Supercritical fluid extraction (SFE) optimization of trans-resveratrol from peanut kernels (Arachis hypogaea) by experimental design.

The aim of this study was to develop the optimal conditions for supercritical fluid extraction (SFE) of bioactive trans-resveratrol from peanut kernels using an experimental design. The variables taken into account were extraction pressure, extraction temperature, extraction time and amount of modifier. The model was first set for significant factor screening by full factorial design, then, optimized by central composite designs. The optimal extraction parameters were a pressure of 7000 psi, temperature of 70 °C and time of 50 min while amount of modifier did not show significant effect. The quantity of trans-resveratrol was predictable by a full quadratic regression equation with R2(predict) = 95.56%. The predicted trans-resveratrol concentration in peanut samples was 0.7998 µg/g while the experimental concentration was 0.7884 ± 0.1553 µg/g. Conventional solvent extraction demonstrated less selectivity and needed more clean-up process prior to HPLC analysis. Our optimized SFE condition was effective to maximize trans-resveratrol extraction with less contaminants and gave the comparable amount of trans-resveratrol between actual and predicted values.

Optimization and comparison of GC-FID and HPLC-ELSD methods for determination of lauric acid, mono-, di-, and trilaurins in modified coconut oil.

Modified coconut oil (MCO) obtained from the glycerolysis of virgin coconut oil (VCO) and glycerol under various conditions should have different amounts of bioactive fatty acids (FAs) and acylglycerols (AGs). Methods were developed to analyze lauric acid (LA), monolaurin (ML), dilaurin (DL), and trilaurin (TL) in MCO samples using gas chromatography - flame ionization detector (GC-FID) and high performance liquid chromatography - evaporative light scattering detector (HPLC-ELSD). The purpose of this research is to optimize and compare GC-FID and HPLC-ELSD methods for determination of LA, ML, DL, and TL in MCO samples. All the standard curves exhibited good linearity (R2 ≥ 0.9995), except for that of LA analyzed by HPLC-ELSD (R2 = 0.9971). The limits of detection (LODs) and quantification (LOQs) were found to be in the range of 0.033-0.260 mg/ml and 0.099-0.789 mg/ml for the GC-FID method and 0.040-0.421 mg/ml and 0.122-1.277 mg/ml for the HPLC-ELSD method, respectively. The GC-FID method (LOD ≤ 0.033 mg/ml) was more sensitive than HPLC-ELSD method (LOD ≤ 0.421 mg/ml) and showed satisfactory recoveries for LA analysis while HPLC-ELSD method (LOD ≤ 0.040 mg/ml) was more sensitive than GC-FID method (LOD ≤ 0.260 mg/ml) and exhibited acceptable recoveries for TL analysis. Both methods were applied to determine the MCO samples produced under varied conditions for glycerolysis. The results revealed that the developed GC-FID method is suitable for the quantification of LA, ML, and DL while the developed HPLC-ELSD method is appropriate for the determination of ML, DL, and TL. Both developed GC-FID and HPLC-ELSD methods produced reproducible results for the determination of LA, ML, DL, and TL in MCO samples.

Incorporation of camptothecin into N-phthaloyl chitosan-g-mPEG self-assembly micellar system.

The capability of N-phthaloylchitosan-grafted poly (ethylene glycol) methyl ether (mPEG)(PLC-g-mPEG) to enhance the aqueous solubility and stability of the lactone form of camptothecin (CPT) was investigated. PLC-g-mPEG formed a core-shell micellar structure after dialysis of the polymer solutions in dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) against water, with a critical micelle concentration (CMC) of 28 microg/ml. CPT was loaded into the inner core of the micelles by dialysis method. The results showed an increase in the CPT-loading amount with an increasing concentration of CPT. The stability of drug-loaded micelles was studied by gel-permeation chromatography (GPC), and their in vitro release behaviors were analyzed. Release of CPT from the micelles was sustained. When compared to the unprotected CPT, CPT-loaded PLC-g-mPEG micelles were able to prevent the hydrolysis of the lactone group of the drug. The kinetics of the CPT hydrolysis in human serum albumin (HSA) and fetal bovine serum (FBS) were pseudo-first order. The hydrolysis rate constants for CPT and CPT-loaded PLC-g-mPEG micelles in phosphate-buffered saline (PBS) pH 7.4, were 7.4 x 10(-3) min(-1) and 9.1 x 10(-3) h(-1), parallel to an increase in half-life of CPT from 94 min to 76.15 h, respectively.

Conductivity detection for molecular mass estimation of per-O-sulfonated glycosaminoglycans separated by high-performance size-exclusion chromatography.

Chemically per-O-sulfonated polysaccharides, including glycosaminoglycans (GAGs) and hyaluronan oligosaccharides were analyzed using high-performance size-exclusion chromatography (HPSEC) with suppressed conductivity detection. The results were compared to those obtained by gel filtration HPLC using UV detection or fluorescence detection after the post-column reaction with 2-cyanoacetamide in strong alkaline solution. Analysis was performed on a TSKgel G3000SWXL HPSEC column in 5 mM boric acid (pH 7.0 adjusted by 10 mM NaOH). The use of conductivity detection, in the absence of any derivatization and under isocratic conditions gave a limit of detection in the picogram range. Preliminary studies suggest that this approach may be particularly useful in examining sulfonated polysaccharides and oligosaccharides having no UV chromophore, such as those prepared from O-sulfonated fucans and galactans isolated from algae.

Effect of (1-->3)- and (1-->4)-linkages of fully sulfated polysaccharides on their anticoagulant activity.

Chemically fully sulfated polysaccharides including xylan (-->4Xylbeta-(1-->4)Xylbeta1-->), amylose (-->4Glcalpha-(1-->4)Glcalpha1-->), cellulose (-->4Glcbeta-(1-->4)Glcbeta1-->), curdlan (-->3Glcbeta-(1-->3)Glcbeta1-->) and galactan (-->3Galbeta-(1-->3)Galbeta1-->), which have been isolated from Korean clam, were prepared, and their anticoagulant activity was investigated. The results strongly suggest that the activity might not be depending on anomeric configuration (alpha or beta) or monosaccharide species but on the glycosidic linkage, either (1-->3) or (1-->4). 1H NMR studies of these modified polysaccharides show that the neighboring sulfate groups at the C-2 and C-3 positions might have caused the conformational changes of each monosaccharide from 4C(1) to 1C(4). Furthermore, the effect of 6-sulfate residues on the anticoagulant activity was investigated using a specific desulfated reaction for the chemically fully sulfated polysaccharides. The 6-sulfate group is very important in determining anticoagulant activity of (1-->3)-linked polysaccharides, whereas the activity is not affected by presence or absence of the 6-sulfate group in (1-->4)-linked polysaccharides.