Organic anion transporter 3 (OAT3)-mediated transport of dicaffeoylquinic acids and prediction of potential drug-drug interaction.

Dicaffeoylquinic acids (DCQAs) are widely distributed in daily food and herb medicine (such as Dengzhanxiyin injection) with multiple health benefits and pharmacological activities. However, drug-drug Interactions (DDIs) between DCQAs and possible concomitant drugs were not fully understood in clinic. The purpose of present study was to investigate the role of organic anion transporters (OATs) in the transport of DCQAs and to explore the potential clinical DDIs using in vitro transporter assays. Uptake study using hOAT1/hOAT3-transfected HEK293 cells revealed that none of DCQAs was OAT1 substrate, while 3,4-DCQA, 3,5-DCQA, and 4,5-DCQA were substrates of OAT3 with Km values of 119.7 ± 28.8, 269.3 ± 129.5 and 53.2 ± 32.1 μM, respectively. The docking analysis revealed that 3,4-DCQA, 3,5-DCQA, and 4,5-DCQA were effectively embedded in the active site of OAT3 and fitted well with the cavity in three-dimensional space. Moreover, the classical substrates/inhibitors of OAT decreased the accumulation of 3,4-DCQA, 3,5-DCQA, and 4,5-DCQA in kidney slices, suggesting potential DDI risks with co-administration of substrate drugs of OAT. In fact, antivirals, antibiotics, neuroprotective agents, and PPIs (proton pump inhibitors) all showed varying degrees of inhibition of OAT3-mediated uptake of 3,4-DCQA, 3,5-DCQA, and 4,5-DCQA in vitro. For cefaclor, ceftizoxime, pantoprazole, and zidovudine, in particular, their IC₅₀ values were <10 times the maximal free plasma concentration, indicating potential clinically relevant DDIs when used together with DCQAs. These findings provided useful information for the prediction of DDIs between DCQAs and OAT3 inhibitors, and rational application of herbal medicines containing DCQAs in clinic.