1305

12(2): Medicinal and poisonous plants 2

Soulamea amara Lamk

Encycl. 1(2): 449 (1785).

SIMAROUBACEAE

2n = unknown

Indonesia: buwa hati, kayu sulamu (Moluccas), sulamu pohon (Ternate). Papua New Guinea: dschiri pangpang (Tami, Morobe Province).

Soulamea amara is a coastal species widespread from Borneo eastward to Micronesia and Melanesia, but not found in New Caledonia. In Malesia Soulamea amara is recorded for Borneo, the Moluccas and New Guinea only.

The roots and fruits of Soulamea amara are the parts usually employed in traditional medicine. They are intensely bitter, and are used especially to treat cholera and pleurisy. The fruits are considered a general febrifuge, and ground with roots and water they are used to treat colic and cough, including asthma. In cases of poisoning the roots are used as an emetic, similar to Eurycoma root, another representative of Simaroubaceae, often as a substitute for snakeroot (Strychnos). As with many other bitter tasting plants the roots are considered to strengthen the stomach, restore appetite, and be a healthy laxative, if taken in appropriate quantities. In Papua New Guinea, juice from heated leaves is applied externally to get rid of lice.

Though Soulamea amara is reputed for its application in traditional medicine, modern research has focused on the Soulamea species from New Caledonia and Fiji. The quassinoids (sometimes also called simaroubolides) glaucarubolone, holacanthone and isobrucein A were found to be responsible for the cytotoxic and antileukaemic activities observed for extracts of the wood, stem bark, and twigs of the Fijian Soulamea soulameoides (A. Gray) Noot. (synonym: Amaroria soulameoides A. Gray). Other cytotoxic constituents isolated include cleomiscosin A (a coumarinolignan) and a hydroxy canthin-6-one alkaloid. The alkaloid cleomiscosine A showed activity against P-388 lymphocytic leukaemia cells in vitro. Several quassinoids from Soulamea soulameoides were evaluated for growth inhibitory and insecticidal effects against the tobacco budworm (Heliothis virescens) and for antifeedant effects against H. virescens and the fall armyworm (Spodoptera frugiperda). The relative activity of the quassinoids as insect growth inhibitors generally parallelled their known relative potency as antileukaemic and cytotoxic agents.
Soularubinone, the C-15 'BETA'-hydroxy-isovaleric ester of glaucarubolone, isolated from the New Caledonian Soulamea tomentosa Brongn. & Gris showed significant antineoplastic activity against mouse leukaemia P-388 and inhibits cell transformation induced by Rous sarcoma virus. The quassinoids chaparrinone I, isobrucine A, isobrucine B, 15-0-benzoyl brucein D and picrasin B have also been isolated.

Quassinoids and canthin-6-one alkaloids showing cytotoxic and anticancer activity can also be found in other Simaroubaceae including Brucea, Eurycoma, Picrasma and Quassia. Some species may well used for certain applications of Soulamea amara.

A shrub or small tree up to 5(—15) m tall; young shoots and buds rusty tomentose. Leaves simple, spirally arranged, crowded at the apex of the branchlets, leaving large scars, blade obovate-oblong, 10—35 cm x 4—12 cm, base cuneate, apex obtuse, sometimes mucronate, margin entire, hairy, midrib prominent below, lateral veins parallel ending in an intramarginal looped vein; petiole 3—8 cm long; stipules absent. Inflorescence an axillary erect raceme, 3—12 cm long. Flowers bisexual, 3(—5)-merous, small; sepals puberulous, erect, appressed, 0.5—1 mm long; petals concave, spreading, finally reflexed, accrescent to 2.5 mm x 1 mm; stamens twice as many as petals, up to 2 mm long; intrastaminal disk present; ovary superior, consisting of 2(—3) carpels, not more than 2 fertile, connate, except at the top, stigma sessile. Fruit an obcordate samara, up to 2.5 cm x 2 cm, pericarp hard corky. Seed round, 0.5—1 cm across, testa thin, cotyledons plano-convex.

Soulamea comprises 10 species, with 1 species endemic to the Seychelles, 1 endemic to Fiji, 7 species confined to New Caledonia and 1 widespread species (Soulamea amara). Soulamea amara is a littoral species, whereas all other species of the genus occur inland. Soulamea very much resembles Lunasia (Rutaceae) in habit.

Soulamea amara is a typical constituent of the Barringtonia formation, which occurs specifically on sandy beaches and behind coral reefs. It is sometimes found as a scattered treelet more inland. Under the parent plants, seedlings may be found in great profusion. The fruits seem well adapted to dispersal by seawater.

Soulamea amara can be propagated easily by seed.

The fruits must be picked when they start to yellow or blacken, since they become less medicinally effective after they have fallen. The roots can be harvested when needed.

As Soulamea amara is a widespread species, the risk of genetic erosion seems to be limited.

In general, quassinoids are known to possess cytotoxic, antimalarial, and insecticidal activities. Although their use as such is often limited by their cytotoxic potential, quassinoids found in Soulamea, including Soulamea amara, might be interesting lead compounds in research and development of future antimalarial or chemotherapeutic agents.

Arisawa, M., Handa, S.S., McPherson, D.D., Lankin, D.C., Cordell, G.A., Fong, H.H.S. & Farnsworth, N.R., 1984. Plant anticancer agents XXIX. Cleomiscosin A from Simaba multiflora, Soulamea soulameoides, and Matayba arborescens. Journal of Natural Products 47(2): 300—307.
Handa, S.S., Kinghorn, A.D., Cordell, G.A. & Farnsworth, N.R., 1983. Plant anticancer agents XXV. Constituents of Soulamea soulameoides. Journal of Natural Products 46(3): 359—364.
Klocke, J.A., Arisawa, M., Handa, S.S., Kinghorn, A.D., Cordell, G.A. & Farnsworth, N.R., 1985. Growth inhibitory, insecticidal and antifeedant effects of some antileukemic and cytotoxic quassinoids on two species of agricultural pests. Experientia 41(3): 379—382.
Kulip, J. & Wong, K.M., 1995. Simaroubaceae. In: Soepadmo, E. & Wong, K.M. (Editors): Tree flora of Sabah and Sarawak. Vol. 1. Sabah Forestry Department, Forest Research Institute Malaysia and Sarawak Forestry Department, Kepong, Malaysia. pp. 421—442.
Mai Van Tri, Polonsky, J., Merienne, C. & Sevenet, T., 1981. Soularubinone, a new antileukemic quassionoid from Soulamea tomentosa. Journal of Natural Products 44(3): 279—284.
Perry, L.M., 1980. Medicinal plants of East and Southeast Asia. Attributed properties and uses. MIT Press, Cambridge, Massachusetts, United States & London, United Kingdom. p. 390.

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J.L.C.H. van Valkenburg

van Valkenburg, J.L.C.H., 2001. Soulamea amara Lamk. 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