Is rhamnolipid biosurfactant useful in cadmium phytoextraction?

Purpose: Successful chelant-assisted phytoextraction requires application of an eco-friendly metal-complexing agent which enhances metal uptake but does not pose a significant risk of off-site movement of metals. Rhamnolipid biosurfactant has been used to enhance cadmium (Cd) removal from contaminated soil by washing. It has a strong affinity for Cd compared to some other hazardous metals, suggesting that rhamnolipid could be useful in Cd phytoextraction. This study investigated the potential use of rhamnolipid to enhance Cd phytoextraction. Materials and methods: Adsorption patterns of rhamnolipid in soils were investigated by batch adsorption experiments. Hydrophobicity of rhamnolipid–metal complexes were determined by assessing partitioning in an octanol/water system. Phytotoxicity of rhamnolipid to maize (Zea mays) and chelant-assisted phytoextraction efficiency of maize and sunflower (Helianthus annuus) were determined in pot experiments. Results and discussion: The results showed that rhamnolipid was prone to adsorb strongly to soil at low application rates (0.1–1.7 mM) possibly due to its hydrophobic interactions with soil organic matter, hence reducing its capacity to complex and transport metals to plant roots. Rhamnolipid mobility increased (i.e. decreased soil phase partitioning) at elevated concentrations (∼4.4 mM), which increased soil solution Cd concentrations possibly due to its reduced hydrophobic nature. The use of rhamnolipid at concentrations >4.4 mM severely reduced maize biomass yield, reducing the potential for chelantassisted phytoextraction. At lower concentrations of rhamnolipid (0.02–1.4 mmol/kg), there was insignificant enhancement of Cd accumulation by plant (Z. mays and H. annuus) shoots, likely through strong retention of the chelant (or Cd-associated rhamnolipid) on soil surfaces. Conclusions: High rates of rhamnolipid addition to soils in this study caused severe phytotoxicity to maize and sunflower. Lower rates of rhamnolpid addition to soils in this study did not improve Cd accumulation by plants. Therefore, the sorption of rhamnolipid (or Cd-associated rhamnolipid) to soils, along with the phytotoxicity and phytoextraction results, suggests that neither low nor high concentrations of rhamnolipid are likely to consistently assist Cd phytoextraction using maize or sunflower.Jia Wen, Mike J. McLaughlin, Samuel P. Stacey and Jason K. Kirb

Pregabalin antagonizes copper-induced toxicity in the brain: in vitro and in vivo studies.

Copper plays key roles in brain metabolism. Disorders of copper metabolism impact on neural signaling. The intracellular and extracellular concentrations of copper are tightly regulated. Pregabalin is a drug with multiple modes of action and has a high-affinity binding site for the alpha2delta subunit of voltage-gated calcium channels.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe