Pressurized liquid extraction followed by high-performance liquid chromatography for determination of beta-ecdysone extracted from Pfaffia glomerata (Spreng.) Pedersen.

Pfaffia glomerata (Spreng.) Pedersen has among its main bioactive compounds saponins, with the phytoestroid ß-ecdysone as its chemical marker. In this study, pressurized liquid extraction (PLE), a green extraction technique used to obtain bioactive compounds from plants, was employed to extract beta-ecdysone from P. glomerata leaves, stems, and roots. The 22 factorial design was used with the variables temperature (333 K and 353 K) and flow rate (1.5 and 2 mL min-1), pressure (300 Bar), time (60 min), and solvent [ethanol and distilled water (70:30 (v/v)] were kept constant for all parts of the plant. The results of experimental responses demonstrated that the factors temperature and flow rate significantly interfere with the yields of leaf (0.499%), root (0.65%) and stem (0.764%) extracts. The latter presented presents the highest yield compared to the other parts of the plant. HPLC results showed the presence of beta-ecdysone in all parts of the plant with concentrations of ß-ecdysone 86.82, 76.53 and 195.86 mg L-1 to leaf, root and stem, respectively. FT Raman results exhibited typical peaks of beta-ecdysone, such as 3310 cm-1, 1654 cm-1, and 1073 cm-1 for all plant parts. Another interesting result was the presence of the peak at 1460 cm-1 in the PLE root extract can be associated with selenium. This foundational knowledge confirms that the PLE extraction process was efficient in obtaining the chemical marker of Pfaffia glomerata in all plant parts.

Gold nanoparticles capped with polysaccharides extracted from pineapple gum: Evaluation of their hemocompatibility and electrochemical sensing properties.

In the present work, gold nanoparticles were synthesized through a green route by using, for the first time, polysaccharides extracted from pineapple gum (PG) as the reducing and capping agent. The obtained nanoparticles (AuNPs-PG) were characterized by UV-VIS, FTIR, TEM, FESEM, EDX, XRD, and zeta potential measurements, which confirmed that PG was effective to produce AuNPs with an average diameter of 10.3 ± 1.6 nm. The AuNPs-PG were employed as the modifier of glassy carbon paste electrodes (CPE/AuNPs-PG), which were applied as sensitive electrochemical sensors to the determination of the antihistamine drug promethazine hydrochloride (PMZ). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements showed that the AuNPs-PG could enhance the electronic transfer properties of the glassy carbon paste, which was due to their large surface area and high electrical conductivity. After optimization of the instrumental parameters of square wave voltammetry (SWV) through a Box-Behnken factorial design, a linear relationship between the anodic peak current and PMZ concentration was obtained in the range from 2.0 to 15.7 µmol L-1 in McIlvaine buffer solution pH 5.0. The detection and quantification limits were found to be equal to 1.33 and 4.44 µmol L-1, respectively. The developed sensors could successfully quantify PMZ in different commercial pharmaceutical formulations, with satisfactory levels of accuracy and precision. In addition to improving the analytical features of the electrodes, hemocompatibility assays carried out on erythrocytes and leukocytes showed that the AuNPs-PG do not exhibit toxic effects on the referred cells. This interesting behavior enables their use in biocompatible electrochemical sensing platforms as well as for future biomedical investigations.

Label-free impedimetric immunosensor based on arginine-functionalized gold nanoparticles for detection of DHEAS, a biomarker of pediatric adrenocortical carcinoma.

Pediatric adrenocortical carcinoma (pACC) is a rare and aggressive malignancy of high occurrence in Southern Brazil. pACC is characterized by the usual overproduction of dehydroepiandrosterone sulfate (DHEAS), whose detection in serum or plasma can be effective to the early diagnosis of the disease. Therefore, the present paper reports, for the first time, the construction and application of a label-free impedimetric immunosensor to detect DHEAS, which was based on the modification of an oxidized glassy carbon electrode with arginine-functionalized gold nanoparticles (AuNPs-ARG) and anti-DHEA IgM antibodies (ox-GCE/AuNPs-ARG/IgM). AuNPs-ARG was synthesized by a green route, and characterized by UV-VIS spectroscopy, FTIR, TEM, DLS, and XRD. The construction of ox-GCE/AuNPs-ARG/IgM was optimized through factorial design and response surface methodology. Cyclic voltammetry and electrochemical impedance spectroscopy measurements were employed to characterize the optimized immunosensor. The DHEAS detection principle was based on the variation of charge transfer resistance (∆Rct) relative to the Fe(CN)64-/3- electrochemical probe after immunoassays in the presence of the biomarker. A linear relationship between ∆Rct and DHEAS concentration was verified in the range from 10.0 to 110.0 µg dL-1, with a LOD of 7.4 µg dL-1. Besides the good sensitivity, the immunosensor displayed accuracy, stability, and specificity to detect DHEAS. The promising analytical performance of ox-GCE/AuNPs-ARG/IgM was confirmed by quantifying DHEAS in real patient plasma samples, with results that were comparable to the reference chemiluminescence assay. Our results suggest that the presented immunosensor can find clinical applications in the early diagnosis of pACC and to monitor DHEAS levels in other adrenal pathologies.