Sterols and polysaccharides of green alga Caulerpa lentillifera grown under laboratory conditions and in mariculture and polysaccharides of green alga C. sertularioides grown under natural conditions were studied. The sterol fraction consisted of C 27 -C 29 steroidal alcohols with Δ 5 -unsaturation in the steroid core regardless of the growth conditions. The dominant (79.9%) steroid component of the sterol fraction was clionasterol. The water-soluble fraction of C. lentillifera grown under laboratory conditions was a mixture of 1,4-α-and 1,3-β-D-glucans and protein. The same fraction isolated from C. lentillifera grown in mariculture contained only protein. The water-soluble fraction of C. sertularioides grown under natural conditions contained 1,3;1,6-β-D-galactan sulfated at C2. The principal components of the base-soluble polysaccharide fractions from all algae samples were 1,4-α-D-glucans.

Sponges of the genus Latrunculia are rich sources of biologically active compounds. Polycyclic alkaloids such as discorhabdins [1][2][3][4][5][6][7][8][9][10][11] and macrolides [12,13], peptides [14][15][16], and norsesterterpene peroxides [17][18][19][20][21] have been found previously in them. Until now, the chemistry of Far-East sponges of the genus Latrunculia has not been studied. We isolated for the first time compound 1 from the new sponge species Latrunculia oparinae (Demospongiae, Poecilosclerida, Latrunculiidae) that was collected during an expedition of the SRS Academic Oparin near the shores of Kuril Islands (Ushishir Island, Rikord Straits, 49°22.10' N, 154°09.5' E).L. oparinae (dry weight 300 g) was extracted three times with EtOH. The extract was concentrated in vacuo. The solid was partitioned between EtOH (90%) and hexane. The aqueous EtOH layer was diluted with water (to 70% EtOH) and extracted with CHCl 3 . The resulting CHCl 3 extract was concentrated in vacuo to a moist oily residue and chromatographed over a column of Al 2 O 3 with elution by CHCl 3 :NH 3 (100:0.1) and CHCl 3 :EtOH:NH 3 (140:1:0.1), then three times over a column of Sephadex LH-20 with elution by CHCl 3 :EtOH (1:1), and then over a column of silica gel with elution by CHCl 3 :EtOH (14:1) to afford 1 (100 mg, 0.03% of dry sponge weight).The molecular formula of 1 was C 18 H 14 79 BrN 3 O 2 S and was confirmed by the HR-ESI mass spectrum: found, m/z 416.0110; calcd, m/z 416.0063. A comparison of the PMR, UV (EtOH), and IR (KBr) spectra with the literature showed that 1 had a structure including the same relative configuration of three asymmetric centers as discorhabdin A from the New Zealand sponge Latrunculia sp. [3] or prianosin A from the Okinawan sponge Prianos melanos [22], which had the same structure. However, 1 isolated by us from L. oparinae had a specific optical rotation index that was opposite in sign to that in the literature. Thus, for 1, [D] D -449° (c 0.01, MeOH); for discorhabdin A, [D] D +440° (c 0.05, MeOH) [3], for prianosin A, [D] D +248° (c 0.19, MeOH) [22]. Furthermore, 1 was obtained by us as reddish crystals whereas discorhabdin A and prianosin A that were isolated previously were reported to be green [3,22]. We hypothesized that these differences were related to the fact that the crystals of 1 that we obtained from EtOH extracts, in contrast with the related compounds, which were obtained from MeOH solutions. An x-ray structure analysis of 1 [23] showed that discorhabdin A was solvated by EtOH, a molecule of which was placed into the unique cavity formed by the N-containing and spirocycles of alkaloid. Obviously, the solvate formed in this manner was rather strong and had a color and optical rotation angle different from the free compound. This hypothesis was confirmed experimentally. We found that storing 1 in MeOH solution at room temperature for 3 d destroyed the strong solvate. The compound acquired an optical rotation close to that reported for discorhabdin A and prianosin A.

No abstract

No abstract

No abstract

No abstract

No 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.