A sensitive UPLC-MS/MS method for the simultaneous determination of the metabolites in the tryptophan pathway in rat plasma.

Tryptophan (TRP) metabolism plays a crucial role in pathology and physiology. An imbalance in TRP metabolism has been implicated in the pathology of renal failure. To explore the changes in the TRP profile that occurred in renal failure, we induced experimental models of renal ischemia-reperfusion injury (RIRI) and chronic renal failure (CRF) in rats. A simple, rapid and sensitive method coupling ultra-high-performance liquid chromatography to triple quadrupole mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of TRP and its seven major metabolites in plasma. The method was validated base on linearity, accuracy, precision, stability, recovery and the matrix effect. In the RIRI group, the levels of kynurenine (KYN), 5-hydroxyindoleacetic acid (5-HIAA), tryptamine (Trpm) and kynurenic acid (KA) were increased, and the level of TRP was decreased significantly compared with those of sham group. Moreover, the levels of most of the metabolites measured using the proposed method changed significantly with CRF progression. In the CRF group, the levels of KYN, 5-HIAA, Trpm, KA, 3-hydroxyanthranilic acid (3-HAA) and 3-hydroxykynurenine (3-HK) were dramatically elevated, and the level of TRP was markedly reduced compared with those of the CON group. Plasma precursor metabolite/product metabolite ratios were calculated to characterize enzyme activity. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) of the metabolites were performed for both groups. A Spearman correlation coefficient analysis between the metabolite concentrations and renal injury indicators was performed. We identified KYN, TRP, and 5-HIAA as potential metabolite biomarkers for AKI, and 5-HIAA, TRP, 3-HAA, KA, KYN and 3-HK as potential metabolite biomarkers for CRF (VIP>1 and p < 0.05). These results showed significant changes in the tryptophan metabolism profile under the two types of renal failure. In summary, the results of our study depict the changes in the TRP pathway, reveal the role of the TRP pathway in AKI and CRF, and provide insight into finding potential peripheral biomarkers of renal failure and elucidating the mechanism of diseases related to TRP metabolism disorders.

Shenling Baizhu San ameliorates ulcerative colitis by regulating the gut microbiota and its tryptophan metabolites: A complementary medicine to mesalamine.

ETHNOPHARMACOLOGICAL RELEVANCE: Shenling Baizhu San (SBS) is commonly employed to improve gastrointestinal dysfunction in patients with ulcerative colitis (UC) in China. SBS combined with mesalamine has been demonstrated to result in improve its curative effects without increasing any adverse reactions, but the underlying mechanism remains unclarified. AIM OF THE STUDY: Our study aimed to illuminate the potential therapeutic effects and mechanisms of SBS, which is a medicine complementary to mesalamine, in the treatment of UC. MATERIALS AND METHODS: A prospective cohort study was conducted to evaluate the efficacy of SBS as a complementary medicine to mesalamine for patients with UC (n = 48). The patients in the control group (n = 24) were given mesalamine alone, whereas those in the experimental group were administered mesalamine combined with SBS. The therapeutic outcome was assessed at 8 weeks. The structures of the gut microbiota (GMB) were characterized by 16S rRNA sequencing, and the microbial tryptophan metabolites were analyzed by UPLC-MS/MS to investigate the mechanism through which SBS achieves its effects. RESULTS: Our results showed that the combination of SBS and mesalamine could significantly improve the clinical signs of UC by achieving mucosal healing and relieving colon damage. Interestingly, the combination of SBS and mesalamine could alter the GMB structures and increase the microbial levels of tryptophan metabolites, including indole-3-propionic acid and indole-3-acetic acid. CONCLUSION: SBS combined with mesalamine is effective in improving the clinical and endoscopic outcomes of patients with UC. SBS, as a complementary therapy to conventional treatment, alleviates UC via the GMB-tryptophan metabolite axis.

UPLC-MS/MS Method for the Determination of Hyperoside and Application to Pharmacokinetics Study in Rat After Different Administration Routes.

A rapid and sensitive UPLC-MS/MS method was developed and fully validated for the quantification of hyperoside in rat plasma after intragastric, intraperitoneal and intravenous administration. Geniposide was used as an internal standard, and simple liquid-liquid extraction by ethyl acetate was utilized for to extracting the analytes from the rat plasma samples. Chromatographic separation was carried out on an InfinityLab Poroshell 120EC-C18column (2.1 mm × 50 mm, 1.9-Micro, Agilent technologies, USA). The mobile phase consisted of methanol (A) and water (B) (containing 0.1% acetic acid) at a flow rate of 0.4 mL/min. A run time of 3 min for each sample made it possible to analyze more than 300 plasma samples per day. The validated linear ranges of hyperoside were 2-1000 ng/mL in rat plasma. The intra-day and inter-day precision were within 2.6-9.3%, and accuracy were ± 8.6%. And the results of recovery and matrix interference studies were well within the accepted variability limits. Finally, this method was fully validated and successfully applied to the pharmacokinetic studies of hyperoside via different administration routes in rats.

Distribution and controlling factors of phytoplankton assemblages in a semi-enclosed bay during spring and summer.

The phytoplankton assemblages' patterns and their correlation to environmental factors were studied in Bohai Bay during spring and summer. Two zones, the northern (NWA) and southern (SWA) water area, were identified by cluster analysis based on their physical and chemical properties. Principal component analysis (PCA) showed that more phytoplankton species was found in the SWA with low nutrient concentration, while high phytoplankton abundance occurred in the NWA with high nutrient concentration. The seasonal variability in phytoplankton can be explained by water temperature, nutrient, and hydrodynamic conditions (includes mixing during spring and stratification during summer). Results of redundancy analysis (RDA) showed that silicate (SiO(4)) and soluble reactive phosphorus (SRP) were the most important environmental factors influencing the phytoplankton distribution during spring and summer, respectively. Hydrodynamics condition plays a key role in controlling variation of the environmental factors, which determined phytoplankton distribution in Bohai Bay.

Decennary variations of dissolved heavy metals in seawater of Bohai Bay, North China.

Characteristics of the spatial and temporal distributions of selected dissolved heavy metals (Cu, Zn, Pb, Hg and Cd) in Bohai Bay, north China was investigated. Water samples from 22 sites were collected and analyzed for the selected metals with atomic absorption spectrometry from the year of 1996 to 2005. Relatively high concentrations of Cu, Zn, Pb and Hg were detected, with maximum concentrations in the 10-year period of 16.30, 422.00, 40.40, 0.23 µg/L respectively. The concentrations of Cd in all samples were quite low, with maximum level of 0.89 µg/L. The spatial distribution of dissolved Cu, Zn and Pb was analogous, where their average concentrations generally descended from the coastline to the central areas of the bay. Differently, for Hg and Cd, relatively high concentrations occurred not only in inshore but also in offshore areas. Measured data of heavy metals were compared with sea water quality standard of China (SWQSC). Cd concentrations in all samples were below SWQSC Grade-I. The percentages of Cu, Zn, Pb, and Hg at Grade-III levels in Bohai Bay were 2.67%, 30.00%, 30.43% and 0.36%, respectively, suggesting the severe contamination of Zn and Pb in this area. Terrestrial inputs via different rivers and sewages may be the important source for the heavy metals contamination.

Long-term (1996-2006) variation of nitrogen and phosphorus and their spatial distributions in Tianjin coastal seawater.

The spatio-temporal varying characteristics of dissolved inorganic nitrogen, reactive phosphate (RP), chemical oxygen demand (COD), and dissolving oxygen (DO) in Tianjin coastal seawater were investigated based on observation from May 1996 to October 2006. The concentrations of dissolved inorganic nitrogen (DIN), RP and COD ascended gradually and their varying ranges were 0.103-2.432, 0.009-0.12, and 0.8-2.9 mg L(-1), respectively. While DO in seawater decreased from 8.9 to 6.1 mg L(-1) gradually. Those indicated that human-induced eutrophication occurred and the seawater quality deteriorated. The spatial distributions of DIN, RP and COD were largely uniform, where isopleths generally descended from estuarine zones and bays to the central areas and from northern area to southern area, indicating that continental input is the dominant source of those pollutants. Especially, peak zones of those pollutants usually appeared near estuaries, Tianjin harbors, and dumping site of dredged sediment, which indicates that the urban and industrial sewage, shipping waste, dredged soil were the main sources for those contaminants in seawater.

Heavy metals in the surface sediments in Lanzhou Reach of Yellow River, China.

The heavy metal pollution and their fractionations in the surface sediments of Yellow River in Lanzhou Reach was monitored for arsenic (As), lead (Pb), Zinc (Zn), chromium (Cr), copper (Cu) and manganese (Mn) with Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The mean sediment concentrations (in microg/g dry weight) ranged from 13.68-48.11 (As), 26.39-77.66 (Pb), 89.80-201.88 (Zn), 41.49-128.30 (Cr), 29.72-102.22 (Cu), and 773.23-1459.69 (Mn). Spatial distribution showed that each heavy metal concentration remained almost constant in this reach. Correlation coefficients indicated that metals were not strongly associated with sediment sand content or organic carbon content (f(oc)). Labile fractions (exchangeable + carbonate + Fe-Mn oxide) had no significant correlations with sand content or f(oc), either. Results from the present study are useful for understanding heavy metal distributions in a torrential river sediment environment.