Dandelion (Taraxacum officinale), a common plant worldwide, is used as both a medicine and food. Fermentation is a food processing technology that has many advantages, such as low energy cost, changes in product characteristics, and enhanced product quality. The purpose of this study was to investigate the effect of solid-state fermentation (SSF) on the content, composition and antioxidant activity of dandelion flavonoids. Response surface methodology was used to optimize dandelion fermentation conditions. Under optimized conditions, the maximum flavone concentration was 66.05 ± 1.89 mg/g. The flavonoid content of the crude extract from fermented dandelion (FDF) was 183.72 ± 2.24 mg/g. The flavonoid compounds in the crude extracts were further identified by UPLC-ESI-MS/MS. A total of 229 flavonoid compounds were identified, and 57 differential flavonoids (including 27 upregulated and 30 downregulated flavonoids) between FDF and the crude extract of unfermented dandelion (DF) were observed, of which 25 were annotated to metabolic pathways. FDF displayed superior antioxidant activity to that of DF in in vitro DPPH radical-scavenging and reducing power assays. The favorable results of our investigation could provide a new way for the exploitation and utilization of dandelion, which could be promising for its application as an antioxidant and functional food additive with flavonoids as ingredients.

The relative abundances of the fragment ions increased with increase in the cone voltage. The experimental results were explained by the favorability of the intermediate structure and the stability of the fragment ion structure. The specific fragmentation patterns could be used for differentiating underivatized AAs.

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Ionization efficiencies and fragmentation patterns of cyanoacrylate ultraviolet (UV) absorbers, Uvinul 3035 and Uvinul 3039, were studied using liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS). Solvent effect on the ionization efficiencies was investigated using methanol, ethanol, acetone, and chloroform. The fragmentation patterns were also investigated by varying the fragmentor voltage. Solvated ions, the [M+H + solvent](+) of methanol, ethanol, and acetone were detected, but the [M+H + chloroform](+) ion was not observed. For Uvinul 3039 in chloroform, the [M+CHCl(2)](+) ion was detected instead of the solvated ion. Relative abundance of the solvated ion was decreased by increasing the fragmentor voltage. Fragment ions of m/z 250, 232, and 204 were detected and their abundance increased with an increase in the fragmentor voltage. The m/z 250 ion can be accounted for by a McLafferty rearrangement. The fragment ions of m/z 232 and 204 were formed not only by subsequent fragmentations of the m/z 250 ion, but also by ion-molecule reactions of solvent ion and neutral analyte.

Two novel monoterpenoid indole alkaloids, alstolarines A and B (1–2), were isolated from the leaves and twigs of Alstonia scholaris. Compound 1 is the first vobasinyl-type alkaloid with a 6/5/8/5/6/5...

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Alkali metal cations easily form complexes with proteins in biological systems; understanding amino acid clusters with these cations can provide useful insight into their behaviors at the molecular level including diagnosis and therapy of related diseases. For the purpose of characterization of basic interaction between amino acids and alkali metal, each of the 20 naturally occurring amino acids were ionized in the presence of lithium, sodium and potassium cations by electrospray ionization, and the resulting product ions were analyzed. We focus our attention on the gas phase alkali metal ion-proton exchanged complexes in current study, specifically complexes with serine, threonine, asparagine and glutamine, which share characteristic pattern unlike other amino acids. All amino acids generated [M + H](+) and [M + Na](+) ions, where M stands for the neutral amino acid. Serine, threonine, asparagine and glutamine generated cluster ions of [nM - nH + (n + 1)Na](+) and [nM - (n - 1)H + (n - 1)Na + K](+) , where n = 1-7. While the (M - H + Li) and (M - H + K) species were not observed, the neutral (M - H + Na) species formed by proton-sodium cation exchange had a highly stable cyclic structure with ketone and amine ligand sites, suggesting that (M - H + Na) serves as a building block in cluster ion formation. Cluster ion intensity distributions of [nM - nH + (n + 1)Na](+) and [nM - (n - 1)H + (n - 1)Na + K](+) showed a magic number at n = 3 and 4, respectively. Extensive B3LYP-DFT quantum mechanical calculations were carried out to elucidate the geometry and energy of the cluster ions, and they provided a reasonable explanation for the stability and structure of the cluster ions.