Synthesis of tokaramide A, a cysteine protease inhibitor from marine sponge Theonella aff. mirabilis

The first synthesis of tokaramide A (1) is described. Tokaramide A (1) was synthesized via the peptide with a side-chain unprotected arginine residue on Weinreb AM resin by reductive cleavage.     

Neuritogenic activity-guided isolation of a free base form manzamine A from a marine sponge, Acanthostrongylophora aff. ingens (Thiele, 1899)

Two manzamine-class alkaloids, manzamine A (1) and 8-hydroxymanzamine (2) were isolated from a Japanese marine sponge Acanthostrongylophora aff. ingens, together with three known alkaloids manzamine E (3), manzamine F (4), and manzamine X (5). The spectral features of 1 and 2 were different from the reported data. Detailed structure analysis using 2D NMR revealed the structure of 1 and 2 as a free base form of hydrochloric salt. These manzamine-class alkaloids showed neuritogenic activity against Neuro 2a cells.     

Smenoqualone a novel sesquiterpenoid from the marine sponge Smenospongia sp.

Smenoqualone, a novel quinonic terpenoid with a rearranged drimane skeleton was isolated from a marine sponge Smenospongia sp. The stereostructure was determined by detailed analyses of ¹H and ¹³C NMR spectra, ¹H-¹H COSY, ¹H-¹³C correlations via HMQC, HMBC and NOE difference NMR experiments.     

Purealin,a novel enzyme activator from the Okinawan marine sponge Psammaplysilla purea

Purealin , a novel secondary metabolite, which modurates enzymic reactions of ATPases, has been isolated from the okinawan marine sponge $\text{Psammaplysilla}$$\text{purea}$ and the structure has been determined by the ¹H-¹H homonuclear and ¹H-¹³C heteronuclear NMR chemical shift correlations and CD spectra.     

Isolation of salsolinol, a tetrahydroisoquinoline alkaloid, from the marine sponge Xestospongia cf. vansoesti as a proteasome inhibitor

Salsolinol (1), a tetrahydroisoquinoline alkaloid, was isolated from the marine sponge Xestospongia cf. vansoesti collected in Indonesia as a proteasome inhibitor, along with three salsolinol derivatives, norsalsolinol (2), cis-4-hydroxysalsolinol (3), and trans-4-hydroxysalsolinol (4). Compounds 1 and 2 inhibited the chymotrypsin-like activity of the proteasome with IC(50) values of 50 and 32 μg/ml, respectively, but 3 and 4 showed no inhibitory effect even at 100 μg/ml.     

Prianosin A,a novel antileukemic alkaloid from the okinawan marine sponge Prianos melanos

A novel alkaloid, prianosin A (1), with potent antineoplastic activity has been isolated from the Okinawan marine sponge Prianos melanos. Its absolute stereostructure was determined by single crystal x-ray diffraction analysis.     

Latonduines A and B,new alkaloids isolated from the marine sponge Stylissa carteri: structure elucidation,synthesis, and biogenetic implications

[structure: see text] Latonduines A (6) and B (7), two new alkaloids with unprecedented heterocyclic skeletons, have been isolated from the Indonesian marine sponge Stylissa carteri. The structures of the latonduines were elucidated by analysis of spectroscopic data and confirmed by the total synthesis of latonduine A (6). It is proposed that ornithine is the biogenetic precursor to the aminopyrimidine fragment of the latonduines.     

Omriolide A and B; two new rearranged spongian diterpenes from the marine sponge Dictyodendrilla aff. retiara

Two new rearranged spongian diterpenes designated omriolide A and B were isolated from the southern Kenyan sponge Dictyodendrilla aff. retiara collected at Wasini Is., Shimoni Channel. Omriolide A possesses an octalin linked to a unique trioxatricyclo[5.2.1.0^4,10]decane ring system, forming a tricyclic ‘cap’. Omriolide B comprised a tricyclo[5.4.0.0^2,4]undecane linked to a dioxabicyclo[3.3.0]octane. The structures of both diterpenes were elucidated by interpretation of MS results and, mainly, 1D and 2D NMR spectra.     

Stereochemical determination of dictyostatin, a novel microtubule-stabilising macrolide from the marine sponge Corallistidae sp

The relative stereochemistry of the 22-membered marine macrolide dictyostatin, a Taxol-like antimitotic agent, was determined based on a combination of extensive high field NMR studies, including J-based configuration analysis, and molecular modelling.     

Plakoridine C, a novel piperidine alkaloid from an Okinawan marine sponge Plakortis sp.

A new piperidine alkaloid plakoridine C (1) has been isolated from an Okinawan marine sponge Plakortis species, and the structure was elucidated from spectroscopic data. Plakoridine C (1) is a new alkaloid possessing a piperidine ring connected to a β-keto-γ-lactone through a double bond.     

Ilimaquinone,a sesquiterpenoid quinone from a marine sponge

Ilimaquinone (1) is a new sponge metabolite of composition C₂₂H₃₀O₄. Its structure, which was determined by spectral correlations and X-ray crystallography, comprises a rearranged drimane sesquiterpene moiety linked to a 2-hydroxy-5-methoxybenzoquinone at C-3.     

Concise synthesis and structure-activity relationship of furospinosulin-1, a hypoxia-selective growth inhibitor from marine sponge

Structure-activity relationship of furospinosulin-1 (1), a hypoxia-selective growth inhibitor isolated from marine sponge, was investigated. Concise synthetic method of 1 was developed, and some structurally modified analogues were prepared. Biological evaluation of them revealed that the whole chemical structure was important for the hypoxia-selective growth inhibitory activity of 1. Among prepared, the desmethyl analogue 30 showed excellent hypoxia-selective inhibitory activity similar to that of 1 and also exhibited in vivo anti-tumor activity with oral administration.     

New tetrahydropyrans from a marine sponge

Two new tetrahydropyrans have been isolated from the sponge Haliclona sp. From chemical and spectroscopic evidence they are shown to be (1′$\text{R}$, 2$\text{S}$, 2″$\text{E}$, 5$\text{R}$, 6$\text{R}$)-2-(1′-bromethyl)-2,5-dimethyl-6-(penta-2″,4″-dienyl)-tetrahydropyran and (1′$\text{R}$, 2$\text{S}$, 5$\text{R}$, 6$\text{R}$)-2-(1′-bromoethyl)-2,5-dimethyl-6-(pent-4″-enyl)-tetrahydropyran.     

Lihouidine, a novel spiro polycyclic aromatic alkaloid from the marine sponge Suberea n. sp. (Aplysinellidae, Verongida)

An investigation of a new species of sponge from the genus Suberea collected at Lihou Reef in the Coral Sea afforded lihouidine, an unprecedented cytotoxic spiro nonacyclic polyaromatic alkaloid. The structure of the alkaloid, which was racemic, was determined by a combination of 1D and 2D NMR techniques and single-crystal X-ray structural analysis.     

Asteropterin, an inhibitor of cathepsin B, from the marine sponge Asteropus simplex

A new pteridine derivative, asteropterin (1), was isolated as a cathepsin B inhibitor from the marine sponge Asteropus simplex. The structure of asteropterin (1) was elucidated by the analysis of spectral data.     

Bioactive marine metabolites II. Halistanol sulfate,an antimicrobial novel steroid sulfate from the marine sponge halichondria cf. moorei bergquist

A new C₂₉ a steroid sulfate, 24ξ,25-dlmethylcholestane-2β,3α,6α-triyl trisodium sulfate has been isolated from the Okinawan sponge Halichondria cf. moorei Bergquist as an antimicrobial constituent.     

Total synthesis of ageladine A, an angiogenesis inhibitor from the marine sponge Agelas nakamurai

[reaction: see text] A 12-step total synthesis of the tricyclic heteroaromatic marine metabolite ageladine A has been achieved using a 6pi-azaelectrocyclization and a Suzuki-Miyaura coupling of N-Boc-pyrrole-2-boronic acid with a chloropyridine as key steps.     

Renierone,an antimicrobial metabolite from a marine sponge

The major antibacterial metabolite in the sponge $\text{Reniera}$ sp. was shown to be an isoquinoline quinone, renierone ($\text{1}$). The structure of renierone ($\text{1}$) was defined by X-ray crystallography.     

Melynes,polyacetylene constituents from a vanuatu marine sponge

The structures of three long chain polyeneyne triols, melynes A, B, C are established from degradation reactions, from NMR data and from extensive HREIMS data.