Laurencia aplysin-20 from

A study of Laurencia tristicha from the South China Sea has discovered the hydroxylated aplysins, 10-hydroxyepiaplysin (406) and 10-hydroxyaplysin (407) (602), and 4-bromo-l,l-epoxylaur-ll-ene (408), which was previously synthesized but not found naturally (603). Laurencia microcladia from the North Aegean Sea has yielded the new 409 and 410, which exhibit significant cytotoxicity against two lung cancer cell lines (604). This red alga also contains the dimeric cyclolaurane 411 (595). An East China Sea collection of Laurencia okamurai has led to the isolation of the novel laureperoxide (412) and 10-bromoisoaplysin (413)... 

The complete chemical and. ST-ray studies of laurinterol (140) have been published. In addition to laurinterol, debromolaurinterol and isolaurinterol (141) are also found in Laurencia intermedia Yamada. Aplysin (142), isolated from Aplysia kurodai Baba, can be derived from laurinterol by acid-catalysed cyclisation. A synthesis of both aplysin and debromoaplysin, involving suitable elaboration of the alcohol (143) has been reported.The synthesis of the methyl... 

Aplysin was first isolated from the opistobranch mollusk Aplysia kurodai before being found in several spedes of Laurencia. The very rare iodine-containing sesquiterpenes have the carbon skeleton of laurane and cyclolaurane and were isolated from Laurencia caraibica and L. microcladia. 

The food chain between the Japanese species Aplysia kurodai and Laurencia concinna (Ceramiales) and Laurencia perforata yielded three closely related brominated diter-penes aplysin-20 was found only in the sea hare (Matsuda et al, 1967) isoaplysin-20 was identified in the mollusk and in Laurencia perforata and concinndiol was isolated only from Laurencia concinna. These three structures and their biosynthetic patterns are presented in Chapter 13. More recently, the food chain between the species Aplysia parvula and the red alga Laurencia filiformis, harvested in Tasmania, has led to similar comments (Jongaramruong et al, 2002). Other examples of brominated diterpenes found in Aplysia and Laurencia are presented in Chapter 13 (see also Komprobst and Al Easa, 2003). 

All natural organobromocompounds are of marine origin and have been found especially in algae. The genus Laurencia has provided a series of brominated acetylenic cyclic ethers and bromosesquiterpenes, two of which, aplysin and aplysinol, were isolated earlier from the sea hare, Aplysia kurodai. Reviews by Scheuer 160) and Premuzic (752) may be consulted and also the more recent papers 87, 93, 102, 103, 107, 128, 129, 130). A brominated bicyclic diterpenoid, aplysin-20, with unusual stereochemical features has been also isolated from Aplysia kurodai 186), and more recently unique brominated and chlorinated monoter-penes have been obtained from A. californica 85) 86). Two of them were also found as components of an extract of the alga Plocamium coccineum... 

A brominated diterpene, concinndiol, an isomer of aplysin-20, has been recently described from the alga Laurencia concinna (171). Some simple bromophenols also occur in algae (160, p. 88) and a highly brominated phenolic pyrrole has been found in a marine bacterium (111, 132). 

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