Isorhizochalin (1) was isolated as its peracetate from the EtOH extract of the sponge Rhizochalina incrustata. Its structure and absolute stereochemistry were elucidated as (2S,3R,26R,27R)-2,27-diamino-3-O-beta-D: -galactopyranosyl-oxy-26-hydroxyoctacosan-18-one by extensive NMR, MS studies, chemical transformations, including micromolar-scale Baeyer-Villiger oxidation, and by analysis of CD spectra of isorhizochalinin perbenzoate (2b). Isorhizochalin is an unprecedented C-2 epimer of rhizochalin having an erythro configuration at the glycosylated 2-amino-3-alkanol alpha-terminus in contrast with a canonical threo configuration for other representatives of this structural group. Probable biogenesis of 1 is discussed in the context of known sphingolipid biosynthesis beginning with condensation of alanine with a fatty acyl CoA thioester. The aglycone, isorhizochalinin (2a), shows cytotoxicity against human leukemia HL-60 and THP-1 cells with IC(50) values of 2.90 and 2.20 microM, respectively.
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http://dx.doi.org/10.1007/s11745-009-3360-0 | DOI Listing |
J Org Chem
January 2013
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, USA.
A five-step transformation of D-glucosamine, commencing with indium-mediated Barbier reaction without isolation of intermediates, into (R,R)-2-aminohex-5-ene-1,3-diol in 45-51% is described. The latter is a useful synthon for assembly of L-threo-sphingoid bases: long-chain aminoalkanols and aminoalkanediols with configurations antipodal to that found in mammalian D-erythro-sphingosine but prevalent among invertebrate-derived sphingolipids. The utility of the method is demonstrated by the first total synthesis of rhizochalinin C, the long-chain, "two-headed" sphingoid base aglycon of the natural product rhizochalin C from the marine sponge Rhizochalina incrustata.
View Article and Find Full Text PDFBiol Pharm Bull
June 2012
BK21 Project Team, College of Pharmacy, Chosun University, Gwangju 501–759, Republic of Korea.
Rhizochalin is a two-headed sphingolipid-like compound isolated from the sponge Rhizochalina incrustata. It has been reported that rhizocalin and its derivates have a chemopreventive and chemotherapeutic effect. However, the molecular mechanism of these effects is not understood.
View Article and Find Full Text PDFLipids
December 2009
Laboratory of MaNaPro Chemistry, Pacific Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 690022 Vladivostok, Russia.
Isorhizochalin (1) was isolated as its peracetate from the EtOH extract of the sponge Rhizochalina incrustata. Its structure and absolute stereochemistry were elucidated as (2S,3R,26R,27R)-2,27-diamino-3-O-beta-D: -galactopyranosyl-oxy-26-hydroxyoctacosan-18-one by extensive NMR, MS studies, chemical transformations, including micromolar-scale Baeyer-Villiger oxidation, and by analysis of CD spectra of isorhizochalinin perbenzoate (2b). Isorhizochalin is an unprecedented C-2 epimer of rhizochalin having an erythro configuration at the glycosylated 2-amino-3-alkanol alpha-terminus in contrast with a canonical threo configuration for other representatives of this structural group.
View Article and Find Full Text PDFLipids
September 2009
Pacific Institute of Bioorganic Chemistry, Vladivostok, 690022, Russian Federation.
Rhizochalin [(2R,3R,26R,27R)-2,27-diamino-3-hydroxy-26-[(2R,3R,4S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy]octacosan-11-one], an antimicrobial and cytotoxic marine two-headed sphingolipid-like natural product, isolated from the sponge Rhizochalina incrustata, and some related compounds were studied as anticarcinogenic and proapoptotic agents. The corresponding effects were tested on the mouse skin epidermal JB6 P(+) Cl 41 cell line, its stable transfectants, THP-1, HeLa, and SNU-C4 human tumor cells using a variety of assessments, including cell viability (MTS), flow cytometry, anchorage-independent soft agar, and luciferase assays. At 5-10 muM concentrations, rhizochalin was effective as an inhibitor of the malignant transformation of JB6 P(+) Cl 41 cells or colony formation of human tumor cells, which exerted its action, at least in part, through the induction of p53-dependent apoptosis.
View Article and Find Full Text PDFBiol Pharm Bull
June 2009
Department of Biochemistry, School of Medicine, Dong-A University, Busan, Korea.
Two-headed sphingolipids bear a certain similarity with sphingolipids in the structure and but differing from classical sphingolipids in alpha,omega-position of the basic groups. We analyzed the apoptotic effects of some two-headed sphingolipids including rhizochalin (Rhz) and its derivatives isolated from sponge Rhizochalina incrustata on human leukemia HL-60 cells. Direct addition of Rhz induced apoptosis of HL-60 cells.
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