Soft coral

Covalent synthesis of complex molecules involves the reactive assembly of many atoms into subunits with aid of reagents and estabUshed as well as innovative reaction pathways. These subunits are then subjected to various reactions that will assemble the target molecule. These reaction schemes involve the protection of certain sensitive parts of the molecule while other parts are being reacted. Very complex molecules can be synthesized in this manner. A prime example of the success of this approach is the total synthesis of palytoxin, a poisonous substance found in marine soft corals (35). Other complex molecules synthesized by sequential addition of atoms and blocks of atoms include vitamin potentially anticancer KH-1 adenocarcinoma antigen,... 

The unexpected source of starting material for partial synthesis i)f these agents was the sea. The isolation of 15CR)-PGA2 and its iicetate (44) from the lowly sea whip, Plexura homomalla, one of I he so-called soft corals, made an approach to prostaglandins rrom natural products possible. 

The sub-phyllum Anthozoa (6,500 species) contains the classes Alcyonaria (soft corals, sea fans, sea pens, sea pansies), Zoantharia (sea anemones and true corals), and Ceriantipatharia. The Scleroactinia (Madreporaria-true or stony corals) build the massive coral reefs and atolls which occur in tropical waters. According to Hashimoto (75), toxicity to humans is mainly found in the fire or stinging corals (Millepora sp.) and, to a lesser extent, in the stony corals (Goniopora sp.). 

Goad (40) and others have extensively reviewed coelenterate and echinoderm sterols including the saponins found in starfish and sea cucumbers. Cholesterol is a common sterol in most families, except for gorgonians and zoanthids some soft corals contain polyhydroxylated sterols. The amount of variation associated with phylogeny is illustrate in the echinoderms by the fact that crinoids, ophuiroids, and echinoids contain A 5 sterols while holothuriodeans and asteroids contain A 7 sterols. Some classes contain uniquely structured sterols. 

The basic constituent of seashells is calcium carbonate, an insoluble compound formed from calcium ions secreted from the cells of the shellfish and carbonate ions present in seawater. But calcium carbonate is a white solid. The colors of seashells often arise from impurities and metabolic waste products captured in the solid shell as it is formed. Coloration is dictated by both diet and water habitat. For example, some cowries that live and feed on soft corals take on the hue of the coral species. Yellow and red colors often arise from carotenoid pigments such as //-carotene. Light refraction often generates the iridescent mother-of-pearl hues. 

The defensive furanocembranes from the adult soft coral Sinularia poly-dactyla are also found in the eggs and larvae of their offspring. HPLC-com-parison of extracts from offspring with those from adults showed that pukalide (39) and 1 ip-acetoxypukalide (40) (Scheme 10) [87,88] are contained in both the blastula and planula of the soft coral [89]. Feeding assays with the larvae and their extracts showed that fish rejected the larvae due to chemical factors -most likely the pukalides. The pukalide-concentrations in the extracts of... 

Scheme 10 Pukalides from the soft coral Sinularia polydactyla... 

The soft coral Gersemia rubiformis was analyzed for its seasonal variation in fatty acids [109]. In April, C18 acids predominated (18 1, 18 2a>6, 18 3co3,... 

Investigations of the natural products chemistry of the Red Sea soft coral Lobophyton depressum (Alcyonacea) led to the isolation of a crystalline prostanoid derivative [70]. On the basis of H NMR data, the planar structure was developed as methyl ll-acetoxy-PGF2tt (56). Stereochemistry at Cl5 was established as S by comparison of the biological and NMR features of the hydrolyzed... 

Rapid-acting neurotoxin that causes irreversible depolarization of neural and muscular tissue by an unknown mechanism. It has a very potent effect on coronary arteries and death may result from constriction of the blood vessels of the heart. It is a solid obtained from bacterium associated with soft corals (Palythoa caribaerum and Palythoa toxica). It is soluble in water and alcohol, and stable to heat. 

The structures of sclerophytins A 17 and B 18, isolated from the soft coral Sclerophytum capitalis, were revised on basis of spectroscopic re-evaluation . Two unusual flavonoid tetrahydrofuranyl skeletons, namely tephrorin A 19 and B 20, were identified from Tephrosia purpurea . An alkaloid cartormin 21 was isolated and identified from Carthamus tinctorius, a plant used widely as a traditional Chinese medicine, <00TL1955>. 

Allelopathic effect on competitor soft coral Sinularia in Australia (De Nys et al. 1991)... 

Although perhaps not an attraction to nutrients in a strict sense, symbiotic dino-flagellates (zooxanthellae) have been known for some time to be attracted to host invertebrates (which ultimately provide them with nutrients), presumably via chemical cues from the hosts (Kinzie 1974 Fitt 1984). These cues may include ammonia and nitrate released from the host (Fitt 1984). Recently Pasternak et al. (2004) demonstrated chemoattraction by Symbiodinium sp. to cell-free homogenates of juvenile soft coral polyps, which did not previously have symbiotic zooxanthellae, but not to adult polyps, which did already have symbiotic algae. The attraction was subsequently shown to be a true chemotactic response with an additional chemoki-netic effect of the algae swimming slower in the presence of host chemical cues (Pasternak et al. 2006). 

Pasternak Z, Bachar A, Abelson A, Achituv Y (2004) Initiation of symbiosis between the soft coral Heteroxenia fuscescens and its zooxanthellae. Mar Ecol Prog Ser 279 113-116 Pasternak Z, Blasius B, Abelson A, Achituv Y (2006) Host-finding behaviour and navigation capabilities of symbiotic zooxanthellae. Coral Reefs 25 201-207 Patel P, Callow ME, Joint I, Callow JA (2003) Specificity in the settlement - modifying response of bacterial biofilms towards zoospores of the marine alga Enteromorpha. Environ Microbiol 5 338-349... 

Abstract Recent chemical studies on the marine soft corals and terrestrial plants have lesnlted in the isolation of several novel componnds. The soft corals, Pseudopterogorgia elisabethae and Cladiella species yielded several novel terpenoids, exhibiting antimicrobial activities. New steroids were isolated from terrestrial fungi, Mucor plumbeus and Coprims micaceus. Phytochemical studies on the Buxus hyrcana, collected from Iran, have yielded steroidal bases. This revdew describes the new natiual products exhibiting different bioactivities from the aforementioned sources. 

Bioactive Sesquiterpenoids from the Marine Soft Coral of Genus Cladiella... 

The structure and relative configuration of six new dolabellanes (30-35) isolated from the soft coral Clavularia inflata collected at Orchid Island located 44 nautical miles off Taiwan s southeast coast is depicted in Fig. 4 [16]. The relative configuration was assigned based on ID and 2D NMR spectroscopy and supports the cis arrangement between the isopropyl group at... 

Fig. 4 Six dolabellanes (30-35) isolated from the soft coral Clavularia inflata (2001)...

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