Xu-mei Wang,Yun-hua Ye,Zong-cai Tu,Yue-ming Hu,Hui Wang,Cheng-yan He
This study aimed to investigate the mechanism underlying the influence of mild glycation on the digestibility and anaphylactic effect of β-lactoglobulin (βLG) and its digests through LC Orbitrap MS/MS. Three glycated sites were discovered after glycation with fructose, whereas only lysine47 (K47) was glycated with maltose . After digestion, the intrinsic fluorescence intensity decreased and red shifted, and the degree of hydrolysis (DH) values showed no significant difference among digests. βLG glycated with Fru showed the lowest IgG and IgE-binding abilities. Meanwhile, the IgG and IgE-binding abilities further decreased and showed no apparent difference among digests. These results were attributed to the proximity to the IgG-binding epitope, the high glycation degree of K47, and mild glycation. Therefore, mild glycation could reduce the anaphylaxis of proteins before digestion, but did not influence the anaphylactic effect of the digests.
Phosphonate is an important phosphorous species in the effluent of wastewater treatment plant (WWTP), contributing to eutrophication and interfering with phosphate removal in WWTP. It is particularly difficult to determine phosphonates in samples of complex solution chemistry, resulting in very limited information on their presence in environmental matrices. Herein, we proposed a sensitive method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine six quantitatively most important phosphonates even at the ng/L level, i.e., 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethane 1,1-diphosphonic acid, nitrilotris(methylene phosphonic acid), ethylenediamine tetra(methylene phosphonic acid), hexamethylenediamine tetra(methylene phosphonic acid) and diethylenetriamine penta(methylene phosphonic acid). Trimethylsilyldiazomethane (TMSCHN 2 ) derivatization of the target phosphonates is pre-requisite since it could greatly increase the sensitivity up to 2-3 orders of magnitude over direct analysis of the virgin ones. The sample pretreatment methods (including ion exchange and solid phase extraction(SPE)), the derivatization procedures, and the LC-MS/MS conditions were systematically optimized. The limits of quantitation for the six phosphonates in the background of tap water ranged from 1.4 μg/L to 57 μg/L for direct analysis, and from 5.0 ng/L to 200 ng/L for SPE enabled pre-concentration analysis, respectively. The reliability of the proposed method was successfully validated by analysis of authentic water samples collected from one river and three WWTPs (0.088–7200 μg/L phosphonates) with satisfactory recoveries (72–126%). To the best of knowledge, this is the first report on quantification of phosphonates in environmental samples in China.
In this study, four Monascus pigments (ankaflavin, AK; monascin MS; rubropunctatin, O 1 ; monascorubrin, O 2 ) were proved to exhibit considerable anti-glycation properties in bovine serum albumin (BSA)-fructose model. AK (40.62 %) and MS (48.38 %) were found to exert lower inhibitory effects on the formation of fluorescent advanced glycation end products (AGEs) than aminoguanidine (59.4 %), while O 1 (90.64 %) and O 2 (93.82 %) displayed much stronger abilities. AK and MS could trap methylglyoxal (MGO) with maximum capture rates of 85.67 % and 84.90 %, respectively, and only mono-MGO adducts of them were detected. LC-Orbitrap MS/MS analysis revealed that four pigments significantly altered the type and reduced the number of the glycated sites and they all covalently bound to BSA, with O 1 and O 2 possessing high reactivity. Altogether, AK and MS suppressed fluorescent AGEs formation mainly via trapping MGO and covalently interacting with BSA, and blocking free amino groups was the dominant mechanism for O 1 and O 2 . These findings presented new insights into Monascus pigments as dietary supplement for inhibiting protein glycation.
危险品化学品经营许可证（带存储）