Maydistacins A–G, Terpestacin-type Sesterterpenoids with Anti-inflammatory Activity from the Phytopathogenic Fungus <i>Bipolaris maydis</i>
Zhengyi Shi, Xueyan Duan, Feng‐Qing Wang, Zhangrong Hou, Fei Song, Lianghu Gu, Changxing Qi, Yonghui Zhang
Abstract
Seven undescribed terpestacin-type sesterterpenoids, maydistacins A–G ( 1 – 7 ), along with two known congeners ( 8 and 9 ), were isolated from the phytopathogenic fungus Bipolaris maydis collected from the leaves of Hypericum longistylum . The structures of 1 – 7 were elucidated based on extensive spectroscopic analysis, chemical methods, NMR calculations with DP4+ probability analysis, and comparison of experimental and calculated electronic circular dichroism (ECD) calculations. In vitro anti-inflammatory effects of these compounds were tested in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Compound 1 exhibited inhibition of the production of nitric oxide in LPS-induced macrophages, with an IC 50 value of 19 ± 2 μM. A dexamethasone control displayed an IC 50 value of 6.7 ± 0.6 μM. Compound 1 is the first terpestacin-type sesterterpenoid reported to display anti-inflammatory activity and may provide a novel chemical scaffold for the discovery of new anti-inflammatory drugs.