School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming China.
School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China.
Phytomedicine. 2021 Feb;82:153445. doi: 10.1016/j.phymed.2020.153445. Epub 2020 Dec 25.
SiO nanoparticles (nm SiO) are ubiquitous in daily life and are acknowledged to be detrimental to human health. Bletilla striata is a traditional medicine used for generations in China and its polysaccharide has the anti-pulmonary fibrosis effect.
To investigate the lung protective effect of the small molecules (n-BuOH extract) of B. striata and clarify the underlying mechanism.
C57BL/6 mice were subjected to intratracheal instillation with nm SiO nanoparticle suspension (7 mg/kg) to construct the in vivo model of nm SiO-induced lung injury. The chemical profile of the n-BuOH extract of B. striata was investigated by HPLC analysis using authentic samples isolated from B. striata. Gymnoside II with the most potent chemoprotective capacity in the n-BuOH extract was used to clarify the potential bio-active molecular basis of the n-BuOH extract using in vitro experiments. The cytotoxicity, apoptosis, oxidative stress, and the Nrf2 signaling pathway were examined in SiO-induced A549 cells. ML385 was adopted to down-regulate the Nrf2 expression.
The n-BuOH extract of B. striata (40 mg/kg) could alleviate the SiO-induced lung injury by increasing Nrf2 expression and thereby suppressing Bax/Bcl-2 pathway in the nm SiO-induced mice model. The chemical profile study showed that militarine, gymnoside II, and 4-allyl-2, 6-dimethoxyphenol glucoside were the main constituents of n-BuOH extract. Studies on gymnoside II revealed that it could partially restore the SiO-induced decline in cell viability while did not affect the growth of normal A549 cells within the concentration range of 1-50 μM, suggesting a protective effect against nm SiO in lung A549 cells. The hoechst 33258 staining, flow cytometry, and western blot experiments demonstrated that gymnoside II (25 μM) could partially reverse the SiO-induced cell apoptosis and ROS production by enhancing Nrf2, HO-1, and γ-GCSc expressions and Nrf2 silencing by ML385 abrogated the effects of gymnoside II (25 μM) on apoptosis and ROS production in A549 cells.
The present study suggests that in addition to the polysaccharide, small molecules (n-BuOH extract) of B. striata can also elicit a protective effect on lung injuries through the Nrf2-dependent mechanism and gymnoside II is one of the main bio-active constituents contributing to the n-BuOH extract-elicited lung protective effect against nm SiO.
SiO 纳米粒子（nmSiO）在日常生活中无处不在，已被确认对人类健康有害。白芨是一种在中国世代使用的传统药物，其多糖具有抗肺纤维化作用。
研究白芨小分子（正丁醇提取物）的肺保护作用，并阐明其潜在机制。
用 nmSiO 纳米颗粒悬浮液（7mg/kg）气管内滴注 C57BL/6 小鼠，构建 nmSiO 诱导的肺损伤体内模型。采用高效液相色谱法（HPLC）结合从白芨中分离得到的对照品对白芨正丁醇提取物的化学成分进行分析。采用 Gymnoside II 进行体外实验，研究正丁醇提取物中最具化学保护能力的潜在生物活性分子基础。检测 SiO 诱导的 A549 细胞中的细胞毒性、细胞凋亡、氧化应激和 Nrf2 信号通路。采用 ML385 下调 Nrf2 表达。
白芨正丁醇提取物（40mg/kg）可通过增加 Nrf2 表达，从而抑制 nmSiO 诱导的小鼠模型中的 Bax/Bcl-2 通路，缓解 SiO 诱导的肺损伤。化学成分研究表明，绵马素、苷元 II 和 4-烯丙基-2,6-二甲氧基苯酚葡萄糖苷是正丁醇提取物的主要成分。苷元 II 的研究表明，它可以部分恢复 SiO 诱导的细胞活力下降，而在 1-50μM 的浓度范围内不影响正常 A549 细胞的生长，提示对肺 A549 细胞中的 nmSiO 具有保护作用。吖啶橙染色、流式细胞术和 Western blot 实验表明，苷元 II（25μM）可部分逆转 SiO 诱导的细胞凋亡和 ROS 产生，增强 Nrf2、HO-1 和γ-GCSc 的表达，而 ML385 沉默 Nrf2 则消除了苷元 II（25μM）对 A549 细胞凋亡和 ROS 产生的作用。
本研究表明，除多糖外，白芨小分子（正丁醇提取物）还可以通过 Nrf2 依赖性机制对肺损伤产生保护作用，苷元 II 是导致正丁醇提取物对 nmSiO 诱导的肺损伤具有保护作用的主要生物活性成分之一。
