Abstract

Antioxidant polyphenols nepetoidin A and B are widely spread in Lamiaceae family yet often remain undetected due to their purported instability and poor extractability with polar solvents typically used for phenolics extraction. Coextraction of nepetoidins may confer additional, or enhance existing, bioactivities of polyphenol extracts. This study includes a detailed analysis of nepetoidin extractability from sweet basil (Ocimum basilicum L.) leaves, and a survey of their occurrence in basil tissue cultures and peltate trichomes. Coextraction of nepetoidins with the major polyphenol rosmarinic acid was possible with solvent mixtures, yet substantially less efficient than that with the respective preferred solvents. Nepetoidin, but not rosmarinic acid levels in extracts from dried leaves were dramatically reduced. However, this was not due to degradation suggested by earlier reports, but to reduced extractability, which could be restored by wetting the tissue with water prior to addition of nonpolar solvent. Nepetoidins were found to accumulate at high levels in basil callus and suspension cultures. Correlation analysis revealed three novel compounds that are coextracted with nepetoidins and are proposed to represent nepetoidin dimers. Candidate signals for nepetoidin and rosmarinic acid glycosides were also detected in dedifferentiated basil cells. By contrast, nepetoidins were not enriched in basil peltate trichomes. This study establishes optimized recovery procedure for nepetoidins, reports their production by dedifferentiated basil cells, and illustrates how sample preparation methodology affects the phytochemical findings.

中文翻译：

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荆芥叶和细胞培养物中荆芥苷的提取能力，稳定性和积累

摘要

抗氧化剂多酚荆芥肽A和B在唇形科中广泛分布，但由于据称不稳定且通常用于酚类提取的极性溶剂的提取性差而常常未被发现。荆芥苷的共提取可以赋予多酚提取物更多的生物活性，或增强其现有的生物活性。这项研究包括从甜罗勒（Ocimum basilicum）中提取荆芥苷的详细分析。L.）叶子，并调查它们在罗勒组织培养物中和有毛的毛状体中的发生情况。荆芥苷与主要的多酚迷迭香酸的共萃取在混合溶剂中是可行的，但其效率远不及在各自优选的溶剂中。荆芥苷，但没有降低干叶提取物中的迷迭香酸水平。但是，这不是由于早期报道建议的降解，而是由于降低的可萃取性，可通过在添加非极性溶剂之前用水润湿组织来恢复可萃取性。发现荆芥苷在罗勒愈伤组织和悬浮培养物中高水平积累。相关性分析显示了与荆芥苷共提取的三种新型化合物，并被提出代表荆芥苷二聚体。在去分化的罗勒细胞中也检测到了荆芥苷和迷迭香酸糖苷的候选信号。相比之下，荆芥苷不富含罗勒叶甲的毛状体。这项研究建立了荆芥苷的最佳回收程序，报告了去分化罗勒细胞的产生，并说明了样品制备方法如何影响植物化学结果。