1079

12(2): Medicinal and poisonous plants 2

Erythrina L.

Sp. pl. 2: 706 (1753); Gen. pl. ed. 5: 316 (1754).

LEGUMINOSAE

x = 7; Erythrina fusca, Erythrina subumbrans: 2n = 42; Erythrina variegata: 2n = 42, 44

Major species Erythrina fusca Lour., Erythrina subumbrans (Hassk.) Merr., Erythrina variegata L.

Coral tree (En). Arbre au corail (Fr). Indonesia: dadap (general). Malaysia: dedap (general), dadap (Sabah), derdap (Peninsular). Philippines: dap-dap (Pilipino). Burma (Myanmar): kathit. Thailand: thong lang. Vietnam: v[oo]ng.

Erythrina comprises about 110 species distributed pantropically. Tropical America is richest in species (about 70), followed by Africa (32), whereas Asia has 18 species. Some 6 to 8 species occur naturally in Malesia, but many more are planted as ornamentals.

the leaves and bark of various Erythrina species are commonly applied for poulticing. The boiled bark is applied for poulticing the forehead of an elephant if it is swollen, after heavy pushing. Erythrina insularis F.M. Bailey 'radap'(synonym Erythrina merrilliana Krukoff)is reportedly used in the highlands of Papua as a contraceptive. Their conspicuous red flowers make many Erythrina species popular as ornamentals, and they are commonly planted in gardens and parks. They are also widely planted as shade trees, e.g. in cocoa, coffee and tea plantations, and as living stakes to support black pepper (Piper nigrum L.), betel (Piper betle L.), yams (Dioscorea spp.) and vanilla (Vanilla planifolia H.C. Andrews). They are additionally used as green manure because they can fix atmospheric nitrogen in symbiosis with rhizobia. The more prickly forms are often planted as live fences. The lightweight wood is of local importance only. The leaves of some species (e.g. Erythrina fusca and Erythrina variegata) are eaten as a vegetable, and also used as fodder. The shiny red seeds are often used to decorate clubs or are made into necklaces, rosaries and good-luck charms. In Thailand, the flowers of Erythrina variegata have been used to dye clothes red.

Many Erythrina species contain in all parts series of related isoquinoline alkaloids, biosynthetically derived from phenylalanine, called erythrina-alkaloids. For instance, erysotrine, erythraline, erysodine, erysovine and erysopine were isolated from Erythrina fusca. The seeds of Erythrina subumbrans contain erysoline, erysopine and erythratine, together with hypaphorine, a tryptophan derived alkaloid. The seeds of Erythrina variegata contain erysodine, erysopine and hypaphorine, and the leaves and bark erythrinine. Hydrocyanic acid has been found in the leaves, stems, roots, and fruits of Erythrina variegata, and their seeds are known to contain considerable amounts of the amino acid histidine, as is the case with those of Erythrina fusca.
Erythrina-alkaloids are known to show curare-like effects, together with a sedative-, hypotensive- and central nervous system (CNS) depressive action. The isolated alkaloidal fraction of Erythrina variegata produces curare-like effects in frogs and rabbits, both in vivo and in vitro. Isolated total alkaloids from the stem bark have a relaxant action on smooth muscles in guinea-pigs (ileum) and rats (uterus), which is not antagonized by adrenergic blocking agents. This fraction also exhibits CNS-depressant action against pentylenetetrazol and electroshock-induced convulsions in rats. A 40% aqueous extract of the seeds of Erythrina fusca at a dose of 16, 23, 32 g/kg body weight showed a sedative effect in male rats, and orally administered alcohol and chloroform extracts of the seeds of Erythrina fusca diminished motor activity and curiosity of mice and rats at a dose of 18.6 g/kg and 13.3 g/kg, respectively. Acute toxicity was investigated in male mice, using the ethanol extract of the seeds of Erythrina fusca; the LD₅₀ was determined to be 277 mg/kg body weight for subcutaneous administration. The crude extract of the root or the total alkaloidal fraction of Erythrina variegata also showed antibacterial activity against Bacillus aureus, Bacillus pumilus, Escherichia coli, Klebsiella pneumoniae, Mycobacterium smegmatis and Staphylococcus aureus.
Several lectins with proteinase inhibiting properties have been isolated from the seeds of Erythrina variegata, e.g. the chymotrypsin inhibitor ECI (Erythrina chymotripsin inhibitor), the trypsin inhibitors ETIa and ETIb (Erythrina trypsin inhibitor) and the galactose-specific binding isolectins ELVI, ELVII and ELVIII. ETIa is unique in its ability to inhibit tissue-type plasminogen activator, while ETIb does not possess this characteristic. However, both ETIa and b prolonged the activated partial thromboplastin and prothrombin times, but EBI and ECI did not. Using the soluble MTT tetrazolium/formazan assay, the cytotoxicity of Erythrina variegata proteinase inhibitors in some tumour hematopoietic stem cell lines was also investigated. Among the proteinase inhibitors, EBI, which belongs to the Bowman-Birk family of inhibitors, was cytotoxic in relatively differentiated cells such as Molt4 and Jurkat lines, derived from acute T lymphoblastic leukemia (T-ALL) cells specifically. ETIa and ECI, which are classified as Kunitz family inhibitors, were not cytotoxic. It was suggested that the differences in the cytotoxicity might be due to the molecular size of the inhibitors. The succinylation of lysine residue of EBI led to about 50% loss of the trypsin inhibitory activity compared with the authentic EBI. When Molt4 cells were incubated with this derivative, no significant cytotoxicity was observed. This suggests that the proteinase inhibitory activity might be involved in the cytotoxicity in human tumour cell lines.
The edible portion of the leaves of Erythrina fusca contains per 100 g dry matter: 20—22 g crude protein; in vitro digestibility ranges from 30—55%. The mineral content of the leaves per 100 g dry matter is: N 3.2 g, P 0.15 g, K 1.0 g, Ca 1.3 g, Mg 0.5 g. Loppings of Erythrina subumbrans contain per 100 g dry matter: N 1.5—3 g, P 0.2—0.35 g, K 1—2 g. Leaves of Erythrina variegata contain per 100 g dry matter 1.5 g N, 1.5 g K, and 0.15 g P. Leaves and seeds have narcotic properties.

Mostly deciduous shrubs or small to medium-sized trees, occasionally small subshrubs or perennial herbs; bole and branches often armed with conical spines, occasionally with buttresses. Leaves arranged spirally, 3-foliolate; stipules persistent or caducous; leaflets entire, lateral ones often asymmetrical; stipels usually fleshy and glandular. Flowers solitary, paired or fascicled in an axillary or terminal, racemose, inverted inflorescence, bisexual, often scarlet or red; calyx tubular-campanulate, bilabiate or spathe-like with a slit down to the base on the lower side, 5-lobed, sometimes inconspicuously so; corolla papilionaceous, often showy, keel and wings usually much smaller than standard; stamens 10, upper one free or partly connate with the staminal tube; ovary superior, stipitate, many-ovuled, style incurved. Fruit a pod, often constricted between the seeds, usually dehiscent, 1—14-seeded. Seed ovoid or ellipsoid, often red or orange, some with a black spot, also brown or black; cotyledons fleshy, endosperm absent. Seedling with epigeal or semi-hypogeal germination; cotyledons emergent or not emergent, fleshy; hypocotyl elongated; first 2 leaves opposite and simple, subsequent ones alternate and 3-foliolate.

Most Erythrina species are deciduous during or after the dry season, and flower when leafless. The pendulous flowers are scentless, strong and elastic, so constructed that cross-pollination is universal, and are typically pollinated by birds, particularly by passerines such as Chloropsis species and crows. They visit the flowers in the morning collecting the copious nectar. The seeds of Erythrina fusca and Erythrina variegata float and are distributed by sea currents.

Erythrina belongs to the tribe Phaseoleae, subtribe Erythrininae, characterized by the very unequal petals and the conspicuous androecium and gynoecium. Mucuna is a lianescent representative of this subtribe.

Most Erythrina species occur in monsoonal climates and on sandy soils. Erythrina fusca prefers wet locations such as freshwater swamps, stream banks and badly drained soils, up to 2000 m altitude; it may develop into almost pure stands. Erythrina subumbrans occurs in open places or in secondary forest, often near streams, up to 1500 m altitude. Erythrina variegata is adapted to coastal forest, but it is frequently cultivated inland, up to 1200 m altitude.
Most Erythrina species are ecologically separated, even when occurring in the same geographical region. Hybrids, however, occur frequently in cultivation, as there appear to be no barriers to interspecific crosses.

Erythrina can be propagated by seed and by large stem cuttings. There are about 1450—5000 seeds of Erythrina fusca per kg and the germination rate is 80—95%. Seed of Erythrina variegata can germinate within 2 weeks after sowing, but sometimes it germinates poorly with only 30% result over a period of 11 months. Generally, large cuttings about 2—3 m long and 5—10 cm in diameter are used, which sprout easily within 2—4 weeks. They establish easily, as the leafy twigs are out of reach of livestock. Cuttings of Erythrina subumbrans up to 25 cm in diameter sprout readily.

At the end of the 19th Century Erythrina subumbrans was severely attacked by a still unknown root disease in Java, which locally destroyed all trees. Around 1930 it was infested by a Fusarium disease in Java and South Sumatra. In Sumatra stakes of Erythrina fusca in pepper plantations are frequently attacked by a stem borer (Bactocera sp.) and by a ring borer (family Lecanidae). Leaf-eating caterpillars commonly found on Erythrina belong to the genera Agathodes, Hypolimnas, Parasa, Phalera and Striglina; they seldom cause severe damage. Top-boring caterpillars of the genus Terastia may cause serious damage in Erythrina.

Erythrina fusca, Erythrina subumbrans and Erythrina variegata have large areas of distribution and are planted widely; they are not liable to genetic erosion. Germplasm collections of Erythrina species including Erythrina fusca and Erythrina variegata are maintained in Hawaii and Costa Rica. There is a selection and breeding programme of Erythrina fusca at CATIE (Costa Rica), whose aim is to improve its shade tree characteristics.

Erythrina species contain several compounds which display interesting pharmacological activities. Both the erythrina-alkaloids with curare-like effects, and especially the lectins with proteinase inhibiting- and cytotoxic activities may be of interest as tools in fundamental research and development of future medicines.

Faridah Hanum, I. & van der Maesen, L.J.G. (Editors), 1997. Plant Resources of South-East Asia No 11. Auxiliary plants. Backhuys Publishers, Leiden, the Netherlands. pp. 121—132.
Kouzuma, Y., Yamasaki, N. & Kimura, M., 1997. Cloning, expression, and mutagenesis of trypsin inhibitor ETIb from Erythrina variegata seeds. Bioscience, Biotechnology and Biochemistry 61(6): 1041—1043.
Nakagaki, T., Shibuya, Y., Kouzuma, Y., Yamasaki, N. & Kimura, M., 1996. Inhibitory potency of Erythrina variegata proteinase inhibitors toward serine proteinases in the blood coagulation and fibrinolytic systems. Bioscience, Biotechnology and Biochemistry 60(8): 1383—1385.
Ohba, H., Nishikawa, M., Kimura, M., Yamasaki, N., Moriwaki, S. & Itoh, K., 1998. Cytotoxicity induced by Erythrina variegata serine proteinase inhibitors in tumor hematopoietic stem cell lines. Bioscience Biotechnology and Biochemistry 62(6): 1166—1170.
Umi Kalsom Yusuf, 1998. Erythrina L. 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. 220—221.
Yamaguchi, O., Kimura, M., Araki, M., Yamasaki, N., Kimura, Y., Nakajima, S. & Takagi, S., 1993. Chemical structures of two subunits, A-subunit and B-subunit, of galactose-specific isolectins from Erythrina variegata seeds. Journal of Biochemistry (Tokyo) 114(4): 560—566.

Undang A. Dasuki

Erythrina fusca
Erythrina subumbrans
Erythrina variegata

Dasuki, U.A., 2001. Erythrina L.. 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:
Erythrina fusca
Erythrina subumbrans
Erythrina variegata