Eunicellin-based diterpenoids from the cultured soft coral Klyxum simplex

Eight new eunicellin-base diterpenoids, klysimplexins A-H (1-8), were isolated from a cultured soft coral Klyxum simplex. Their structures were elucidated by spectroscopic methods, particularly in 1D and 2D NMR experiments. The structure of 1 was further confirmed by a single-crystal X-ray diffraction analysis and the application of modified Mosher's method. Metabolites 2 and 8 were found to be cytotoxic toward a limited panel of cancer cell lines.     

软珊瑚中的新次生代谢物Lobocalone

前文~[1,2]曾从豆荚属软珊瑚中分离出两种大环二萜内酯,最近又在喀里多豆荚软珊瑚(Lobophytum caledonense Tix Dur)中分离出一种罕见的新型结构的次生代谢产物豆荚软珊瑚酮Lobocalone(1)].本文报道了1的结构测定结果.     

A novel chlorinated norsesquiterpenoid and two related new metabolites from the soft coral Paralemnalia thyrsoides

A structurally unique chlorinated norsesquiterpenoid, paralemnolin A (1), along with two new metabolites, paralemnolin B (2) and C (3), have been isolated from the soft coral Paralemnalia thyrsoides. Their structures were determined by extensive spectroscopic analyses. Single-crystal X-ray diffraction analysis of 1 further establish the absolute stereochemistry of 1.     

Dynamics of coral reef models in the presence of parrotfish

The decline of coral reefs characterized by macroalgae increase has been a global threat. We consider a slightly modified version of an ordinary differential equation (ODE) model proposed in Blackwood, Hastings, and Mumby [Theor. Ecol. 5 (2012), pp. 105–114] that explicitly considers the role of parrotfish grazing on coral reef dynamics. We perform complete stability, bifurcation, and persistence analysis for this model. If the fishing effort (f) is in between two critical values and , then the system has a unique interior equilibrium, which is stable if and unstable if . If is less (more) than these critical values, then the system has up to two (zero) interior equilibria. Also, we develop a more realistic delay differential equation (DDE) model to incorporate the time delay and treating it as the bifurcation parameter, and we prove that Hopf bifurcation about the interior equilibria could occur at critical time delays, which illustrate the potential importance of the inherent time delay in a coral reef ecosystem. Recommendations for Resource Managers

• One serious threat to coral reefs is overfishing of grazing species, including high level of algal abundance. Fishing alters the entire dynamics of a reef (Hughes, Baird, & Bellwood, 2003), for which the coral cover was predicted to decline rapidly (Mumby, 2006). One major issue is to reverse and develop appropriate management to increase or maintain coral resilience.
• We have provided a detailed local and global analysis of model (Blackwood, Hastings, & Mumby, 2012) and obtained an ecologically meaningful attracting region, for which there is a chance of stable coexistence of coral–algal–fish state.
• The healthy reefs switch to unhealthy state, and the macroalgae–parrotfish state becomes stable as the fishing effort increases through some critical values. Also, for some critical time delays, a switch between healthy and unhealthy reef states occurs through a Hopf bifurcation, which can only appear in the delay differential equation (DDE) model. Eventually, for large enough time delay, oscillations appear and an unhealthy state occurs.

     

New Verticillane‐Type Diterpenoids from the Taiwanese Soft Coral Cespitularia hypotentaculata

Investigation of the MeOH/CH₂Cl₂ extract of the soft coral Cespitularia hypotentaculata collected in Taiwan has resulted in the isolation of four new verticillane‐type diterpenoids, cespihypotins M–P ( 1 – 4 ). Compounds 2 and 3 are C(20)‐epimers. Compound 4 with a C?O group at C(10) and a methoxycarbonyl group at C(12) may be an important precursor of cespitularins and cespihypotins. The structures of these compounds were determined on the basis of spectroscopic analyses.     

两个新的化合物线四肽和单羟基甾醇的分离与结构鉴定

采用现代分离手段,从采自中国南海硇洲岛的白穗软珊瑚Nephthea sp.中分离纯化得到两个新的化合物分别为线四肽化合物和单羟基甾醇,经过MS,1H NMR,13C NMR(DEPT),HSQC,HMBC和NOE等光谱技术鉴定它们的结构为:亮氨酰-N-甲基亮氨酰-亮氨酰-N-甲基亮氨酸(1)和(20S,22R)-孕甾-1,4-二烯-22-乙酰基-3-酮(2),这两个化合物均为新化合物.肿瘤活性实验表明两个新的化合物显示微弱的细胞毒性.     

Elisapterosin F: a polycyclic gorgonian-derived diterpene with a facially amphiphilic structure

Analysis of the terpene metabolites of Pseudopterogorgia elisabethae collected in San Andrés island, Colombia has resulted in the discovery of a novel metabolite, elisapterosin F (1). The tangled molecular structure of 1, which was elucidated after extensive spectroscopic data interpretation, possesses hydrophilic and hydrophobic groups located on two opposite faces, rather than at two ends as in the more conventional head/tail amphiphiles.     

Novaxenicins A-D and xeniolides I-K, seven new diterpenes from the soft coral Xenia novaebrittanniae

Seven new diterpenes, novaxenicins A-D (1-4) and xeniolides I-K (5-7), have been isolated from the Kenyan soft coral Xenia novaebrittanniae. The structures and relative stereochemistry of the compounds were elucidated by interpretation of MS, COSY, HSQC, HMBC, and NOESY experiments. The structure of novaxenicin A (1) was secured by X-ray diffraction analysis. Compound 5 possesses anti-bacterial activity at a concentration of 1.25 μg/ml and compound 2 induces apoptosis in transformed mammalian cells at a concentration of 1.25 μg/ml.     

Sinularianins A and B, novel sesquiterpenoids from the Formosan soft coral Sinularia sp.

Two novel sesquiterpenoids, sinularianins A and B (1 and 2), have been isolated from the Formosan coral Sinularia sp. The skeleton of sinularianins A (1), namely sinulariolane, was found to be unprecedented. Sinularianin B (2), with a novel spiro-butenolide moiety, possesses a valerenane skeleton, which had been reported mostly from the plant. The structures of both metabolites were established by extensive analysis of spectroscopic data.     

Novel cyclic sesquiterpene peroxides from the Formosan soft coral Sinularia sp.

Four novel cyclic peroxide-containing sesquiterpenes (1-4), with a γ-alkylidene-α-methyl-α,β-unsaturated γ-lactone moiety, have been isolated from a Formosan soft coral of the genus Sinularia. Their structures were elucidated mainly by extensive 1D and 2D NMR experiments.