The complex degradation and metabolism of quercetin in rat hepatocyte incubations.

1. The current study demonstrated that there is still new information to be obtained on the chemical and biological transformation of the widely studied flavonoid quercetin. 2. In rat hepatocytes, 35 metabolites of quercetin were observed by using high-resolution mass spectrometry. The metabolites included glucuronides, sulfates, mixed sulfate/glucuronide metabolites and methylated versions of these metabolites. 3. Several metabolites were formed from chemical degradation products of quercetin which were found to form in Krebs-Henseleit (KH) buffer, degradants of quercetin were also formed in the buffer under the conditions used for hepatocyte incubations. 4. The degradants and metabolites of quercetin were characterized by using high-resolution MS(2). It was observed that the glutathione (GSH) conjugates of quercetin formed in large amounts in ammonium bicarbonate solution although the pattern of conjugates formed was different from that observed in hepatocytes suggesting some degree on enzymatic control on GSH conjugate formation in the hepatocyte incubations. 5. GSH conjugates were not formed when GSH was included in incubations of quercetin in KH buffer alone and only small amounts of quercetin degradation occurred. Instead, GSH was extensively converted into GSSG, thus presumably reducing the levels of oxygen in the incubation thus preventing quercetin degradation.

Comprehensive multivariate correlations between climatic effect, metabolite-profile, antioxidant capacity and antibacterial activity of Brazilian red propolis metabolites during seasonal study.

The standardization of apiceutical products like as propolis extracts has been widely debated worldwide and variations in the propolis chemical composition are still very relevant topics for use-standardized of different propolis-type as medication by much of the world's population. The present manuscript discuss important issues related to the climate effect and variations in propolis metabolite-profiling changes, antioxidant capacity and variations of the antibacterial activity of the Brazilian red propolis metabolites using comprehensive multivariate correlations. It was observed the increasing of guttiferones concentrations during the intense drought period and drastic decreasing in rainy period. The climate variation induced the high concentration of flavonoids in rainy period with pronounced dropped in some rainy months. The Pearson´s analysis demonstrated correlation between IC50 from DPPH and guttiferones and flavonoids concentrations. The PCA-X and Hotelling T2 test showed outliers during the months with lowest concentrations of formononetin and isoliquiritigenin was observed in antibacterial tests. The PLS-DA, OPLS-DA and VIP analysis demonstrate guttiferone E, guttiferone B, liquiritigenin, naringenin are considered important substances responsible by anti-staphylococcal activity in red propolis composition during the rainy season and drought period, but a synergistic effect with other flavonoids and isoflavonoids are not ruled out.