Anaxagorea (PROSEA)
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Introduction |
Anaxagorea A. St.-Hil.
- Protologue: Bull. Sci. Soc. Philom. Paris 1825: 91 (1825).
- Family: Annonaceae
- Chromosome number: x= 8;A. javanica: 2n= 16
Origin and geographic distribution
Anaxagorea consists of about 25 species, most of which are confined to tropical America. In South-East Asia, 3 (perhaps 4) species have been found, all also in Malesia.
Uses
A number of uses in traditional medicine have been recorded for Anaxagorea in South-East Asia: leaves are applied topically to treat rheumatism, and a decoction of the roots is given as a protective medicine after childbirth. In Thailand the heartwood is used as a blood tonic and to treat muscle pain. Seeds are used as camphor to preserve clothes. The wood of larger plants is occasionally used, e.g. for rafters, and the bark as cordage.
In tropical America an infusion of bark and wood is sometimes used against cough, the bark to treat headache and rheumatism, for cleaning the teeth, as a deodorant and as cordage, and the wood occasionally for construction work.
Properties
The occurrence of cyanogenic glycosides has been recorded in A. luzonensis leaves. 8-Isopentenylnaringenin was isolated from a methanolic extract of A. luzonensis . This prenylflavonoid compound is a non-steroidal oestrogen agonist with a more potent activity than genistein (from Leguminosae such as Pueraria montana (Lour.) Merr.). In-vivo tests with ovariectomized rats showed that 8-isopentenylnaringenin acts as an oestrogen agonist in the uterus as well as in bone. Several xanthones and flavonoids were isolated from the bark and heartwood. Several of these showed antioxidant activity.
From some tropical American Anaxagorea species, the aporphine alkaloids asimilobine and anaxagoreine have been isolated.
Botany
Shrubs to small trees; twigs terete, densely brownish-puberulous but often soon glabrescent. Leaves alternate, distichous, simple and entire, petiolate; stipules absent. Inflorescence terminal, leaf-opposed, in axils of leaves, on short axillary shoots or cauliflorous, short-pedunculate or sessile. Flowers with apically thickened pedicels, bisexual, regular, (2-)3-merous, white, greenish-white or yellowish-white; sepals ovate to broadly ovate; petals in 1 or 2 whorls, fleshy; stamens numerous, innermost often staminodial; carpels several to numerous, superior. Fruit consisting of several to many monocarps, these stipitate and more or less distinctly beaked, densely puberulous but often later glabrescent, greenish, dehiscing along the ventral suture, 2-seeded. Seeds with outer side convex, inner side flat, smooth, shiny black.
The fragrant flowers are probably pollinated by insects. The fleshy petals, which are often appressed, may form a small pollination chamber. The seeds can be ejected through the ventral slit of the monocarps for several metres by an exploding mechanism when the pressure caused by the drying and shrinking wall is high enough.
Anaxagorea is one of the comparatively few genera of Annonaceae with dehiscent, pod-like monocarps, and is clearly distinct from all other genera.
Ecology
Anaxagorea occurs in lowland rain forest, often primary forest but sometimes also in secondary forest, up to 600(-1100) m altitude.
Genetic resources
A. javanica and A. luzonensis are both widespread and locally common, and consequently not likely to be endangered. However, a third species, A. borneensis (Becc.) J. Sinclair, is only known from Borneo and may therefore be more at risk of genetic erosion.
Prospects
Plant-derived oestrogens may exert beneficial effects in the treatment of cardiovascular diseases, osteoporosis and menopause. Non-steroidal oestrogens such as 8-isopentenylnaringenin isolated from A. luzonensis wood may open the way to design drugs that selectively block the unwanted effects of oestrogen (particularly the development of breast and uterine cancer) and that mimic its beneficial effects.
Literature
486, 582, 583, 634.
Selection of species
Authors
R.H.M.J. Lemmens
