School of Pharmaceutical Sciences, Zhejiang University, Zijingang Campus, No. 866 Yuhangtang Rd, Hangzhou 310058, PR China.
Fitoterapia. 2012 Dec;83(8):1506-13. doi: 10.1016/j.fitote.2012.08.018. Epub 2012 Sep 1.
In the present study, it was demonstrated that the petroleum extract of Andrographis paniculata (AP) had quinone reductase (QR) inducing activity, which might be attributed to the modification of key cysteine residues in Keap1 by Michael addition acceptors (MAAs) in it. To screen MAAs in AP, glutathione (GSH) was employed, and a LC/MS/MS method was implied. Three compounds, andrographoside, andrographolide, 14-deoxy-14,15-dehydroandrographolide were revealed could well conjugated with GSH. Then, andrographolide along with 4 new and 14 known compounds were isolated to conduct QR induction evaluation, and the CD (the concentration required to double the activity of QR) value of andrographolide is 1.43μM. The QR induce activity of andrographolide might be attributed to its targeting multiple cysteine residues in Keap1, therefore, the alkylation of Keap1 by andrographolide was further studied and the result showed that four cysteine residues: Cys77, Cys151, Cys273 and Cys368 were alkylated, which indicated that Keap1 is a potential target for the QR induce activity of andrographolide.
在本研究中，已证实穿心莲的石油提取物（AP）具有醌还原酶（QR）诱导活性，这可能归因于其中的 Michael 加成受体（MAAs）修饰了 Keap1 中的关键半胱氨酸残基。为了筛选 AP 中的 MAAs，采用了谷胱甘肽（GSH），并应用了 LC/MS/MS 方法。结果表明，三种化合物，穿心莲苷、穿心莲内酯和 14-去氧-14,15-脱水穿心莲内酯能够与 GSH 很好地结合。然后，分离出穿心莲内酯以及 4 种新化合物和 14 种已知化合物，以进行 QR 诱导评估，穿心莲内酯的 CD（使 QR 活性增加一倍所需的浓度）值为 1.43μM。穿心莲内酯的 QR 诱导活性可能归因于其靶向 Keap1 中的多个半胱氨酸残基，因此，进一步研究了穿心莲内酯对 Keap1 的烷基化作用，结果表明，四个半胱氨酸残基：Cys77、Cys151、Cys273 和 Cys368 被烷基化，表明 Keap1 是穿心莲内酯 QR 诱导活性的潜在靶标。
