Improvement of in vitro antioxidant activity of kaempferol by encapsulation in copolymer micelles

Antioxidant capacity of poorly soluble natural antioxidant kaempferol, in particular free or loaded in two types of cationic micelles, was studied on non-enzyme induced lipid peroxidation (LPO) in vitro. The micelles were based on triblock copolymers - poly(2-(dimethylamino)ethyl methacrylate-b-poly(propylene oxide)-b-poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA-PPO-PDMAEMA) and poly(2-(dimethylamino)ethyl methacrylate-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA-PCL-PDMAEMA). The lipid peroxidation was induced by incubating of rat liver microsomes with iron sulphate and ascorbic acid (Fe2+/AA). The effect of free and micellar kaempferol (at concentrations 25, 50 and 75 μg/ml) was assessed after 20 min incubation time. In the non-enzyme lipid peroxidation model, the kaempferol-loaded micelles significantly decreased the formation of malondialdehyde (MDA). The effect of kaempferol loaded in PDMAEMA-PCL-PDMAEMA micelles was more pronounced, showing an improved antioxidant activity in the conditions of oxidative stress and lipid peroxidation in vitro.

Synthesis of Lignosulfonate-Based Dispersants for Application in Concrete Formulations

Lignosulfonates (LS) are products from the sulfite pulping process that could be applied as renewable environmentally-friendly polymeric surfactants. Being widely used as plasticizers and water-reducing admixtures in concrete formulations LS compete in the market with petroleum-based superplasticizers, such as naphthalene sulfonate formaldehyde polycondensate (NSF) and copolymer polycarboxylate ethers (PCE). In this work, different chemical modification strategies were used to improve LS performance as dispersants for concrete formulations. One strategy consisted in increasing the molecular weight of LS through different approaches, such as laccase and polyoxometalate-mediated polymerization, glyoxalation, and reversible addition-fragmentation chain transfer (RAFT) polymerization. The other strategy consisted of preparing LS-based non-ionic polymeric dispersants using two different epoxidized oligomer derivatives of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). Modified LS were used to prepare cement pastes, which were examined for their fluidity. Results revealed that the most promising products are PPG-modified LS due to the introduction of PPG chains by reaction with phenolic moieties in LS. The enhanced dispersant efficiency of the ensuing products is probably related not only to electrostatic repulsion caused by the sulfonic ionizable groups in LS but also to steric hindrance phenomena due to the grafted bulky PPG chains.