N propylbenzene

Pharmaceutical herbal formula powder Yin-Chen-Hao-Tang (YCHT) was purchased from Koda Pharmaceutical Co., Ltd., (Taoyuan, Taiwan). Artemisia capillaris Thunb., Gardenia jasminoides J.Ellis, and Rheum officinale Baill were made from the crude drug at a ratio of 18:6:6 with an extract of 6.0 g (crude drug and extract ratio 30:6 = 5:1), according to the pharmaceutical company’s instructions. Diuretic spironolactone was purchased from Sigma‒Aldrich Research Biochemicals, Inc., (St. Louis, MO, United States). The pharmaceutical herbal formula powder YCHT was quantified using a UHPLC–MS/MS analysis system coupled to an electrospray ionization (ESI) source equipped with a triple quadrupole mass spectrometer (LCMS-8030 system; Shimadzu, Kyoto, Japan) to guarantee consistent quality of the herbal formula powder, which contained .207 mg/g of scoparone, 7.241 mg/g of geniposide, and .093 mg/g of rhein (Hsueh et al., 2016 (link)). The metabolite of spironolactone canrenone (purity ≥97%) and the internal standard n-propylbenzene for urinary pharmacokinetic analysis were both obtained from Sigma‒Aldrich Inc., (St. Louis, MO, United States). Other chemicals for analysis, including formic acid (98%–100%) and ethanol, were of analytical grade and purchased from Merck (Darmstadt, Germany).

A reference standard of spironolactone was purchased from Research Biochemicals International. Canrenone (purity ≥97%) and the internal standard n-propylbenzene were obtained from Sigma-Aldrich Inc. All chemicals were of analytical grade, including formic acid (98–100%) and ethanol, which were purchased from E. Merck. The pharmaceutical herbal powder formula Yin-Chen-Hao-Tang was purchased from Kaiser Pharmaceutical Co., Ltd. and was quantified by a Shimadzu UHPLC system coupled to an electrospray ionization (ESI) source equipped with an LCMS-8030 triple quadrupole mass spectrometer to guarantee the consistent quality of the herbal formula powder [33 ].