Pandanus (PROSEA Medicinal plants)

Plant Resources of South-East Asia Introduction

List of species

Pandanus Parkinson

Protologue: J. voy. South Seas: 46 (1773).

Family: Pandanaceae

Chromosome number: x= 30; P. klossii: 2n= 60

Pandanus comprises about 700 species and occurs in Africa, Madagascar, islands of the Indian Ocean, Nepal, India, Sri Lanka, Burma (Myanmar), Indo-China, southern China, Taiwan, Japan, Thailand, throughout the Malesian region, Australia and islands of the Pacific Ocean.

Leaf decoctions of P. affinis and P. klossii, and probably other Pandanus species, are administered after childbirth in Peninsular Malaysia. Several other Pandanus species are used in traditional medicine in South-East Asia but have another primary use. After soaking P. amaryllifolius Roxb. leaves in coconut oil, the oil is employed as an embrocation for rheumatic troubles. Infusions of P. amaryllifolius leaves are used internally and externally as a sedative against restlessness, and in Thailand they are used as a traditional medicine as a diuretic. Young leaf tops of P. furcatus Roxb. are used as an antidote and, after roasting over a fire, to treat cough, whereas the leaf sap is used against diarrhoea and dysentery. In Papua New Guinea (New Ireland) P. tectorius Parkinson bark is scraped into a wild ginger leaf, water is added and the solution is squeezed into a cup and drunk to sedate mental patients. The leaves of P. odoratissimus L.f. are used in the Philippines as a cardiotonic and purgative, and those of P. odoratissimus and P. tectorius are said to be useful against leprosy, smallpox, rabies and heart and brain diseases. The roots of P. tectorius are considered diuretic and used in Vietnamese folk medicine to treat oliguria and urinary troubles. The roots of P. odoratissimus are considered antipyretic, expectorant and diuretic in Thailand, and the male inflorescence cardiotonic. Decoctions of fresh or dried prop roots of P. luzonensis Merr. are credited with diuretic properties in the Philippines. Fresh fruits of P. polycephalus Lamk are used in Sulawesi as an abortifacient. P. antaresensis St. John is used in New Guinea in healing rituals to treat fever, headache, diarrhoea and difficult breathing.

Pandanus is very important for the production of fibre, especially P. atrocarpus Griffith, P. furcatus, P. odoratissimus and P. tectorius. Leaf material, usually reduced to strips, is used for weaving a range of articles, from small handbags and containers to large floor mats or light interior wall panels. Some Pandanus species provide food products; fruits of P. conoideus Lamk and P. leram Jones ex Fontana, and seeds of P. brosimos Merr. & Perry are eaten in South-East Asia, and leaves of P. amaryllifolius are used fresh in cooking as a spice to impart flavour and colour (chlorophyll) to rice, sweets, jellies and many other food products. Finely cut leaves of the latter species are an ingredient of a hair oil used in Java. Pandanus is commonly grown as an ornamental, especially cultivars of P. tectorius, and is also used in fences and windbreaks.

The application of P. amaryllifolius as antidiabetic drug seems linked to 4-hydroxybenzoic acid, which has been isolated from the roots. It shows hypoglycaemic effects in normal rats (oral administration of 5 mg/kg), and increases serum insulin levels and liver glycogen content. This compound caused a dose-dependent decrease in plasma glucose levels in steptozotocin-diabetic rats, but did not affect serum insulin level and liver glycogen content in the diabetic model. It increased glucose consumption in normal and diabetic rat diaphragms, suggesting a hypoglycaemic effect mediated by an increase in the peripheral glucose consumption.

The oil from P. odoratissimus inflorescences is considered to have stimulant and antispasmodic properties, whereas root extracts have shown great antioxidative activity. The leaf juice was found to inhibit the formation of skin, liver and colon tumours in tests with mice.

In New Guinea Pandanus fruits have been reported to contain toxic substances capable of producing mental change. Among other alkaloids, dimethyltryptamine has been isolated from the fruits. Fresh fruits may also cause sore lips and blistered tongue.

• Dioecious, evergreen, often palm-like trees or shrubs with an erect to decumbent stem, usually with rigid prop roots descending from leaf axils; stem often branched in a trichotomous or dichotomous pattern, often knobbly or prickly, with manifest leaf scars.
• Leaves arranged in 3 spiral rows, simple, linear, usually M-shaped in cross-section, usually with prickles along the margins and the underside of the midrib, with numerous longitudinal veins, usually amplexicaul.
• Inflorescence unisexual, male one a bracteate spike, usually arranged in a raceme, female one a globose to cylindrical head, sometimes arranged in a spike.
• Flowers unisexual, without perianth; male flowers with a cluster of stamens; female flowers with massed 1-many-celled carpels, style indistinct.
• Fruit a drupe or a syncarp of drupes, resembling a pineapple, ripening to yellow, orange or red, occasionally purplish-red.
• Seed fusiform or obovoid, with thin seedcoat, containing endosperm.

Seed germination is often very slow, and within the bony endocarp of the fruit. Apomixis is common and parthenocarpy is the rule. Fruit dispersal is usually by birds, mammals or water currents.

The very large genus Pandanus is divided into 8 subgenera and over 70 sections. P. affinis belongs to subgenus and section Acrostigma, P. klossii to subgenus and section Rykia. The identifications of species in such a large and difficult genus are often doubtful and this makes literature difficult to interpret. It is also somewhat doubtful whether the uses cited for P. affinis and P. klossii in Peninsular Malaysia really refer to these species. However, several Pandanus species are probably used interchangeably for the same purpose.

Pandanus mainly occurs on tropical sea coasts, often on sandy beaches, littoral thickets, on the edges of brackish marshes and mangroves and more inland along water courses, less common at higher altitudes (e.g. P. klossii). Rainfall should be high, but soil requirements are low, although heavy, poorly drained loams are not suitable.

Pandanus is usually propagated vegetatively, from sucker shoots or stem fragments. Cleanly removed from the leaf axils, suckers can be planted straight away or rooted first in a sandy medium. Pandanus may also be propagated by seed, but seeds should be soaked for 24 hours before planting.

Pandanus is known for its high degree of endemism and thus many species are liable to genetic erosion and sometimes even threatened by extinction. Collection from the wild and habitat destruction endanger many species. Germplasm collection is badly needed.

Although Pandanus may be of considerable local importance in South-East Asia, it has so far only been of marginal interest to agricultural institutions. These multipurpose plants deserve more attention, not only for enhancing their value as fibre plants, food plants and ornamentals, but also to evaluate their pharmacological value. The comparatively few pharmacological tests carried out showed promising results.

196, 357, 391, 671, 738, 739, 760, 817, 838, 967.

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• Lean Teik Ng & Su Foong Yap