scholarly journals Absolute Structure Determination and Kv1.5 Ion Channel Inhibition Activities of New Debromoaplysiatoxin Analogues

Marine Drugs ◽  
2021 ◽  
Vol 19 (11) ◽  
pp. 630
Author(s):  
Sicheng Shen ◽  
Weiping Wang ◽  
Zijun Chen ◽  
Huihui Zhang ◽  
Yuchun Yang ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
2D Nmr ◽  
Ring System ◽  
X Ray Diffraction ◽  
Planar Structures ◽  
Channel Inhibition ◽  
Ic50 Values ◽  
The Absolute ◽  
New Treatments ◽  
Fused Ring System

Potassium channel Kv1.5 has been considered a key target for new treatments of atrial tachyarrhythmias, with few side effects. Four new debromoaplysiatoxin analogues with a 6/6/12 fused ring system were isolated from marine cyanobacterium Lyngbya sp. Their planar structures were elucidated by HRESIMS, 1D and 2D NMR. The absolute configuration of oscillatoxin J (1) was determined by single-crystal X-ray diffraction, and the absolute configurations of oscillatoxin K (2), oscillatoxin L (3) and oscillatoxin M (4) were confirmed on the basis of GIAO NMR shift calculation followed by DP4 analysis. The current study confirmed the absolute configuration of the pivotal chiral positions (7S, 9S, 10S, 11R, 12S, 15S, 29R and 30R) at traditional ATXs with 6/12/6 tricyclic ring system. Compound 1, 2 and 4 exhibited blocking activities against Kv1.5 with IC50 values of 2.61 ± 0.91 µM, 3.86 ± 1.03 µM and 3.79 ± 1.01 µM, respectively. However, compound 3 exhibited a minimum effect on Kv1.5 at 10 µM. Furthermore, all of these new debromoaplysiatoxin analogs displayed no apparent activity in a brine shrimp toxicity assay.

scholarly journals Absolute Configuration of Cembrane Diterpenoids from Bursera multijuga

2014 ◽  
Vol 9 (9) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Juan D. Hernández-Hernández ◽  
Hugo A. García-Gutiérrez ◽  
Luisa U. Román-Marín ◽  
Yunuen I. Torres-Blanco ◽  
Carlos M. Cerda-García-Rojas ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Absolute Configuration ◽  
2D Nmr ◽  
Vibrational Circular Dichroism ◽  
Conformational Preference ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute ◽  
First Time ◽  
Good Agreement

The stems of Bursera multijuga afforded (-)-(1 S,3 E,7 R,8 R,11 E)-7,8-epoxycembra-3,11-dien-1-ol (1) and its acetate 2, together with cembrene A (3), nephthenol (4), and cembrenol (5). The structures of 1 and 2 were elucidated by 1D and 2D NMR, HRESIMS, and X-ray diffraction. The conformational preference of flexible 1 was studied by molecular modeling at the DFT B3LYP/DGDZVP level of theory. Good agreement between calculated and experimental vibrational circular dichroism curves established the absolute configuration of 1. This is the first time that cembrane derivatives have been isolated from the genus Bursera.

scholarly journals New Cytotoxic Cytochalasans from a Plant-Associated Fungus Chaetomium globosum kz-19

Marine Drugs ◽  
2021 ◽  
Vol 19 (8) ◽  
pp. 438
Author(s):  
Tantan Li ◽  
Yun Wang ◽  
Li Li ◽  
Mengyue Tang ◽  
Qinghong Meng ◽  
...  
Keyword(s):  
Hela Cell ◽  
Cell Lines ◽  
Absolute Configuration ◽  
2D Nmr ◽  
Chaetomium Globosum ◽  
Electronic Circular Dichroism ◽  
Spectroscopic Analyses ◽  
Hela Cell Lines ◽  
Ic50 Values ◽  
The Absolute

Four new cytochalasans, phychaetoglobins A–D (1–4), together with twelve known cytochalasans (5–16), were isolated from a mangrove-associated fungus Chaetomium globosum kz-19. The new structures were elucidated on the basis of extensive 1D and 2D NMR, HR ESIMS spectroscopic analyses, and electronic circular dichroism (ECD) calculations. The absolute configuration of 2 was established by application of Mosher’s method. Compounds 4–8 exhibited moderate cytotoxicities against A549 and HeLa cell lines with the IC50 values less than 20 μM.

scholarly journals The Purification, Characterization, and Biological Activity of New Polyketides from Mangrove-Derived Endophytic Fungus Epicoccum nigrum SCNU-F0002

Marine Drugs ◽  
2019 ◽  
Vol 17 (7) ◽  
pp. 414 ◽  
Author(s):  
Zhangyuan Yan ◽  
Shitong Wen ◽  
Meng Ding ◽  
Huixian Guo ◽  
Cuiying Huang ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Endophytic Fungus ◽  
Radical Scavenging ◽  
Phytopathogenic Fungi ◽  
Cytotoxic Activities ◽  
X Ray Diffraction ◽  
Epicoccum Nigrum ◽  
Ic50 Values ◽  
The Absolute ◽  
Coumarin 1

Six new polyketides, including one coumarin (1), two isocoumarins (2 and 3), dihydroradicinin (4), and two benzofuranone derivatives (7 and 8), together with seven known analogues (5–6 and 9–13) were isolated from the culture of the mangrove endophytic fungus Epicoccum nigrum SCNU-F0002. The structures were elucidated on the interpretation of spectroscopic data. The absolute configuration of Compounds 2 and 3 were determined by comparison of their ECD spectra with the data of their analogue dihydroisocoumarins described in the literature. The absolute configuration of 4 was determined by single-crystal X-ray diffraction. All the compounds were screened for their antioxidant, antibacterial, anti-phytopathogenic fungi and cytotoxic activities. Using a DPPH radical-scavenging assay, Compounds 10–13 showed potent antioxidant activity with IC50 values of 13.6, 12.1, 18.1, and 11.7 μg/mL, respectively. In addition, Compounds 6 and 7 showed antibacterial effects against Bacillus subtilis (ATCC 6538), Escherichia coli (ATCC 8739), and Staphylococcus aureus (ATCC 6538), with MIC values in the range of 25–50 μg/mL.

scholarly journals Massiliamide, a cyclic tetrapeptide with potent tyrosinase inhibitory properties from the Gram-negative bacterium Massilia albidiflava DSM 17472T

2020 ◽  
Author(s):  
Andri Frediansyah ◽  
Jan Straetener ◽  
Heike Brötz-Oesterhelt ◽  
Harald Gross
Keyword(s):  
Absolute Configuration ◽  
Inhibitory Activity ◽  
Liquid Culture ◽  
Spectroscopic Analysis ◽  
2D Nmr ◽  
Negative Bacterium ◽  
Gram Negative ◽  
The Absolute ◽  
Potent Inhibitory Activity ◽  
Cyclic Tetrapeptide

AbstractA cyclic tetrapeptide, designated massiliamide, was isolated from the liquid culture of the Gram-negative bacterium Massilia albidiflava DSM 17472T. The structure was elucidated through extensive spectroscopic analysis, including HR-MS and 1D and 2D NMR experiments. The absolute configuration was determined using the Marfey´s method. Massiliamide showed potent inhibitory activity towards tyrosinase with an IC50 value of 1.15 µM and no cytotoxicity.

Alkaloids of Rauvolfia salicifolia GRISEB species

1982 ◽  
Vol 47 (11) ◽  
pp. 2912-2921 ◽  
Author(s):  
Patricia Sierra ◽  
Ladislav Novotný ◽  
Zdeněk Samek ◽  
Miloš Buděšínský ◽  
Ladislav Dolejš ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

From the endemic Cuban species Rauvolfia salicifolia GRISEB nine alkaloids were isolated of which the following seven had been already described: (+)-ajmalidine (I), (-)-reserpiline (II), (-)-isoreserpiline (III), (-)-isocarapanaubine (IV), (-)-ajmalicine (V), (+)-vellosimine (VI), and (+)-yohimbine (VII). The structure of (-)-raucubaine (VIII) had been previously determined by X-ray diffraction and the structure of the alkaloid (-)-raucubainine (IX) was suggested on the basis of its conversion to (-)-raucubaine (VIII). The absolute configuration of (-)-raucubaine and (-)-raucubainine was elucidated by CD spectroscopy.

scholarly journals Mono- and Dimeric Xanthones with Anti-Glioma and Anti-Inflammatory Activities from the Ascidian-Derived Fungus Diaporthe sp. SYSU-MS4722

Marine Drugs ◽  
2022 ◽  
Vol 20 (1) ◽  
pp. 51
Author(s):  
Senhua Chen ◽  
Heng Guo ◽  
Minghua Jiang ◽  
Qilin Wu ◽  
Jing Li ◽  
...  
Keyword(s):  
High Resolution Mass Spectrometry ◽  
2D Nmr ◽  
Crystallographic Analysis ◽  
Selective Cytotoxicity ◽  
X Ray ◽  
Planar Structures ◽  
Spectroscopic Analyses ◽  
Ic50 Values ◽  
Anti Inflammatory ◽  
Resolution Mass

Seven new xanthones, diaporthones A−G (1−7), together with 13 known analogues, including five mono- (8−14) and six dimeric xanthones (15−20), were obtained from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were established by extensive spectroscopic analyses, including 1D and 2D NMR and high-resolution mass spectrometry (HR-ESIMS). The absolute configurations of 1−7 were clearly identified by X-ray crystallographic analysis and calculation of the ECD Spectra. Compounds 15−20 showed significant anti-inflammatory activity with IC50 values between 6.3 and 8.0 μM. In addition, dimeric xanthones (15−20) showed selective cytotoxicity against T98G cell lines with IC50 values ranging from 19.5 to 78.0 μM.

scholarly journals Colletinin A and 2,2″-Diepicolletinin A: Two New Bisflavan-3-ols from Rhododendron Collettianum

2008 ◽  
Vol 3 (5) ◽  
pp. 1934578X0800300
Author(s):  
Viqar Uddin Ahmad ◽  
Farman Ullah ◽  
Hidayat Hussain ◽  
Gilles Dujardin ◽  
Arnaud Martel ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
2D Nmr ◽  
Nmr Analysis ◽  
Relative Configuration ◽  
The Absolute

Two new bisflavan-3-ols, named colletinin A (1) and 2,2″-diepicolletinin A (2) have been isolated from Rhododendron collettianum. Their structures were determined by means of 1D and 2D NMR analysis, aided by HREIMS data. The relative configuration was determined by means of 1H-1H NOESY correlation but the absolute configuration could not be established.

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