Rhizochalin A, a Novel Two-Headed Sphingolipid from the Sponge Rhizochalina incrustata

Abstract

Rhizochalin A (4), the fourth representative of two-headed glycosphingolipids, was isolated as its peracetate from the sponge Rhizochalina incrustata. Its structure has been established as the 2-ethyl carbamoate of rhizochalin on the basis of spectroscopic data and chemical transformations.

Differential Induction of Apoptosis of Leukemic Cells by Rhizochalin, Two Headed Sphingolipids from Sponge and Its Derivatives

“…7,11) From these results, we concluded that the minimum Rhz structure necessary for apoptosis induction in HL-60 cells is one possessing a twoheaded sphingosine. Moreover, our study suggests that the aglycon derivatives of Rhz or its analog AglRhzA induce apoptosis more effectively than intact Rhz or its peracetylated derivatives, which makes the former better analogs of two-headed sphingolipids than the intact toxin as anti-tumor agents.…”

“…The D-galactose is the most common sugar encountered among the Rhzs from the sponge R. insrustata. 7) Hydrolysis of Rhz yields the aglycon derivatives. Results of the present study show that aglycon derivatives are more potent than Rhz in inducing apoptosis of HL-60 cells.…”

“…7,14) Compound BRS1 was shown to inhibit protein kinase C. 15) Studies on the structure-activity relationships of natural products or synthesized analogs as cytotoxic agents provide insight on the mechanism of action of these toxins. The aim of the present work was to investigate the antileukemic activity of several compounds, including Rhz and its derivatives such as aglycon of Rhz (AglRhz), Rhz peracetate (AcRhz), peracetylaglycon of Rhz (AcAglRhz), and aglycon of Rhz A (AglRhz A).…”

“…The chemicals were extracted, purified, and prepared as described previously. 7,9) Cell Culture Human promyelocytic HL-60 cells and human acute monocytic leukemia THP-1 (THP-1) cells were obtained from the Korean Cell Line Bank (Seoul National University, Seoul, Korea) and maintained in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS), 100 U/ml penicillin and 100 mg/ml streptomycin, and were incubated at 37°C in a humidified atmosphere of 95% air/5% CO 2 .…”

“…1), isolated in 1989 by our group from the Madagascarian sponge Rhizochalin incrustata. 6) The group of two-headed sphingolipids includes a limited number of compounds: Rhz, Rhz A, Rhz C, Rhz D and rhizochalinin A from the marine sponge Rhizochalina incrustata, [6][7][8][9][10] oceanapiside from Oceanapia phillipensis, 11) oceanalin A, Rhz B, and rhizochalinin B from Oceanapia sp., 7,12) calyxoside from Calyx sp., 13) leucettamols A and B from Leucetta leptorhapsis 14) and compound BRS1 from an unidentified sponge. 15) Their structures have been established on the basis of spectroscopic data and chemical transformations.…”