Removal of tramadol from water using Typha angustifolia and Hordeum vulgare as biological models: Possible interaction with other pollutants in short-term uptake experiments

Tramadol (TRD) is widely detected in aquatic ecosystems as a result of massive abuse and insufficient removal from wastewater facilities. As a result, TRD can contaminate groundwater sources and/or agricultural soils. While TRD toxicity has been reported from aquatic biota, data about TRD detection in plants are scarce. Moreover, information regarding plant capability for TRD removal is lacking. To understand the fate of this opioid, we have investigated the uptake, translocation and removal capacity of TRD by plants, addressing short-term and long-term uptake. The uptake rates of TRD, in excised barley and cattail roots, were 5.18 and 5.79 μg g⁻¹ root fresh weight day⁻¹, respectively. However, TRD uptake was strongly inhibited after co-exposing these roots either with the drug venlafaxine (similar molecular structure as TRD) or with quinidine (an inhibitor of cellular organic cation transporters). When barley seedlings were exposed to TRD in a hydroponic experiment a removal efficiency up to 90% (within 15 days) was obtained, with bioconcentration and translocation factors close to 9 and 1, respectively. The combination of results from both plants and the inhibition observed after treatment with quinidine revealed that organic cation transporters may be involved in the uptake of TRD by plants.