Expand Document  |  Expand Chapter  |  Full TOC  |  Printable HTML version
WHO Monographs on Selected Medicinal Plants - Volume 2
(2004; 358 pages) View the PDF document
Table of Contents
View the documentIntroduction
View the documentGeneral technical notices
View the documentRadix Althaeae
View the documentHerba Andrographidis
View the documentRadix Angelicae Sinensis
View the documentFlos Calendulae
View the documentFlos Caryophylli
View the documentRhizoma Cimicifugae Racemosae
View the documentFolium cum Flore Crataegi
View the documentRadix Eleutherococci
View the documentAetheroleum Eucalypti
View the documentFolium Eucalypti
View the documentCortex Frangulae
View the documentFolium et Cortex Hamamelidis
View the documentSemen Hippocastani
View the documentHerba Hyperici
View the documentAetheroleum Melaleucae Alternifoliae
View the documentFolium Melissae
View the documentAetheroleum Menthae Piperitae
View the documentFolium Menthae Piperitae
View the documentFolium Ocimi Sancti
View the documentOleum Oenotherae Biennis
View the documentRhizoma Piperis Methystici
View the documentCortex Pruni Africanae
View the documentCortex Rhamni Purshianae
View the documentFlos Sambuci
View the documentRadix Senegae
View the documentFructus Serenoae Repentis
View the documentFructus Silybi Mariae
View the documentHerba Tanaceti Parthenii
View the documentRadix Urticae
View the documentFolium Uvae Ursi
View the documentAnnex: Participants in the Second WHO Consultation on Selected Medicinal Plants

Radix Senegae


Radix Senegae consists of the dried roots and root crowns of Polygala senega L., Polygala senega L. var. latifolia Torrey et Gray, or other closely related Polygala species (Polygalaceae) (1-3).


Polygala senegum L. (1), P. rosea Steud., Senega officinalis Spach (4).

Selected vernacular names

Bambara, bulughâ lon, gizr uththuban, Klapperschlangenwurzel, mountain flax, peuhl, polygala de virginie, racine de polygala, racine de senega, Radix polygalae, Radix polygalae senegae, rattlesnake root, seneca snakeroot, Senegakreuzblume, senega root, senega snakeroot, Senegawurzel, snake root, szenega gyökér, tsuknida, vahulill, virginische Schlangenwurzel, yoruba (1-3, 5-7).

Geographical distribution

Indigenous to eastern Canada and north-eastern United States of America (6-8).


A perennial herbaceous plant with numerous stems sprouting from a single thick gnarled crown arising from a conical, twisted, branched yellow root. Aerial portion consists of several erect or ascending, smooth stems up to 15-40 cm high, bearing alternate, lanceolate or oblong-lanceolate leaves with serrulate margins. Inflorescence a spike of small, white flowers, which are almost sessile with rounded-obovate wings, concave with a short crested carina (1, 7).

Plant material of interest: dried roots and root crowns

General appearance

Root crown greyish-brown, wider than the root; diameter of the root crown up to 3 cm, gradually tapering to the tip; surface transversely and longitudinally striated, often shows a more or less distinct decurrent, elongated spiral keel. Forms an irregular head consisting of numerous remains of stems and tightly Radix Senegae packed purplish-brown to red buds. Taproot, 0.5-1.5 cm in diameter and 3-20 cm in length, brown to yellow, occasionally branched, sometimes flexuous, usually without secondary roots, except in the Japanese varieties and species, which contain numerous fibrous branched rootlets. Fracture short and shows a yellowish cortex of varying thickness surrounding a pale central woody area somewhat circular or irregular in shape, depending on the species (1-3).

Organoleptic properties

Odour: characteristic, faint, sweet, slightly rancid or reminiscent of methyl salicylate, sternutatory when in powder form; taste: sweet, subsequently acrid and irritating to the throat (1-3).

Microscopic characteristics

Cork layer consisting of several rows of light-brown cork cells; secondary cortex composed of parenchyma cells and sieve tubes, traversed by medullary rays, 1-3 cells wide. Phelloderm of slightly collenchymatous cells containing droplets of oil. Phloem and xylem arrangement usually normal, especially near the crown, but where a keel is present, it is formed by increased development of phloem; other anomalous secondary development sometimes occurs, resulting in formation of 1 or 2 large wedge-shaped rays in phloem and xylem, the parenchymatous cells of which contain droplets of oil. Xylem usually central, consists of vessels up to 60mm in diameter associated with numerous thinwalled tracheids and a few small lignified parenchymatous cells. Starch grains and calcium oxalate crystals absent (1-3).

Powdered plant material

Light brown. Longitudinal fragments of lignified tissue made up of pitted tracheids and somewhat larger vessels with numerous bordered pits or with reticulate thickening; yellowish parenchyma and collenchymatous cells containing droplets of oil; occasional fragments of cork and epidermal tissue with stomata and unicellular trichomes from bud scales. Calcium oxalate crystals and stone cells are absent (1-3).

General identity tests

Macroscopic and microscopic examinations (1-3), chemical tests and froth formation (1, 2), and thin-layer chromatography for the presence of saponins (3).

Purity tests


Tests for specific microorganisms and microbial contamination limits are as described in the WHO guidelines on quality control methods for medicinal plants (9).

Foreign organic matter

Not more than 2% stems and not more than 1% other foreign matter (2).

Total ash

Not more than 6% (3).

Acid-insoluble ash

Not more than 2% (1, 2).

Alcohol-soluble extractive

Not less than 30% in 20% alcohol (2).

Loss on drying

Not more than 13% (2).

Pesticide residues

The recommended maximum limit of aldrin and dieldrin is not more than 0.05 mg/kg (3). For other pesticides, see the European pharmacopoeia (3) and the WHO guidelines on quality control methods for medicinal plants (9) and pesticide residues (10).

Heavy metals

For maximum limits and analysis of heavy metals, consult the WHO guidelines on quality control methods for medicinal plants (9).

Radioactive residues

Where applicable, consult the WHO guidelines on quality control methods for medicinal plants (9) for the analysis of radioactive isotopes.

Other purity tests

Chemical, sulfated ash and water-soluble extractive tests to be established in accordance with national requirements.

Chemical assays

Quantitative analysis of triterpene saponins by high-performance liquid chromatography (11).

Major chemical constituents

Methyl salicylate (0.1-0.3%), the compound responsible for the characteristic odour of the drug (12). The major reported biologically active constituents are triterpene saponins (6-16%) (6, 8, 13). The saponins are 3-glucosides of presenegenin, which also contain at C-28 an oligosaccharide chain that has a fucose moiety esterified with 3,4-dimethoxycinnamic or 4-methoxycinnamic acid (14-16). The structures of the representative saponins are presented below.





(E)-senegasaponin A




(Z)-senegasaponin A




desacylsenegasaponin A




(E)-senegasaponin B




(Z)-senegasaponin B




senegin II




(Z)-senegin II




desacylsenegin II




(E)-senegin III




(Z)-senegin III




desacylsenegin III





R = H


R = OCH3


R = H


R = OCH3



Medicinal uses

Uses supported by clinical data


Uses described in pharmacopoeias and in traditional systems of medicine

As an expectorant for symptomatic treatment of coughs due to bronchitis, emphysema and catarrh of the upper respiratory tract (1, 6, 14, 17-19).

Uses described in folk medicine, not supported by experimental or clinical data

Treatment of amenorrhoea, asthma, constipation, rheumatism and snake bites (5).


Experimental pharmacology

Expectorant activity

Intragastric administration of a fluidextract of Radix Senegae (0.1-10ml/kg body weight) enhanced the production of respiratory tract fluid in decerebrate or anaesthetized animals. Three to four hours after administration, the output of respiratory tract fluid increased by up to 173% in cats and 186% in guineapigs, but no effect was observed in rabbits (20). In another study, administration of a syrup of the root to anaesthetized dogs significantly increased the volume of respiratory tract fluid within 5-30 minutes (P < 0.001); after 2 hours, the fluid volume in the treatment group was 0.114ml as compared with 0.01 ml in control animals treated with saline (21). Intragastric administration of a 50% methanol extract of the root (2 g/kg body weight) inhibited stressinduced gastric ulcers in rats by 98.5% (22). Intragastric administration of an aqueous suspension of a 50% methanol extract of the root (2 g/kg body weight) to rats reduced congestive oedema by 62% and significantly increased the 24- hour urine volume as compared with control animals (P < 0.01) (23).

Effect on blood cholesterol and triglyceride levels

Intraperitoneal administration of an n-butanol extract of the root (5 mg/kg body weight) reduced blood triglyceride levels in mice fed a normal diet, and reduced blood cholesterol and triglyceride levels in mice fed a high cholesterol diet (24).

Antihyperglycaemic activity

Intraperitoneal administration of an n-butanol extract of the roots (10mg/kg body weight) reduced blood glucose levels in healthy mice and in mice with streptozocin-induced hyperglycaemia (25). Intragastric administration of a saponin fraction of a root extract reduced glucose-induced hyperglycaemia in rats at a dose of 200 mg/kg body weight (16). Intraperitoneal administration of a saponin fraction of a root extract (25mg/kg body weight) significantly increased the plasma levels of adrenocorticotropic hormone, cortisone and glucose in rats (P < 0.01) (26). Intragastric administration of a 100% methanol extract of the root decreased the absorption of ethanol in rats (500mg/kg body weight) (15).


The LD50 of the root was 17 g/kg body weight after intragastric administration to mice. The LD50 of the root bark was 10 g/kg body weight and that of the root core (which had the lowest saponin concentration of the three root samples) was 75 g/kg body weight (13).

Clinical pharmacology

Expectorant activity

The expectorant activity of the crude drug is due to the constituent saponins which produce local irritation of the mucous membranes of the throat and respiratory tract. This irritation stimulates an increase in bronchial secretions, thereby diluting the mucus, reducing its viscosity and facilitating expectoration (19-21, 27, 28). Saponins may also reduce the surface tension of mucus, thus reducing its viscosity (29). Oral administration of a fluidextract of the root was shown to reduce the viscosity of mucus in patients with bronchiectasis (17).


Pregnancy (See Precautions).


If coughing persists for more than 7 days, seek medical advice. Radix Senegae may exacerbate existing gastrointestinal inflammations such as gastritis or gastric ulcers, and excessive doses may cause vomiting (30).


Carcinogenesis, mutagenesis, impairment of fertility

No mutagenic effects of an aqueous or 50% methanol extract of the root were observed in the Bacillus subtilis recombination assay or in the microsome reversion assay in Salmonella typhimurium strains TA98 and TA100 (31).

Pregnancy: teratogenic effects

See Contraindications.

Pregnancy: non-teratogenic effects

Traditional uses for Radix Senegae include its use as an emmenagogue (5). As extracts of the root have been shown to stimulate uterine contractions in animal models (32), Radix Senegae should not be taken during pregnancy.

Other precautions

No information available on general precautions or precautions concerning drug interactions; drug and laboratory test interactions; nursing mothers; or paediatric use. Therefore, Radix Senegae should not be administered during lactation or to children without medical supervision.

Adverse reactions

Overdose with Radix Senegae preparations may cause nausea, diarrhoea and vomiting due to gastrointestinal upset (13). In sensitive individuals, gastrointestinal upset may occur even at the therapeutic dosage (33, 34).

Dosage forms

Chopped crude drug for decoctions and extracts (6, 18). Store in a tightly closed container, protected from light and humidity (3).


(Unless otherwise indicated)
Daily dosage: 1.5-3.0 g crude drug as an infusion or decoction in divided doses (18, 35). A 60% ethanol extract (made slightly alkaline with dilute ammonia): 0.9-3 ml; tincture: 2.5-7.5 g. Equivalent preparations (18).


1. African pharmacopoeia. Vol. 1, 1st ed. Lagos, Organization of African Unity, Scientific Technical & Research Commission, 1985.

2. The Japanese pharmacopoeia, 13th ed. (English version). Tokyo, Ministry of Health and Welfare, 1996.

3. European pharmacopoeia, 3rd ed. Strasbourg, Council of Europe, 1996.

4. Hooker JD, Jackson BD. Index Kewensis. Vol. 1. Oxford, Clarendon Press, 1895.

5. Farnsworth NR, ed. NAPRALERT database. Chicago, University of Illinois at Chicago, IL, February 9, 1998 production (an online database available directly through the University of Illinois at Chicago or through the Scientific and Technical Network [STN] of Chemical Abstracts Services).

6. Bisset NG. Herbal drugs and phytopharmaceuticals. Boca Raton, FL, CRC Press, 1994.

7. Youngken HW. Textbook of pharmacognosy, 6th ed. Philadelphia, PA, Blakiston, 1950.

8. Bruneton J. Pharmacognosy, phytochemistry, medicinal plants. Paris, Lavoisier, 1995.

9. Quality control methods for medicinal plant materials. Geneva, World Health Organization, 1998.

10. Guidelines for predicting dietary intake of pesticide residues, 2nd rev. ed. Geneva, World Health Organization, 1997 (document WHO/FSF/FOS/97.7).

11. Kanazawa H et al. Determination of acidic saponins in crude drugs by highperformance liquid chromatography on octadecylsilyl porous glass. Journal of Chromatography, 1993, 630:408-414.

12. Hayashi S, Kameoka H. Volatile compounds of Polygala senega L. var. latifolia Torrey et Gray roots. Flavour and Fragrance Journal, 1995, 10:273-280.

13. De Smet PAGM. Polygala species. In: De Smet PAGM et al., eds. Adverse effects of herbal drugs. Vol. 2. Berlin, Springer-Verlag, 1993.

14. Samuelsson G. Drugs of natural origin, a textbook of pharmacognosy. Stockholm, Swedish Pharmaceutical Press, 1992.

15. Yoshikawa M et al. E-Senegasaponins A and B, Z-senegasaponins A and B, Zsenegins II and III, new type inhibitors of ethanol absorption in rats from Senegae radix, the roots of Polygala senega L. var. latifolia Torrey et Gray. Chemical and Pharmaceutical Bulletin, 1995, 43:350-352.

16. Yoshikawa M et al. Bioactive saponins and glycosides. II. Senegae radix. (2): Chemical structures, hypoglycemic activity, and ethanol absorption-inhibitory effect of E-senegasaponin C, Z-senegasaponin C, and Z-senegins II, III and IV. Chemical and Pharmaceutical Bulletin, 1996, 44:1305-1313.

17. Basch FP, Holinger P, Poncher HG. Physical and chemical properties of sputum. II. Influence of drugs, steam, carbon dioxide and oxygen. American Journal of Diseases of Childhood, 1941, 62:1149-1171.

18. Blumenthal M et al., eds. The complete German Commission E monographs. Austin, TX, American Botanical Council, 1998.

19. Reynolds JEF, ed. Martindale, the extra pharmacopoeia, 30th ed. London, Pharmaceutical Press, 1996.

20. Boyd EM, Palmer ME. Effect of Quillaja, Senega, Grindelia, Sanguinaria, Chionanthus and Dioscorea upon the output of respiratory tract fluid. Acta Pharmacologia Toxicologia, 1946, 2:235-239.

21. Misawa M, Yanaura S. Continuous determination of tracheobronchial secretory activity in dogs. Japanese Journal of Pharmacology, 1980, 30:221-229.

22. Yamahara J et al. Biological active principles of the crude drugs. II. Antiulcerogenic and anti-inflammatory actions of the crude drugs containing saponin. Yakugaku Zasshi, 1975, 95:1179-1182.

23. Yamahara J et al. Effects of crude drugs on congestive edema. Chemical and Pharmaceutical Bulletin, 1979, 27:1464-1468.

24. Masuda H et al. Intraperitoneal administration of Senegae Radix extract and its main component, senegin-II, affects lipid metabolism in normal and hyperlipidemic mice. Biological and Pharmaceutical Bulletin, 1996, 19:315-317.

25. Kato M et al. Hypoglycemic effect of the rhizomes of Polygala senega in normal and diabetic mice and its main component, the triterpenoid glycoside senegin-II. Planta Medica, 1996, 62:440-443.

26. Yokoyama H et al. Effects of total saponins extracted from several crude drugs on rat adrenocortical hormone secretion. Yakugaku Zasshi, 1982, 102:555-559.

27. Boyd EM. Expectorants and respiratory tract fluid. Journal of Pharmacy and Pharmacology, 1954, 6:521-542.

28. ESCOP monographs on the medicinal uses of plant drugs. Fascicule 3. Devon, European Scientific Cooperative on Phytotherapy, 1997.

29. Hostettmann K, Marston A. Saponins. Cambridge, Cambridge University Press, 1995.

30. Newall CA, Anderson LA, Phillipson JD. Herbal medicines, a guide for healthcare professionals. London, Pharmaceutical Press, 1996.

31. Morimoto I et al. Mutagenicity screening of crude drugs with Bacillus subtilis rec-assay and Salmonella/microsome reversion assay. Mutation Research, 1982, 97: 81-102.

32. Goto M et al. Uterus-contracting ingredients in plants. Takeda Kenkyusho Nempo, 1957, 16:21.

33. Briggs CJ. Senega snakeroot - a traditional Canadian herbal medicine. Canadian Pharmaceutical Journal, 1988, 121:199-201.

34. Wichtl M. Senegawurzel. In: Wichtl M, ed. Teedrogen. Ein Handbuch für die Praxis auf wissenschaftlicher Grundlage. 2. Auflage. Stuttgart, Wissenschaftliche Verlagsgesellschaft, 1989.

35. Bradley PR, ed. British herbal compendium. Vol. 1. Bournemouth, British Herbal Medicine Association, 1992.


to previous section
to next section
The WHO Essential Medicines and Health Products Information Portal was designed and is maintained by Human Info NGO. Last updated: October 29, 2018