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蓝刺头是治疗骨质疏松的传统蒙药,其所含的有效成分不明确是限制其现代化、国际化发展的关键因素.传统活性物质筛选策略费时费力,本研究采用在线HPLC-自由基清除检测-ESI-IT-TOF-MS“技术对蓝刺头中有效成分进行筛选,实现分离、鉴定、活性筛选一体化.此外,该技术还有助于阐明活性成分间的构效关系.由于骨质疏松发病过程与氧化应激有关,因此本研究主要针对蓝刺头中抗氧化成分进行筛选,通过DPPH等效法确定其中抗氧化活性最高的成分.该策略不仅能够筛选、鉴定出蓝刺头中抗氧化活性成分,还能够评价这些成分的构效关系.最终,蓝刺头中20个成分(包括芹菜素葡萄糖苷、咖啡酸、双咖啡酰奎尼酸、双咖啡酰奎尼酸甲酯等)被准确鉴定,其中18种成分具有抗氧化活性.通过研究14种蓝刺头中分离所得的化合物发现各物质氧化活性与以下结构特点有关:(1)有酚羟基的成分具有抗氧化活性;(2)酚羟基的数目并不能影响抗氧化活性的强弱,但咖啡酰基的数目会影响抗氧化剂的活性;(3)咖啡酰基在奎宁酸上的取代位置对DPPH活性有较大影响;(4)甲氧基可降低其抗氧化活性.综上所述,该研究以生化视角将蓝刺头中的活性化合物与其抗骨质疏松作用联系起来,为进一步阐释蓝刺头如何在骨质疏松症中发挥作用提供依据.”,"Echinops latifolius Tausch(ELT)is the traditional Mongolian medicine for the treatment of osteoporosis,and the ambiguous composition of active ingredients is an important factor in restricting the modernization and globalization of this herb.Considering the traditional activity screening strategy is time-consuming and labor intensive,online HPLC active ingredient detection coupled with ESI-IT-TOF-MSn strategy was employed in this study to isolate,identify and screen active compounds from the herbal medicines at the same time.The structure-activity relationship of these compounds was elucidated as well.Owing to the association of osteoporosis progression and oxidative stress,the antioxidants screening from ELT could be a good interpretive of the active substance in this herb.Meanwhile,DPPH equivalent method was an indicative of the most powerful antioxidant in ELT.Consequently,the screening and identification of the antioxidants in ELT was performed by using on-line HPLC-radical scavenging detection coupled with ESI-IT-TOF-MSn strategy,and the structure-activity relationship was investigated based on DPPH equivalent method.Finally,20 constituents(including apigenin glucosides,caffeic acid,biscaffeoylquinic acids,biscaffeoylquinic acid methyl esters,ect.)were characterized in ELT extracts,and 18 components showed appreciable radical scavenging capacity.In addition,the structure-activity relationship study was carried out based on 14 compounds isolated from our laboratory,and the structural requirements of the compounds on antioxidant activity were obtained:(1)compounds with phenolic hydroxyl groups could have antioxidant activity;(2)the antioxidant activity could not be facilitated by the number of hydroxyl groups,but affected by the number of caffeoyl groups;(3)the substitution position of caffeoyl on quinic acid had a greater influence on DPPH activity;(4)methoxy groups could reduce the antioxidant activity.Collectively,this work provided the biochemical perspective to link active compounds and anti-osteoporosis action of ELT,and further explained how ELT worked in osteoporosis patients with bone loss.