Shatianyu dietary fiber (Citrus grandis L. Osbeck) promotes the production of active metabolites from its flavonoids during in vitro colonic fermentation

BACKGROUND

Recent studies reveal that dietary fiber (DF) might play a critical role in the metabolism and bioactivity of flavonoids by regulating gut microbiota. We previously found that Shatianyu (Citrus grandis L. Osbeck) pulp was rich in flavonoids and DF, and Shatianyu pulp flavonoid extracts (SPFEs) were dominated by melitidin, obviously different from other citrus flavonoids dominated by naringin. The effects of Shatianyu pulp DF (SPDF) on the microbial metabolism and bioactivity of SPFEs is unknown.

RESULTS

An in vitro colonic fermentation model was used to explore the effects of SPDF on the microbial metabolism and antioxidant activity of SPFEs in the present study. At the beginning of fermentation, SPDF promoted the microbial degradation of SPFEs. After 24 h-fermentation, the supplemented SPFEs were almost all degraded in SPFEs group, and the main metabolites detected were the dehydrogenation, hydroxylation and acetylation products of naringenin, the aglycone of the major SPFEs components. However, when SPFEs fermented with SPDF for 24 h, 60.7% of flavonoid compounds were retained, and SPFEs were mainly transformed to the ring fission metabolites, such as 3-(4-hydroxyphenyl) propionic acid, 3-phenylpropionic acid and 3-(3-hydroxy-phenyl) propionic acid. The fermentation metabolites of SPFEs showed stronger antioxidant activity than the original ones, with a further increase in SPDF supplemented group. Furthermore, SPFEs enriched microbiota participating in the deglycosylation and dehydrogenation of flavonoids, while co-supplementation of SPDF and SPFEs witnessed the bloom of Lactobacillaceae and Lactobacillus, contributing to the deglycosylation and ring fission of flavonoids.

CONCLUSION

SDPF promote SPFEs to transform to active metabolites probably by regulating gut microbiota. © 2023 Society of Chemical Industry.

Multivariate Analyses and Human Health Assessments of Heavy Metals for Surface Water Quality in the Xiangjiang River Basin, China

Pollution by heavy metals in river water is becoming a major subject of global drinking water concern, and the Xiangjiang River is one of the most heavily polluted rivers in China. Water samples were collected from 17 sites spanning the entire Xiangjiang watershed from 2005 to 2016 to investigate spatial-temporal distributions and potential human health risks related to 8 metal pollutants (As, Cd, Hg, Cr, Cu, Pb, Zn, and Se). The results of spatial-temporal distribution analyses proved that most metals were below the guideline limits the majority of the time. However, the hazard index and carcinogenic risk analyses indicated that As and Cr were associated with a potential risk of cancer, although noncarcinogenic heavy metals in general and carcinogenic risk declined year by year. A nonparametric seasonal Mann-Kendall's test revealed that there were notable decreasing trends in As, Cd, Zn, Cu, Cr, and Pb for most sites, whereas Se and Hg significantly increased in some areas over the targeted 12 yr. The results of principal component analysis agreed with those of dual hierarchical cluster analysis in the identification of pollution sources, the results of which are as follows: 1) As, Cd, Pb, Hg, and Zn were mainly derived from anthropogenic activities and the smelting industry; 2) Cr and Cu mainly originated from agricultural or industrial activities; and 3) Se was predominantly from natural erosion. The present study will be conducive to optimizing the distribution of water monitoring stations and drafting remediation strategies pertaining to the protection of public health in metal-polluted areas. Environ Toxicol Chem 2019;38:1645-1657. © 2019 SETAC.