Study of a complex secondary metabolites with potent anti-radical activity by two dimensional TLC/HPLC coupled to electrospray ionization time-of-flight mass spectrometry and bioautography

Development of a thin-layer chromatography bioautographic assay for neuraminidase inhibitors hyphenated with electrostatic field induced spray ionisation-mass spectrometry for identification of active Isatis indigotica root compounds

The identification of neuraminidase inhibitors from natural products is a promising strategy in the field of anti-influenza research. In this study, a new thin-layer chromatography (TLC) bioautographic assay for the screening of neuraminidase inhibitors from natural products was developed. This TLC bioassay is based on the one-step reaction of neuraminidase with the sodium salt of 5‑bromo‑4‑chloro‑3-indolyl-α-d-N-acetylneuraminic acid (substrate) and the subsequent formation of blue coloured products. Neuraminidase inhibitory activity was shown by the development of white spots against the blue TLC background. The key factors affecting the assay (such as enzyme concentration, substrate concentration, incubation time, reaction time, and pH) were investigated and optimised by a combination of a one-factor-at-a-time design and a Box-Behnken design/response surface method. The developed TLC bioautographic method was applied to identify neuraminidase inhibitory compounds in the roots of Isatis indigotica. Eleven active compounds including six alkaloids, three lignans, one sterol, and one fatty acid were identified in situ by direct coupling with an electrostatic field induced spray ionisation-mass spectrometry approach through analysis of their MSⁿ (n = 4) data or comparison with reference substances. The developed TLC bioautographic assay is simple, rapid, and efficient for screening potential neuraminidase inhibitors from natural products.

Simultaneous determination of 14 bioactive citrus flavonoids using thin-layer chromatography combined with surface enhanced Raman spectroscopy

Citrus flavonoids consist of diverse analogs and possess various health-promoting effects dramatically depending on their chemical structures. Since different flavonoids usually co-exist in real samples, it's necessary to develop rapid and efficient methods for simultaneous determination of multiple flavonoids. Thin layer chromatography combined with surface enhanced Raman spectroscopy (TLC-SERS) was established to simultaneously separate and detect 14 citrus flavonoids for the first time. These target compounds could be characterized and discriminated when paired with SERS at 6-500 times greater the sensitivity than TLC alone. TLC-SERS exhibited high recovery rates (91.5-121.7%) with relative standard deviation lower than 20.8%. Moreover, the established TLC-SERS method was successfully used to simultaneously detect multiple flavonoids in real samples, which exhibited comparable accuracy to high performance liquid chromatography with shorter analytical time (10 vs 45 min). All the results demonstrated that this could be a promising method for simultaneous, rapid, sensitive and accurate detection of flavonoids.

Determination of Progestin Residues in Fish by UPLC-Q-TOF/MS Coupled with QuEChERS

A novel method was developed for simultaneous determination of 10 progestin residues in fish by ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) combined with a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The homogenized samples were dispersed by water, extracted with acetonitrile, and then purified by QuEChERS reagent. The concentrated analytes were detected by UPLC-Q-TOF/MS. High linearities (R ² > 0.995) and recoveries (85.71-117.08%) at three spiked levels (5, 10, and 20 ng/g) and low relative standard deviation values (<8.83%, n = 7) and limits of detection (0.23-0.66 ng/g) were obtained. This method is simple, rapid, reliable, sensitive, and efficient and can be used for monitoring of progestin residues in fish. This method provides a strong guarantee to deal with food emergencies for the laboratory, provides technical support for the screening and quantitative detection of progesterone in fish, and provides technical support for the food safety of aquatic products.

Recent Trends in Potential Therapeutic Applications of the Dietary Flavonoid Didymin

Didymin (isosakuranetin 7-O-rutinoside) is an orally bioactive dietary flavonoid glycoside first found in citrus fruits. Traditionally, this flavonoid has long been used in Asian countries as a dietary antioxidant. Recent studies have provided newer insights into this pleiotropic compound, which could regulate multiple biological activities of many important signaling molecules in health and disease. Emerging data also presented the potential therapeutic application of dietary flavonoid glycoside didymin against cancer, neurological diseases, liver diseases, cardiovascular diseases, and other diseases. In this review, we briefly introduce the source and extraction methods of didymin, and summarize its potential therapeutic application in the treatment of various diseases, with an emphasis on molecular targets and mechanism that contributes to the observed therapeutic effects. The dietary flavonoid didymin can be used to affect health and disease with multiple therapeutic targets, and it is anticipated that this review will stimulate the future development of this potential dietary medicine.