Suppressive effect of the hot-water extract of Ficus pseudopalma Blanco leaves on the postprandial increase in blood glucose level in mice.

The use of medicinal plants with anti-diabetic properties continues because of the high cost of diabetes mellitus treatment. In the Bicol region of the Philippines, one local source is the leaves of Ficus pseudopalma Blanco (Philippine fig), which is utilized as an ingredient of their cuisine, and the decoction of its leaves is believed to have a blood-glucose lowering effect. The aim of this study was to evaluate the blood-glucose lowering effect of F. pseudoplama using sugar/carbohydrate-loaded and normoglycemic mice. The results showed that the hot-water extract of the leaves significantly suppressed the increase of blood glucose levels after glucose, maltose and starch loading. On the other hand, the extract did not show any hypoglycemic activity in either fasted or non-fasted mice as compared to the positive control drugs. These results suggest that F. pseudopalma is potentially useful for the management of blood glucose levels in the postprandial condition, as believed in the Bicol region of the Philippines.

PVK/MWNT electrodeposited conjugated polymer network nanocomposite films.

The facile preparation of poly (N-vinyl carbazole) (PVK) and multiwalled carbon nanotubes (MWNTs) solution and conjugated polymer network (CPN) nanocomposite film is described. The stable solutions of PVK/MWNT were prepared in mixed solvents by simple sonication method, which enabled successful deaggregation of the MWNTs with the polymer matrix. MWNT was most effectively dissolved in N-cyclohexyl-2-pyrrolidone (CHP) compared to other solvents like N-methyl pyrrolidone (NMP), dimethyl formamide, and dimethyl sulfoxide (DMSO). The composite solution was relatively stable for months with no observable precipitation of the MWNTs. Thermogravimmetric analysis (TGA) revealed the thermal stability of the nanocomposite while the differential scanning calorimetry (DSC) showed an increasing melting (T(m)) and glass transition (T(g)) temperatures as the fraction of the MWNTs in the nanocomposite was increased. Cyclic voltammetry (CV) allowed the electrodeposition of the nanocomposite film on indium tin oxide (ITO) substrates and subsequent cross-linking of the carbazole pendant group of the PVK to form CPN films. Ultraviolet-visible (UV-vis), fluorescence, and Fourier transform infrared (FTIR) confirmed film composition while atomic force microscopy (AFM) revealed its surface morphology. Four-point probe measurements revealed an increase in the electrical conductivity of the CPN nanocomposite film as the composition of the MWNTs was increased: 5.53 × 10(-4) (3% MWNTs), 0.53 (5%), and 1.79 S cm(-1) (7%). Finally, the interfacial charge transfer resistance and ion transport on the CPN nanocomposite film was analyzed by electrochemical impedance spectroscopy (EIS) with a measured real impedance value of ∼48.10 Ω for the 97% PVK and 3% MWNT ratio of the CPN nanocomposite film.

Biomimetic piezoelectric quartz sensor for caffeine based on a molecularly imprinted polymer.

A piezoelectric quartz sensor coated with molecularly imprinted polymer (MIP) for caffeine was developed. The MIP was prepared by co-polymerizing methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) in the presence of azobis(isobutyronitrile) as initiator, caffeine as template molecule, and chloroform as solvent. The MIP suspension in polyvinyl chloride/tetrahydrofuran (6:2:1 w/w/v) solution was spin coated onto the surface of the electrode of a 10 MHz AT-cut quartz crystal. The sensor exhibited a linear relationship between the frequency shift and caffeine concentration in the range of 1 x 10(-7) mg mL(-1 )up to 1 x 10(-3) mg mL(-1) [correlation coefficient ( r)=0.9935] in a stopped flow measurement mode. It has a sensitivity of about 24 Hz/ln(concentration, mg mL(-1)). A steady-state response was achieved in less than 10 min. The performance characteristic of the sensor shows a promising and inexpensive alternative method of detecting caffeine. Surface studies were carried out for the reagent phase of the sensor using SEM, AFM, and XPS analysis in order to elucidate the imprinting of the caffeine molecule. The SEM micrograph, AFM image, and XPS spectra confirmed the removal of caffeine by Soxhlet extraction in the imprinting process and the rebinding of caffeine to the MIP sensing layer during measurement.