Three new non-brominated pyrrole alkaloids from the South China Sea sponge Agelas nakamurai

Three new non-brominated pyrrole alkaloids,nakamurines A-C(1-3) were isolated from the South China Sea sponge Agelas nakamurai.Their structures were elucidated on the basis of spectroscopic data.Compound 2 showed weak antimicrobial activity against Candida albicans with MIC of 60μg/mL.     

Three new dibromopyrrole alkaloids from the South China Sea sponge Agelas nemoechinata

Three new dibromopyrrole alkaloids, 9-N-methylcylindradine A (1), 1-N-methylugibohlin (2), nemoechine H (3), together with one known dibromopyrrole alkaloid N-methyldibromoisophakellin (4) were isolated from the South China Sea sponge Agelas nemoechinata. Their structures were elucidated by comprehensive spectroscopic methods including HRESIMS and NMR, and the absolute configuration of compound 1 was further confirmed by comparison of optical rotation. Compound 3 exhibited moderate cytotoxic activity against K562 and L-02 with IC₅₀ values of 6.1 μM and 12.3 μM, respectively.     

New bromopyrrole alkaloids from the marine sponge Agelas sp.

Chemical investigation of the marine sponge Agelas sp. collected from the South China Sea resulted in the isolation of four new dimeric bromopyrrole alkaloids, including hexazosceptrin (1) with a rare cyclohexane-fused-cyclobutane skeleton, agelestes A and B (2–3), the sceptrin analogues without any aminoimidazole substitution, and (9S, 10R, 9′S, 10′R)-nakamuric acid (4), of which the absolute configuration was confirmed for the first time. The structure elucidation and absolute configuration assignments were unambiguously determined via extensive spectroscopic analyses and the comparison of experimental and calculated electronic circular dichroic spectra. Compounds 1 and 4 exhibited moderate antimicrobial activity.     

Two new diterpene alkaloids from Delphinium chrysotrichum

Chemical investigation on the ethanol extract from the whole plants of Delphinium chrysotrichum resulted in the isolation of two new diterpene alkaloids named delphatisine A (1) and delphatisine B (2), respectively. The structures of the new compounds were deduced on the basis of their spectral data (IR, HREIMS, EIMS, 1D, 2D-NMR). This is the first report on the isolation of diterpenoid alkaloids from the D. chrysotrichum.     

Two furano-sesquiterpenes from the South China Sea Sponge Dysidea fragilis

A new sesquiterpene, ent-furodysin (1), has been isolated from the South China Sea Sponge Dysidea fragilis, along with a known sesqui-terpene, ent-furodysinin (2). The structure and relative stereochemistry of 1 and 2 were established by spectral analysis.     

Two new steroids with cytotoxicity from the marine sponge Dactylospongia elegans collected from the South China Sea

A new steroid, (3S,5R,9R,10S,13R,17R,20R,24S,22E)-ergosta-6,8,22-triene-3,25-diol (1), and its sulfonated analogue (2) together with a known one, 5α,8α-epidioxy-cholest-6-en-3β-ol (3) were isolated from the marine sponge Dactylospongia elegans collected from the South China Sea. The new structures including absolute configurations were established by the HRESIMS and 1D and 2D NMR analysis coupled with the X-ray crystal analysis. Both of 1 and 2 exhibited cytotoxicity against cancer cell line MCF-7 with IC₅₀ values of 9.7 and 8.5 μM, respectively.     

New Sterol Derivatives from the Marine Sponge Xestospongia sp.

Chemical examination of a marine sponge Xestospongia sp. resulted in the isolation of 20 sterol derivatives ( 1 – 20 ), including eight new sterols namely aragusterols J – L ( 1 – 3 ), (5α,7α,12β,22E)‐7,12,18‐trihydroxystigmast‐22‐en‐3‐one ( 4 ), (5α,7α,12β,24R)‐ and (5α,7α,12β,24S)‐7,12,20‐trihydroxystigmastan‐3‐one ( 5 / 6 ), and (5α,7α,12β,22E,24R)‐ and (5α,7α,12β,22E,24S)‐7,12,20‐trihydroxyergost‐22‐en‐3‐one ( 7 / 8 ). The structures of new compounds were determined through extensive spectroscopic analyses and chemical conversion. The sterol diversity was mainly characterized by the presence of a cyclopropane unit at side chain, while compound 4 with 18‐hydroxymethyl group was found in stigmasterol family for the first time. Cytotoxic test revealed the inhibitory effects of compounds 1 , 4 , and 17 against human leukemia cell line K562 with IC₅₀ values of 18.3, 24.1, and 34.3 μm , respectively.     

Agelasines O-U, new diterpene alkaloids with a 9-N-methyladenine unit from a marine sponge Agelas sp.

New diterpene alkaloids, agelasines O-U (1-7), have been isolated from an Okinawan marine sponge Agelas sp. The gloss structures and relative stereochemistries of 1-7 were elucidated from the spectroscopic data. Agelasines O-R (1-4) were the third examples of diterpene alkaloid with a 9-N-methyladenine and a pyrrole units. Agelasine O (1) has a halimane skeleton, while agelasines P-R (2-4) have a clerodane skeleton. Agelasines S-U (5-7) were new diterpene alkaloids with a 9-N-methyladenine unit consisting of a halimane skeleton, a labdane skeleton, and a clerodane skeleton, respectively. Agelasines O-R (1-4) and T (6) showed antimicrobial activities against several bacteria and fungi.     

南海海绵Axinyssa aplysinoides的化学成分研究(二)

从中国南海采集的海绵Axinyssaaplysinoides中分离得到一白色结晶 ,通过UV ,IR ,MS ,NMR等波谱方法和光谱技术 ,确定了它的结构为Δ2 2 (2 3 ) (E) - 2 4 ,2 6 ,2 6-三甲基 - 2 5(30 ) -亚甲基胆甾醇     

海绵Ircinia selaginea中一种罕见的长共轭二萜烯酮

海绵的代谢产物中含有多种多样结构新异的生理活性物质[1～ 4 ] ,从中发现了不少抗肿瘤、抗病毒的活性物质 .我们在系统地研究海绵次生代谢产物的生理活性物质中 ,从海绵 Ircinia selagineaL amarck(Dictyoceratida目 ,Thorectidae科 )中分离出一种结构罕见的长共轭二萜烯酮 (1 ) . 1是新化合物 ,命名为 irciniketene,采用波谱方法测定了其化学结构 (Scheme 1 ) .生物活性试验表明 ,化合物 1对肿瘤细胞具有较强的抑制作用 .1 21 31 4 1 5 011 11 92 01 89871 7654 31 6C2 C1 OScheme1　Structure of irciniketene( 1 )1　实验部分1 .1　…     

南海海绵Biemna fortis中一种环二氧甾醇

从中国南海海绵Biemnafortis的乙酸乙酯可溶部分分离出一个已知的有机化合物 ,经IR ,EIMS ,1HNMR等光谱分析确定其化学结构式为 :5α ,8α -环二氧 -2 4 ξ -甲基胆甾 -6,2 2 -二烯 -3 β -醇。     

中国南海海绵Phakellia sp化学成份的分离和结构鉴定

海绵是最原始的多细胞动物,我国南海有几千种。国外从海绵中发现了多种新颖萜类、甾体和一些含氮、硫、卤素和带特异官能团的化合物。其中有些化合物具有学术上的重要意义,有些具有很强的生理活性,有些则已发展     

Determination of Heavy Metals and Other Water Quality Parameters from the South China Sea

This study investigated the distribution and concentrations of chromium, copper, arsenic, zinc, cadmium, and lead in seawater and suspended particles in the South China Sea by collection of samples from different depths at sixteen stations. The salinity, temperature, pH, dissolved organic carbon, dissolved oxygen, and silicon concentration were also measured in seawater. The results showed that the concentration levels in seawater from 0 m to 4000 m followed this pattern: zinc > arsenic > copper > lead > chromium > cadmium. Significant correlations were observed between lead and chromium and between arsenic, cadmium, and lead at r > 0.728. Very weak correlations were observed between copper and arsenic and between copper and cadmium. The concentrations of dissolved metals and particulate metals had negative correlations except for zinc. The metal concentrations in seawater and suspended particles showed different correlation behavior with salinity, temperature, pH, dissolved oxygen, dissolved organic carbon, and silicon.     

P-T stability conditions of methane hydrate in sediment from South China Sea

For reasonable assessment and safe exploitation of marine gas hydrate resource, it is important to determine the stability conditions of gas hydrates in marine sediment. In this paper, the seafloor water sample and sediment sample (saturated with pore water) from Shenhu Area of South China Sea were used to synthesize methane hydrates, and the stability conditions of methane hydrates were investigated by multi-step heating dissociation method. Preliminary experimental results show that the dissociation temperature of methane hydrate both in seafloor water and marine sediment, under any given pressure, is depressed by approximately -1.4 K relative to the pure water system. This phenomenon indicates that hydrate stability in marine sediment is mainly affected by pore water ions.     

南海海绵Iotrochota ridley化学成分的研究(-)

从中国南海海绵Iotrochotaridley中分离到一种长链甘油醚，其结构经IR，MS，1HNMR，13CNMR，1H－1HCOSY确定为3-十八烷氧基-1，2-丙二醇（鲨肝醇）（Ⅰ）。本文是首次报道该种属海绵的化学成分。     

Distribution characteristics and source tracing of petroleum hydrocarbons in the northeastern South China Sea

In recent years,oil spills caused by human activities have occurred frequently,and the resultant oil pollution has received extensive attention worldwide.In this paper,a total of 50 water samples were collected from the northeastern part of the South China Sea,and total petroleum hydrocarbons(TPHs)and n-alkane content in the samples were analyzed by gas chromatography-flame ionization detector(GC-FID) technology.The petroleum hydrocarbon characteristic indices,such as carbon predominance index(C...     

Investigating direct routes to an advanced intermediate for the synthesis of C-20 diterpene alkaloids

Rapid access to the ABCE ring system of the C-20 diterpene alkaloids was achieved by silver (I) promoted intramolecular Friedel-Crafts arylation of a functional group specific 5-bromo-3-azabicyclo[3.3.1]nonane derivative.     

Hyrtimomines,indole alkaloids from Okinawan marine sponges Hyrtios spp.

Six new indole alkaloids, hyrtimomines F–K (1–6), were isolated from Okinawan marine sponges Hyrtios spp. The structures of 1–6 were elucidated on the basis of spectroscopic analysis. Hyrtimomine F (1) is a structurally unique bisindole alkaloid possessing an α-keto-?-caprolactam ring, while hyrtimomine G (2) is a symmetrical bisindole alkaloid. Hyrtimomines H–K (3–6) are indole alkaloids possessing β-carboline skeleton with an imidazolium unit. Antimicrobial activities of hyrtimomines F–K (1–6) were evaluated.