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Type 2 diabetes mellitus (T2DM) has become a major disease threatening human health worldwide. At present, the treatment of T2DM cannot cure diabetes and is prone to many side effects. Psidium guajava L. leaves have been reported to possess hypoglycemic activity, and they have been widely used in diabetes treatment in the folk. However, the antidiabetic mechanism has not been clearly explained. Also, the change in amino acid profile can reflect a metabolic disorder and provide insights into system-wide changes in response to physiological challenges or disease processes. The study found that P. guajava L. leaves can decrease fasting blood glucose and lipid levels in type 2 diabetic rats induced by streptozotocin. Through the analysis of amino acid profiling following 20 days of gavage administration, the concentration data were modeled by principal component analysis and orthogonal partial least squares discriminant analysis to find the different metabolites and related metabolic pathways (including cysteine and methionine metabolism, valine, leucine, and isoleucine biosynthesis, phenylalanine, tyrosine, and tryptophan biosynthesis) for the explanation of the hypoglycemic mechanism of P. guajava L., which provides an experimental and theoretical basis for diabetes prediction and for the development of new drugs for the treatment of diabetes.

Dispersive liquid–liquid microextraction (DLLME) based on Fe3O4 magnetic nanoparticle-assisted in situ ionic liquid was developed as a novel method for the pretreatment of pyrethroid pesticides (flumethrin, bifenthrin and silafluofen) in urine samples. [N4,4,4,4]Cl and Na[N(CN)2] formed a ionic liquid ([N4,4,4,4][N(CN)2]), which provides an alternative to highly toxic solvents; moreover, high extraction recoveries and enrichment factors were achieved. The extraction parameters affecting the extraction recoveries were investigated. Under optimum conditions, the analytical method showed a good linear response, with correlation coefficient (R2) values ranging from 0.9994 to 0.9996. The enrichment factor, limit of detection and recovery were 108–125, 2.7–5.0 μg L−1 and 88.0–101.1%, respectively. Therefore, this green and simple method is suitable for the microextraction of pyrethroid pesticides in urine samples. It is valuable to establish a sensitive method for monitoring trace levels of pyrethroids, which could contribute to the use of rapid and green sample preparation procedures in urine samples.

The synthesized sheet-like polypyrrole (ppy) nanowires were used as solid phase extraction materials, followed by gas chromatography-mass spectrometry (GC–MS) for the detection of traces residues of pyrethroid pesticides in human plasma. A multiresidue method was developed and verified for the determination of trace pyrethroid residues (transfluthrin, allethrin, resmethrin, fenpropathrin, etofenprox, fenvalerate) in human plasma. In this study, using the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a soft template, ppy nanowires with regular morphology were prepared by oxidative polymerization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and other techniques were employed for characterization. Molecular dynamics analyses were used to simulate the adsorption mechanism of each pyrethroid and ppy nanowires. Based on density analysis, molecular recognition analysis, and binding energy, the van der Waals force was considered as an important driving force for the adsorption of pyrethroids and ppy nanowires. The limits of detection (LOD) of six pyrethroids were 0.008–0051 ng mL−1, and the limits of quantification (LOQ) were 0.028–0.162 ng mL−1. The relative standard deviations of ppy nanowires were 2.12–5.09%, and the recoveries of six pyrethroids ranged from 76.9 to 110.4%. The enrichment factors were within the range of 47.09–51.30. The experimental results showed that the method could be an efficient detection method for trace residue analysis of pyrethroid pesticides in complex biological samples. It would be advantageous for clinical monitoring and toxicological studies of pyrethroids.