seco-Briarellinone and Briarellin S, Two New Eunicellin-Based Diterpenoids from the Panamanian Octocoral Briareum asbestinum

Abstract

Two new eunicellin-based diterpenes, seco-briarellinone (1) and briarellin S (2), and a known seco-asbestinin (3) have been isolated from the methanolic extract of the common octocoral Briareum asbestinum collected in Bocas del Toro, Caribbean of Panama. The structures and relative stereochemistry of the compounds were defined using extensive spectroscopic analysis including 1D, 2D-nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). compounds 1 and 2 displayed anti-inflammatory properties inhibiting nitric oxide (NO) production induced by lipopolisacharide (LPS) in macrophages with an Inhibitory concentration 50% (IC50) of 4.7 μM and 20.3 μM, respectively. This is the first report of briarellin diterpenes containing a ketone group at C-12.

New Eunicellin-Type Diterpenes from the Panamanian Octocoral Briareum asbestinum

“…Seven degrees of unsaturation were calculated from the molecular formula: three accounted for carbonyls of ester and ketone and one double bond, hence compound 1 possesses four rings. Detailed analysis of 1 H and 13 C NMR data indicated the structure of briarellin T (1) was similar to briarellin S, previously reported from our group [10]. 13 C-NMR and DEPT spectra showed the presence of one ketone (δ C 214.3), one ester carbonyl (δ C 173.5), one double bond (δ C 124.8, 129.9) and five methyl groups (δ C 11.4, 19.6, 18.8, 22.6, 14.0) (Table 1).…”

“…Briarellins and asbestinins are biologically active marine natural products with great pharmacological potential due to their variety of properties, including antimicrobial, antiviral, antimalarial, and cytotoxic activities [9,14]. Moreover, a previous study from our group has reported that briarellin S reduced NO levels in LPS-stimulated primary murine macrophages [10]. However, there is no more evidence that reports the anti-inflammatory activity of these marine compounds.…”

“…Briareins, briarellins and asbestinins have shown a wide range of biological activities including cytotoxic, antiviral, anti-inflammatory, antimicrobial, antifouling and antiprotozoal activities [5,8,9], revealing the pharmacological potential of these compound families.Along the Caribbean coast of Panama, two species of Briareum have been reported, B. polyanthes and B. asbestinum. Of these, B. asbestinum has been chemically studied, with our group reporting eunicellin-based diterpenes with inhibitory activity on the production of nitric oxide (NO) induced by lipopolysaccharide (LPS) in macrophages [10]. The aim of this research was to reexamine a diterpene-rich fraction of B. asbestinum collected in Bocas del Toro, Panama.…”

“…Along the Caribbean coast of Panama, two species of Briareum have been reported, B. polyanthes and B. asbestinum. Of these, B. asbestinum has been chemically studied, with our group reporting eunicellin-based diterpenes with inhibitory activity on the production of nitric oxide (NO) induced by lipopolysaccharide (LPS) in macrophages [10]. The aim of this research was to reexamine a diterpene-rich fraction of B. asbestinum collected in Bocas del Toro, Panama.…”

Marine Pharmacology in 2012–2013: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis, and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

“…As shown in Table 2, and in contrast to the 20 marine compounds ( 115 – 134 ) with described anti-inflammatory mechanisms of action, for marine compounds ( 135 – 157 ), only anti-inflammatory activity, namely IC 50 , was reported, but the molecular mechanism of action remained undetermined: A. polyacanthus steroids ( 135 , 136 ) [137]; barettin ( 137 ) [138]; briarenolide F ( 138 ) [139]; diketopiperazine ( 139 ) [140]; 6- epi -cladieunicellin F ( 140 ) [141]; crassarosteroside A ( 141 ) [142]; cystodione A ( 142 ) [143]; densanins A and B ( 143 , 144 ) [144]; dissesterol ( 145 ) [145]; echinohalimane A ( 146 ) [146]; eunicidiol ( 147 ) [147]; flexibilisolide C ( 148 ) [148]; flexibilisquinone ( 149 ) [149]; lobocrassin F ( 150 ) [150]; perthamide J ( 151 ) [151]; pseudoalteromone A ( 152 ) [152]; sarcocrassocolide M ( 153 ) [153]; sclerosteroids K and M ( 154 , 155 ) [154]; seco-briarellinone ( 156 ) [155]; and sinularioside ( 157 ) [156]. …”