Investigation of new products and reaction kinetics for myricetin in DMEM via an in situ UPLC–MS–MS analysis

Abstract Myricetin, with its pyrogallol B‐ring, is evidently instable in DMEM (Dulbecco's modified Eagle's) medium at 37°C. However, the underlying mechanism of this instability is not clear yet. Herein, the reaction products of myricetin in DMEM were investigated via an in situ UPLC–MS–MS analysis. Myricetin was mixed with prewarmed DMEM in an autosampler screw top vial for UPLC. Immediately, a 50‐µl sample was automatically injected every 50 min. Myricetin was highly stable in dimethyl sulfoxide (DMSO) when kept at 37°C for 2 weeks. Myricetin was very unstable in DMEM at 37°C and largely converted to new products A ( m / z = 635.07) and B ( m / z = 633.05) within 1 min. Another new product, C ( m / z = 469.04), was detected after the fourth injection (150 min). Myricetin was much more stable in DMEM at 4°C as compared to 37°C. There was a minor conversion of myricetin to the new product A ( m / z = 635.07) within 1.0 min, but it subsequently increased until the sixth injection (250 min), and disappeared after the fifteenth injection (700 min). In summary, myricetin first formed a dimer A ( m / z = 635.07) and then was oxidized to B ( m / z = 633.05), which was finally degraded to C ( m / z = 469.04) in DMEM. This process was significantly affected by the temperature, and low temperature is helpful to detect the unstable products.