Calophyllum (PROSEA Medicinal plants)
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Introduction |
Calophyllum L.
- Protologue: Sp. pl. 1: 513 (1753); Gen. pl. ed. 5: 229 (1754).
- Family: Guttiferae
- Chromosome number: x= unknown; C. inophyllum: 2n= 32
Origin and geographic distribution
Calophyllum is a very large genus comprising about 190 species. The Indo-Malesian region, Micronesia, Melanesia and northern Australia are rich in species, tropical America, Madagascar and surrounding islands less rich. Peninsular Malaysia, Sumatra, Borneo and New Guinea show an abundance of species, about 40, 35, 65 and 35, respectively.
Uses
Many Calophyllum species supply a good multipurpose timber, known as bintangor. Timber is definitely the primary use for these species. However, the recent discovery of compounds that are very promising as drugs for the treatment of acquired immunodeficiency syndrome (AIDS) throws new light on Calophyllum as a medicinal plant.
A decoction of the bark and the latex of some Calophyllum species is used in traditional medicine, internally against diarrhoea and after childbirth, externally against skin and eye diseases and rheumatism; leaves, flowers and seeds are also used. A balsam made from the fruits of C. inophyllum is used as a healing and analgesic agent in the treatment of burns. The poisonous latex from the bark of several species is used to stupify fish and, mixed with rice, to kill rats. Several other species not treated here are used in traditional medicine or as poisonous plant, e.g. C. calaba L. (latex used as fish poison and shampoo), C. canum Hook.f. (latex used as fish poison in Sarawak), C. dioscurii P.F. Stevens (decoction of roots used after childbirth in Peninsular Malaysia), C. pisiferum Planchon & Triana (decoction of bark used to treat diarrhoea in Cambodia), and C. rubiginosum M.R. Henderson & Wyatt-Smith (latex used to poison rats and as fish poison in Indonesia).
The fruits of some species are edible but often sour; caution is necessary as they contain toxic substances. The oil from the seeds is sometimes used as an illuminant and in soap making. The seed-oil and the latex from the bark have occasionally been used for dyeing batik cloth in Java. A decoction of the bark is sometimes used to toughen and dye fishing-nets. C. inophyllum is commonly planted as an ornamental.
Properties
In the past decades, many natural products have been screened to identify compounds from which drugs against cancer and AIDS might be developed. Several coumarins have been isolated from Calophyllum that are able to inhibit HIV reverse transcriptase. Inophyllums have been isolated from the leaves and seeds of C. inophyllum and calanolides from fruits and twigs of C. lanigerum and C. teysmannii, and these compounds proved to be non-nucleoside inhibitors of HIV type 1. The compounds are essentially inactive against strains of the less common HIV type 2. The most promising compounds seem to be the dipyranocoumarin (+)-calanolide A isolated from C. lanigerum var. austrocoriaceum and the closely related compound (-)-calanolide B from C. teysmannii var. inophylloide. These compounds are under development as an AIDS chemotherapeutic. A study demonstrated the safety and favourable pharmacokinetic profile of single doses of (+)-calanolide A in healthy, HIV-negative individuals. Inophyllum B and P are the most active compounds isolated from C. inophyllum. Soulattrolide, another coumarin isolated from the latex of C. teysmannii, was also found to be a potent inhibitor of HIV-1 reverse transcriptase. The seeds of C. cerasiferum Vesque from the Fiji Islands contain (-)-calanolide B as its major coumarin constituent. Cordatolide A and B, which also inhibit HIV-1 reverse transcriptase, have been isolated from C. cordato-oblongum Thwaites, an endemic of Sri Lanka.
An analysis of the essential oil from C. inophyllum flowers showed the presence of 25 compounds, with a naphthalene derivative as the most abundant component. Antibacterial, anti-inflammatory and phagocytosis stimulant activities have been reported for this species. Seed extracts of C. inophyllum showed significant molluscicidal activity; the hydroxy acid calophyllic acid was isolated as the active compound. The ether extract of the leaves showed piscicidal activity.
Xanthones and coumarins with cytotoxic activity against cancer cells have been isolated from various Calophyllum species. For example, some of the 4-phenylcoumarins isolated from C. inophyllum might be valuable as potential cancer chemopreventive agents.
Botany
- Evergreen trees up to 40(-60) m tall, rarely shrubs, with sticky latex; twigs more or less flattened and angled.
- Leaves decussately opposite, simple and entire, leathery, glabrous, with closely parallel secondary venation, petiolate; stipules absent.
- Inflorescence terminal or axillary, racemose.
- Flowers usually bisexual, but sometimes functionally unisexual, regular, sweetly scented; perianth with 4-16 tepals in several whorls, usually whitish; stamens numerous, with filaments usually only slightly connate at base; ovary superior, unilocular, style often with a peltate stigma.
- Fruit a drupe, outer layer of pericarp often with large air spaces, 1-seeded.
- Seed with large cotyledons and radicle pointing to the base of the fruit; endosperm absent.
- Seedling with cryptocotylar germination and short epicotyl.
Growth of the young trees appears to be discontinuous and branching is rhythmic. Growth may be rather slow, and trees may take about 70 years to attain a diameter of 50 cm. However, there is reason to believe that growth may be considerably faster under favourable conditions.
The flowers are insect-pollinated, e.g. by bees. Hybridization may occur, often with C. inophyllum as one of the parents. Trees often bear fruits throughout the year. The fruits are eaten and dispersed by mammals (bats, squirrels, monkeys) and birds. However, the fruits of some species are dispersed by water, e.g. those of C. inophyllum which are dispersed by sea currents, but also by fruit bats.
Calophyllum is classified in the subfamily Calophylloideae together with its immediate relatives Mammea and Mesua, and some small genera of Madagascar and India. It is easily distinguishable by its single basal ovule and particularly by its nearly always strictly parallel and close venation of the leaves.
Ecology
Calophyllum belongs to the lowland tropical rain forest, but a few species occur in montane rain forest. Calophyllum trees often reach to the top of the main canopy at maturity, but are not emergent. Only a few species grow in drier or more open habitats; C. inophyllum occurs mainly on sandy beaches.
Management
Natural regeneration usually occurs near the mother tree. Seedlings grown in nurseries require shade. In plantation trials in Indonesia the spacing of seedlings is usually 2 m √ó 3 m.
Genetic resources
Although Calophyllum is abundant in several areas (e.g. in Peninsular Malaysia, Borneo and New Guinea), in many other areas it is much less common and occurs scattered in the forest. The rarer species may become easily liable to genetic erosion when indiscriminate logging and large-scale destruction of lowland rain forest is practised. An example is C. blancoi, the stands of which are depleted in the Philippines due to logging and shifting cultivation.
Prospects
The studies on the activity of several coumarins isolated from Calophyllum indicate that these compounds have a novel mechanism of interaction with human immunodeficiency virus type 1 reverse transcriptase. These non-nucleoside inhibitors differ mechanistically from the chain terminators AZT and DDI, which are at present the chemotherapeutic agents used to treat HIV infections, and as such could conceivably play a role in combination therapy against AIDS. Moreover, Calophyllum is a source of potential cancer chemopreventive agents.
Literature
183, 452, 607, 616, 722, 878, 891.
Selection of species
Authors
- R.H.M.J. Lemmens
