Title
Compositacins A–K: Bioactive chamigrane-type halosesquiterpenoids from the red alga Laurencia composita Yamada
Author
Xiao-Qing Yu, Chang-Sheng Jiang, Yi Zhang, Pan Sun, Tibor Kurtán, Attila Mándi, Xiao-Lu Li, Li-Gong Yao, Ai-Hong Liu, Bin Wang, Yue-Wei Guo, Shui-Chun Mao
Year
2017
Journal
Phytochemistry
Abstract
Eleven highly halogenated chamigrane sesquiterpenoids, compositacins A–K, including one unusual rearranged chamigrane sesquiterpenoid, compositacin A, were isolated from the red alga Laurencia composita Yamada, along with seven known structural analogues. Compositacins B and D are the first examples of chamigranes bearing an ether bridge involving C-5/C-9 and C-3/C-5, respectively, while compositacins B and C represent the first chamigranes with a C-10 carbonyl group. Their structures were elucidated on the basis of extensive spectroscopic analysis. The absolute configuration of compositacin B was determined by ECD calculation, whereas the absolute configurations of compositacins A and C–L were proposed on biosynthetic grounds by comparison to compositacin B and the related known sesquiterpenoids johnstonol and yicterpene A. We also suggest that the structure of the previously reported sesquiterpenoid laurokamin A should be revised. Cytotoxicity and antifungal activity of these isolates were also investigated. The results showed that compositacin G exhibited good antifungal activity against Microsporum gypseum (Cmccfmza) with a MIC80 value of 4 μg/mL relative to positive controls. Four of the chamigrane halosesquiterpenoids showed marginal cytotoxicity against the A-549 human lung adenocarcinoma cell line with IC50 values ranging from 48.6 to 85.2 μM.
Instrument
J-810
Keywords
Circular dichroism, Absolute configuration, Natural products, Pharmaceutical