Sinucrassins A—K, Casbane‐type Diterpenoids from the South China Sea Soft Coral Sinularia crassa

Abstract

Main observation and conclusion A detailed chemical study on the Hainan soft coral Sinularia crass has resulted in the isolation and characterization of eleven casbane‐type diterpenoids, named sinucrassins A—K (1—11), along with six known related ones (12—17). Their structures were elucidated by extensive spectroscopic analyses and comparison with the reported data. The absolute configurations of new compounds were determined by the X‐ray diffraction analysis and computer‐assisted structural elucidation including 13C NMR data calculation and time‐dependent density functional theory/electronic circular dichroism calculation.

Marine natural products

“…547 Of six new examples of diterpene glycosides 1226-1231 isolated from Lemnalia bournei, the former two compounds exhibited weak antibacterial activity towards S. aureus and Bacillus subtilis. 548 Several groups reported new examples of casbane-or cabane-related diterpenoids, including sinucrassins A-K 1232-1242 isolated from Sinularia crassa, 549 sinuereperoxides B 1243 and C 1244, 5-deoxy-10-oxo-11,12-dihydrodepressin 1245 and sinueracasbanones A-D 1246-1249 from S. erecta, 550 and two sets of casbane-related and casbanediterpenoids from S. nanolobata (1250-1252), 551 and S. erecta (1253-1255), respectively. 552 XRD was used to characterise the structures and assign absolute conguration of a number of these new MNPs (1243-1255) as well as the previously reported casbane 10-oxo-11,12-dihydrodepressin 1256.…”

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

“…The procedure of the extraction and isolation in a manner was similar to our previous report [16]. The frozen animals (351.6 g, dry weight) were cut into pieces and extracted exhaustively with acetone at room temperature (3 × 3.0 L, 20 min in an ultrasonic bath).…”

“…As part of our ongoing research on discovering chemically and biologically interesting metabolites from Chinese marine invertebrates [12][13][14][15][16], the soft coral Sinularia sp. were collected off the Ximao Island, Hainan Province, China.…”

Uncommon Capnosane Diterpenes with Neuroprotective Potential from South China Sea Soft Coral Sarcophyton boettgeri

“…The head-to-tail cyclization of a geranylgeranyl diphosphate (GGPP) is considered to generate a 14-membered marcocyclic carbon framework named cembrane [ 9 ]. Initiated by the 1,14-cyclisation of a GGPP precursor, the following bond formations of cembrane lead to a range of polycyclic diterpenes with diverse scaffolds, including 1,2-cyclized casbanes [ 10 ], 2,11-cyclized eunicellins [ 11 ], 3,7-cyclized capnosanes [ 12 , 13 ], and 2,20-cyclized sarsolenanes [ 12 , 13 ], as well as the newly discovered carbocyclic skeletons [ 14 , 15 ]. Additionally, the bond cleavages of cembrane afford an array of norcembranoids [ 16 , 17 ] and seco-cembranes [ 18 , 19 ].…”