Two new germacrane sesquiterpenoids from the inflorescences of Mikania micrantha

• Published in: Phytochemistry letters Vol. 54; pp. 141 - 145
• Main Authors: Lou, Tao, Xu, Qiao-Lin, Tan, Yu-Ling, Liu, Shao-Bo, Zhang, Shan-Xuan, Zeng, Ying, Jiang, Feng-Qiang, Tan, Jian-Wen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2023
• Subjects: Antibacterial activity; Germacrane; Inflorescence; Mikania micrantha; Sesquiterpenoid; Germacrane; Antibacterial activity; Mikania micrantha; Inflorescence; Sesquiterpenoid
• ISSN: 1874-3900; 1876-7486
• DOI: 10.1016/j.phytol.2023.02.010

Two new germacrane sesquiterpenoids, 3β-hydroxyl-11β,13-dihydrodeoxymikanolide (1) and 2β,3β-dihydroxyl-13-methoxy-11β,13-dihydrodeoxymikanolide (2), together with four known ones (3–6) were isolated from the inflorescences of Mikania micrantha. Their structures were elucidated on the basis of extensive spectroscopic analysis including 1D, 2D NMR and MS techniques. All the compounds were obtained from the inflorescences of M. micrantha for the first time. These compounds were tested for their in vitro antibacterial activity against Gram-positive bacteria of Staphyloccocus aureus, methicillin-resistant Staphylococcus aureus, Bacillus cereus and Bacillus subtilis, and the Gram-negative bacterium of Escherichia coli. Compounds 5 and 6 were found to show strong or moderate in vitro antibacterial activity toward all the tested bacteria with MIC values ranging from 6.25 to 12.5 µg/mL. [Display omitted] •Two new germacrane sesquiterpenoids (1 and 2) were isolated from inflorescences of Mikania micrantha.•Four known compounds (3−6) were also obtained from M. micrantha for the first time.•The structures of the isolated compounds were elucidated by spectroscopic means.•Compounds 5 and 6 showed strong or moderate in vitro antibacterial activity.