Rosemary: Background. Actions

Common Name


Other Names

Compass plant, compass-weed, garden rosemary, old man, polar plant, Rosmarini folium

Botanical Name / Family

Rosmarinus officinalis (family Labiatae or Lamiaceae)

Plant Part Used

Fresh or dried leaf

Chemical Components

Phenolic acids and diterpenoid bitter substances, including carnosic acid and carnosol, triterpenoid acids, flavonoids, tannins and volatile oils (0.5-2.5%) that consist of cineole, pinene, terpineol, camphor, camphene, borneol and bornyl acetate. Rosemary has also been found to contain high amounts of salicylates.

Historical Note

Since ancient times rosemary has been used as a tonic and stimulant. The ancient Greeks used it to strengthen memory function and scholars wore garlands of rosemary during examinations in order to improve their memory and concentration. It is widely used as a food spice and as an antioxidant to preserve foods.

Rosemary: Main Actions


Rosemary has strong antioxidant activity and is widely used to preserve food and cosmetics. Rosemary leaf extract has been shown to enhance superoxide dismutase activity and to have an effect stronger than vitamin E in scavenging oxygen radicals. It is suggested that carnosol and carnosic acid account for over 90% of its antioxidant properties. Carnosic acid has been shown to have a photoprotective action on human dermal fibroblasts exposed to UVA light in vitro and rosemary extract inhibits oxidative alterations to skin surface lipids, both in vitro and in vivo, as well as enhancing cell-mediated immunity in rats under oxidative stress. In a study of 150 patients with bronchitis exposed to essential oils of rosemary, basil, fir and eucalyptus, an antioxidant effect was observed.


Rosemary extract demonstrates in vitro antibacterial activity against a variety of bacteria including Helicobacter pylori and Staphylococcus aureus. Topical application of rosemary essential oil preparations has been found to have antifungal activity and to inhibit the growth and aflatoxin production of Aspergillus spp. at concentrations between 0.2% and 1 %. Carnosol has been found to have anti-HIV activity and carnosicacid has also been shown to have an inhibitory effect on HIV-1 protease in cell-free assays. Rosemary extract has some antiviral activity against HSV. Powdered rosemary leaves are said to be effective as a natural flea and tick repellent and rosemary essential oil has been found to be ovicidal and repellent towards mosquito.


In vitro studies have found that rosemary extracts inhibited inflammatory-induced peroxynitrite radical and nitrite production and that carnosol suppresses NO production. Rosmarinic acid has been found to increase the production of PGE2, reduce the production of leukotriene B4 in human polymorphonuclear leucocytes, and inhibit the complement system.


The hepatoprotective properties of rosemary extract are attributed to its antioxidant properties and improving detoxification systems dependent on glutathione S-transferase. Rosemary extract has been shown to reduce thioacetamide-induced cirrhosis and azathioprine-induced toxicity in rats, as well as partially prevent carbon tetrachloride induced liver damage in both rats and mice.


In vivo studies suggest that rosemary extract may reduce the effects of carcinogenic or toxic agents on many cell lines, including rat mammary gland, mouse liver and stomach, bone marrow and skin.

An in vitro study on human bronchial cells found that rosemary extract and its constituents, carnosol and carnosic acid, may have chemoprotective activity through decreasing carcinogen activation via inhibition of the enzyme cytochrome P450 (CYP1A1) and increasing carcinogen detoxification by induction of phase II enzymes. Carnosol has been found to also restrict the invasive ability of mouse melanoma cells in vitro by reducing MMP-9 expression and activity.


Feeding female mice a 2% rosemary diet enhanced the liver microsomal metabolism of endogenous oestrogens, thereby reducing oestrogen levels.

Rosemary: Other Actions

Carnosic acid and carnosol, which are major components of rosemary, have been found to markedly enhance synthesis of nerve growth factor in vitro. Rosemary has been also demonstrated to have significant antithrombotic activity in vitro and in vivo, possibly through a direct inhibitory effect on platelets. Rosemary essential oil and its constituent monoterpenes, such as borneol, have been found to inhibit bone resorption in the rat. Aqueous and ethanol extracts of rosemary have been found to produce significant antinociceptive activity and diminish morphine withdrawal syndrome in rats.

Rosemary extract may delay and inhibit tumour formation in women with breast cancer and prevent mesangial cell proliferation in cultured murine mesangial cells.

When used topically, rosemary essential oil is said to stimulate the skin and increase blood circulation.