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Acorus calamus (Sweet Flag) is a perennial herbaceous plant, growing 60–100 cm tall. The rhizome is thick, cylindrical, and winding, covered spirally on top with dark broad leaf scars. It lies horizontally, almost at the surface, reaching up to 1.5 meters in length. The roots are thin, fibrous, and located at the nodes. The rhizome and other parts of the plant have a characteristic strong aroma.
The stem is erect, unbranched, flattened, grooved on one side, and sharply ridged on the other. The leaves are sword-shaped. The flowers are small, greenish-yellow, bisexual, arranged in a spike (spadix) 4–12 cm long. The flower formula for Acorus calamus is O3+3T6P(3). It blooms from May to July.
The fruit is a leathery, multi-seeded red berry. In the climatic conditions of Russia, the fruits usually do not ripen, and the plant propagates by rhizomes.
Harvesting of Raw Materials
In medicine, both dry and fresh rhizomes of Acorus calamus (Rhizoma Calami) are used as medicinal raw materials. The rhizomes are harvested in early spring and autumn. The plant’s rhizomes are dug up, then the remaining leaves, stems, and roots are cut off with a knife. The rhizomes are washed, air-dried briefly, cut into pieces up to 20 cm long, and dried at a temperature not exceeding 30°C.
Chemical Composition
The rhizomes of Acorus calamus contain up to 3% essential oil, which includes monoterpenes (camphene, camphor, borneol) and sesquiterpenes (acorenone, isoacorenone, acoroxide, and others), aromatic compounds (asarone, eugenol), and more.
In addition to the essential oil, the rhizomes contain a plant-specific bitter glycoside called acorin, the bitter principle acoretin, tannins, ascorbic and palmitic acids, starch, choline, vitamins, and iodine. The characteristic aroma of the rhizomes is due to asaraldehyde.
Pharmacological Properties
The essential oil of Acorus calamus and the bitter glycoside acorin stimulate taste receptors, increase appetite, support gallbladder tone, improve digestion, and reflexively stimulate gastric juice secretion. They also promote gas expulsion and increase diuresis. Tannins enhance the therapeutic effect and exhibit antidiarrheal properties.
Experimental studies have confirmed that Acorus calamus preparations possess antispasmodic effects. Due to the presence of terpenoids in the rhizomes (including proazulene and asarone), extracts from Acorus calamus exhibit bacteriostatic, fungistatic, and anti-inflammatory properties. The essential oil shows antimicrobial activity against Staphylococcus aureus and Escherichia coli. Aqueous and alcoholic extracts from the rhizomes moderately inhibit the growth of Shigella, Proteus, and Pseudomonas aeruginosa.
Traditional Medicine Uses
In traditional medicine, an infusion of Acorus calamus rhizomes is used to treat gastritis with low acidity, stomach and intestinal colic, diarrhea, hepatitis, cholecystitis, inflammation of the kidneys and bladder, urinary tract disorders, irregular menstruation, and diseases of the biliary system and gallbladder. The green parts and roots of Acorus calamus are also used to prepare therapeutic baths, which are applied in the treatment of rickets and scrofula in children, as well as neurosis in adults.