Native to Portugal and the Mediterranean area, rosemary is widely cultivated in several parts of the world, especially Morocco, Spain, Tunisia, and France. Rosemary takes it name from ros marinus, a Latin term which means "sea dew." Well known to the ancients, this plant was touted as a remedy for improving memory.

Rosemary today is used more frequently as a household spice and a food flavoring than a medicinal agent. However, it has traditionally been employed as a diuretic, emmenagogue, and antispasmodic remedy. The oil is a skin irritant in humans, and when administered externally, it increases blood supply. During the 19th century, rosemary leaf and its essential oil were used as a tonic for hypotension and other circulatory ailments. However, the evidence for the effectiveness of rosemary given orally in treating chronic circulatory weakness is controversial.

Rosemary oil is often unsafe for internal consumption since a large amount of it is required for therapeutic benefits. Ingesting excessive quantities of rosemary can irritate the stomach, intestines, and kidneys.

Rosmarinus officinalis is an erect evergreen shrub that grows to a height of two meters. It thrives in somewhat dry soil and a light, warm environment. The woody rootstock bears rigid branches with fissured bark. The long, linear, needle-like leaves are dark green above and white beneath. Both the fresh and dried leaves are pungently aromatic with a slight camphor-like scent. The small, labiate flowers are pale-blue. Volatile oil is found in the leaves and calyces of the flowers.

Part Used/Pharmaceutical Designation

• Leaves
• Twigs

• Volatile oil (1.0% to 2.5%); chief components are monoterpene hydrocarbons, camphene and limonene, 1,8-cineole (20% to 50%), alpha-pinene (15% to 25%), camphor (10% to 25%); other compounds include cineole, linalool, verbinol, camphene, borneol, isobutyl acetate, beta-caryophyllene, p-cymene, myrcene, terpineol, 3-octonone, isobornyl acetate)
• Terpenoids: carnosol (diterpene, bitter), carnosolic acid (picrosalvin), oleanolic acid (10%), ursolic acid (5%) (triterpenes), isorosmanol, rosmadial, rosmaridiphenol, rosmariquinone
• Phenols: caffeic acid derivatives (e.g., rosmarinic, neochlorogenic, cholorogenic, and labiatic acids)
• Flavonoids: cirsimarin, diosmetin, diosmin, hesperidin, luteolin and derivatives, hispidulin, apigenin, homoplantiginin, phegopolin
• Tannins: oligomeric proanthocyanidins (15%)

Commercial preparations of rosemary are available as powdered herb, dry extract, and other preparations derived from fresh or dried leaves. Infusions for internal and external use are made with cut or ground dried leaf material collected during flowering. Rosemary herb generally contains a minimum of 1.2% (v/w) volatile oil, and is often added to remedies for dyspeptic and rheumatic conditions. Plant material grown in southern regions such as Dalmatia is especially valued for medicinal preparations because of its more pungent aroma.

Traditional internal uses: dyspepsia (gastrointestinal ailments), headache, spasmolytic, sedative, diuretic, antimicrobial, diaphoretic (perspiration-promoting), emmenagogues (menstrual-flow stimulating), abortifacients

Traditional external uses: poultice for wound healing, eczema; topically for myalgia, sciatica, intercostal neuralgia, rubefacient, mild analgesic, parasiticidal; balneotherapy; supportive therapy (adjuvant) for circulatory disorders, rheumatic conditions

Conditions: digestive (dyspepsia), circulatory, pain, neuralgia, spasm nervousness, diuretic, wounds, eczema, myalgia, sciatica, rheumatism, parasites

Clinical applications: loss of appetite, blood pressure problems, liver and gallbladder complaints, rheumatism

Numerous studies have shown that rosemary has a wide array of pharmacological properties. Rosemary oil exhibited antibacterial and antifungal activities in vitro. Two of its constituents, carnosol and ursolic acid, had antioxidant effects against spoilage microbes. The oil and several of its active principles produced spasmolytic effects in smooth muscle (gallbladder and small intestines) and, to a lesser extent, in cardiac muscle. A calcium antagonistic action of rosemary may be responsible for the antispasmolytic activity.

In an in vivo study, rosemary extract added to the diet produced a significant (47%) decline in mammary tumor incidence compared to controls. Topical preparations of both carnosol and ursolic acid inhibited tumor promotion. In other research, carnosol inhibited the initiation of carcinogenesis by increasing detoxification of a procarcinogen in human bronchial epithelial cells.

Recent evidence suggests that rosmarinic acid, one of the major constituents of the leaves, has anticomplement and antioxidant properties, thus making rosemary a potential prophylactic for endotoxin shock and adult respiratory distress syndrome. In another investigation, ethanol extracts of young sprouts from rosemary produced significant dose-related choleretic effects while aqueous extracts of young sprouts showed significant hepatoprotective activity.

In an animal study evaluating the abortive effects of rosemary, an extract elicited an anti-implantation effect during the pre-implantation period. However, rosemary did not interfere with the normal development of conception following implantation.

Rosemary oil administered orally or by inhalation enhanced locomotion activity in animals. Other constituents isolated from rosemary reduced capillary permeability.

Internal:

• Tincture (1:5): 2 to 4 ml tid
• Infusion: 2 to 4 g tid
• Fluid extract (1:1 in 45% alcohol): 1 to 2 ml tid
• Essential oil (traditional preparation): 2 to 4 drops (however, Germany's Commission E advises against internal use of essential oil)
• Rosemary wine: 20 g herb is added to 1 liter of wine and allowed to stand for five days, shake occasionally

External:

• Essential oil (6% to 10%): 2 drops semisolid or liquid in 1 tablespoon base oil
• Infusion: 50 g herb in 1 liter hot water is added to bath water

Rosemary oil is generally non-irritating and non-sensitizing when used topically in humans. However, erythema and dermatitis can occur in hypersensitive individuals, and photosensitivity has been reported. The toxicity of rosmarinic acid in mice is low (LD₅₀, 561 mg/kg IV), and this compound is readily removed from the circulation. Doses above 50 mg/kg IV can exacerbate transient cardiovascular actions.

Rosemary is generally considered safe and devoid of adverse side effects when administered in recommended therapeutic dosages. However, there have been occasional reports of contact allergies.

Large quantities of rosemary leaves, particularly rosemary oil, can cause adverse side effects of coma, spasm, vomiting, gastroenteritis, uterine bleeding, kidney irritation, and in some cases, concomitant pulmonary edema fatal to humans. Rosemary should not be used during pregnancy or lactation.

Topical preparations containing rosemary oil are potentially harmful to hypersensitive individuals who may be allergic to camphor. Excessive quantities of rosemary oil (10% to 20% camphor) taken orally can trigger epileptiform convulsions. Epileptic patients should thus exercise caution in using rosemary and never ingest quantities larger than those used in foodstuffs.

In vitro, rosemary extract increased the sensitivity of drug-resistant MCF-7 human breast cancer cells to doxorubicin (Plouzek et al. 1999). This interaction may have been due to inhibition of doxorubicin binding to P-glycoprotein, which is responsible for efflux of chemotherapeutic agents from cells. Additional clinical studies are needed to confirm these effects in humans.

In the United Kingdom, rosemary is listed in the General Sale List (GSL). Both the herb and oil are listed in category N2 as a source of natural food flavoring by the Council of Europe. Herbs in this category can be added to foodstuffs in small quantities.

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