Clusia (PROSEA)
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Introduction |
Clusia L.
- Protologue: Sp. pl. 1: 509 (1753); Gen. pl. ed. 5: 226 (1754).
- Family: Guttiferae
- Chromosome number: x= unknown
Origin and geographic distribution
Clusia comprises approximately 250 species and is confined to the tropics of the New World. Some species are planted in gardens elsewhere in the tropics, including Malaysia and Thailand, and have sometimes become naturalized, e.g. C. rosea in Sri Lanka.
Uses
Clusia is used in traditional medicine in tropical America. The bitter gum is well known because of its drastic, sometimes dangerous, purgative properties. It is used in ointments to treat sores and wounds, and also to allay toothache and calluses on the feet. The dried and powdered gum is widely traded and used as a resolutive plaster to treat fractures, dislocations and burns. Decoctions of bark and fruit rind are applied to soothe rheumatic pains. A leaf or flower decoction is used internally as a pectoral to relieve chest complaints.
The gum is burned in houses as a disinfectant and is also used for caulking boats. The reddish wood is used in house construction, e.g. for poles, but timber is not usually available in merchantable sizes. There are no records on medicinal use of Clusia in South-East Asia; it is occasionally planted as an ornamental in gardens. Elsewhere, Clusia is also planted for ornamental purposes.
Properties
The polyisoprenylated benzophenone derivatives guttiferone E and xanthochymol have been isolated from C. rosea leaves. These compounds inhibit the cytopathic effects of in-vitro human immunodeficiency virus (HIV) infection in human cells. They also exhibited cytotoxic activity against CA-human colon CO-115 cell lines. Other polyisoprenylated benzophenones have been found in the resin of the flowers and in fruits of Clusia species.
Three biphenyl derivatives, clusiparalicolines A, B and C, have been isolated from C. paralicola G. Mariz roots. The first 2 of these compounds were found to be active in the DNA strand-scission assay, whereas all 3 compounds exhibited modest cytotoxicity against KB human cancer cell lines. In tests with rats, an aqueous extract of the leaves of C. coclensis Standl. injected intravenously induced a rapid and transitory decrease in blood pressure and heart frequency.
Propolis is a resinous hive product collected by honey bees that has been used in folk medicine in tropical America since around 300 BC. Various biological activities have been attributed to it, such as anticancer, antioxidant, anti-inflammatory, antibiotic and antifungal effects. It is also extensively used in food and beverages to improve health and prevent diseases such as inflammation, heart complaints, diabetes and even cancer. The resins exuded by Clusia flowers are a major source of propolis. Several compounds isolated from propolis showed cytotoxic activity on human fibrosarcoma and murine colon carcinoma cell lines.
Botany
Trees or shrubs, mostly dioecious, often epiphytic, with whitish or yellowish sap. Leaves opposite, simple and entire, usually stiffly leathery, veins often anastomosing at the margins to form marginal veins; petiole distinct or indistinct; stipules absent. Inflorescence an axillary or terminal cymose panicle, or flowers solitary. Flowers unisexual, regular, in bud mostly globose; sepals (2-)4-5(-8), mostly free, decussate or imbricate, rotund; petals 4-9(-12), free, ovate or rotund; male flowers with numerous stamens basally connate and rudimentary ovary; female flowers with superior ovary consisting of 4-10 basally or entirely connate carpels with sessile stigmas and rudimentary stamens. Fruit a fleshy or leathery tardily dehiscent capsule, with a stigmatic area on top, many-seeded. Seeds enveloped in an arillode.
Both C. rosea and C. minor are usually shrubs or poorly formed trees, but occasionally they occur as an epiphyte, sometimes strangling the host in the manner of figs ( Ficus species). Free-living trees grow from terrestrial seedlings or from epiphytic seedlings eventually strangling and shading their host trees. Although the large flowers are often produced continuously, they last for only short periods and are usually not in great number. They are commonly visited by bees, which collect the viscous, hydrophobic resin, and use this as a nest-building material with antimicrobial properties.
It has been suggested that C. rosea is wholly apomictic and that C. minor is commonly apomictic in reproduction. In the latter some forms may be facultatively apomictic or may reproduce by normal sexual means. Apomictic specimens produce functional seed, probably by adventitious embryony. C. rosea shows crassulacean acid metabolism (CAM), with nocturnal CO2fixation.
Ecology
In the natural area of distribution, C. rosea often occurs on coastal limestone and in savanna, and C. minor most commonly in forest in areas with a seasonally dry climate. For cultivated plants, drainage must be good, but otherwise little care is required where conditions are guaranteed hot and humid.
Management C. rosea can be propagated successfully by softwood cuttings. The best results have been obtained from shoot-tip cuttings 15 cm long with 2 leaves, treated with indole-3-butyric acid, and rooted in washed, coarse sand under mist. Alternative propagation is by seed or air-layering. Planting should preferably be done in a medium-fertile loam-based mix with additional sand. The plants respond well to pruning.
Genetic resources
C. rosea and C. minor are widespread in their natural areas of distribution in tropical America, and have also spread elsewhere for cultivation as an ornamental (particularly C. rosea ). They are therefore unlikely to be at risk from genetic erosion. The apomictic reproduction and the ease of vegetative propagation by cuttings are interesting for breeding activities.
Prospects
Although not indigenous in South-East Asia, Clusia may have good prospects for this region, not only as an ornamental plant, but also as medicinal plant, for which it is valued in tropical America. More research on anti-cancer and anti-HIV activities seems desirable.
Literature
71, 286, 646, 836.
Selection of species
Authors
R.E. Nasution
