Botanical Name: Turnera diffusa, Turneraceae

Botanical synonyms: Turnera aphrodisiaca, Damiana aphrodisiaca, Turnera microphyllia

Common names: Damiana, Hierba del amor (Mexico), Chanana (Brazil)

Plant description: Damiana branches have a reddish-brown bark, and when young, are covered with white, cottony hairs. The leaves are about 2 cm long, obovate, tapering at the base to a short, slender leafstalk.  When young the leaves are slightly pubescencent but become smooth when old. They are pinnately veined, and the margin is toothed with 8 to 10 teeth.  The flowers are small, yellow and subsessile near the end of the short branches. The calyx is tubular, hairy externally, colored like the petals, and 5-toothed at the apex. There are five yellow petals inserted on the tube of the calyx. The fruit are 1-celled, globular, rough, and contain from 3 to 6 kidney-shaped seeds.  Although T. diffusa is considered officinal it is likely that commercial preparations may contain allied species, such as Turnera ulmifolia.

Habitat, ecology and distribution: Turnera is found throughout sub-tropical to tropical regions of South America, Mexico, the West Indies, and the southern United States.

Part used: Herb.

History: Damiana is purported to have been used by both the Mayan and Aztecs as a sexual sacrament, traditionally smoked or drunk as a tea before making love.  Today this tradition has continued in the commercial preparation of a Damiana cordial that is commonly available in Mexico.  Damiana was also used more generally however as a folk medicine in Mexico in the treatment for genitourinary disorders, infertility, and bronchial asthma.

Constituents: Good quality Damiana has an aromatic colour and taste, containing about 0.5 ≠ 1.5% volatile oil, from which the sesquiterpenes alpha-copaene, delta-cadinene, gamma-cadinene, and calamine, as well as monoterpenes alpha-pinene and beta-pinene, and thymol, have been isolated.  Other constituents include small amounts of arbutin (0.7%), a cyanogenetic glycoside called tetraphyllin B (0.26%), alkanes triacontane and hexacosanol, a bitter principle called damianin (7%), beta sitosterol, tannins (3.5%), 5-hydroxy-7,3',4-trimethoxyflavone, resin (6.5%), gum (13.5%), starch (6%) and albuminoids (Bradley 1992, 71; Newall et al 1996, 94; Duke 1992).

Medical research:
•Infertility: Sexually potent and sexually sluggish/impotent male rats were treated orally with Turnera diffusa.  While having no effect on the copulatory behavior of sexually potent rats, Turnera improved the copulatory performance of sexually sluggish/impotent rats, increasing the percentage of rats achieving ejaculation and significantly reduced mount, intromission and ejaculation latencies, post-ejaculatory interval and intercopulatory interval (Arletti et al 1999).
•Anti-ulcerogenic: An aqueous fraction (AqF) of the aerial parts of Turnera ulmifolia was investigated for its ability to prevent ulceration of the gastric and duodenal mucosa was examined in mice and rats, respectively. The AqF significantly reduced the formation of lesions associated with HCl, ethanol, indomethacin and bethanechol administration. Preliminary phytochemical screening confirmed that flavonoids were the major constituents of the AqF of T. ulmifolia (Gracioso et al 2002). 
•Anti-inflammatory: Anti-inflammatory studies were conducted on rats or mice using a crude hydroalcoholic extract of the aerial parts of Turnera ulmifolia and its partitioned fractions (i.e. the aqueous, ethyl acetate and ethanolic fractions). The hydroalcoholic extract and its fractions (aqueous and ethanolic) inhibited carrageenan-induced edema.   The hydroalcoholic extract also inhibited cotton pellet granuloma and the increase of vascular permeability induced by histamine, 5-hydroxytryptamine and prostaglandin E2, but not that produced by bradykinin. The anti-inflammatory action of the extract and the fraction may be due to an inhibitory effect on histamine and cyclooxygenase II, but not, the authors report, on cyclooxygenase I. The major substances present in the ethanolic fraction are flavonoids (Antonio and Souza Brito 1998).
•Hyperglycemia: The intragastric administration of a traditional extract of Turnera diffusa significantly decreased the hyperglycemic peak and/or the area under the glucose tolerance curve in hyperglycemic rabbits (Alarcon-Aguilara et al 1998).

Toxicity: Newall et al report one case of convulsions with the ingestion of 200 mg of a Damiana extract (196, 94).  No other cases could be found in the literature.  Damiana is  widely consumed as a beverage in Mexico, and is classed as a food additive by the U.S. F.D.A

Herbal action: aphrodisiac, antidepressant, thymoleptic, stomachic, aperient, astringent, expectorant

Indications: Depression, anxiety, impotence, frigidity, infertility, nervous dyspepsia, atonic constipation, bronchial congestion.

Contraindications and cautions: In very large amounts (>100 g) there is a theoretical concern of arbutin poisoning.  Concern has been voiced other the presence of the cyanogenetic glycoside tetraphyllin in Damiana, and thus should probably not be used during pregnancy and lactation (Newall et al 1996, 94).

Medicinal uses: Although Damiana has venerable history of use as an aphrodisiac, how it achieves this effect is not only poorly understood, but has been a subject of debate among western-trained herbalists.  It seems reasonable to suggest however that this effect is mediated by Damiana's established antidepressant and anxiolytic properties.  Thus Damiana may be more akin to a 'mood-enhancer' such as marijuana, rather than the rejuvenating aphrodisiac used in China and India (e.g. Panax ginseng, Withania somnifera).  In the treatment of genitourinary disorders however its efficacy is not in dispute, and mention it in chronic cystic and renal catarrh, where it helps to relieve irritation of the urinary mucous membranes.  As a bitter tonic Damiana improves digestion, and may help constipation, especially in cases where fear and anxiety prevail.  In respiratory disorders Damiana is used in irritation and cough, and as an astringent, to check hypersecretionfrom the respiratory mucosa.

Pharmacy and dosage:
•Fresh Plant Tincture: 1:2, 95% alcohol, 2-6 mL
•Dry Plant Tincture: 1:2, 50% alcohol, 2-10 mL
•Hot Infusion: 1:20, 150-300 mL

REFERENCES

Alarcon-Aguilara FJ, Roman-Ramos R, Perez-Gutierrez S, Aguilar-Contreras A, Contreras-Weber CC, Flores-Saenz JL. 1998. Study of the anti-hyperglycemic effect of plants used as antidiabetics. J Ethnopharmacol  Jun;61(2):101-10
Antonio MA, Souza Brito AR. 1998. Oral anti-inflammatory and anti-ulcerogenic activities of a hydroalcoholic extract and partitioned fractions of Turnera ulmifolia (Turneraceae). J Ethnopharmacol  Jul;61(3):215-28
Arletti R, Benelli A, Cavazzuti E, Scarpetta G, Bertolini A. 1999. Stimulating property of Turnera diffusa and Pfaffia paniculata extracts on the sexual-behavior of male rats. Psychopharmacology (Berl). Mar;143(1):15-9
Bradley, Peter R. ed. 1992. British Herbal Compendium. Bournemouth, UK: British Herbal Medicine Association.
Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press. Digitized database available from http://www.ars-grin.gov/duke/.
Felter, HW and JU Lloyd. 1893. King's American Dispensatory. Digitized version available from http://www.ibiblio.org/herbmed/eclectic/kings/main.html.
Gracioso Jde S, Vilegas W, Hiruma-Lima CA, Souza Brito AR. 2002. Effects of tea from Turnera ulmifolia L. on mouse gastric mucosa support the turneraceae as a new source of antiulcerogenic drugs. Biol Pharm Bull Apr;25(4):487-91
Grieve, Maude. 1971. A Modern Herbal. New York: Dover Publications.
Newall, Carol A., Linda A. Anderson and J.D. Phillipson. 1996. Herbal Medicines: A Guide for Health-Care Professionals. London: The Pharmaceutical Press.