Synthesis of (±)‐Spongiolactone Enabling Discovery of a More Potent Derivative

An eleven‐step synthesis of (±)‐spongiolactone from 1,3‐cyclohexanedione is reported that relies on a diastereoselective, nucleophile‐catalyzed aldol lactonization (NCAL) process with an advanced ketoacid intermediate that installed the anticipated β‐lactone pharmacophore of the natural product. In addition, a stereoselective cyclohexenyl zinc addition to a substituted cyclohexanone simultaneously installed two fully substituted vicinal stereocenters. The reported synthesis enabled preliminary structure–activity studies that revealed a regio‐ and stereoisomeric derivative of spongiolactone with greater antiproliferative activity towards a leukemia (K562) cell line. Furthermore, unusual antiproliferative selectivity of these spongiolactone derivatives toward the K562 cell line was observed with no inhibition of the breast, liver, and lung cancer cell lines tested.     

Structure and Antiarhythmic Activity of 12-Acetyl-12-epinapelline, a New Diterpenoid Alkaloid from Aconitum soongoricum

The structure of the new diterpenoid alkaloid 12-acetyl-12-epinapelline that was isolated from the mother liquor of Aconitum soongoricum was established. The conformational state of ring A was analyzed. Spectral properties and data for the antiarhythmic activity were presented.     

Structural determination of a new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane from Taxus cuspidata

A new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane were isolated from the methanol extract of the needles of Taxus cuspidata. The structures were established as 2alpha,7beta-diacetoxy-5alpha,10beta,13beta-trihydroxy-2(3 --> 20)abeotaxa-4(20), 11-dien-9-one (1) and 2alpha,5alpha,7beta,9alpha,13alpha-pentahydroxy-10beta-acetoxytaxa-4(20),11-diene (2) on the basis of 1D and 2D NMR spectral data and high-resolution FAB-MS analyses.     

A new rosane-type diterpenoid from Stachys parviflora and its density functional theory studies

A new rosane-type diterpenoid (1) has been isolated from the chloroform fraction of Stachys parviflora. Structure of 1 was proposed based on 1D and 2D NMR techniques including correlation spectroscopy, heteronuclear multiple quantum coherence, heteronuclear multiple bond correlation and nuclear Overhauser effect spectroscopy. A theoretical model for the electronic and spectroscopic properties of compound 1 is also developed. The geometries and electronic properties were modelled at B3LYP/6-31G^* and the theoretical scaled spectroscopic data correlate nicely with the experimental data.     

A new casbane diterpene from Euphorbia pekinensis

A new casbane diterpenoid, referred to as pekinenin G, together with one cembrane diterpene and four known casbane diterpenoids were isolated from the roots of Euphorbia pekinensis. Their structures were elucidated on the basis of spectroscopic studies and comparison with related known compounds. The six compounds showed different cytotoxic activities against four human cancer cell lines.     

An indole diterpenoid isolated from the fungus Drechmeria sp. and its antimicrobial activity

One new indole diterpenoid, drechmerin I (1), was isolated from the fermentation broth of Drechmeria sp. isolated from the root of Panax notoginseng. Its structure was elucidated based on 1 D and 2 D nuclear magnetic resonance (NMR), high resolution electrospray ionization mass spectrum (HRESIMS), and electronic circular dichroism (ECD) spectroscopic analyses as well as TD DFT calculations of ECD spectra. Drechmerin I (1) was assayed for its antimicrobial activity against Candida albicans, Staphylococcus aureus, Bacillus cereus, B. subtillis, Pseudomonas aeruginosa, and Klebsiella pneumonia, respectively. Drechmerin I (1) showed antimicrobial activities against B. subtillis with an MIC value of 200 μg/mL. The interaction of S. aureus peptide deformylase with drechmerin I (1) was investigated by molecular docking.     

A new ent-labdane diterpenoid from Andrographis paniculata

<正>A new ent-labdane diterpenoid,19-O-β-D-glucopyranosyl-ent-labda-8(17),13-dien-15,16,19-triol,together with six known ent-labdane diterpenoids,was isolated from the aerial parts of Andrographis paniculaia.The structure of the new compound was elucidated by extensive spectral analysis.     

New C19－Diterpenoid Alkaloids from the Roots of Delphinium Giraldii

Three new C19-diterpenoid alkaloids, giraldines A (1), B (3) and C (4), were isolated from the roots of Delphinium giraldii Diels, together with three known C19-diterpenoid alkaloids, dihydrogadesine (5), tatsiensine (6) and siwanine A (7), as well as their structures were elucidated by chemical evidence and spectral analyses, including IR, MS, 1D NMR and 2D NMR.     

An unreported bis-abeo cembrane-type diterpenoid with antioxidative and anti-lipoxygenase activities from the muricid gastropod mollusc Chicoreus ramosus

Abstract

The chemical analyses of ethyl acetate-methanol (EtOAc-MeOH) extract of muricid gastropod mollusk, Chicoreus ramosus from the southeastern coast of Indian peninsular led to the identification of unprecedented cembrane-type diterpenoid, which was characterized as (3E, 6E, 10E)-8a-butoxy-17(15→14), 20(12→11)-bis-abeo-cembra-3,6,10,14(17),15-pentaene (1). The structure of the studied cembrane was unambiguously assigned through the extensive spectroscopic experimentations. The antioxidant potentials of the bis-abeo cembrane as determined by in vitro 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid diammonium salt radical quenching potentials were greater (IC₅₀?<?0.40?mg/mL) related to α-tocopherol (IC₅₀?>?0.60?mg/mL). The pro-inflammatory anti-5-lipoxygenase potential of studied cembrane was higher (IC₅₀?<?0.80?mg/mL) related to those demonstrated by ibuprofen and sodium salicylate (IC₅₀?>?0.90?mg/mL).     

雷公藤内脂四醇的晶体结构

雷公藤系卫矛科植物( Tripterygium wlfordii Hook. f) , 1972) 年,Kupechan从分得三种环二萜内酯类化合物,显示出较强的抗白血压病活性。为了寻找低毒有效的类似物,本文从雷公藤根皮乙醇提取物的氯仿溶出部分,反复经硅胶柱层析分理,得到一种新的环氧二萜酯;雷共藤内酯四醇(Tripletraolide)。在乙酸乙酯重结晶,得无色长极状晶体,m.p.258~260℃。经高分辩质谱确定其分子为C~0H~26O~8,M~r=394.2。