Sterols from the toxin-containing far-east sponge Monanchora pulchra

Abstract

It was shown earlier that toxin-containing marine invertebrates, in particular sponges (phylum Porifera) and sea cucumbers (phylum Echinodermata, class Holothurioidea), often contain unusual sterols instead of cholesterol and other ' 5 -sterols, in contrast with other animals [1]. They differ from cholesterol either by the position of the double bond in the steroid core (sometimes its absence) [2][3][4] or by the presence of highly alkylated side chains [5,6]. According to a hypothesis proposed by us, the unusual sterols protect the biomembranes of toxin-producing marine invertebrates from the lytic action of their own toxins as a result of sterol-toxin biochemical coordination occurring in such instances [7].In continuation of the search for new sources of biologically active compounds among invertebrates of Far-East seas, we recently found that EtOH extracts of the sponge Monanchora pulchra exhibited high cytotoxic activity. It was shown that this sponge contained a new cytotoxic polycyclic guanidine alkaloid that we called monanchocidin [8]. We investigated the sterol fraction from this sponge collected near the shores of Urup Is. (Kuril Islands, 46°07.0 N, 150°02 E) in August 2008 in order to test further this hypothesis.The sponge for chemical investigation was stored at -20°C. Thawed ground biological material (18.9 g dry wt.) was extracted (3u) with EtOH. The combined extracts were concentrated to dryness in vacuo and distributed between H 2 O and BuOH. The evaporated BuOH layer (2.14 g) was dissolved in EtOH (90%) and extracted (3u) with hexane. The combined hexane layers were concentrated to afford total nonpolar substances (0.69 g). A part (0.215 g) of this total was chromatographed over a column of silica gel (KSK, 50-160 Pm) using a hexaneoEtOAc gradient (4:1) to afford the total sterol fraction (57 mg, 0.92% of dry wt) that was separated using HPLC into three subfractions consisting of ' 5 -(1.3 mg) and ' 7 -sterols (24.3 mg), and stanols (21 mg). These were analyzed using PMR as described before [2,3,9,10].The structures of the free sterols as the acetylated derivatives were identified using GC and comparison with the relative retention times (RRT) of standard sterols and using GC-MS as before [2,3,9,10]. Table 1 presents the results. Table 1 shows that the sterol fraction from the studied sponge contained 29 previously known C 26 , C 27 , C 28 , C 29 , and C 30 compounds that had double bonds in the ' 7 , ' 7,22 , ' 7,24(28) , ' 0 , ' 22 , ' 5 , ' 5,22 , and ' 5,24(28) positions. Sterols of the ' 7 series were basic and made up 52.1% of the total sterol fraction. The stanol content was 45.1% whereas ' 5 -sterols were a minor fraction with a content of 2.8%. The principal components of the fraction were identified as 5-D-cholestan-3E-ol and 5D-cholest-7-en-3E-ol. Thus, yet another instance of toxin-(unusual sterols) biochemical coordination was found.

Batzella, Crambe and Monanchora: Highly Prolific Marine Sponge Genera Yielding Compounds with Potential Applications for Cancer and Other Therapeutic Areas

“…Marine sponges belong to Monanchora genus have also produced a small number of terpenoid metabolites and classical sterols [ 102 ]. Nine sesterterpenoids 126 – 134 were isolated from the Korean Monanchora sp.…”

Sesterterpenoid and Steroid Metabolites from a Deep-Water Alaska Sponge Inhibit Wnt/β-Catenin Signaling in Colon Cancer Cells

“…Cytotoxic sesterterpenoids and anti-inflammatory steroids have been isolated from a Monanchora sp., collected in Korean waters [ 24 , 25 ]. A number of sterols have also been elucidated from this genus [ 26 , 27 ]. Based on these diverse findings, we herein report the investigation of an undescribed species of Monanchora , closely related to the Northeastern Pacific species, Monanchora pulchra [ 28 ], collected from deep waters off the Aleutian Islands of Alaska.…”

Crambescidin Acid from the French Polynesian Monanchora n. sp. Marine Sponge

“…Marine sponges are a distinct multicellular phylum and represent the biggest class of marine invertebrates with approximately 8,900 registered species, though 15,000 species are distributed over seas and oceans [3][4][5]. Monanchora marine sponges are well recognized for producing a high number of structurally divergent bioactive secondary metabolites [6], including acyclic and polycyclic guanidine alkaloids [7][8][9], steroids [10], terpenoids [11,12], and long chain fatty acids [13]. These compounds display a myriad of biological potentialities as antimalarial [14], anticancer [15], anti-infective [16], and antiviral [17].…”