Abstract
A new sterol, (23R)-methoxycholest-5,24-dien-3β-ol (1), two new ceramides, (2S,3R,4E,8E)-2-(tetradecanoylamino)-4,8-octadecadien-l,3-diol (6) and (2S,3R,2′R,4E,8E)-2-(tetradecanoylamino)-4,8-octadecadien-l,3,2′-triol (7), together with three known sterols (2–4), a lactone (5) and two ceramides (8,9), were isolated from the marine bryozoan Cryptosula pallasiana, collected at Huang Island of China. The structures of the new compounds were elucidated by extensive spectroscopic analyses, chemical methods and quantum electronic circular dichroism (ECD) calculations. Among the isolated compounds, sterol 1 possessed a rare side chain with a methoxy group at C-23, and a double bond between C-24 and C-25. Ceramides 6 and 7 possessed 14 carbons in their long-chain fatty acid base (FAB), which were different from the normal ceramides with 16 carbons in the FAB. Moreover, compounds 5 and 8 were isolated for the first time from marine bryozoans. Compounds 1–9 were evaluated for their cytotoxicity against human tumor cell lines HL-60, Hep-G2 and SGC-7901. The results showed that lactone 5 appears to have strong cytotoxicity against the test tumor cell lines, with IC50 values from 4.12 μM to 7.32 μM, and sterol 1 displayed moderate cytotoxicity with IC50 values between 12.34 μM and 18.37 μM, while ceramides 6–9 showed weak cytotoxicity with IC50 ranging from 21.13 μM to 58.15 μM.
Highlights
IntroductionMarine bryozoans are important sources for the discovery of new bioactive secondary metabolites
Marine bryozoans are important sources for the discovery of new bioactive secondary metabolites.There are three reports containing 19 new metabolites isolated from this understudied phylum in the last year alone [1]
CCl portion was separated by column chromatography (CC) and high‐performance liquid chromatography (HPLC) to afford a new sterol (CC) (1)
Summary
Marine bryozoans are important sources for the discovery of new bioactive secondary metabolites. Modern phytochemical and pharmacological investigations of marine bryozoans demonstrated that secondary metabolites, including macrolides, alkaloids, sterols, as well as halogen-containing compounds, etc., exhibited remarkable cytotoxic activities on tumor cell lines, such as human myeloid leukemia HL-60, human leukemia U937, murine lymphocytic leukemia P388, Mar. Drugs 2017, 15, 120; doi:10.3390/md15040120 www.mdpi.com/journal/marinedrugs. Infrom the the new biologically secondary metabolites marine bryozoans, C. pallasiana, course of our ongoing discovery of new biologically active secondary metabolites from marine coasts of Huang Island in Qingdao City, Shandong Province of China, was investigated. C. pallasiana, collected from the coasts of Huang Island in Qingdao City, Shandong the isolation and structure elucidation of three new compounds including one sterol (1) and Province of China, was investigated. The structures of the known compounds were identified secondary metabolites including three sterols (2–4), one lactone (5) and two ceramides (8,9).
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