perilla leaf, with 6 grams of coptis (huanglian). The combination of perilla and coptis is well-known in China for stomach heat syndromes, somewhat like the combination of evodia (wuzhuyu) and coptis (9).
With the advent of new technologies for isolating active components, a considerable effort has been devoted to evaluating the pharmacology of certain substances in perilla, in particular α-linolenic acid (ALA) from the seeds and rosmarinic acid from the leaves.
Perilla seeds have about 50% fats and 30% volatile oil. The fats of perilla seed are comprised of about 60% ALA (typical range is 55%-64%), an omega-3 fatty acid, along with about 15% linoleic acid (omega-6) and 13% oleic acid (omega-9); the seed oil also contain about 4–6% glycolipids and 2–3% phospholipids (10). Perilla seed oil is the richest known plant source of ALA, surpassing even flax seed (linseed) oil, which is the most widely used source of this compound for supplement products. Omega-3 fatty acids are attributed several health benefits, including possible reduction of cardiovascular disease risk factors (such as high blood pressure and excess lipids) and serving as a “brain nutrient,” but of particular importance is the fact that a diet rich in omega-3 fatty acids can contribute to lessening of inflammation. In order to attain the desired effects, a total of about 2.5 grams or more of omega-3 fatty acid should be consumed daily. The primary sources would be fish (especially salmon, halibut, and snapper) and fish oil supplements; flax seed and flax oil; and perilla seed oil. Walnut oil, canola oil, and soy oil (and soy products, such as tofu) have smaller percentages of ALA, but can be used as common dietary contributors. Alternative sources of omega-3, such as hemp seed oil and sea buckthorn oil, have been made available in recent years.
Because of the high content of unsaturated fatty acids, perilla seed oil is used industrially in the same way as linseed oil, as a “drying oil,” that is, an oil that when applied to surfaces dissipates to leave behind what is dissolved in it; it has thus been used in paints, varnishes, printing ink, lacquers, and for protective waterproof coatings on cloth. The seed has about 17% protein, so the residue after removal of the oil serves as a nutritious mash used as a food for cattle and other ruminants. A wax material in perilla seed has stimulated interest (11); it is comprised mainly of policosanols: 67-68% octacosanol, 16-17% hexacosanol, 6-9% triacontanol. These substances, obtained from other plants, such as sugar cane, have been used in supplements for lowering cholesterol and neuroprotective effects, though the research remains preliminary. A combination of berberine (12) and red rice yeast along with policosanols is claimed to lower cholesterol (13).
Rosmarinic acid is named for one of its source plants, rosemary, and it is a component of several other kitchen spices, including oregano, marjoram, thyme, and basil. Rosmarinic acid and these spices are reputed to aid digestion and inhibit bacteria. According to preliminary pharmacology research, rosmarinic acid influences IL-4, IL-8, IgE, and histamine, all involved in allergy reactions (14, 15), and that it can reduce the intensity of allergic responses in clinical use according to a small study (16). Commercial extracts of perilla containing 20% rosmarinic acid are currently available for this purpose. The ingredients luteolin, omega-3 fatty acids, and rosmarinic acid confer a neuroprotective effect to perilla leaf and seed taken together.
Left: Example of a product, made in Europe, for treatment of allergy, called “Allermin”; it contains capsules of perilla extract. Right: Canned perilla leaves are sold in Korean markets
Book about perilla from 1997, indicating the great interest in this as a crop
for future development and use of the herb for treatment of allergy.