Terpenoic acid glycerides from the dorid nudibranch Archidoris montereyensis

Extracts of the dorid nudibranch $\text{Archidoris montereyensis}$ contain a diterpenoic acid glyceride 1 whose structure has been determined by x-ray diffraction analysis. The structure of a minor metabolite, the sesquiterpenoic acid glyceride 2, was determined by chemical correlation.     

Verrucosin-a and -b,ichthyotoxic diterpenoic acid glycerides with a new carbon skeleton from the dorid nudibranch doris verrucosa

The dorid nudibranch Doris verrucosa contains in its skin extracts two glycerides (2-3)linked to diterpenoid acid residues. The terpenoids show a rearranged tricyclic skeleton. The structures, inferred from spectral and chemical evidence, were unambiguously determined by X-ray diffraction analysis of 3. Both 2 and 3 are highly ichthyotoxic.     

Semisynthesis of labdane diterpene metabolites from the nudibranch Pleurobranchaea meckelii

Two isomeric labdane aldehyde metabolites (1 and 2), first isolated from the skin of the Notaspidean nudibranch Pleurobranchaea meckelii, were synthesized in six steps from manool in 19 and 6% overall isolated yields, respectively.     

Chemical constituents of the nudibranch chromodoris marislae

The major metabolite of Chromodoris marislae, marislin ($\text{1a}$) was identified from spectral data and converted into the sponge metabolite pleraplysillin-2 ($\text{1b}$).     

New oxygenated diterpenes from an Australian nudibranch of the genus Chromodoris

Chemical analysis of a chromodorid nudibranch has provided two new diterpene metabolites 1 and 2 together with the known metabolites 3-6. In an NMR study, the dialdehyde metabolite 1 underwent facile conversion to cyclic hemiacetals 8-9 on exposure to methanol, a reaction that mimics chemical conversions that may occur during the isolation of some diterpenes from molluscs and sponges. Compounds 1, 2, 5 and 8 showed moderate cytotoxicity against P388 cells (IC₅₀=1.2-4.1 μg/mL).     

Austrodoral and austrodoric acid: nor-sesquiterpenes with a new carbon skeleton from the Antarctic nudibranch Austrodoris kerguelenensis

Two unprecedented nor-sesquiterpenes, austrodoral (4) and its oxidised derivative austrodoric acid (5), have been isolated from the skin of the marine dorid Austrodoris kerguelenensis, collected in Antarctica. The structures and the relative stereochemistry were elucidated on the basis of spectroscopic data. A role of stress-metabolites could be suggested for these compounds.     

Terpenoid metabolites of the nudibranch Hexabranchus sanguineus from the South China Sea

Chemical analysis of the secondary metabolite pattern of the nudibranch Hexabranchus sanguineus collected from the South China Sea revealed the presence of both sesquiterpenoids and diterpenoids, exhibiting very different structural features. Two new molecules, compounds 1 and 4, were isolated together with known compounds 2 and 3, and chemically characterized. This is the first report of terpenoids from H. sanguineus. The remarkable diversity of metabolites possessed by H. sanguineus supports some recent phylogenetic studies that place the mollusc near the steam of the dorid nudibranch tree.     

A chemical defense mechanism for the nudibranch cadlina luteomarginata

The nudibranch Cadlina luteomarginata from San Diego, California, concentrates selected metabolites from the sponges that constitute its diet. Gut analyses revealed that C. leutomarginata consumes at least ten sponges although Axinella sp. and Myxilla incrustans are most frequently eaten. Field observations and analysis of metabolites suggest that keratose sponges Leiosella idia (=Spongia idia) and Dysidea amblia are also consumed. Three novel compounds, the furan 20, the isonitrile 23 and the isothiocyanate 24 were identified by analysis of spectral data. The secondary metabolites of C. leuteomarginata were found only in the dorsum, which is exposed to potential predators. Five metabolites of C. luteomarginata were screened for antifeedant activity against fish and all showed some activity at 10–100 μ/mg in food pellets.     

Pelseneeriol-1 and -2: new furanosesquiterpene alcohols from porostome nudibranch Doriopsilla pelseneeri

The paper reports the first chemical study of the porostome nudibranch Doriopsilla pelseneeri collected off the Portuguese coast (Atlantic Ocean). Two new furanosesquiterpene alcohols, pelseneeriol-1 (1) and pelseneeriol-2 (2), have been isolated together with known compounds, 15-acetoxy-ent-pallescensin-A (5), and dendocarbin-A (6), from the mantle of the nudibranch, whereas euryfuran (3) and drimane ester mixture 4 were identified in the extract of the internal glands. The structures of 1 and 2 have been determined by extensive spectroscopic studies as well as by comparison with literature model compounds. In order to assess the relative stereochemistry of 1 and 2, full NMR assignment of related sponge metabolite microcionin-2 (8) and of co-occurring sesquiterpenes 9-11, that have been re-isolated from the Mediterranean sponge Fasciospongia cavernosa, has been also conducted. In particular, the relative stereochemistry of tricyclic sesquiterpene microcionin-1 (9) has now been rigorously assigned by detailed analysis of NOE difference experiments.     

Terpenoids from the dorid nudibranch cadlina luteomarginata

Methanol extracts of intact specimens of Cadlina luteomarginata, collected in Howe Sound and Barkley Sound, British Columbia, have been shown to contain sesquitepenoids and a degraded terpenoid. Albicanol (2) and its acetate 1 possess the drimane skeleton. Furodysin (4) and microcionin-2 (5) and microcionin-2 (6) are furanosesquiterpenoids of sponge origin. Luteone (8), the degraded terpenoid, represents a new carbon skeleton.     

Plectranthoic acid A & B, two new triterpenoids from Plectranthus rugosus

Two new triterpenoid acids, designated as plectranthoic acid A and plectranthoic acid B, have been isolated from P. rugosus and are characterised as (20-S)-3α-hydroxy-18α,19α-$\text{H}\text{-}$-urs-12-en-30β-oic acid and (14-S)-3α-hydroxy-18α, 19α $\text{H}\text{-}$-urs-12-en-27α-oic acid.     

Unusual amino acid derivatives from the mushroom Pleurocybella porrigens

Three new amino acid derivatives (1-3) and three known ones (4-6) were isolated from the mushroom Pleurocybella porrigens. The structures of 1-6 were determined by the interpretation of spectroscopic data. Compounds 1, 3, 4, and 5 were toxic to mouse cerebrum glial cells.     

Novel sesquiterpenoid esters from the nudibranch dendrodoris limbata

A novel sesquiterpenoid esterified by different fatty acids has been isolated from the digestive gland of the nudibranch $\text{Dendrodoris limbata}$.     

Malyngic acid,a new fatty acid from Lyngbya majuscula

Malyngic acid, a major fatty acid in several varieties of the marine blue-green alga Lyngbya majuscula, has been determined to be 9(S),12(R),13(S)-trihydroxyoctadeca-10(E),15(Z)-dienoic acid from chemical and spectral data and by its conversion to 9(S),12(R),13(S)-trihydroxystearic acid and degradation to 2-deoxy-D-ribitol.     

Cinnamic acid amides and lignanamides from Aptenia cordifolia

Examination of the hydroalcoholic extract of the leaves of Aptenia cordifolia has afforded three cinnamic acid amides and two lignanamides. Structures were established on the basis of spectroscopic data, including 2D-NMR analyses.     

Coelodiol and coeloic acid, ent-isocopalane diterpenes from the Indonesian sponge Coelocarteria cfr. singaporensis

Two novel ent-isocopalane diterpenes, coelodiol (1) and coeloic acid (2), the latter characterized by an unique oxidative degradation of ring A, have been isolated from the Indonesian sponge Coelocarteria cfr. singaporensis. The stereostructure of these metabolites has been established through interpretation of NMR data and application of the exciton chirality CD method. Coelodiol (1) and coeloic acids (2) were found to inhibit the growth of MKN-45 cell line (human gastric adenocarcinoma).     

High molecular weight polyacetylenes from the nudibranch Peltodoris actromaculata and the sponge Petrosia ficiformis

Two series of high molecular weight straight chain polyacetylenes (C₄₆, C₄₉ and C₄₉, C₅₂, C₅₅) have been isolated from two marine invertebrates and partially characterized.     

Fuligoic acid, a new yellow pigment with a chlorinated polyene-pyrone acid structure isolated from the myxomycete Fuligoseptica f. flava

Fuligoic acid (1), a new yellow pigment with a chlorinated polyene-pyrone acid structure, was isolated from field-collected fruit bodies of the myxomycete Fuligoseptica f. flava, and its structure was elucidated by spectral data, including its absolute configuration based on CD data.     

Lacitemzine, a novel sesquiterpene acid from the Tunisian plant Pulicaria laciniata (Coss. et Kral.) Thell.

The flowers of Pulicaria laciniata (Coss. et Kral.) Thell. (Asteraceae) afforded a new sesquiterpene acid 1, named lacitemzine together with the three known compounds, 4-hydroxy-3-methoxypyridine 2, β-sitosterol-3-O-β-d-glucoside 3 and 1,3,5-trimethoxybenzene 4. The structure of compound 1, 2-(2,6-dimethyl-3,4,5,6,7,8,9,10-octahydro-5,8-oxaazulen-9-yl)acrylic acid, contains a guaiane skeleton and was elucidated by spectroscopic procedures including 2D-NMR and X-ray diffraction.     

Further chemical studies on the Antarctic nudibranch Austrodoris kerguelenensis: new terpenoid acylglycerols and revision of the previous stereochemistry

The diterpenoid acylglycerol fraction from an extract of the mantle of a new collection of the Antarctic dorid gastropod mollusc Austrodoris kerguelenensis has been chemically analysed. Two novel 2-monoacylglycerols 9 and 12, along with known 1,2-diacyl glyceryl esters 5 and 6, now reassigned as 7 and 8, have been isolated. The linkage of a diterpenoid moiety at C-2 of glycerol characterizes all the compounds. Because the R absolute stereochemistry at C-2 of glycerol has been established for the corresponding 1,3-glyceryl esters 1 and 2, derived from 7 and 8 by acyl-migration of the terpenoid moiety from C-2 to C-3, our finding implies that 1,2-derivatives from Antarctic nudibranchs have the same S stereochemistry as all 1,2-sn-diacylglycerols from the other dorids.