1220

12(2): Medicinal and poisonous plants 2

Parkia R.Br.

in Denham & Clapp., Narr. Travels Africa, Bot. App.: 234 (1826).

LEGUMINOSAE

x = 12, 13; Parkia speciosa: 2n = 24, 26

Major species Parkia sumatrana Miq., Parkia timoriana (DC.) Merr.

Parkia is a pantropical genus with about 35 species, most of them found in tropical America, especially in the Amazon basin. In Asia, Parkia occurs from north-eastern India and Bangladesh eastward through the whole of the South-East Asian region, with more isolated species in Micronesia and Fiji. About 6 species occur within Malesia. Peninsular Malaysia and Sumatra have 4 species, Borneo has 5 species. Parkia timoriana has the largest area of distribution, occurring from India to New Guinea.

The seeds of Parkia speciosa and Parkia timoriana are considered beneficial in the treatment of hepatalgia, oedema, nephritis, diabetes and colic, probably as a result of their diuretic and relaxing activity. They are also used as an anthelmintic. The leaves are used against jaundice. In Indo-China, the bark of Parkia sumatrana is used medicinally. In Kalimantan, the inner red bark of Parkia speciosa is applied as a dressing on burns, followed several hours later by an infusion of the pounded white wood, which is used to wash the skin. The wood of Parkia is used locally for non-durable or indoor applications. Parkia speciosa and Parkia timoriana are sometimes used as shade tree for coffee and nurseries. The fresh or cooked seeds of various Parkia species, most importantly Parkia speciosa, are relished as a sidedish or condiment.

In 1984, 145 t Parkia timoriana seeds were used locally for medicinal purposes in Java, whereas export was only marginal. In 1990 production was about 142 t from nearly 14 000 trees. It is expected to rise to 180 t by 2000 to fulfill the needs of the 'jamu' industry in Indonesia in which Parkia timoriana seeds play an important role.

The seeds of Parkia speciosa and Parkia timoriana contain several non-protein sulphurous amino acids, e.g. djenkolic acid (S,S'-methylenebis-L-cysteine), N-acetyl-djenkolic acid, and glutalyl-cystine. Cyclic poly-sulphides also occur in the seeds of Parkia speciosa, which contribute to the foul smell. After boiling, seeds of Parkia timoriana and Parkia speciosa contain thio-proline at a concentration of 0.54 ' 0.2 and 0.14 ' 0.02 mmol/100g, respectively.
Furthermore, lectins with haemagglutinating activity have been isolated from the seeds of Parkia speciosa and Parkia timoriana. Purified Parkia timoriana lectin showed 2 bands using SDS-PAGE; both of them appeared to be single polypeptide chains with molecular weights of 47 900 and 45 700. The purified lectin could agglutinate red blood cells of rabbits and rats, but not those of humans, sheep or goose. Its haemagglutinating activity was completely inhibited by methyl-'ALFA'-D-mannosamine and mannose. In addition, Ca²⁺, Mn²⁺ and Mg²⁺, but neither ethylenediaminetetraacetic acid (EDTA) nor agtazic acid (EGTA), were effective activators of the purified lectin.
Oral administration of the chloroform extracts of Parkia speciosa seeds to alloxan-induced diabetic rats produced a significant depression in blood glucose levels. Extraction, isolation and structure elucidation of the hypoglycaemic fraction (called S-9.4) gave a mixture of 'BETA'-sitosterol (66%) and stigmasterol (34%). Fraction S-9.4 produced 83% hypoglycaemic activity at 100 mg/kg body weight (BW) compared with 111% activity of glibenclamide at 5 mg/kg BW dosages. The minimum effective dose which produced a statistically significant hypoglycaemic effect was 25 mg seeds/kg BW. When tested individually 'BETA'-sitosterol and stigmasterol showed no hypoglycaemic effects, indicating that synergism between 'BETA'-sitosterol and stigmasterol was necessary to effect the hypoglycaemic activity. The hypoglycaemic effect was not observed in healthy rats.
In addition, administration of the chloroform extracts of Parkia speciosa empty pods to alloxan-induced diabetic rats produced a significant reduction in blood glucose levels. A hypoglycaemic assay guided extraction, isolation and structure elucidation gave stigmast-4-en-3-one. Stigmast-4-en-3-one produced 84% activity at 100 mg/kg BW compared to 111% activity of glibenclamide at 5 mg/kg BW dosages. The minimum effective dose which produced statistically significant hypoglycaemic effect was 50 mg pericarp/kg. Hypoglycaemic effects were not observed in healthy rats.

Deciduous, medium-sized to large trees up to 50 m tall; bole up to 100(—250) cm in diameter, buttresses present or absent. Leaves alternate or opposite, bipinnate with up to 30(—42) pairs of pinnae; petiole and rachis usually with extrafloral nectaries; stipules small, caducous; leaflets opposite, sessile. Inflorescences compound, consisting of a stout twig to 50 cm long, sparsely branched or unbranched, bearing 2—10(—more) flexible peduncles, each to 50 cm or more long. Flowers in a long-stalked, pendulous, pyriform to clavate, dense head, sterile flowers at base of the head, male ones in middle portion and bisexual ones at apex, 5-merous; calyx long-tubular or funnel-shaped with imbricate lobes; corolla longer than calyx; stamens 10, connate below, shortly exserted; ovary superior, short-stiped, style exserted. Fruit a linear to strap-shaped or oblong pod, stalked, leathery or woody, usually indehiscent, many-seeded, usually several pods together in a pendent infructescence with swollen receptacle. Seeds in 1 row, ellipsoid, with a pleurogram. Seedling with epigeal germination; cotyledons fleshy, peltate; epicotyl with a scale leaf and subsequently bipinnate leaves.

Parkia speciosa and Parkia timoriana show a synchronized annual cycle of flowering, fruiting and leaf fall; the trees are without leaves for 2—3 weeks each year. They start flowering when 10—15 m tall, but vegetatively propagated Parkia speciosa starts flowering and fruiting a few years after planting. The flowering heads are usually pollinated by bats, but are also visited by insects and birds. They produce a fetid odour and a copious nocturnal supply of nectar. Hornbills, monkeys, squirrels, deer, elephants and wild pigs feed on the fruits and probably disperse the seeds. In Java, Parkia timoriana flowers in April—July and usually many fruits are found in June—August.

Parkia is classified in the tribe Parkieae of the subfamily Mimosoideae, together with Pentaclethra, which is confined to tropical Africa and America.
Parkia timoriana is often cited as Parkia javanica (Lamk) Merr., especially in Malaysian literature. Although the latter name is older and would therefore have priority, it has been superseded because the correct identity of the species concerned cannot be recovered. The status of Parkia intermedia Hassk. is uncertain, but it is probably a hybrid between Parkia speciosa and Parkia timoriana; it is found almost exclusively in Java. Parkia sherfeseei Merr. from the Philippines (Mindanao) is possibly conspecific with Parkia sumatrana.

Parkia occurs scattered in lowland rain forest and sometimes also in tall secondary forest, on sandy, loamy and podzolic soils, also in waterlogged locations, in freshwater swamp forest and on river banks, up to 1000(—1400) m altitude. Parkia sumatrana and Parkia timoriana also occur in dry evergreen forest, often along streams.

Parkia can be propagated by seed and by vegetative means. Seeds of Parkia timoriana are hand-picked from underneath mother trees. The hard, indehiscent pods need to be opened with a chopping knife. Parkia timoriana has 1000—1400 dry seeds/kg. The germination rate of the hard seeds of Parkia timoriana is about 55% in 8—103 days; mechanical scarification is recommended. In a test in Thailand, 3-year-old seed had a germination rate of only 8.5% whereas nicked seed had a germination rate of 90.5% in only 4—8 days. A pretreatment with concentrated sulphuric acid for 15 minutes gave a germination rate of 95%. Whereas Parkia speciosa can be propagated by stem cuttings and budding, attempts with Parkia timoriana have failed. Seedlings of Parkia timoriana can be stumped with 10—20 cm shoot and 20—40 cm root length, and survival after planting is 100%. In Java, growth during the first 5 years was fast, but then slowed down. Ample space and light are necessary for optimal growth.

Parkia species have a number of pests in common with other leguminous trees and shrubs. The stem and bark borers Xystrocera festiva and Cossus subfuscus can cause severe damage in Parkia speciosa, especially at lower elevations in Java. Other pests are the pod borers Cryptophlebia ombrodelta and Mussidia pectinicornella, and the caterpillars of the leaf feeders Polyura hebe, Eurema blanda and Eurema hecabe. The seeds are relished by a great number of arboreal mammals.

Mature pods of Parkia are collected by climbing the trees and using long poles. Climbing is sometimes facilitated by pegs in the trunk.

A population of about 100 mature Parkia timoriana trees in East Java yielded on average 12 kg of seeds/tree; 70% of the trees were fruiting and the yield ranged from 4—45 kg of seeds/tree.

Seeds of Parkia can be dried in the sun to improve storability and to facilitate transport over long distances.

Within Malesia no seed or germplasm collections of Parkia are known to exist and no breeding programmes are being carried out. The Parkia species of medicinal importance have a fairly wide area of distribution and are also cultivated, suggesting that it is unlikely that they are threatened.

Extracts and isolated compounds from Parkia species exhibit an interesting anti-diabetic effect, which merits further research. Lectins may have possibilities as tools in research. In view of the increase in the human population, local demand for Parkia timoriana seeds is expected to rise. Therefore efforts should be made to cultivate Parkia in order to sustain market demand.

Fortune Hopkins, H.C., 1992. Parkia. In: de Wilde, W.J.J.O., Nooteboom, H.P. & Kalkman, C. (Editors): Flora Malesiana. Series 1, Vol. 11(1). Foundation Flora Malesiana, Leiden, the Netherlands. pp. 193—204.
Jamaluddin, F., Mohamed, S. & Lajis, M.N., 1994. Hypoglycaemic effect of Parkia speciosa seeds due to the synergistic action of beta-sitosterol and stigmasterol. Food Chemistry 49(4): 339—345.
Jamaluddin, F., Mohamed, S. & Lajis, M.N., 1995. Hypoglycaemic effect of stigmast-4-en-3-one, from Parkia speciosa empty pods. Food Chemistry 54(1): 9—13.
Setyowati, F.M., 1998. Parkia R.Br. In: Sosef, M.S.M., Hong, L.T. & Prawirohatmodjo, S. (Editors): Plant Resources of South-East Asia No 5(3). Timber trees: Lesser-known timbers. Backhuys Publishers, Leiden, the Netherlands. pp. 430—433.
Utarabhand, P. & Akkayanont, P., 1995. Purification of a lectin from Parkia javanica beans. Phytochemistry (Oxford) 38(2): 281—285.
Wiriadinata, H. & Bamboongrugsa, N., 1993. Parkia speciosa Hassk. In: Siemonsma, J.S. & Kasem Piluek (Editors): Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, the Netherlands. pp. 222—224.

Umi Kalsom Yusuf & Ervizal A.M. Zuhud

Parkia sumatrana
Parkia timoriana

Yusuf, U.K. & Zuhud, E.A.M., 2001. Parkia R.Br.. In: van Valkenburg, J.L.C.H. and Bunyapraphatsara, N. (Editors): Plant Resources of South-East Asia No 12(2): Medicinal and poisonous plants 2. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea

The following species in this genus are important in this commodity group and are treated separatedly in this database:
Parkia sumatrana
Parkia timoriana