Guanidine Alkaloids from Monanchora arbuscula: Chemistry and Antitumor Potential

Abstract

Five guanidine alkaloids, mirabilin B (1), 8bb-hydroxyptilocaulin (2), ptilocaulin (3), and a mixture of the 8b-and 8a-epimers, 4 and 5, of 8-hydroxymirabilin (1,8a;8b,3a-didehydro-8-hydroxyptilocaulin), were isolated from Monanchora arbuscula colonies collected off the northeastern Brazilian coast. All structures were elucidated by spectroscopic analysis, including 1D ( 1 H-, 13 C-(BB), and 13 C-DEPT) and 2D (COSY, HSQC, and HMBC) NMR experiments, and comparison with the literature data. The cytotoxicity of the isolated compounds were evaluated against four tumor cell lines, showing that mirabilin B (1) and the two epimers were inactive, while 8bb-hydroxyptilocaulin (2) and ptilocaulin (3) presented IC 50 values in the range of 7.9 to 61.5 mm, and 5.8 to 40.0 mm, respectively. Further studies on the mechanism of action of ptilocaulin, using HL-60 leukemia cells, demonstrated that this guanidine compound induced apoptosis of the treated cells.

Chemical and Biological Aspects of Marine Sponges from the Family Mycalidae

“…[35], a Batzella sp. [36], and Monanchora arbuscula [37,38]. Mirabilins are members of a structurally diverse class of compounds that have been reported in a range of taxa, including both marine and terrestrial microorganisms, invertebrates, and plants (see [39] and previous reviews in series).…”

“…Mirabilins are members of a structurally diverse class of compounds that have been reported in a range of taxa, including both marine and terrestrial microorganisms, invertebrates, and plants (see [39] and previous reviews in series). Related tricyclic alkaloids with a guanidine moiety have been reported in five other sponge genera including Acanthella [40], Batzella [34,36,41], Clathria (Isociella) [35,42], Monanchora [37,38,43,44], and Ptilocaulis [45]. Some of these mirabilins have been reported to possess moderate biological activities.…”

“…Mirabilin A (84) has displayed antimalarial activity against Plasmodium falciparum (IC 50 value of 20.7 µM) [34], and mirabilin B (85) has been reported to have antifungal activity against the strain Cryptococcus neoformans (IC 50 value of 7.0 µg/mL) as well as antiprotozoal activity against Leishmania donovani (IC 50 value of 17 µg/mL) [38]. Other members of this structure class have also displayed antimalarial activity [34] and several have displayed cytotoxicity to tumour cells [34,37,41]. A new cyclic amine 1,5-diazacyclohenicosane (90, l " Fig.…”

Secondary Metabolites

“…The compounds ( Figure 18) were identified by 1 H and 13 C NMR, IR and MS (Ferreira et al, 2011). Two new brominated arginine-derived alkaloids were isolated from the Red Sea sponge Suberea mollis (Aplysinellidae), namely subereamine A and subereamine B (Figure 19).…”

Palyosulfonoceramides A and B: Unique Sulfonylated Ceramides from the Brazilian Zoanthids Palythoa caribaeorum and Protopalyhtoa variabilis

“…This region is characterized by a high degree of endemism over different taxonomical groups [8,9]. Its biotechnological potential is robust and has been noted in a series of recent studies [10,11,12,13,14,15]. As part of a program to expand natural product science in Brazil, we were interested in further exploring Zoanthidea, as a potential source for new structural classes.…”