[structure: see text] A new hemiketal steroid, named cladiellin A (1), was first isolated from the soft coral Cladiella sp. Its structure was determined by spectroscopic methods and X-ray analysis. Compound 1 easily converted to 1a when NMR spectra were measured in CDCl(3) solution and quickly changed to 1b when pyridine was used. The structures of dehydrated products 1a and 1b were determined by spectroscopic analysis. Bioassay showed that all these three compounds showed antioxidant activity.
Two new sesquiterpenes, 1S*, 4R*, 5S*, 6R*, 7S*, 10S*-1(5), 6(7)-diepoxy-4-guaiol (1) and 1S*, 4S*, 5S*, 10R*-4,10-guaianediol (2) have been isolated from the ethyl acetate soluble portion of the soft coral Sinularia sp., and their stereostructure were determined by spectroscopic methods and by X-ray single crystal analysis. Both compounds showed antioxidant and cytotoxic activities.
A new 4-sulfated ceramide, ircisulfamide ( N-[(1S*,2S*,3R*)-2-hydroxy-1-(hydroxymethyl)-3-(sulfooxy)-heptadecyl]hexadecanamide; 1), and a new glycosphingolipid, ircicerebroside ( (2R*)-N-{(1S*,2R*,3E,7E)-1-[(b-d-glucopyranosyloxy)methyl]-2-hydroxy-8-methylheptadeca-3,7-dienyl}-2-hydroxyeicosanamide; 2), were isolated from the aqueous EtOH extract of the marine sponge Ircinia fasciculata (Pallas). The structures of the new compounds were elucidated on the basis of spectroscopic analysis and by means of chemical methods.Introduction. ± Different sphingolipids such as ceramide, sphingosine, and sphingosine-1-phosphate have been isolated from marine vertebrates, invertebrates, algae, and fungi etc. [1 ± 3]. These compounds have received increasing attention in the last years as some of their derivatives act as endogenous cell-function modulators and secondary messengers [4]. Sphingolipids have been shown to be potent and specific inhibitors of protein kinase C [5], Na-and K-ATPase, and calmodulin kinase, and to activate phospholipase C, phospholipase D, casein kinase II, tyrosine kinase, and DG kinase [6]. In addition, sphingolipids can also induce Ca 2 release [7], proliferate cells [8], protect human keratinocytes from apoptosis [9], suppress colon carcinogenesis in rats [10], and enhance apoptosis of radiation-resistant prostate cancer cells [11].In continuation of our search for potent bioactive secondary metabolites from the marine invertebrates [12 ± 14], a new 4-sulfated ceramide, ircisulfamide (1), and a new glycosphingolipid, ircicerebroside (2), were isolated from the aqueous EtOH extract of the marine sponge Ircinia fasciculata. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic analysis and chemical methods.
Steroids U 0300New Hemiketal Steroid from the Soft Coral Cladiella sp. -The title steroid cladiellin (I) is isolated and structurally characterized. It is easily transformed to (II) in CDCl3 solution and to (III) in pyridine. All three compounds exhibit antioxidant activity. -(ZHANG, G.-W.; MA, X.-Q.; KURIHARA, H.; ZHANG, C.-X.; YAO, X.-S.; SU, J.-Y.; ZENG*, L.-M.; Org. Lett. 7 (2005) 6, 991-994; Sch. Chem. Chem. Eng., Sun Yat-Sen Univ., Guangzhou 510275, Peop. Rep. China; Eng.) -R. Steudel 33-221
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