Long-chain α,ω-bisisothiocyanates from a marine sponge

Eighteen long-chain aliphatic α,ω-bisisothiocyanates were isolated from a marine sponge, Pseudaxinyssa sp. from Fiji. Eight compounds are di-, ten are monolefinic. Three additional constituents are α-isothiocyano-ω-formyl compounds.     

Simplexolides A–E and plakorfuran A,six butyrate derived polyketides from the marine sponge Plakortis simplex

Six new polyketides, simplexolides A–E (1–5) and a furan ester, plakorfuran A (6), together with four known furanylidenic methyl esters (7–10) were isolated from the marine sponge Plakortis simplex. Compounds 1–5 feature a tetrahydrofuran ring opened seco-plakortone skeleton. These new structures, including relative configurations, were determined on the basis of extensive analysis of spectroscopic data. The absolute configurations of 1–6 were established by the modified Mosher’s method, and the CD exciton chirality method. However, configurations of the remote stereocenters at C-8 in compounds 1–5 were not determined. Antifungal, cytotoxicity, antileismanial, and antimalarial activities of these polyketides were evaluated.     

(−)-Wistarin from the marine sponge Ircinia sp.: the first case of enantiomeric sesterterpenes

The sestertepene (−)-wistarin has been isolated from a Red Sea sponge of the genus Ircinia. This metabolite is the enantiomer of (+)-wistarin, a tetracyclic metabolite previously isolated from the sponge Ircinia wistarii. The enantiomeric relationship was proved by comparison of the CD spectrum of (−)-wistarin with that of a synthetic sample of the (+)-isomer. A hypothetical biosynthesis of (−)-wistarin is discussed starting from a putative linear precursor.     

The in vivo anti-plasmodial activity of haliclonacyclamine A, an alkaloid from the marine sponge, Haliclona sp

The compound haliclonacyclamine A was isolated from the Haliclona sponge at Solomon Islands. It acts as a powerful in?vitro and in?vivo anti-plasmodial agent against the chloroquine-resistant Plasmodium falciparum strain FCB1and Plasmodium vinckei petteri-infected mice, respectively.     

Sesquiterpenoids with PPARδ agonistic effect from a Korean marine sponge Ircinia sp.

One monocyclofarnesol-derived sesquiterpenoid (1), four new meroterpenoids (2–5) as well as two isolation artifacts (6–7) and a known sesquiterpenoid (8) were isolated from the marine sponge Ircinia sp. Their chemical structures were elucidated via analyses of spectroscopic data, which included NMR and HRMS data. Two terpenoids, 1 and 4, showed PPARδ agonistic activities, with EC₅₀ values of 18 and 30 μg/mL, respectively.     

Pellynols M−O,cytotoxic polyacetylenic alcohols from a Niphates sp. marine sponge

Three new polyacetylenic alcohols, pellynols M?O (1–3), along with two known ones, melyne A (4) and melyne B (5), were isolated from a Niphates sp. marine sponge collected off the South China Sea. The structures of new compounds were determined based on a combination of 1D and 2D NMR analysis, ESI-MSⁿ fragmentation, and chemical (ozonolysis) method. Their absolute configurations were assigned by modified Mosher's method. All the isolates showed potent cytotoxic activity against PC9 and HepG2 human cancer cell lines with IC₅₀ values of 2.9–7.6?μM.     

Cyclodysidins A–D,cyclic lipopeptides from the marine sponge-derived Streptomyces strain RV15

Four new cyclic lipopeptides, cyclo-(AFA-Ser-Gln-Asn-Tyr-Asn-Ser-Thr), named cyclodysidins A–D, were isolated from the broth culture of Streptomyces strain RV15 associated with the marine sponge Dysidea tupha. The sequences of the amino acid building blocks in the compounds and their structures were determined by 1D- and 2D-NMR techniques and CID-MS/MS experiments. The absolute configurations of all α-amino acids were determined by HPLC analysis after derivatization with Marfey’s reagent and comparison with commercially available reference samples, while those two of the β-amino fatty acids were determined by using racemic and enantiopure reference samples synthetically prepared.     

Euryjanicins E–G,poly-phenylalanine,and poly-proline cyclic heptapeptides from the Caribbean sponge Prosuberites laughlini

A new investigation of the active sponge extracts of Prosuberites laughlini collected off the West coast of Puerto Rico has yielded three new cyclic heptapeptides, namely euryjanicins E (1)–G (3), containing multiple phenylalanine and proline residues. In CDCl₃ solution, each euryjanicin F (2) and G (3) exists as an inseparable complex mixture of conformational isomers. The molecular structures of 1–3 were elucidated by a combination of chemical degradation, extensive ESI-MS/MSⁿ analyses, and 2D NMR methods. The elucidation of the absolute configuration was achieved by HPLC following analysis of the acid hydrolysates after derivatization with Marfey's reagent. When assayed against the National Cancer Institute 60 tumor cell line panel, the new cyclic peptides did not display significant in vitro cytotoxicity.     

Monamphilectine A, a potent antimalarial β-lactam from marine sponge Hymeniacidon sp: isolation, structure, semisynthesis, and bioactivity

Monamphilectine A (1), a new diterpenoid β-lactam alkaloid showing potent antimalarial activity, was isolated in milligram quantities following bioassay-directed extraction of a Puerto Rican marine sponge Hymeniacidon sp. Its structure, established by interpretation of spectral data, was confirmed unequivocally by chemical interconversion and comparison of physical, chemical, and bioactivity data with the natural product. The one-step semisynthesis of monamphilectine A was based on a multicomponent Ugi reaction that also established its absolute stereostructure.     

(+)-7-Bromotrypargine: an antimalarial β-carboline from the Australian marine sponge Ancorina sp.

Mass-directed isolation of the CH₂Cl₂/MeOH extract from the Australian marine sponge Ancorina sp. resulted in the purification of a new antimalarial β-carboline, (+)-7-bromotrypargine 1, along with the previously isolated natural product, 6-bromotryptamine 2. The structure of 1 is determined by extensive 1D/2D NMR and MS data analyses. Comparison of the chiro-optical data for 1 with literature values of related natural products is used to determine the absolute stereochemistry of (+)-7-bromotrypargine as 1R. Antimalarial activity data for 1 and 2 against a chloroquine-resistant (Dd2) and chloroquine-sensitive (3D7) Plasmodium falciparum strain are also provided.     

Dysamide U,a new trichlorinated diketopiperazine from the sponge Dysidea sp.

Dysamide U,a new tricblorinated diketopiperanne(1)along with seven known ones(2-8)were isolated from the sponge of Dysidea sp.collected from the Pacific ocean.The structure of dysamide U(1)was elucidated by high resolution FARMS and 1H NMR data induding COSY and RCT-COSY.     

Iodo–sesquiterpene hydroquinone and brominated indole alkaloids from the Thai sponge Smenospongia sp.

6′-Iodoaureol, an iodo–sesquiterpene hydroquinone, 6′-aureoxyaureol, a bissesquiterpene hydroquinone, and four brominated indole alkaloids 3–6 were isolated from the Thai sponge Smenospongia sp. Additionally, four known sesquiterpene hydroquinones 12–15, ten known brominated indole alkaloids 7–11, 17–18, and 20–22, ergosterol, and furospinosulin-1 were also isolated. Compound 1 is the first reported iodo–sesquiterpene hydroquinone and compounds 7–11 were isolated for the first time from natural sources. The structures were characterized by spectroscopic analyses as well as comparison with literature data. Several of these metabolites were evaluated for cytotoxic activity against seven tumor cell lines.     

Capillosananes S–Z,new sesquiterpenoids from the soft coral Sinularia capillosa

Chemical examination of the soft coral Sinularia capillosa resulted in the isolation of eight new sesquiterpenoids named capillosananes S–Z (1–8) and six known sesquiterpenes. The structures of the new compounds were determined on the basis of extensive spectroscopic analysis, including CD effects and Mosher method for the assignment of their absolute configurations. Capillosananes S–U (1–3) presented as the novel carbon skeletons with bicyclo[3,6,0] and bicyclo[4,5,0] systems, while capillosanane V (4) was characteristic of an unprecedented tricyclic skeleton. Capillosananes W–X (5–6) were assigned to the unusual dumortane-type sesquiterpenes. In addition, the absolute configurations of the stereoisomers of isodaucene-9,14-diol were assigned for the first time.     

Structure of a new sterol from the South China sponge Dysidea fragilis

A new sterol, 5a-cholesta-8(14),24(25)-diene-3/β, 6a-diol (1) and a known sterol (24Z)-24-ethyl-cholesta-7(8),24(28)-diene-3β,5a,6β-triol (2) have been isolated from the South China Seasponge Dysidea fragilis. The structure and relative stereochemistry of 1 were established by spectralanalysis, including 2D NMR experiments.     

Viscosalines B(1,2) and E(1,2): challenging new 3-alkyl pyridinium alkaloids from the marine sponge Haliclona viscosa

Four new 3-alkyl pyridinium alkaloids, the viscosalines?B(1) (1?a), B(2) (1?b), E(1) (2?a), and E(2) (2?b), were isolated from the Arctic sponge Haliclona viscosa. The structure elucidation of these isomeric compounds was challenging due to ambiguous fragments that derive during "standard" mass spectrometric fragmentation experiments. The final structure elucidation relied on the use of a combination of synthesis, liquid chromatography, and mass spectrometry. Three different mass spectrometers were used to differentiate between the synthetic structural isomers: a time-of-flight (TOF) mass spectrometer and two ion-trap mass spectrometers with different ion-transfer technologies (i.e., skimmer versus funnel optics). Although at first none of the spectrometers returned spectra that permitted structure elucidation, all three mass spectrometers provided analysis that successfully differentiated between the isomers after thorough method optimization. The use of in-source collision-induced dissociation (CID) with the ion trap and TOF instrument returned the most interesting results. The mode of fragmentation of the viscosalines under different experimental conditions is described herein. After successful optimization of the mass spectrometric method applied, the chromatographic method was improved to distinguish the previously inseparable isomers. Finally, both the liquid chromatography and mass spectrometric methods were applied to the natural products and the results compared to those from the synthetic compounds.     

Mechanism of the unusual substituent exchange in the reactions of alkylene oxides with organic compounds bearing β-hydroxyalkyl groups at heteroatoms S,Se, N,and P

The review summarizes the data on the study of the unusual exchange reaction between alkylene oxides and organic compounds of groups 15 and 16 of the Periodic Table bearing β-hydroxyalkyl substituents at the S, Se, N, and P heteroatoms. Despite the apparent identity of one of the starting reagents and the reaction product (retention of the three-membered ring), the structures of the formed alkylene oxide and organic compound with β-hydroxyalkyl group at the heteroatom differ from the structures of the starting materials. Using β-hydroxyalkyl sulfides as a model, the plausible mechanisms of the exchange reactions were discussed taking into account the change in the reaction order in β-hydroxyalkyl sulfide with its concentration increase. Irrespectively of the mechanism, the first stage of the reaction is the formation of an intermediate H-complex due to the H-bond formation between the OH sulfide group and the alkylene oxide oxygen atom and subsequent (for the dilute solutions) monomolecular intracomplex transformation of this H-complex. The mechanism was confirmed by semi-empirical quantum chemical calculations. In the case of concentrated solutions of β-hydroxyalkyl sulfides, possibility of the formation of intermediate sulfonium salt was discussed. Each pathway proceeds via its unique intermediates and transition states but the final stage results in the same intermediate bipolar ion with an intramolecular H-bond thus leading to the same nature and compositions of the reaction products for all reaction pathways.     

Munronoids A–J,ten new limonoids from Munronia unifoliolata Oliv

Ten new limonoids, named munronoids A–J (1–10), were isolated from Munronia unifoliolata Oliv. These limonoids involved in the skeletons of peieurianin, evodulone, euphane, and havanensin-types of limonoids, and their structures were established on the basis of spectroscopic data and X-ray crystallographic method. Compounds 1 and 2 were rollout of the conjugated Δ^8,30 and Δ^14,15 double bonds in peieurianin-type, 3–6 featuring a γ-lactone ring instead of the β-substituted furan ring were found in the evodulone-type for the first time. The insecticidal and anti-TMV activities of compounds 1–10 were also evaluated.