Alkaloids mollusks

Thiazolopyridoacridine alkaloids obtained from marine sources, kuanoniamines (2a-c), bright yellow metabolites from the mollusk Chelynotus semperi, display... 

Chemical bias toward certain molecular arrangements may also determine the commonness of certain metabolites (Pietra 1995), such as the aplysinopsins (indole alkaloids of many sponges, cnidarians, and mollusks. Chart 8.2. A), bis-indole and guanidine alkaloids (Chart 8.2.A), isoprenoids (Pietra 1995, Chart 8.2.1), and polypropionates of mollusks, sponges, and fungi (Chart 8.2.FA/PO). 

Another interesting investigation of the use of microwave irradiation for the synthesis of alkaloids was recently reported by M. Alvarez et al., where the authors investigated a modular total synthesis of Lamellarin D [93]. After 20 years of the first isolation of this compound from the marine prosobranch mollusk Lamellaria sp, this family currently comprises more than 30 members, isolated from various natural sources. With its recent identification as... 

Evidence that supports an enzymatic basis to these biotransformations includes (1) cell free extracts from other sponges were unable to transform isoxazoline alkaloids (2) when tissue from the sponge Crambe crambe or from the mollusk Tylodina perversa (see Section 4.12.8.4) that feeds on Aplysina spp. was spiked with 58, no biotransformation was detected (3) in contrast to the increased concentrations of 60 and 61, the concentration... 

An examination of the composition of polyaromatic alkaloids of the mollusk Chelynotus semperi and an unidentified tunicate, both collected from Mante channel, Pohnpei, resulted in the identification of shermilamine B [129] and kuanoniamines A-D [130-133] (105). Shermilamine was originally found as a metabolite of a tunicate of the genus TruUdanmon (106). 

Caroll, A. R. and Scheuer, P. J. (1990) Kuanoniamines A, B, C, and D pentacyclic alkaloids from a tunicate and its prosobranch mollusk predator Chelynotus semperi. J. Org. Chem. 55,4426-4431. 

In 1990, Scheuer et al. reported the isolation and structure elucidation of four thiazolopyridoacridine alkaloids, of which kuanoniamine A (439) possesses a quinolinequinoneimine (1) subunit, from both the lamellariid mollusk Chelynotus semperi and an unidentified purple colonial tunicate collected at the Mante Channel, Pohnpei 186). 

Recent research progresses on lamellarins and analogous hexacyclic polyaromatic pyrrole alkaloids of bioactive marine mollusk 05CJO641. 

Alkaloids are diverse in number and form. They can be produced naturally, artificially, or by chance or accident (mutations) and they are therefore a part of global and local biodiversity. Protection of the biodiversity of our Earth was proclaimed by the United Nations Conference on Environment and Development (UNCED) and the Earth Summit in Rio de Janeiro in 1992, and it is continuously under public attention in all nations and international discussions. A problem connected with biodiversity, sometimes silenced by scientists, politicians, and nature protection leaders and movements is that the absolute exact number of species existing on the Earth is not known. The answer to the question of how many species exist on the globe is not known and probably never will be known exactly, because the answer needs final documentation of every form of life in all environments and places on the Earth. This is possible only theoretically. Today, more than 275,000 plant species have been described, and about 1.65 million living fungi species are known. About 186,(X)0 species of mollusks are estimated... 

Notoamides A-R could currently be the only indole alkaloids isolated from the culture of a fxmgus assodated with a mollusk. Produced from an Aspergillus collected on the common mussel, Mytilus edulis, from Japan (Noto Peninsula), notoamides A-O are cytotoxic for the HeLa " cell line (Kato et cd., 2007 Tsukamoto et al., 2008, 2009a, b, 2010). Postulated as a biosynthetic precursor of notoamides, notoamide E was isolated in 2009 and the first biosynthetic gene cluster was characterized in 2010 (Ding et al., 2010). Notoamide P is currently the only brominated notoamide. 

Most of these alkaloids have already been encountered in didemnid ascidians (Figure 28.7) and mollusks Chelynotus semperi see Chapter 23). Isolation of bacteria associated with blue and green chemotypes showed that the antiproliferative activity of the extracts from these ascidians is not of bacterial origin (Martinez-Garcia et al., 2007). 

Kigoshi, H., Imamura, Y, Yoshikawa, K., and Yamada, K. (1990) Three new cytotoxic alkaloids, aplaminone, neoaplaminone and neoaplaminone sulfate from the marine mollusk Aplysia kurodai. Tetrahedron Lett., 31, 4911—4914. 

Thoms, C Ebel, R., Hentschel, U and Proksch, P. (2003) Sequestration of dietary alkaloids by the spongivorous marine mollusk Tylodina perversa. Z. Natuiforsch. C. Biosci., 58, 426-432. 

The monodontamides A-F form an original series of alkaloids derived from putrescine and isolated from the species Monodonta labio (Niwa, Watanabe, and Yamada, 1993 Niwa et al, 1994). None of these nitrogen-containing derivatives appear to have particular biological activity, as is also the case for most derivatives isolated from prosobranch mollusks, which can take refuge in their shell. 

Thiazolopyridoacridine alkaloids obtained from marine sources, kuanoniamines (2a-c), bright yellow metabolites from the mollusk Chelynotus semperi, display only modest cytotoxicity. They strongly coordinate divalent ions (Fe, Co , Cu, Xeq 10 ° M ) and are pH indicators, their color changing from... 

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