Perilla

Scientific Name(s): Perilla frutescens (L.) Britt. Family: Lamiaceae

Common Name(s): Beefsteak plant , perilla , wild coleus , purple mint

Clinical Overview

Uses of Perilla

Perilla leaves are used in Chinese medicine to treat a wide variety of ailments and in Asian cooking as a garnish and to prevent food poisoning. Leaf extracts have shown antiallergic, anti-inflammatory, and tumor-preventing effects and may prevent the progression of glomerulonephritis. Health benefits have been attributed to perilla oil, including reduction in cholesterol levels, tumor prevention, and improvement in age-related learning deficiencies. However, there is a lack of clinical data to support perilla for any use.

Perilla Dosing

An extract of perilla enriched to contain 200 mg rosmarinic acid has been used to alleviate the symptoms of seasonal allergic rhinoconjunctivitis.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Perilla Interactions

None well documented.

Perilla Adverse Reactions

Perilla oil may cause dermatitis.

Toxicology

Perilla has been associated with deaths in grazing animals from atypical interstitial pneumonia. This has been attributed to perilla ketone that reaches high levels in the plant during the flowering and seed stages.

Botany

This annual herb is indigenous to eastern Asia. It has become naturalized to North America and is now commonly seen growing wild in the southeastern United States, particularly in semishaded areas such as damp woodlands. 1 The plant is attractive, with deep purple, square stems and reddish-purple leaves. The leaves are ovate, hairy, and petioled, with ruffled or curly edges; some very large red leaves are reminiscent of a slice of raw beef, hence the common name of beefsteak plant. Numerous small tubular flowers are borne on long spikes that arise from the leaf axils between July and October. 2 The plant has a strong fragrance sometimes described as minty.

History

The leaves and seeds are eaten in Asia. In Japan, perilla leaves are used as a garnish on raw fish dishes such as sashimi. It is believed that this serves the dual purposes of flavoring and as an antidote to possible food poisoning. 3 The seeds are expressed to yield edible oil that is also used in commercial manufacturing processes for the production of varnishes, dyes, and inks. Dried leaves are used for many applications in Chinese herbal medicine. Uses include treatment of respiratory conditions such as asthma, coughs, and colds, as an antispasmodic, to induce sweating, to quell nausea, and to alleviate sunstroke. 4

Chemistry

Perilla leaves yield about 0.2% of a delicately fragrant essential oil that varies widely in composition. 5 The seeds have a fixed oil content of approximately 40%, with a large proportion of unsaturated fatty acids, mainly α-linoleic acid. The plant also contains pseudotannins and antioxidants typical of the mint family. An anthocyanin pigment, perillanin chloride, is responsible for the reddish-purple coloration of some cultivars.

Several different chemotypes have been identified. 5 In the most frequently cultivated chemotype the main component is perillaldehyde, with smaller amounts of limonene, linalool, β-caryophyllene, menthol, α-pinene, perillene, and elemicin. The oxime of perilla aldehyde (perillartin) is reported to be 2,000 times sweeter than sugar; it is used as an artificial sweetener in Japan. Other compounds of possible commercial interest include citral, a pleasantly lemon-scented compound; rosefurane, used in the perfume industry; and simple phenylpropanoids of value to the pharmaceutical industry. Rosmarinic and tormentic acids and luteolin, agents identified as having anti-inflammatory properties, have also been isolated from perilla.

A high myristin content renders one chemotype toxic; ketones such as perilla ketone and isoegomaketone found in others are potent pneumotoxins. 5

Perilla Uses and Pharmacology

The leaves of perilla have been used traditionally to treat inflammatory conditions. Laboratory studies have confirmed efficacy in this regard using several different models, indicating several possible mechanisms of action. In one model, perilla produced a marked influx of neutrophils and formation of leukotriene B ₄ , along with changes in thromboxane B ₂ levels. In another, large increases in prostaglandin levels were seen, while in a contact dermatitis model perilla induced hypersensitivity mediated by leukotrienes, prostaglandins, histamine, inflammatory cytokines, and IgE. 6 Extracts of perilla have also been shown to suppress the overproduction of tumor necrosis factor-α, a cytokine important in immunologic and inflammatory reactions. Several anti-inflammatory components of perilla leaf have been identified including luteolin 3 and tormentic acid. 7

Topically applied triterpene acids isolated from dried perilla leaves have been associated with marked reduction in induced ear inflammation in mice. 8 Greatest improvement was observed with the application of tormentic acid, an ursane-type triterpene acid. Inhibition of inflammation with this agent was similar to that produced by hydrocortisone and indomethacin. Orally administered perilla leaf extract inhibited acute inflammation in 3 different models, including one for contact dermatitis, in another study. 6

Improvement in the symptoms of seasonal allergic rhinoconjuctivitis was reported in a small study (N = 30) of perilla extract enriched with rosmarinic acid. 8 Although objective symptom scores were not affected, patient evaluation of symptoms showed improvement scores of 30%, 55.6%, and 70% for patients receiving placebo, rosmarinic acid 50 mg, and rosmarinic acid 200 mg, respectively ( P = 0.05 placebo vs rosmarinic acid 200 mg). Numbers of inflammatory cells in nasal lavage fluid was significantly lower at 3 days in patients receiving rosmarinic acid. However, this effect was no longer apparent at 21 days.

The inhibitory effects of topically applied tormentic acid on carcinogenesis have been investigated in mice. 7 Incidence of papillomas in the control group treated with carcinogens alone was 100% at 11 weeks; incidence in mice treated with carcinogens and tormentic acid was 27% at 10 weeks and 87% at 18 weeks. Tumor-inhibiting effects were also evident as a reduction in the number of tumors (4.5 and 8.6 papillomas per mouse in treatment and control groups, respectively, at 18 weeks). Similar results were observed with the topical application of a perilla leaf extract; 9 the active principle in this study was thought to be luteolin. Tumor incidence after topical application of luteolin was 29% vs 55% and 85%, respectively, for control and perilla extract-treated groups; the number of tumors per mouse was also lower (0.9, 2.6, and 5.5 luteolin, perilla leaf extract, and controls, respectively). The effects of orally administered perilla leaf extract were less marked and no difference in numbers of tumors was observed between controls and perilla-treated groups at 20 weeks.

Reduction in the incidence of mammary 10 and colonic tumors 11 has been associated with perilla oil dietary supplementation in laboratory animals.

Research reveals no clinical data regarding the tumor-preventing effects of perilla.

An orally administered perilla leaf decoction resulted in reductions in proteinuria and in the numbers of glomerular and proliferative cell nuclear antigen-positive cells in animals with mesangioproliferative glomerulonephritis. 12 These antiproliferative effects suggest that perilla leaves may be useful in preventing the progression of glomerulonephritis.

Research reveals no clinical data regarding the effects of perilla on glomerulonephritis.

Perilla oil is rich in α-linolenate; health benefits have been associated with its use. Serum cholesterol and triglyceride levels decreased in rats fed perilla oil. Beneficial changes in the levels of eicosapentaenoic acid and arachidonic acid were also observed in these animals. 13 In a model of age-related deficits in learning and memory, mice fed a diet enriched with perilla oil exhibited better learning performance and less hyperactive behavior than those fed an α-linolenate-deficient diet. 14

In vitro and in vivo immunoenhancing effects have been described for a crude polysaccharide extract isolated from the leaves of perilla. 15 Luteolin, extracted from perilla seed oil, showed marked antimicrobial activity against bacteria commonly associated with dental caries. 16 Apigenin, a perilla component, was found to have antidepressant-like effects in mice. 17 However, these effects were only apparent at 2 intermediate doses of the 6 tested; relevance of these findings is unclear.

Dosage

An extract of perilla enriched to contain 200 mg rosmarinic acid has been used to treat the symptoms of seasonal allergic rhinoconjunctivitis.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

None well documented.

Adverse Reactions

Dermatitis has been reported in perilla oil workers. Patch testing suggests that 1-perillaldehyde and perilla alcohol contained in the oil are responsible for the effect. 4 , 18 Interestingly, extracts of perilla leaf have shown in vivo anti-inflammatory and antiallergic activity in several models, including one for contact dermatitis (see Uses and Pharmacology: Anti-inflammatory and anti-allergic effects).

Toxicology

Animals grazing on perilla have developed fatal pulmonary edema and respiratory distress. 1 Perilla ketone, chemically related to the toxic ipomeanols derived from moldy sweet potatoes, is a potent agent for the induction of pulmonary edema in laboratory animals. 19 Highest levels of perilla ketone occur in the plant during the flowering and seed stages. 1 It acts by increasing the permeability of endothelial cells and may not require the presence of cytochrome P450 to increase vascular permeability. 20

The toxicity of perilla ketone has been examined in several animal species. 1 Low intraperitoneal LD ⁵⁰ values were observed for mice and hamsters (5 and 13.7 mg/kg, respectively) with far higher lethal doses being required for dogs and pigs (106 and 158 mg/kg, respectively). Perilla ketone-related pathology in dogs and pigs was primarily hepatic, with only minor pulmonary effects, while mice and hamsters displayed only pulmonary lesions. Enzyme bioactivation of perilla ketone is hypothesized to be required for toxicosis, with species unable to produce the perilla metabolite having reduced susceptibility to its poisoning.

The volatile perilla oil contains aldehyde antioxide that has been used in the tobacco industry as a sweetener; however, this compound may be toxic.

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