Carboxymethyl flavonoids and a chromone with antimicrobial activity from Selaginella moellendorffii Hieron

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• 作者：ZhenXing Zou^a ; ^b ; PingSheng Xu^b ; CanRong Wu^c ; WeiXing Zhu^a ; GangZhi Zhu^d ; XiaoAi He^d ; GuoGang Zhang^b ; JianZhong Hu^b ; Shao Liu^b ; Wei Zeng^b ; KangPing Xu^a ; ^{xukp395@csu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; GuiShan Tan^a ; ^b ;
• 关键词：Selaginella ; Selaginella moellendorffii Hieron ; Carboxymethyl flavonoids ; Antibacterial activity
• 刊名：Fitoterapia
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：111
• 期：Complete
• 页码：124-129
• 全文大小：714 K

文摘

Five new carboxymethyl flavonoids named 5-carboxymethyl-3′, 4′, 7-trihydroxyflavone (1), (2S)- 5-carboxymethyl-3′, 4′, 7-trihydroxyflavonone (2a), (2R)-5-carboxymethyl-3′, 4′, 7-trihydroxyflavonone (2b), (2S)-5-carboxymethyl-4′, 7-dihydroxyflavonone (3), 5- carbomethoxymethyl-4′, 7-dihydroxyflavone (4), and a new chromone named 5-carboxymethyl-7-hydroxychromone (5), together with two known compounds 5-carboxymethyl-4′-hydroxyflavone-7-O-β-d-glucopyranoside (6), 5-carboxymethyl-4′, 7-dihydroxyflavone (7) were isolated from Selaginella moellendorffii Hieron. Their structures including absolute configuration were elucidated by extensive spectroscopic methods and experimental electronic circular dichroism (ECD) spectra. What's worth mentioning is that a carboxymethyl substituent appeared at the C-5 position of all isolated compounds, only recently discovered in genus Selaginella. Compounds 2a and 2b were identified as a pair of chiral isomers; compound 5 was discovered as the first chromone comprising a carboxymethyl side chain. Furthermore, all compounds were evaluated for their antibacterial activities against various Gram-positives and Gram-negatives, and compared to the reference drugs amoxicillin and norfloxacin. As a result, compounds 3 and 4 exhibited as potent antimicrobial agents with a broad spectrum, and compound 5 appeared as the most promising one to combat Gram-positives.