Linoleic acid was isolated effectively from Sambucus williamsii (SW) seed oil which was extracted by high-pressure fluid and its biological activities were investigated. Linoleic acid was isolated from the oil by urea inclusion, the yield was 65.81% and the purity was 92.12%. 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was used to determine the antioxidant activity of linoleic acid. IC 50 of DPPH radical scavenging activity of linoleic acid was 61.92 mg/mL. The antiglycemic activity of linoleic acid was evaluated by determining its inhibitory effect on α-glucosidase. The results showed that α-glucosidase was inhibited to a certain extent by linoleic acid (1.56-25 mg/mL). In addition, the hypolipidemic activity of linoleic acid was investigated in vivo using hyperlipidemia mice models fed with the linoleic acid at doses of 1, 2, 4 g/kg BW (body weight). The results showed that serum lipid levels were highly significantly (p < 0.01) improved, which indicated the hypolipidemic activity of linoleic acid. The linoleic acid extracted from SW seed oil was proved to possess good antioxidant, antiglycemic and hypolipidemic activity in human diets, which may have industrial use.
Lack of capacity to cross the nucleus membrane seems to be one of the main reasons for the lower transfection efficiency of gene vectors observed in vivo study than in vitro. To solve this problem, a new non-viral gene vector was designed. First, a degradable polyethylenimine (PEI) derivate was synthesized by crosslinking low-molecular-weight (LMW) PEI with N-octyl-N-quaternary chitosan (OTMCS), and then adopting a designed trifunctional peptide (RGDC-TAT-NLS) with good tumor targeting, cell uptake and nucleus transport capabilities to modify OTMCS-PEI. The new gene vector was termed as OTMCS-PEI-R18 and characterized in terms of its chemical structure and biophysical parameters. Gene transfection efficiency and nucleus transport mechanism of this vector were also evaluated. The polymer showed controlled degradation and remarkable buffer capabilities with the particle size around 100–300 nm and the zeta potential ranged from 5 mV to 40 mV. Agraose gel electrophoresis showed that OTMCS-PEI-R18 could effectively condensed plasmid DNA at a ratio of 1.0. Besides, the polymer was stable in the presence of sodium heparin and could resist digestion by DNase I at a concentration of 63U DNase I/DNA. OTMCS-PEI-R18 also showed much lower cytotoxicity and better transfection rates compared to polymers OTMCS-PEI-R13, OTMCS-PEI and PEI 25 KDa in vitro and in vivo. Furthermore, OTMCS-PEI-R18/DNA complexes could accumulate in the nucleus well soon and not rely on mitosis absolutely due to the newly incorporated ligand peptide NLS with the specific nuclear delivery pathway indicating that the gene delivery system OTMCS-PEI-R18 could reinforce gene transfection efficiency in vivo.
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