A polyamidoamine-mediated competitive colorimetric assay based on gold nanoparticles for determining acid values in edible sunflower seed, corn and extra virgin olive oils.

We synthesized polyamidoamine (PAMAM) dendrimers and citrate-capped gold nanoparticles (AuNPs), and explored the applicability of the PAMAM/AuNP assay in determining total free fatty acid (FFA) contents in edible oils based on a competitive colorimetry, in which the PAMAM-triggered AuNP aggregation was suppressed by FFAs. The generation and concentration of PAMAMs, the chain lengths of FFAs as well as the concentration and pH of the background electrolytes of the assay were optimized. The average acid values of the sunflower seed, corn and extra virgin olive oils determined by PAMAM/AuNP assay were 1.31 ±â€¯0.07, 0.33 ±â€¯0.02 and 1.49 ±â€¯0.07, respectively, which were not significantly different from the corresponding 1.27 ±â€¯0.08, 0.32 ±â€¯0.01 and 1.61 ±â€¯0.06 by the standard nonaqueous titration. Our results suggest that the method is promising in detecting FFAs in edible oils, and implementation of the method expands the technological scope for FFA analysis.

Grape seed procyanidin B2 ameliorates hepatic lipid metabolism disorders in db/db mice.

Diabetes is commonly associated with liver lipid metabolism disorders. AMP-activated protein kinase (AMPK) has a key role in regulating lipid metabolism. Grape seed procyanidin B2 (GSPB2), a natural polyphenol polymer, ameliorates mitochondrial dysfunction and inhibits oxidative stress or apoptosis via AMPK pathways. In the present study, the hypothesis that GSPB2 treatment may ameliorate liver lipid metabolic disorders by activating AMPK and downstream pathways was tested in diabetic mice. Db/m mice were used as controls, and diabetic db/db mice were randomly divided into 2 groups for treatment: Vehicle and GSPB2 (30 mg/kg/day for 10 weeks). Animals were weighed every week. Fasting blood was collected prior to sacrifice to measure fasting blood glucose (FBG), triglycerides (TG) and total cholesterol (TC). Hepatic TG and free fatty acid (FFA) levels were analyzed. Hepatic sections were examined by light microscopy following hematoxylin and eosin staining. The expression of hepatic AMPK, phosphorylated acetyl­CoA carboxylase (ACC), carnitine palmitoyl transferase 1 (CPT1) and 4­hydroxynonenal (4­HNE) was measured by western blot analysis. Liver mitochondria were isolated to assess electron transport complex I (CI), complex II (CII) and complex IV by high-resolution respirometry. The results demonstrated that GSPB2 significantly decreased body weight and serum TG, TC and FFA levels, but not FBG levels in diabetic mice. GSPB2 visibly decreased lipid droplet accumulation in the liver and significantly reduced hepatic TG and FFA levels. In diabetic mice, GSPB2 restored liver AMPK and ACC phosphorylation, increased CPT1 protein expression, ameliorated lipid peroxidation damage, which was assessed by comparing 4­HNE levels, and partially restored the damaged mitochondrial respiratory capacity of CI and CII in the liver. In conclusion, long­term oral treatment with GSPB2 may benefit hepatic lipid metabolism disorders, potentially by decreasing hepatic lipid synthesis and increasing hepatic FFA ß­oxidation via the AMPK­ACC pathway.

Combination of running-buffer-mediated extraction and polyamidoamine-dendrimer-assisted capillary electrophoresis for rapid and sensitive determination of free fatty acids in edible oils.

A method was developed for determining free fatty acids in edible plant oils by incorporation of running-buffer-mediated liquid-liquid extraction and polyamidoamine-dendrimer-assisted capillary electrophoresis-capacitively coupled contactless conductivity detection. The recoveries for the extraction were in the range of 90.1% and 110.3%. Addition of dendrimer to the running buffer improved the separation of fatty acids. Under the optimized buffer conditions, i.e., 3 mM pelargonic acid, 39 mM tris(hydroxymethyl)aminomethane, 30 mM polyoxyethylene 23 lauryl ether, 35% acetonitrile, 15% 2-propanol, 2.5% 1-octanol, and 300 µM polyamidoamine generation 2 at apparent pH 8.53, the 10 model fatty acids were separated in 18 min with detection limits ranging from 0.46 to 3.28 µM. The successful determination of fatty acids in real samples suggests that the method is simple, cost-effective, and easy to operate and is suitable for scanning free fatty acid in edible plant oils.

Quick and sensitive determination of flavonoids by capillary electrophoresis-potential gradient detection.

A capillary electrophoresis (CE)-potential gradient detection (PGD) method was developed for quick and sensitive determinations of puerarin, farrerol and baicalin. The flavonoids were baseline separated in 1.9 min with a buffer comprised of 20 mM tris(hydroxymethyl)aminomethane (Tris) and 3 mM HCl at pH 8.69. The analysis time is, to the best of our knowledge, the shortest for the CE analysis of flavonoids. The association constants, determined by affinity CE, suggested an ion-dipole or ion-induced dipole interaction between Tris and flavonoid molecules. The detection limits, in the range of 0.068 and 0.116 mg L(-1), were lower than the early reported UV and chemiluminescence detection techniques. A solvent-extraction method was coupled to CE to determine baicalin in a Chinese herbal preparation Scutellaria Baicalensis Georgi. The concentration of baicalin in the sample was determined to be 5.1%. Validation of the method suggested its applicability in real sample analysis.