Protoflavones are unique natural flavonoids with a non-aromatic B-ring, known for their potent antitumor properties. However, their cytotoxicity represents a strong limitation in the further exploration of their pharmacological potential. In the current study, we sought to selectively saturate the p-quinol B-ring of protoapigenone and that of its 1'-O-butyl ether, in order to obtain non-toxic protoflavone analogues expressing the dihydro- or tetrahydroprotoflavone structure also occurring in nature. The benefits of a strictly controlled continuous-flow environment in combination with on-demand electrolytic H2 gas generation were exploited to suppress undesired side reactions and to safely and selectively yield the desired substances. The obtained tetrahydroprotoflavones were free of the cytotoxicity of their parent compounds, and, even though tetrahydroprotoapigenone 1-O-butyl ether showed a weak inhibition of DNA damage response through Chk1, neither compounds influenced the cytotoxicity of doxorubicin either.

中文翻译：

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通过类黄酮B环的选择性连续流加氢合成无毒原黄酮衍生物。

原黄酮是具有非芳香族B环的独特天然黄酮类化合物，以其强大的抗肿瘤特性而闻名。然而，它们的细胞毒性在进一步探索其药理潜力方面表现出强烈的局限性。在当前的研究中，我们试图选择性地使原芹菜酮及其1'-O-丁基醚的对喹啉B环饱和，以获得表达二氢或四氢原黄酮结构的无毒原黄酮类似物。自然。开发了严格控制的连续流环境与按需生成电解氢气的优点，可抑制不希望的副反应并安全，选择性地产生所需物质。所获得的四氢原黄酮没有其母体化合物的细胞毒性，并且