Deborah Michel

HPLC-MS/MS analysis of anthocyanins in human plasma and urine using protein precipitation and dilute-and-shoot sample preparation methods, respectively

A high-performance liquid chromatography tandem-mass spectrometry (HPLC-MS/MS) method has been developed to analyze anthocyanins in urine and plasma to further understand their absorption, distribution, metabolism and excretion. The method employed a Synergi RP-Max column (250 × 4.6 mm, 4 μm) and an API 4000 mass spectrometer. A gradient elution system consisted of mobile phase A (water-1% formic acid) and mobile phase B (acetonitrile) with a flow rate of 0.60 mL/min. The gradient was initiated at 5% B, increased to 21% B at 20 min, and then increased to 40% B at 35 min. The analysis of anthocyanins presents a challenge because of the poor stability of anthocyanins during sample preparation, especially during solvent evaporation. In this method, the degradation of anthocyanins was minimized using protein precipitation and dilute-and-shoot and sample preparation methods for plasma and urine, respectively. No interferences were observed from endogenous compounds. The method has been used to analyze anthocyanin concentrations in urine and plasma samples from volunteers administered saskatoon berries. Cyanidin-3-galactoside, cyanidin-3-glucoside, cyanidin-3-arabinoside, cyanidin-3-xyloside and quercetin-3-galactoside, the five major flavonoid components in saskatoon berries, were identified in plasma and urine samples.

Molecular Engineering as an Approach To Modulate Gene Delivery Efficiency of Peptide-Modified Gemini Surfactants

The unique molecular structure confers the diquaternary ammonium gemini surfactants with enhanced nucleic acid complexation ability, bottom-up design flexibility, and relatively low cytotoxicity. To capitalize on their potential as gene delivery vectors, novel structural modifications should be explored. In this work, 22 novel peptide-modified gemini surfactants with various alkyl tails and peptide spacer modifications were evaluated. This work represents the first report of dendrimer-like gemini surfactants and first evaluation of the impact of incorporating a hydrocarbon linker into the peptide chain. Our aim was to establish a structure activity relationship of the peptide-modified gemini surfactants and to identify the fundamental architectural requirements needed for the ultimate gene delivery systems. In vitro assessment revealed that the highest transfection efficiency and lowest cytotoxicity were associated with the glycyl-lysine modified gemini surfactants having the hexadecyl tail, 16-7N(G-K)-16. In fact, it showed an 8-fold increase in secreted protein with 20% increase in cell viability relative to the first-generation unsubstituted gemini surfactants. Further increase in the size of the attached peptides resulted in a decrease in the transfection efficiency and cell viability. Whereas the incorporation of a hydrocarbon linker into the peptide chain decreased the transfection efficiency of compounds with dipeptides, it increased the transfection efficiency of compounds with larger peptide chains. Such an increase was more prominent with the incorporation of a longer hydrocarbon linker. We conclude that a balance between the hydrophilic and hydrophobic characteristics of the compound is necessary since it results in physicochemical parameters conducive to the gene delivery process.

Evaluating the Anticancer Activity of Hedyotis diffusa Water Extract Against Human Breast Cancer MCF7 Cells

Hedyotis diffusa has been used to treat cancers in traditional Chinese medicine for many years. Recently, sev- eral anthraquinone compounds were extracted from Hedyotis diffusa and identified as its anticancer ingredients. These compounds are able to induce apoptosis in several types of cancer cells. In this study, we showed that the anticancer activ- ity of Hedyotis diffusa was highly selective, possessing high cytotoxicity towards human breast cancer MCF7 cells but almost no cytotoxicity against the mammary epithelial MCF12A cells. The Hedyotis diffusa water extract also elevated the energy metabolism in both MCF12A and MCF7 cells; but the ATP/ADP ratio was still maintained at about 1.0 in the MCF12A cells to avoid either apoptosis or uncontrolled proliferation. In addition, Sheshecaojing, a health product of He- dyotis diffusa marketed in China, gave a dose-dependent cytotoxic response against the MCF7 cells.