Structurally Diverse Metabolites from the Soft Coral Sinularia verruca Collected in the South China Sea

Abstract

Nineteen metabolites with diverse structures, including the rare pyrroloindoline alkaloid verrupyrroloindoline (1), the unprecedented highly fused benzosesquiterpenoid verrubenzospirolactone (2), the new asteriscane-type sesquiterpenoid 10-deoxocapillosanane D (3), and the two new cyclopentenone derivatives (4S*,5S*)-4-hydroxy-5-(hydroxymethyl)-2,3-dimethyl-4-pentylcyclopent-2-en-1-one (4) and (S)-4-hydroxy-5-methylene-2,3-dimethyl-4-pentylcyclopent-2-en-1-one (5), were isolated from a South China Sea collection of the soft coral Sinularia verruca. Eleven previously described marine metabolites (7−15, 18, and 19) were also obtained as well as three new EtOH-adduct artifacts (6, 16, and 17). The structures of the new compounds were elucidated by extensive spectroscopic analysis and by comparison with previously reported data. Compounds 4, 5, and 16 showed protection against the cytopathic effects of HIV-1 infection with EC 50 values of 5.8−34 μM, and 4, 6, and 16 exhibited inhibition against LPS-induced NO production with IC 50 values of 24−28 μM. S oft corals of the genus Sinularia (family Alcyoniidae) are commonly distributed in the tropical coral reef systems of the world and are well known for being a rich source of biologically active secondary metabolites. In the past several decades, more than 50 Sinularia species have been chemically investigated, resulting in the discovery of hundreds of secondary metabolites including sesquiterpenoids, diterpenoids, polyhydroxylated steroids, cyclopentenones, and butenolides.

A New Cyclopentylidene and Other Chemical Constituents from Malaysian Crotalaria pallida

“…The pentyl side chain is connected to the hydroxyl-dimethyl-2-furanone moiety at C(4), a deduction from the HMBC results with the observation of 2 J correlation from C(4) to H(5), hence completing the structure of 2 as 5-hydroxy-3,4-dimethyl-5-pentylfuran-2(5H)-one. Compound 2 has been previously isolated from microorganism (Koshino et al 1989;Wu et al 2011;Yuan et al 2016) and named as hydroxydihydrobovolide and was reported to show mild antimicrobial activity. The experiment data were similar with those reported and this is the first isolation report of hydroxydihydrobovolide from a plant source (Figure 3).…”

Marine natural products

“…), 598 lochmolin H 1028 (Sinularia lochmodes), 599 cadinane-type endo-and hydro-peroxides 1029-1031 (Sinularia sp. ), 600 1032 and 1033 from S. verruca, 601 from which was also reported a rare pyrroloindoline alkaloid 1034 in addition to two simpler cyclopentenones 1035 and 1036, bisabolanes 1037-1045, cadinanes 1046-1051 and a sesquiterpene bearing a new tricyclic skeleton 1052 (Pseudopterogorgia rigida), 602 cadinane 1053 (Menella sp. ), 603 eudesmane-type 1054 (Subergorgia suberosa), 604 and guaiane lactones 1055 and 1056 (Menella woodin).…”

Biomimetic Total Synthesis of (±)‐Verrubenzospirolactone

“…We intended to use an intramolecular Diels–Alder between a 2 H ‐chromene and a diene as the final step of a concise total synthesis of verrubenzospirolactone ( 1 ), a meroterpenoid recently isolated from the soft coral Sinularia verruca along with its proposed biosynthetic precursor, capillobenzopyranol ( 2 ) . The unique pentacyclic structure of 1 features a spirocyclic butenolide and an intimidating array of five contiguous stereocenters, including one quaternary center, yet its biosynthesis could be remarkably simple.…”