Polyketides piperidine

Over half of the compounds reported for lithistid sponges were isolated from Theonella (family Theonellidae). Theonella species have been reported to contain a wide variety of cyclic and linear peptides and polyketides, as well as 3-alkyl piperidine derivatives nearly identical to those reported from the order Haplosclerida.58 There is also a single report of cyano- and isothiocyano-sesquiter-penes similar to those isolated from Axinellidae (order Halichondrida).42 Bewley et al. performed a cellular localization study on Theonella swinhoei in which several types of microorganisms were separated from the sponge cells. Chemical analysis of the extracts from the separated cells indicated that the bicyclic peptide theopalauamide was found exclusively in filamentous bacteria while the polyketide swinholide A was localized to a mixed population of unicellular bacteria.59... 

Phthalimide-N-sulfenyl chloride, 375 Phthaloylamino acids, 212 Phthaloyl-L-valine, 212 Phytuberin, 197 Phytyl chloride, 499, 500 Picrotoxinin, 265, 430 Pictei-Spengler cyclization, 308 Pinacol-typc reduction, 513 -Pinene, 346, 367 Piperidine acetate, 318 Piperidinium acetate, 375-376 Polonovski reaction, 484 Polyaminolactams, 378-379 Polycyclic phenols, 102 Polyene cyclization, 291-292 Polyethylene glycols, 360, 376 Polyketides, 302 Polyphosphate ester, 376-377 Polyprenylation, 499-500 Potassium-Ammonia, 273, 377 Potassium-t-Butylamine-18-Crown-6, 377-378... 

Pinidine and Coniine.—Pinidine (8) and the hemlock alkaloid coniine (9) are unusual among simple piperidine alkaloids in being derived exclusively from acetate units. The combination is in each case a simple linear one and proceeds either via polyketide intermediates or, arguably in the case of coniine, via the fatty acid (10). Strong evidence from tracer and enzyme studies points to (11) as an intermediate... 

Pyne et al. proposed an alternative biosynthetic pathway for pyrido[l,2-fl] azepine stemona alkaloids starting from the polyketide derivative 21. Condensation of the latter with 1,4-diaminopropane, a biosynthetic product from the HSS production of homospermidine 3, could provide the piperidine ring intermediate 22. 

Pelletierine is biosynthesized through the incorporation of lysine. Among the several types of alkaloid possessing the piperidine nucleus, lobeline involves a similar biosynthetic pathway (Section 4.4) as that of pelletierine, whereas arecoline and coniine are biosynthesized through completely different pathways. The former alkaloid is derived lirom nicotinic acid (Section 10.3), and the latter alkaloid is biosynthesized via the polyketide pathway (Section 15.1). 

Arecoline is thought to be derived with nicotinic acid (niacin) as a precursor (Section 10.1). On the other hand, coniine, a toxic alkaloid of Conium maculatum (Apiaceae) and also possessing the piperidine skeleton, is biosynthesized through the polyketide pathway, which is completely different from that of arecoline. Coniine will be discussed in Chapter 15. 

Biological Activity of Tropane Alkaloids Distribution of Tropane Alkaloids Piperidine Alkaloids Alkaloids from Piper Species Piperine Alkaloids Involving Condensation with Acetate/Malonate Sedum Alkaloids Lobelia Alkaloids Lycopodium Alkaloids Piperidine Alkaloids in Insects Polyketide-Derived Alkaloids Coniine... 

Polyketide Alkaloid Phytotoxins Polyhydroxy Piperidine Alkaloids References... 

Although the alkaloids coniine (48) and y-coniceine (51) bear a structural resemblance to the piperidine alkaloids, these compounds are derived from a polyketide pathway (Fig. 29.17). Lysine is a poor precursor, and early attempts to show incorporation of this compound resulted in failure. Acetate is a much better precursor. Coniine is a highly toxic alkaloid and is one of the toxic components of poison hemlock (Conium maculatum, Apiaceae) (Cutler, 1992). Otherwise, alkaloids are very uncommon in the Apiaceae. Coniine does occur in several other plants, for example, Sarracenia (Sarracenia). y-Coniceine is found in several species of Aloe (Liliaceae) (Dring et al., 1984). Coniine is toxic to the aquatic plant Lemna (Wink, 1993). The LDioo p.o. in the... 

While for developing of simple piperidine alkaloids, e.g., pelletierine (Punica granatum), piperine (Piper nigrum et longum), and lobeline (Lobelia inflata), only one molecule of lysine is necessary, for quinolizidine alkaloids - e.g., lupinine (Lupinus luteus), sparteine of antiarrhythmic activity (Sarothamnus scoparius), and cytisine of respiratory stimulant effect (Laburnum species) - two molecules of lysines are indispensable. It was also proved that lycopodine (Lycopodium tristachyum, clubmoss) of quinolizidine structure has no polyketide origin, but it is a modified dimer of pelletierine, which, in turn, is derivable from lysine and acetate. 

In 2009 in a study of metabolites from Okinawan marine sponges, Kobayashi and coworkers [96] isolated and characterized a novel piperidine-containing polyketide alkaloid, plakoridine C from a sponge of the genus Plakortis sp. The authors noted that several pairs of resonances in the and NMR spectra were observed with a ratio of approximately 1 1 suggesting an epimeric or isomeric mixture of structures. The mixture was inseparable by semipreparative HPLC so the authors characterized the sample as the mixture. A HMQC spectrum showed the... 

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