Bioactive (3Z,5E)-11,20-Epoxybriara-3,5-dien-7,18-olide Diterpenoids from the South China Sea Gorgonian Dichotella gemmacea

Abstract

Six new (3Z,5E)-11,20-epoxybriara-3,5-dien-7,18-olide diterpenoids, gemmacolides N–S (1–6), were isolated together with four known analogues, juncenolide D, and juncins R, S and U (7–10), from the South China Sea gorgonian Dichotella gemmacea. The structures of the new compounds were elucidated by the detailed analysis of spectroscopic data in combination with the comparison with reported data. The absolute configuration of 1 was determined by a TDDFT calculation of its solution ECD spectrum, affording the determination of absolute configuration of other analogues by simply comparing their ECD spectra with that of 1. The cytotoxic and antimicrobial activities of these compounds were evaluated. In preliminary in vitro bioassays, compounds 4, 5, 6, 8 and 9 showed cytotoxicity against A549 and MG63, while compounds 1, 2, 4, 7–10 showed antimicrobial activity against the fungus Septoria tritici and the bacterium Escherichia coli.

Briarane Diterpenoids Isolated from Gorgonian Corals between 2011 and 2013

“…Cytotoxicities of known briaranes 12- epi -fragilide G, juncins R, S and U, juncenolides D and J and praelolide towards A549 (IC 50 = 47.3, 13.9, 20.2, >43.2, 37.1, >46.7, >50.1 μM) and MG63 cells (IC 50 = 54.0, 5.6, 16.5, >43.2, >46.0, >46.7, >50.1 μM) were also reported [25,26,27]. …”

“…By NOESY experiments, the diene system between C-3/4 and C-5/16 in 25 – 27 was established as a conjugated s-cis diene moiety [29,30]. The absolute configurations of 31 – 60 were elucidated by TDDFT calculation of their solution ECD spectrum and by biosynthetic consideration [26,27,28]. …”

Chemistry and Bioactivity of Briaranes from the South China Sea Gorgonian Dichotella gemmacea

“…These metabolites are reported to display a wide spectrum of bioactivities, including cytotoxic, anti-inflammatory, antiviral, antifouling, insecticidal, and immunomodulatory effects [1,2,3,4]. In the course of our searching for novel and bioactive secondary metabolites from the South China Sea invertebrates [5,6,7,8,9,10,11,12], the cluster of metabolites attracted our attention due to their significant tumor tell growth inhibitory activity [7,8,9,10,11,12]. Considering the structural complexity of the metabolites, specific research regarding the determination of absolute configuration was carried out using a solution TDDEFT/ECD approach [12].…”

“…In the course of our searching for novel and bioactive secondary metabolites from the South China Sea invertebrates [5,6,7,8,9,10,11,12], the cluster of metabolites attracted our attention due to their significant tumor tell growth inhibitory activity [7,8,9,10,11,12]. Considering the structural complexity of the metabolites, specific research regarding the determination of absolute configuration was carried out using a solution TDDEFT/ECD approach [12]. Successive investigation on several collections of the gorgonian Dichotella gemmacea and Junceella gemmacea led to the isolation and structure elucidation of 48 new briaranes and 29 known analogues.…”

“…Successive investigation on several collections of the gorgonian Dichotella gemmacea and Junceella gemmacea led to the isolation and structure elucidation of 48 new briaranes and 29 known analogues. On the basis of in vitro screening, a structure–activity relationship analysis of the metabolites was performed [7,8,9,10,11,12]. Three new briaranes, gemmacolides J, V, and Y, showed significant growth inhibitory activity towards A549 cells, being more active than the positive control adriamycin [10,11].…”