Optimization of total flavonoid compound (TFC) extraction from Gynura medica leaf was investigated using response surface methodology (RSM) in this paper. The conditions investigated were 30–60% (v/v) ethanol concentration (X1), 85–95 °C extraction temperature (X2) and 30–50 (v/w) liquid-to-solid ratio (X3). Statistical analysis of the experiments indicated that temperature and liquid-to-solid ratio significantly affected TFC extraction (p < 0.01). The Box-Behnken experiment design showed that polynomial regression models were in good agreement with the experimental results, with the coefficients of determination of 0.9325 for TFC yield. The optimal conditions for maximum TFC yield were 55% ethanol, 92 °C and 50 (v/w) liquid-to-solid ratio with a 30 min extraction time. Extracts from these conditions showed a moderate antioxidant value of 54.78 μmol quercetin/g dry material (DM), 137.3 μmol trolox/g DM for 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 108.21 μmol quercetin/g DM, 242.31 μmol trolox/g DM for 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS+), respectively. HPLC-DAD-MS analysis showed that kaempferol-3-O-glucoside was the principal flavonoid compound in Gynura medica leaf.

Mannuronate oligosaccharide (MOS) is α-D-mannuronic acid polymer with 1,4-glycosidic linkages that possesses beneficial biological properties. The aim of this study was to investigate the hypouricemic effect of MOS in hyperuricemic mice and demonstrate the possible protective mechanisms involved. In this research, 200 mg/kg/day of MOS was orally administered to hyperuricemic mice for four weeks. The results showed that the MOS treatment significantly reduced the serum uric acid (SUA) level from 176.4 ± 7.9 μmol/L to 135.7 ± 10.9 μmol/L (p < 0.05). MOS alleviated the inflammatory response in the kidney. Moreover, MOS promoted uric acid excretion by regulating the protein levels of renal GLUT9, URAT1 and intestinal GLUT9, ABCG2. MOS modulated the gut microbiota in hyperuricemic mice and decreased the levels of Tyzzerella. In addition, research using antibiotic-induced pseudo-sterile mice demonstrated that the gut microbiota played a crucial role in reducing elevated serum uric acid of MOS in mice. In conclusion, MOS may be a potential candidate for alleviating HUA symptoms and regulating gut microbiota.

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An ultra performance liquid chromatography-electrospray ionization tandem mass spectrometric method (UPLC-ESI MS/MS) has been developed for the determination of 11 carbamate pesticide residues in Glycyrrhizae radix et rhizoma and its extracts. After extracted by acetonitrile and cleaned up by gel permeation chromatography (GPC), the samples were determined by UPLC-ESI MS/MS. Glycyrrhizae radix et rhizoma and its extracts were analyzed as model examples. When the spiked levels were 0.02, 0.04, and 0.1 mg/kg in the samples, the average recoveries of 11 carbamate pesticides from Glycyrrhizae radix et rhizoma were obtained from 72.2% to 94.0%, the relative standard deviations (RSDs) ranged from 0.7% to 7.8%. The average recoveries of 11 carbamate pesticides in Glycyrrhizae radix et rhizoma extract ranged from 73.8% to 94.7% and the RSDs ranged from 1.5% to 12.7%. The sensitivity, accuracy, and precision of this method can meet the requirements of the pesticide residue analysis, and the method can be applied to determine carbamate pesticide residues in Glycyrrhizae radix et rhizoma, Astragali radix and their extracts.