Macrocyclic bis-quinolizidine alkaloids from Xestospongia muta

Abstract

A new stereoisomer Meso-araguspongine C together with nine reported macrocyclic bis-quinolizidine alkaloids araguspongines A, C, E, L, N−P, petrosin, and petrosin A were isolated from marine sponge Xestospongia muta. Stereochemistry of meso-araguspongine C (2) and araguspongines N-P (3−5) were established by their NMR data and conformational analyses. Both araguspongine C (1) and meso-araguspongine C (2) exhibited great cytotoxic activity towards HepG-2, HL-60, LU-1, MCF-7, and SK-Mel-2 human cancer cells (IC₅₀ in the range of 0.43–1.02 μM). At a concentration of 20 μM, isolated compounds (1−10) also showed modest inhibitory effects (from 7.6 to 40.8%) on the NO production in LPS activated RAW264.7 macrophages.

Keywords:

• meso araguspongine C
• bis quinolizidine alkaloid
• cytotoxicity
• Xestospongia muta