The Kawakawa Tree

(Source: New Zealand Association of Medical Herbalists)

Kawakawa is a small evergreen shrub-like tree with large shiny heart-shaped leaves. It grows to a height of 6m and is commonly found in shady gullies and on shaded rocky outcrops in coastal regions. The zigzag branches are swollen and jointed at the nodes. The leaves are approximately 5-10cm long and are often badly holed by chewing insects. The fruit is a yellow, conical berry.

Active Constituents:

• Volatile Oil - 1.5-3.5% in the leaves (mostly myristicin)

• Lignans - in the leaves and wood

• Juvadecene & derivatives – in the root Little else is known, although the presence of other pharmacologically active compounds such as flavonoids and alkaloids seems likely, based upon analyses of related species. Pharmacology Very little scientific investigation has been undertaken into the pharmacology of Kawakawa to date. Our understanding of the actions and uses of this plant is therefore derived largely from information about its historical uses, as well as knowledge gleamed from present day use by traditional Maori medicine practitioners and phytotherapists using Kawakawa in their practices.

Primary Actions:

• Anti-dyspeptic

• Anti-inflammatory

• Analgesic

• Alterative/Depurative

• Diaphoretic & Circulatory stimulant

Medicinal Uses:

For the gastrointestinal tract actions as an anti-dyspeptic, antispasmodic, antiinflammatory and/or carminative seem likely for Kawakawa leaves, based upon these customary uses, our phytochemical knowledge about the volatile oil, and experience from clinical practice. Historically, decoctions or infusions of Kawakawa leaf, or simple chewing of the leaves, were widely used for stomach pains and indigestion, particularly where due to over-eating. Use for stomach problems and indigestion is a common theme for a wide variety of Piper species around the world.

Possible anticholinergic activity of the volatile oil constituents myristicin and elemicin, may contribute to Kawakawa’s efficacy as a digestive aid. Kawakawa also has a reputation as an appetite stimulant, and it’s mildly bitter taste probably contributes to this. The root was also chewed for both dysentery and diarrhoea.

While no anti-inflammatory activity has been proven for Kawakawa to date, such activity seems likely upon the gastrointestinal tract and with topical use at least. Kawakawa leaf applications were used topically for bruises and rheumatism, the pain of neuralgia and nettle stings, as well as for eczema. Antiinflammatory activity has been shown for volatile oil constituents such as myristicin and elemicin. Leaves and fruit of Kawakawa were frequently chewed for toothache in times gone by.

Volatile oil constituents related to eugenol, a main constituent with analgesic activity found in oil of Cloves, are probably contributory. The leaves of various related Piper species are also used to relieve toothache and other pains, including those of Kava and the Australian Piper novae hollandiae.

A decoction of Kawakawa leaves was a popular drink for purifying the blood, as well as for boils. In more recent years decoctions or infusions have become popular for a variety of skin ailments including eczema. Kawakawa was taken or steam baths of it used also for various sexually transmitted diseases including gonorrhoea and syphilis, as well as for leprosy.

Hot Kawakawa infusions or decoctions have long been a popular treatment for colds and influenza, and this probably relates at least in part to the significant diaphoretic effect produced by such preparations. Expectorant activity due to the volatile oil is also likely, and these actions, as well as possible anti-microbial effects, probably contribute to its efficacy in conditions such as colds, influenza, coughs and chest complaints.

Like other Piperaceae family plants, stimulation of the circulation is an effect of internal consumption of reasonable doses of Kawakawa preparations. Such activity could make it useful in conditions such as chilblains, varicose veins, and arterial and venous insufficiency.

Like Manuka, Kawakawa leaves were once commonly used as a substitute for tea, and early settlers attributed it with having refreshing and sustaining properties. Preparations made from Kawakawa leaves were sometimes used for their tonic and stimulant properties by those suffering general debility.

A poultice or juice application of Kawakawa was one of the most popular of many treatments used by Maori for cuts, boils, abscesses, septic infections and old wounds. Steam baths of Kawakawa with other herbs were also used with some success by women to treat venereal disease. Antifungal activity is shown by myristicin and elemicin, and antiprotozoal activities have also been shown for lignans related to those found in Kawakawa.

These uses as well as microbiological tests on a series of Kawakawa leaf tinctures commisioned by Phytomed, implicate significant antimicrobial activity for this plant.

Copyright Phytomed Medicinal Herbs Ltd. 2007