Isolation and absolute configuration of alkylpyridine alkaloids from the marine sponge Hippospongia lachne.

Marine sponges are well known as prolific producers of structurally diverse molecules with valuable pharmacological potential. As part of our ongoing program to discover bioactive compounds from marine sponges collected from the Xisha Islands in the South China Sea, a chemical study on the specimens of Hippospongia lachne was conducted. As a result, eight undescribed compounds, including four zwitterionic alkylpyridinium salts, hippospondines A−D (1 − 4), and four 3-alkylpyridine alkaloids, hippospondines E (5), F (6), and (±)-hippospondine G (7), were isolated from the marine sponge H. lachne , together with one known 3-alkylpyridine alkaloid (8). The undescribed structures were elucidated by HRESIMS, NMR, DP4+ and CP3 probability analysis, and the Snatzke's method. Hippospondines A−D (1 − 4) represent the rare example of inner salt type alkylpyridinium alkaloid with a farnesyl moiety. Compounds 1 − 3 and 8 were subjected to cytotoxic and lymphocyte proliferation assays. Compound 3 exhibited a weak promotion effect on the ConA-induced T lymphocyte proliferation. Nine alkylpyridine alkaloids including eight undescribed ones were isolated from the marine sponge Hippospongia lachne. And four of them represent the rare example of zwitterionic alkylpyridinium alkaloid with a farnesyl moiety. [Display omitted] • Eight undescribed compounds were isolated from Hippospongia lachne. • Compounds 1 − 4 represent the rare example of inner salt type alkylpyridinium alkaloid. • Compounds 1 and 3 have a sulfonate group, which is uncommon. • Compound 3 exhibited a promotion effect on the ConA-induced lymphocyte proliferation. [ABSTRACT FROM AUTHOR]