School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea.
College of Medicine, University of Ulsan, Seoul 05505, Korea.
Int J Mol Sci. 2018 Sep 6;19(9):2640. doi: 10.3390/ijms19092640.
Insect-associated bacteria have been recognized as a very promising natural resource for discovering bioactive secondary metabolites with diverse pharmacological effects. One new isoflavonoid glycoside, termisoflavone D (), together with seven known isoflavonoids (⁻), were identified from MeOH extracts of the fungus-growing termite-associated sp. RB1. The chemical structure of the new compound was elucidated using comprehensive spectroscopic methods including 1D and 2D NMR, along with LC/MS analysis. The existence of two rhamnose moieties in was determined with comparative NMR analysis, and the absolute configuration was elucidated using chemical reactions. The neuroprotective activities of compounds ⁻ were thoroughly investigated using the murine hippocampal HT22 cell line. Compound prevented glutamate-induced HT22 cell death by blocking intracellular reactive oxygen species (ROS) accumulation. The present study provides the first experimental evidence for the potential use of isoflavonoids from termite-associated bacteria as lead compounds that can prevent neuronal damage induced by glutamate.
昆虫相关细菌已被公认为是发现具有多种药理作用的生物活性次生代谢产物的极具前景的天然资源。从真菌培养的白蚁相关菌 RB1 的甲醇提取物中分离得到了一种新的异黄酮糖苷化合物 termisoflavone D (1) ，以及 7 种已知的异黄酮化合物 (2–8)。通过综合光谱方法（包括 1D 和 2D NMR 以及 LC/MS 分析）阐明了新化合物 1 的化学结构。通过比较 NMR 分析确定了 1 中存在两个鼠李糖部分，并用化学反应阐明了其绝对构型。使用鼠海马 HT22 细胞系对化合物 ⁻ 的神经保护活性进行了深入研究。化合物 1 通过阻断细胞内活性氧 (ROS) 积累来阻止谷氨酸诱导的 HT22 细胞死亡。本研究首次提供了实验证据，证明白蚁相关细菌中的异黄酮可用作预防谷氨酸诱导的神经元损伤的潜在先导化合物。
