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Homalanthus nutans is a small, tropical tree species in the large family Euphorbiaceae, found on islands in the South Pacific.It has heart-shaped or triangular leaves and grows up to about 12 feet (4 m) tall, often in secondary forest or disturbed areas.Forster (1994) synonymized H. nutans with H. populifolius (known as native bleeding heart or Queensland poplar), a far more commonly known and wide-spread species endemic to Australia, New Zealand and Malesia.These two species (or variants, depending on your perspective) are now both widely considered H. nutans, however this synonymy is not accepted universally as several significant characters (detailed in Esser 2012) differentiate them.
In Samoa, H. nutans is known by locals as the mamala tree, where native healers use extracts from various parts of the tree for treating Yellow Fever, hepatitis, back pain and wounds, among other maladies.In the 1990s, ethnobotanist Paul Alan Cox from University of California, Berkeley sent samples of H. nutans from Samoa to the NIH, where it was discovered to contain prostatin, a compound holding promise in treatment of the AIDS virus.A pioneering memorandum of understanding was drawn up between UC Berkeley and the Samoan government and native healers to protect the indigenous intellectual property rights and ensure sharing of profits from successful HIV drugs made from the mamala tree (Pacific Island Treaty Series 2004).This document also specified that Samoan trees would be used for research where ever possible and involved Samoan industry in choosing and growing H. nutans cultivars, as research showed different populations of the tree contained variable prostatin concentrations (Gufstafson et al. 1992; Johnson et al. 2008).Chemical synthesis of prostatin was later accomplished (Wender et al. 2008) so the limited quantity that could be extracted directly from H. nutans no longer impedes progress in developing antiviral therapies, and doesn’t threaten the limited forests of Samoa.
Homalanthus nutans, known locally as the mamala tree, is a species of plant in the family Euphorbiaceae. In Australia it is known as the bleeding heart and the Queensland poplar.[3]
Samoan healers use the tree's bark in a concoction made to treat hepatitis. Research has indicated that a chemical from the bark called prostratin has in vitro activity against HIV.[4]
Homalanthus nutans is a small tree or bushy shrub up to 5 m (16 ft) tall. The trunk has fairly smooth, greyish-brown bark. The rather stout branches are green or reddish, and the twigs exude a white, milky sap when damaged. The alternately arranged leaves have a pair of small stipules at the base of the long petiole, which is often a reddish colour. The leaf blade is hairless, heart-shaped or triangular, 7 to 12 cm (3 to 5 in) long by 6 to 8 cm (2.4 to 3.1 in) wide, with a smooth, untoothed margin. The underside is often greyish and mature leaves turn red as they age. The inflorescence is a terminal yellowish-green spike, the male and female flowers being separate. The male flowers are small and petal-less, with globose anthers. The few female flowers, near the base of the spike, are also without petals, and have a pair of short styles. The female flowers are followed by capsules about 1 cm (0.4 in) long, with two compartments, the seeds being partially enclosed by a fleshy aril.[3]
Homalanthus nutans is native to various tropical Pacific islands: the Caroline Islands, the Cook Islands, Fiji, New Caledonia, Niue, Samoa, the Society Islands, Tonga, Tubuai Island, Vanuatu and Wallis and Futuna.[2] It also grows in northeastern Australia, in Queensland and the coastal strip of New South Wales at altitudes of up to 500 m (1,600 ft).[3] The seeds have a long dormancy period, but germinate readily when the conditions are suitable, such as when the previously shady forest floor becomes illuminated by direct sunlight.[3] It is a pioneer species, found in woodland and on roadside verges, readily colonising disturbed ground.[5]
The fruits of Homalanthus nutans are attractive to birds, including the brown cuckoo-dove, the silvereye, Lewin's honeyeater, bowerbirds and currawongs.[3] In Samoa, the plant has a number of uses in traditional medicine. An extract from the bark is used against hepatitis, and freshly crushed leaves are used to control bleeding.[3] Modern research confirms the plant's pharmacological activity, with the anti-HIV drug prostratin having been isolated from the plant.[6]
Homalanthus nutans, known locally as the mamala tree, is a species of plant in the family Euphorbiaceae. In Australia it is known as the bleeding heart and the Queensland poplar.
Samoan healers use the tree's bark in a concoction made to treat hepatitis. Research has indicated that a chemical from the bark called prostratin has in vitro activity against HIV.
