1.Identification of lipopeptide isoforms by MALDI-TOF-MS/MS based on the simultaneous purification of iturin, fengycin, and surfactin by RP-HPLC.
Yang H1, Li X, Li X, Yu H, Shen Z. Anal Bioanal Chem. 2015 Mar;407(9):2529-42. doi: 10.1007/s00216-015-8486-8. Epub 2015 Feb 10.
A three-stage linear gradient strategy using reverse-phase high-performance liquid chromatography (HPLC) was optimized for rapid, high-quality, and simultaneous purification of the lipopeptide isoforms of iturin, fengycin, and surfactin, which may differ in composition by only a single amino acid and/or the fatty acid residue. Matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) was applied to detect the lipopeptides harvested from each reversed-phase HPLC peak. Amino acid analysis based on phenyl isothiocyanate derivatization was further used for confirmation of the amino acid species and molar ratio in a certain HPLC fraction. By this MALDI-TOF-MS/MS coupled with amino acid analysis, it was revealed that iturin at m/z 1,043 consists of a circular Asn-Tyr-Asn-Gln-Pro-Asn-Ser peptide and C14 β-OH fatty acid. Surfactin homologs from Bacillus subtilis THY-7 at m/z 1,030, 1,044, 1,058, and 1,072 possess a circular Glu-Leu-Leu-Val-Asp-Leu-Leu peptide and the β-OH fatty acid with a different length (C13-C16).
2.Investigation of fluorinated and bifunctionalized 3-phenylchroman-4-one (isoflavanone) aromatase inhibitors.
Amato E1, Bankemper T1, Kidney R1, Do T1, Onate A1, Thowfeik FS2, Merino EJ2, Paula S1, Ma L3. Bioorg Med Chem. 2014 Jan 1;22(1):126-34. doi: 10.1016/j.bmc.2013.11.045. Epub 2013 Dec 5.
Fluorinated isoflavanones and bifunctionalized isoflavanones were synthesized through a one-step gold(I)-catalyzed annulation reaction. These compounds were evaluated for their in vitro inhibitory activities against aromatase in a fluorescence-based enzymatic assay. Selected compounds were tested for their anti-proliferative effects on human breast cancer cell line MCF-7. Compounds 6-methoxy-3-(pyridin-3-yl)chroman-4-one (3c) and 6-fluoro-3-(pyridin-3-yl)chroman-4-one (3e) were identified as the most potent aromatase inhibitors with IC₅₀ values of 2.5 μM and 0.8 μM. Therefore, these compounds have great potential for the development of pharmaceutical agents against breast cancer.
3.Purification and identification of antioxidative peptides from dry-cured Xuanwei ham.
Xing LJ1, Hu YY1, Hu HY1, Ge QF1, Zhou GH1, Zhang WG2. Food Chem. 2016 Mar 1;194:951-8. doi: 10.1016/j.foodchem.2015.08.101. Epub 2015 Aug 28.
This study mainly focused on the purification and identification of antioxidative peptides generated in dry-cured Xuanwei ham. Based on scavenging effect on free radicals and ferrous ion, the antioxidant activity of crude peptides from Xuanwei ham was assessed. From the scavenging effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (OH) radicals and superoxide anion (O2(-)), it was suggested that XHP generated during the ripening period had a strong antioxidant activity. By using size exclusion chromatography, anion exchange column and reversed-phase HPLC, fractions with a strong antioxidative activity were separated based on their molecular weight and polarity differences. The fraction with strong antioxidant effect was further characterized by LC-MS/MS. The results suggest that antioxidative peptides are produced during the long processing of Xuanwei ham among which the tetrapeptide Asp-Leu-Glu-Glu could be one of the main peptides that play key role in the antioxidant activity.
