Interactions of the major effective components in Shengmai formula with breast cancer resistance protein at the cellular and vesicular levels.

Shengmai Formula (SMF) is one of the traditional Chinese medicine representative formulas and is widely used for the treatment of cardio- and cerebrovascular disease. Previous studies demonstrated that the major effective ingredients in SMF can interact with each other based on some uptake transporters. However, the role of the efflux transporter breast cancer resistance protein (BCRP) in these interactions involving SMF remains unclear. The purpose of this study was to investigate the interactions of the major active components of SMF with BCRP and the compatibility mechanism of these complex components in SMF based on BCRP. We selected 4 main fractions, including ginseng total saponins (GTS), ophiopogon total saponins (OTS), ophiopogon total flavonoids (OTF), and fructus schisandrae total lignans (STL), and 12 bioactive components, including ginsenosides Re, Rd, Rb1, and Rg1, ophiopogonins D and D', methylophiopogonanones A and B, schizandrins A and B, and schizandrols A and B to explore the interactions of SMF with BCRP in LLC-PK1 and LLC-PK1/BCRP cells and BCRP membrane vesicles. The results showed that ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A can be transported by BCRP into LLC-PK1/BCRP cells. Schisandrol B exhibited a markedly inhibitory effect on the transport function of BCRP and can significantly inhibit the uptake of methylophiopogonanone B and schizandrin A into LLC-PK1/BCRP cells. In "Inside-Out" BCRP membrane vesicles, BCRP mediated the transport of ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A, with K values of 111.9 ± 31.26 μM, 82.01 ± 16.72 μM, 57.06 ± 8.789 μM, and 37.19 ± 6.512 μM, respectively. GTS, STL, ginsenosides Rd and Rb1, and schisandrol B were potent inhibitors of BCRP and showed different degrees of inhibition on the transport of ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A via BCRP. In conclusion, GTS, STL, ginsenosides Rd and Rb1, and schizandrol B are potential inhibitors of BCRP. Ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A are potential substrates of BCRP, and their transport, which is mediated by BCRP, may be inhibited by potential inhibitors in SMF. There are potential interactions of these main effective components of SMF at the cellular and vesicular levels that are mediated by BCRP. The interplay of these bioactive components based on BCRP may be an important compatibility mechanism in SMF.