Chromene stability: The most potent estrogenic compounds in White Kwao Krua (Pueraria candollei var mirifica) crude extract

• A new method for simultaneous determine the chromenes in crude extract of PM.
• The chromenes were unstable at higher temperature.
• The chromenes were less stable in alkaline environment than in acidic environment.
• The extract should store as solid form at lower temperature.

Pueraria candollei var. mirifica (PM) is a phytoestrogen-rich herb with rejuvenating qualities. Stability of chromenes, comprising deoxymiroestrol, miroestrol and isomiroestrol, in crude extract of PM was investigated. The effects of acid-base condition and temperature on stability of the chromene standard solution and the PM crude extract were analysed using gradient HPLC. The degradation of the chromenes in the extract was sensitive to high temperatures and strongly acidic or alkaline solutions. Specifically, deoxymiroestrol, which exhibited the highest estrogenic activity, can be easy degraded to miroestrol or isomiroestrol. However, chromene standard solution was stable in ethanol after storage for 360 days at 25 °C. The crude extract of PM in the solid form was stable when stored at −20 or 4 °C for 360 days. Therefore, the extract could be stored in the solid form at low temperatures. This method provides a system to simultaneously identify chromenes in crude extract of PM.

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