Digenea simplex (PROSEA)
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Introduction |
Digenea simplex (Wulfen) C. Agardh
- Protologue: Spec. alg. 1: 389 (1822).
- Family: Rhodomelaceae
- Chromosome number: 2n= unknown
Synonyms
- Conferva simplex Wulfen (1803),
- Digenia wulfenii Kütz. (1843), nom. illeg.
Vernacular names
- Philippines: bodo-bodo. Japan: kaininso, makuri
- China: hairencao (when referring to medicine the name zhegucai is also used, but that is a misapplication of a name originally used for Caloglossa leprieurii (Mont.) G. Martens).
Origin and geographic distribution
D. simplex is recorded from many localities in tropical and warm temperate areas. In South-East Asia it is only recorded from the Philippines (Luzon, Palawan), Indonesia (Tukangbesi Islands, east of Bitung, Sulawesi) and the northern coast of Papua New Guinea.
Uses
D. simplex is mainly used as an anthelmintic medicine or vermifuge. Its use as a vermifuge was first described in Fujian Province (China) in 1530 A.D. It is the most efficient seaweed used in the treatment of Ascaris and Oxyuris, as well as whipworm (Trichuris) and tapeworm (Taenia) because it contains kainic acids. A single dose of 5-10 mg of α-kainic acid is capable of driving out Ascaris in adults and no unpleasant side effects have been observed. It can also be used together with santonin, where a synergetic action results in a marked increase of the ascaricidal effect. This algal compound is one of the few "drugs from the sea" used in orthodox medicine. An extract of D. simplex from Asia is on the market under the names "Helmia" and "Digenea" for use in the treatment of worms. D. simplex also is a source of agar, but because of its small size and low agar content it is unlikely to gain any commercial importance.
Production and international trade
The centre of collection of D. simplex is a very small area in the South China Sea, off the island of Pratas (= Donsha), Guandong Province (China), in an open lagoon of 16 km in diameter. About 300 t per year is produced there by some 45 divers. In addition to the Chinese production, almost the same amount of the alga used to be collected in southern Kyushu, Japan.
Properties
D. simplex contains agar (10-15% of its dry weight) and kainic acids. Especially α-kainic acid is an effective anthelmintic agent, which is said to be about ten times stronger than santonin, a compound of the salt marsh plant Artemisia maritima L. Another anthelmintic agent from D. simplex, named α-allokainic acid, is only slightly anthelmintic.
Description
- Thalli erect, up to 10(-20) cm tall, dull brownish-red, cartilaginous, bushy, wiry below; main axes terete and heavily clothed with many radial, dichotomously branched, 3-15 mm long, stiff laterals; main axes without well-defined apical cell or polysiphonous structure.
- Medulla of large broadly parenchymatous cells; cortex of smaller cells; determinate lateral branchlets uncorticated, showing 6-10 pericentral cells with small deciduous trichoblasts at the apices.
- Life cycle diplo-haplontic and triphasic, isomorphic for tetrasporophytes and gametophytes.
- Tetraspores tetrahedral, in irregularly swollen, chiefly uncorticated upper parts of branchlets.
- Spermatangia in small ovoid disc clustered at tips of fertile branchlets; cystocarps ovoid, terminal and lateral on branchlets.
Ecology
D. simplex is common and often abundant in the intertidal zone on rather exposed reefs and rocks. It is frequently much dwarfed and hardly more than 3-5 cm tall, but in sheltered spots it grows much larger, and is dredged to a depth of 20 m. It is a favoured support for many other algae and is commonly so heavily epiphytized that a dense colony of the dwarfed form may be completely concealed.
Propagation and planting
D. simplex is not kept in phycoculture.
Diseases and pests
D. simplex is usually heavily overgrown by epiphytes.
Harvesting
D. simplex is only harvested from natural populations by hand-collecting, often by divers.
Handling after harvest
D. simplex is probably sun-dried.
Prospects
Since kainic acids are now produced by the pharmaceutical industry, it is unlikely that D. simplex will be used for their production.
Literature
- Blunden, G. & Gordon, S.M., 1986. Medical and pharmaceutical uses of algae. Pharmacy International 7: 287-290.
- Michanek, G., 1979. Seaweed resources for pharmaceutical uses. In: Hoppe, H.A., Levring, T. & Tanaka, Y. (Editors): Marine algae for pharmaceutical science. Walter de Gruyter & Co., Berlin, Germany. pp. 203-235.
- Moore, R.E., 1977. Volatile compounds from marine algae. Accounts of Chemical Research 10: 40-47.
- Tseng, C.K. & Chang, C.F., 1984. Chinese seaweeds in herbal medicine. Proceedings of the 11th International Seaweed Symposium. Hydrobiologia 116/117: 152-154.
- Yoo, S.E. & Kim, N.J., 1988. An efficient synthesis of the basic pyrrolidine ring for the kainoids. Tetrahedron Letters 29(18): 2195-2196.
Sources of illustration
Børgesen, F., 1918-1920. The marine algae of the Danish West Indies, Part 3: Rhodophyceae (4, 6). Dansk Botanisk Arkiv 3: fig. 281, p. 281 (tetrasporangial branchlet); fig. 427, p. 469 (spermatangial branchlets); Saenger, P., 1973. Additions and comments on the Rhodomelaceae of Inhaca Island, Mozambique. Nova Hedwigia 24: figs 9 & 10, p. 335 (transverse sections of terminal branches); Trono, G.C., 1986. Philippine seaweeds. In: Guide to Philippine flora and fauna. Vol. 1. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines. Goodwill Bookstore, Manila, The Philippines. Fig. 92, p. 280 (habit). Redrawn and adapted by P. Verheij-Hayes.
Authors
- G.C. Trono Jr
