Guar gum-enhanced emission of gold nanoclusters for α-glucosidase activity detection and anti-diabetic agents screening in plant extracts.

The development of efficient fluorescent methods for α-glucosidase (α-Glu) detection and α-Glu inhibitor screening plays a critical role in the therapy of type 2 diabetes (T2D). Herein, guar gum (GG), a high-abundant and non-toxic natural polymer originated from the seeds of a drought-tolerant plant, Cyamposis tetragonolobus, was found to be able to enhance the fluorescence emission of gold nanoclusters (AuNCs) probe. The emission enhancement effect was achieved by using GG at very low concentrations (<1.0 wt%) and presented in a viscosity-dependent manner through increasing solvent reorientation time and inhibiting intramolecular motions of AuNCs. Furthermore, the enhanced emission of the AuNCs was quenched by Fe3+via dynamic quenching and then restored by α-Glu. Accordingly, a fluorimetric method was proposed for the determination of α-Glu. Owing to the fluorescence enhancement effect of GG on the AuNCs probe, the detection limit of the approach was 0.13 U L-1 and the detection range was up to 5 orders of magnitude from 0.2 to 4000 U L-1, which was much better than most current α-Glu detection methods. The approach was further applied to α-Glu inhibitors screening from natural plant extracts, providing great prospects for the prevention and treatment of T2D.

A narrative review of the protective effects of curcumin in treating ischemia-reperfusion injury.

Background and Objective: Ischemia-reperfusion (IR) injury is the cause of morbidity and mortality in a variety of diseases and surgical procedures including organ transplantation surgeries, acute coronary syndrome, strokes, and limb injuries. IR injury causes dysfunction of tissues and organs, and oxidative stress plays an important role in driving this process. Curcumin (CUR), a polyphenolic compound derived from turmeric, protects against IR injury by alleviating oxidative stress, reactive oxygen species (ROS) inflammation, apoptosis, and fibrosis. We review the protective effects of CUR against IR. Methods: We searched PubMed, ScienceDirect, and Web of Science databases using the keywords: ischemic reperfusion, CUR and summarized the results. Key Content and Findings: The effects of CUR during IR have been reported for animal models in vitro and in vivo and the compound has been shown in various organs by suppression of oxidative stress, prevention of inflammation, inhibition of apoptosis and autophagy. CUR with nanocarriers showed many advantages than free CUR in the treatment of IR injury, such as improved bioavailability, sustained-release, better water solubility, better target organ accumulation, improved permeability across the blood-brain-barrier and more effective. Conclusions: Nanotechnology offers significant improvements and promising strategies to improve drug delivery to IR-injured tissues and achieve the desired protective effects. Thus, it is necessary to promote further clinical trials to promote the clinical application of CUR with nanocarriers.

An LC-MS/MS method for simultaneous determination of four flavonoids from Semen Oroxyli in rat plasma and its application to a pharmacokinetic study.

Semen Oroxyli, a Traditional Chinese Medicine, has many significant pharmacological activities such as analgesic, apoptotic, anti-inflammatory, anticancer, and immunostimulant activities. A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantitation of four flavonoids (oroxin A, oroxin B, baicalin, and chrysin) of Semen Oroxyli in rat plasma. After the addition of internal standard, plasma samples were pretreated with acetonitrile via a single-step protein precipitation. Chromatographic separation was performed on a Capcell Pak C18 column (100 mm × 2.0 mm, 5 µm particles) with isocratic elution using a mobile phase of methanol and 2mM ammonium acetate buffer solution (75:25, v/v) at a flow rate of 0.45 mL/min. The analytes were detected without interference in the selection reaction monitoring mode with negative electrospray ionization. The validated method exhibited good linearity over a wide concentration range (r ≥ 0.9958), and the lower limits of quantification were 1.0-5.5 ng/mL for all the analytes. The mean extraction recoveries of the analytes from rat plasma exceeded 80.6%. The intra- and inter-day precisions at three QC levels were both less than 11.5%, and the accuracies ranged from -6.2% to 10.3%. The LC-MS/MS method was successfully applied to a pharmacokinetic study of the four flavonoids in rat plasma after oral administration of Semen Oroxyli extract.

Development and validation of an LC-MS/MS method for the determination of bullatine A in rat plasma: application to a pharmacokinetic study.

Bullatine A is a diterpenoid alkaloid of Xue-Shang-Yi-Zhi-Hao (Aconitum brachypodum), which is widely used in traditional Chinese medicine for the treatment of rheumatism and pain. The plasma levels of bullatine A were measured by a rapid and sensitive LC-MS/MS method. Samples were prepared using acetonitrile precipitation and the separation of bullatine A was achieved on a Capcell Pak MG-C18 column by isocratic elution using acetonitrile (phase A) and 0.1% formic acid (phase B, pH 4.0; A:B, 30:70, v/v) as the mobile phase at a flow rate of 0.5 mL/min. Detection was performed on a triple-quadrupole tandem mass spectrometer by multiple-reaction monitoring of the transitions at m/z 344.2 → 105.2 for bullatine A and m/z 256.2 → 167.1 for the internal standard. The linearity was found to be within the concentration range of 1.32-440 ng/mL with a lower limit of quantification of 1.32 ng/mL. Only 1.3 min was needed for an each analytical run. This method was successfully applied in the determination of the active component bullatine A in rat plasma after intramuscular administration of A. brachypodum injection.

Simultaneous determination of sesquiterpene lactones isoalantolactone and alantolactone isomers in rat plasma by liquid chromatography with tandem mass spectrometry: application to a pharmacokinetic study.

A selective, sensitive, and accurate LC-MS/MS method for the simultaneous determination of isoalantolactone and alantolactone in rat plasma has been developed using psoralen as the internal standard. LC-MS/MS analysis was carried out on a Triple Quadrupole mass spectrometer using positive ion ESI and the selected reaction monitoring mode. The assays were linear in the range of 7.5-750 ng/mL for isoalantolactone and 5.5-550 ng/mL for alantolactone. The average recoveries in plasma samples both were better than 85%. The intra- and inter-day precision and accuracy values were found to be within the assay variability criteria limits according to the US FDA guidelines. The method was successfully applied to pharmacokinetic studies of the two structural isomers after an intravenous injection of Inula helenium formulation to rats.