Sweet Vernal Grass

Scientific Name(s): Anthoxanthum odoratum L., Family: Poaceae (grasses)

Common Name(s): Grass , spring grass , sweet vernal grass

Uses

Sweet vernal grass is used as a flavoring and sometimes in the manufacture of brandy. Recent veterinary poisonings show reason to discourage its use in humans.

Dosing

There is no clinical evidence to support specific doses of sweet vernal grass. It classical use was only external. Caution should be exercised due to the high coumarin content, which can interfere with clotting.

Contraindications

No longer considered safe.

Pregnancy/Lactation

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

Interactions

None well documented.

Adverse Reactions

In cattle, hay made from sweet vernal grass has caused progressive weakness, stiff gait, breathing difficulties and hemorrhage followed by quick death. This reaction has been attributed to the dicoumarol content of the hay and makes human consumption dangerous.

Toxicology

Other than historical reference to the use of sweet vernal grass as a flavoring, no other pharmacological or toxicological studies are found in the recent literature.

Botany

Sweet vernal grass is a fragrant plant in the grass family that has flat leaves and narrow spike-like panicles of proterogynous flowers. It grows perennially in tufts, without stolons or basal scaly offshoots. The culms are slender, erect, and 2 to 10 dm high. Its spikelets are brownish-green, 8 to 10 mm long, and spread at the time of flowering. The grass is originally native to Eurasia and Africa, but is common in American fields, pastures, and waste places as far north as southern Ontario and as far south as Louisiana. 1

History

Like many aromatic plants, sweet vernal grass has been used historically as a flavoring agent because of its vanilla-like aroma. In Russia and related countries, it was used in the manufacture of special brandy. 2

Chemistry

Except where veterinary poisoning has shown the presence of dicoumarol in its hay, very few chemical studies have been carried out directly on sweet vernal grass. 3

Uses and Pharmacology

Animal data

An outbreak of a hemorrhagic diathesis has been reported in cattle fed sweet vernal grass hay. The same syndrome was later reproduced experimentally in calves fed the same hay. 3 The poisoning is characterized by increased prothrombin and partial thromboplastin times, while the leukocyte and erythrocyte counts stayed normal until the terminal hemorrhage was evidenced. Symptoms include rapid onset of progressive weakness, mucosal pallor, stiff gait, tachypnea, tachycardia, and hematomata, quickly ending in death. Necropsy revealed no blood coagulation, but petechial, ecchymotic, and free hemorrhages were observed in most organs. Most striking were the massive ecchymotic hemorrhages on the peritoneal rumen surface. Each kidney was enveloped by a bloody gelatinous mass. A second feeding trial was undertaken to see if vitamins K 1 and K 3 were antidotal. No trichothecene mycotoxins were found in the hay.

A multi-allergen dipstick IgE assay to skin-prick test and RAST tests have been compared. Generally, immunological sensitivity to sweet vernal grass is low. 4

Based on the current warnings about the use of natural sources of coumarin and dicoumarol, and their known anticoagulant properties, use of A. odoratum for flavoring should be discouraged. Coumarin is widely distributed in plants, and the FDA has banned its use for flavoring purposes. 5

Clinical data

Research reveals no clinical data regarding the use of sweet vernal grass for any condition.

Dosage

There is no clinical evidence to support specific doses of sweet vernal grass. It classical use was only external. Caution should be exercised due to the high coumarin content, which can interfere with clotting.

Pregnancy/Lactation

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

Interactions

None well documented.

Adverse Reactions

In cattle, hay made from sweet vernal grass has caused progressive weakness, stiff gait, breathing difficulties and hemorrhage followed by quick death. This reaction has been attributed to the dicoumarol content of the hay and makes human consumption dangerous.

Toxicology

Other than historical reference to the use of sweet vernal grass as a flavoring, no other pharmacological or toxicological studies are found in the recent literature.

Bibliography

1. Fernald ML. Gray's Manual of Botany, ed. 8. New York: American Book Co., 1950.
2. Hocking GM. Dictionary of Terms in Pharmacognosy. Springfield, IL: Charles C. Thomas Publ. 1955.
3. Pritchard DG, et al. Vet Rec 1983;113(4):78.
4. Iwamoto I, et al. Clin Expt Allergy 1990;20(2):175.
5. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics, ed. 2. New York: John Wiley & Sons, 1996.

Copyright © 2009 Wolters Kluwer Health

Hide
(web4)