Passion Flower

Scientific Name(s): Passiflora incarnata L., occasionally P. lutea L. Family: Passifloraceae

Common Name(s): Passion flower ; passion fruit , granadilla (species with edible fruit); water lemon ; Maypop , apricot vine , wild passion flower ( P. incarnatus ); Jamaican honeysuckle ( P. laurifolia ).


Passion flower has been used to treat sleep disorders and historically in homeopathic medicine to treat pain, insomnia related to neurasthenia or hysteria, and nervous exhaustion.


No clinical trials of passion flower as a single agent have been reported; however, a daily dose of 4 to 8 g is typical.


Contraindications have not yet been identified.


Documented adverse effects. Avoid use. Passion flower is a known uterine stimulant.


None well documented.

Adverse Reactions

Though no adverse effects of passion flower have been reported, large doses may result in CNS depression.


No major clinical trials have been conducted to assess the plant's toxicity.


The term “passion flower” connotes many of the approximately 400 species of the genus Passiflora , which are primarily vines. Some of the species are noted for their showy flowers, others for their edible fruit. Common species include P. incarnata , P. edulis , P. alata , P. laurifolia , and P. quadrangularis . Those with edible fruit include P. incarnata , P. edulis , and P. quadrangularis , the latter being one of the major species grown commercially for its fruit. 1 Passiflora species are native to tropical and subtropical areas of the Americas. In the United States, P. incarnata is found from Virginia to Florida and as far west as Missouri and Texas. The flowers of Passiflora have 5 petals, sepals, and stamens, 3 stigmas, and a crown of filaments. The fruit is egg-shaped, has a pulpy consistency, and includes many small seeds. 1 , 2


The passion flower was discovered in 1569 by Spanish explorers in Peru, who saw the flowers as symbolic of the passion of Christ and, therefore, a sign of Christ's approval of their efforts. This is the origin of the scientific and common names. 3 The folklore surrounding this plant possibly dates further into the past. The floral parts are thought to represent the elements of the crucifixion (3 styles represent 3 nails, 5 stamens for the 5 wounds, the ovary resembles a hammer, the corona as the crown of thorns, the petals representing the 10 true apostles, with the white and bluish-purple colors those of purity and heaven). 2 , 4 In Europe, passion flower has been used in homeopathic medicine to treat pain, insomnia related to neurasthenia or hysteria, and nervous exhaustion. Other indications have included bronchial disorders (particularly asthma), compresses for burns, inflammation, inflamed hemorrhoids, climacteric complaints, pediatric attention disorders, and pediatric nervousness and excitability. 5


Researchers have identified a number of constituents in different passion flower species. The official passion flower is considered to be P. incarnata , which is used for the drug. 6 Key constituents in P. incarnata include flavonoids, maltol, cyanogenic glycosides, and harman indole alkaloids. 2 Flavonoid content (2.5%) includes flavone di-C-glycosides shaftoside, isoshaftoside, isovitexin (found in highest concentration between preflowering and flowering stages in 1 report), 7 iso-orientin, vicenin, lucenin, saponarin, and passiflorine. 8 Free flavonoids include apigenin, luteolin, quercetin, and kamferol. 6 Another report confirms similar constituents by mass spectral analysis. 9 Flavonoid determination by high-performance liquid chromatography and other methods has been extensively reported. 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 The stability of dried extract also has been studied. 18 P. incarnata components include phenolic, fatty, linoleic, linolenic, palmitic, oleic, and myristic acids, as well as formic and butyric acids, 5 , 19 coumarins, phytosterols, essential oil, maltol (0.05%), 6 , 20 and harman and its derivatives (0.03%). Harmala alkaloids include harmine, harmaline, and harmalol. Quantitative determination of harman and harmin in P. incarnata also has been performed. 21

Comparative studies

Thin layer chromatographic methods to differentiate P. incarnata from P. edulis and P. caerulea have been described. 19 Quantitative analysis of different plant parts from P. incarnata and P. edulis indicate that P. edulis leaves have the highest alkaloid content, and that fruit rinds contain approximately 0.25% alkaloids. Seeds and root tissue have the lowest alkaloid content. These findings may have economic importance. P. edulis fruit rinds, by-products of passion fruit juice production, may provide an economical source of alkaloids. 22 Flavonoids from P. trinervia and P. sanguinolenta also have been reported. 23 A review of the chemical constitution of Passiflora species is available. 24

Uses and Pharmacology

Passion flower has been researched for its sedative and anxiolytic effects. 2 , 6 , 8 A 1986 survey of British herbal sedatives revealed passion flower as the most popular. Other popular species included Valeriana officinalis , Humulus lupulus , and Scutellaria lateriflora . 25 , 26 Martindale, The Extra Pharmacopoeia lists many multi-ingredient preparations from other countries. 27

The pharmacological activity of Passiflora is attributed primarily to the alkaloids and flavonoids. The harmala alkaloids inhibit monoamine oxidase, which may account for part of their pharmacologic effect. 20

Animal data

Animal studies have shown that Passiflora extracts have a complex action on the central nervous system (CNS), inducing dose-dependent stimulation and depression. 28 A report describes CNS-receptor binding sites of P. incarnata . 29

Passiflora species exhibit sedative activity in animals 30 and anxiolytic activity in mice. 31 When given to rats, P. incarnata extract led to diminished general activity when tested in a 1-arm, radial maze. 32 In mice, P. incarnata 's sedative and anxiolytic properties were associated with aqueous extracts of aerial plant parts. 33 The sedative effect of Passiflora may require both the alkaloids and flavonoids to be present. 22 Mice injected subcutaneously with 400 mg/kg of maltol and ethyl maltol showed reduced spontaneous activity, bradycardia, hypothermia, relaxation of skeletal muscle, and diminished pinna, corneal, and ipsilateral flexor reflexes. An ethylene chloride-soluble fraction at 2 mg/mL reduced brain oxygen consumption and the effect with the acid-soluble fraction was greater. Maltol and ethyl maltol potentiated the sleep-inducing effect of hexobarbital and counteracted the convulsive effects of pentylene or strychnine. These findings indicate that maltol and ethyl maltol may mask the stimulant effects of harmala alkaloids in Passiflora . 20

Other Passiflora species exhibit similar effects. P. coerulea has sedative actions. 34 Constituent chrysin, isolated from this same species (a central benzodiazepine [BZ] ligand) has anxiolytic effects, due in part to this role as a partial agonist of central BZ receptors. 35 Tranquilizing effects have been seen with alkaloids from the harman group in P. edulis species. 36

Clinical data

Human studies of Passiflora species as a sedative/anxiolytic have been conducted. A case report using the plant in a combination natural product, Calmanervin , for successful sedation before surgery was reported. 37 In a multicenter, double-blind trial of 91 patients, Passiflora (in combination, Euphytose ) exhibited statistically significant differences when compared with placebo in the treatment of adjustment disorder with anxious mood. 38 A study of Passiflora in the combination product Compoz contradicts these last 2 studies. It was not possible to differentiate between aspirin or placebo when tested as a daytime sedative. However, the duration of this study was only 2 weeks. 39

Miscellaneous uses

Passion flower's ability to reduce anxiety makes it useful for asthma, palpitations, and other cardiac rhythm abnormalities, high blood pressure, insomnia, neurosis, nervousness, pain, and other conditions. 2 , 6 , 8 However, no clinical data is available to support any of these potential uses.

In vitro experiments have demonstrated that Passiflora kills a wide variety of molds, yeasts, and bacteria. Group A hemolytic streptococci are much more susceptible than Staphylococcus aureus , with Candida albicans being intermediate in susceptibility. The antimicrobial activity of Passiflora disappears rapidly from dried plant residues but fades more gradually in aqueous extracts. Addition of dextran, milk, or milk products has a stabilizing effect on dry Passiflora . 40 , 41 A later report describes the P. tetrandra component, 4-hydroxy-2-cyclopentenone, as having antipseudomonal actions. This constituent was also found to be cytotoxic to P388 murine leukemia cells. 42

Other uses of passion flower include herbal treatment for menopausal complaints 43 and as a flavored syrup to mask drug taste. 44


No clinical trials of passion flower as a single agent have been reported; therefore, the typical daily dose of 4 to 8 g is not supported.


Use of passion flower is contraindicated during pregnancy because of the uterine stimulant action of its alkaloids harman and harmaline, and the content of the cyanogenic glycoside gynocardin. 45 , 46 , 47


None well documented.

Adverse Reactions

Extracts produced no adverse effects in mice when administered intravenously. 40 Cyanogenesis from species P. edulis has been suggested. 48 The plant's known actions may reduce arterial pressure affecting circulation and increasing respiratory rate. 8 There are no controlled human trials using single herb preparations of Passiflora extracts before the mid-1990s. 49 There have been cases of vasculitis 50 and altered consciousness in 5 patients taking the herbal product Relaxir , produced mainly from P. incarnata fruits. 51 Occupational asthma and rhinitis may occur from the species P. alata , which was substantiated by skin testing and Western blotting in vivo and in vitro studies. 52


Little information is available on the clinical toxicity of Passiflora . P. adenopoda fruits may produce some toxic effect. 53


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