Non-targeted screening of illegal added hypoglycemic drugs and their derivatives in functional foods using characteristic fragment ions scanning based on liquid chromatography-high-resolution mass spectrometry

Functional foods that are illegally adulterated with chemical hypoglycemic drugs or their derivatives pose serious risks to human health. However, the detection of these compounds is a challenge due to the unknown nature of their structures, particularly as many of these compounds are newly synthesized and lack standardized references. In this study, we developed a non-targeted screening strategy for detecting illegally added hypoglycemic drugs and their derivatives in oral solution and hard capsule functional foods. This strategy utilizes a self-established characteristic fragment ions mass spectrum database based on ultrahigh-performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry. Nine characteristic fragment ions were identified by analyzing the mass spectrometric fragmentation patterns of hypoglycemic drugs. Meanwhile, the precursor and fragment ions of 38 known hypoglycemic drugs were collected and incorporated into the mass database. The detection limits of hypoglycemic drugs in oral solution and hard capsule samples were 0.01-10 μg/L and 0.01-50 μg/kg, respectively. Applying the non-targeted method to 20 batches of suspicious samples, we found that 3 batches of samples contained illegal added drugs. Furthermore, we identified a previously unrecorded hypoglycemic drug not present in the mass database. These results indicate that the developed strategy is a powerful tool for the rapid and highly sensitive identification of both known and unknown hypoglycemic drugs, as well as their derivatives in functional foods.

Determination of Chemical Stability of Two Oral Antidiabetics, Metformin and Repaglinide in the Solid State and Solutions Using LC-UV, LC-MS, and FT-IR Methods

Firstly, metformin and repaglinide were degraded under high temperature/humidity, UV/VIS light, in different pH and oxidative conditions. Secondly, a new validated LC-UV method was examined, as to whether it validly determined these drugs in the presence of their degradation products and whether it is suitable for estimating degradation kinetics. Finally, the respective LC-MS method was used to identify the degradation products. In addition, using FT-IR method, the stability of metformin and repaglinide was scrutinized in the presence of polyvinylpyrrolidone (PVP), mannitol, magnesium stearate, and lactose. Significant degradation of metformin, following the first order kinetics, was observed in alkaline medium. In the case of repaglinide, the most significant and quickest degradation, following the first order kinetics, was observed in acidic and oxidative media (0.1 M HCl and 3% H₂O₂). Two new degradation products of metformin and nine new degradation products of repaglinide were detected and identified when the stressed samples were examined by our LC-MS method. What is more, the presence of PVP, mannitol, and magnesium stearate proved to affect the stability of metformin, while repaglinide stability was affected in the presence of PVP and magnesium stearate.

Application of salting-out thin layer chromatography in computational prediction of minimum inhibitory concentration and blood-brain barrier penetration of some selected fluoroquinolones

The 2017 FDA safety review regarding the CNS (central nervous system) side effects associated with the systemic use of fluoroquinolones antibacterials (FQs) was the key motivation to carry out this work. The main objective of this study is to investigate lipophilicity and retention parameters of some selected fluoroquinolones antibacterials (FQs) namely; levofloxacin (LEV), ofloxacin (OFL), gatifloxacin (GAT), norfloxacin (NOR), sparfloxacin (SPA), ciprofloxacin (CIP) and lomefloxacin (LOM) using salting-out thin layer chromatography (SOTLC). Statistically significant correlations between the chromatographically-obtained retention parameters and experimental log P values were found and expressed as quantitative structure retention relationship (QSRR) equations. Principal component analysis was carried out to explain the variation between chromatographic and both experimental and computed lipophilicity parameters. In another aspect of this study, a comparison between the chromatographically-determined retention parameters (for five of the drugs under study) obtained using SOTLC (current study) and relative lipophilicity (R_M0) determined using a previously reported RP (reversed-phase)-TLC method was carried out. Statistically significant correlation between the two methods was found, although R_M0 values obtained using SOTLC was lower than those reported using RP-TLC. Multiple linear regression analysis was performed to predict MIC (minimum inhibitory concentration) and blood brain barrier (BBB) penetration of the examined drugs in which efficient QSAR (quantitative structure-activity relationship) and QSPR (quantitative structure-property relationship) models were generated using the calculated chromatographic parameters (R_M0 and C₀). The described models can provide a useful approach to predict MIC and BBB penetration of newly synthesized FQs targeting to increase their activity against Gram-positive organisms and to minimize the associated CNS side effects.