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The Baiyinnuoer skarn Zn-Pb deposit, located in the Southern Great Xing'an Range, Northeast China, is the largest Zn-Pb deposit of the northern China, with a total reserve of 32.74 Mt at average grades of 5.44% Zn and 2.02% Pb. The Zn-Pb ore bodies are hosted in the Lower Permian Huanggangliang Formation. The results of zircon U-Pb geochronology show that the ore-associated granodiorite porphyry, granodiorite, and diorite were emplaced at 248 ± 1.3, 251 ± 1.8, and 249 ± 1.4 Ma, respectively. The granodiorites and granodiorite porphyry have low P2O5 (0.13-0.23 wt %) and A/CNK (0.79-1.05) values, and their SiO2 and P2O5 contents are negatively correlated, indicating I-type affinity. The positive εNd(t) values (+1.3 to +1.8) and young two-stage model ages (TDM2) (880-916 Ma) of the Baiyinnuoer intrusive rocks suggest that they might have formed by the mixing of both mantle and crustal materials. The variations in the major elements, Rb, Sr, and Ba, and the negative Nb-Ta-Ti anomalies indicate that fractional crystallization might have occurred during magma ascent. In combination with the regional geology, the new geochronological, geochemical, and isotopic data reveal that the ore-associated intrusive rocks at Baiyinnuoer were formed in a post-collision setting in the Late Permian. [ABSTRACT FROM AUTHOR]

Betulin, betulinic acid and lupeol are naturally occurring pentacyclic triterpenoids with significant medicinal values. Great amounts of triterpenoids are found in the bark of white birch (Betula platyphylla Suk.) trees, which can be affected by climatic factors along the geographical gradients. In this study, site-based data of triterpenoids' (betulin, betulinic acid and lupeol) concentrations were determined in barks of white birch trees from 48 sites in Northeast China. Triterpenoid concentration in white birch tree barks did not change in response to any geographical gradients along latitudes, longitudes or elevations. Instead, concentrations of betulin and lupeol in birch tree barks increased with the increase of temperature and precipitation but declined with the increase of relative humidity. As a result, betulin concentration was higher in birch trees in the northeastern and southwestern parts of the study area, and lower in the central part of the study area in Northeast China. Although betulinic acid concentration did not change with climatic factors, its distribution pattern was similar to betulin concentration. Lupeol concentration was highest in the north-eastern part and along the southern and eastern boundaries in the study area. Our results can supply information for precondition of triterpenoids' extraction for industrial production, which can be an available approach to solve the issue of bark waste processing of white birch. [ABSTRACT FROM AUTHOR]

Salidroside and its aglycone p-tyrosol are two major phenols in the genus Rhodiola and have been confirmed to possess various pharmacological properties. In our present study, p-tyrosol was identified as the deglycosylation metabolite of salidroside after intravenous (i.v.) administration to rats at a dose of 50 mg/kg, but was not detectable after intragastric gavage (i.g.) administration through HPLC-photodiode array detection (PDA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Next, an accurate and precise LC-MS/MS method was developed to quantitatively determine salidroside and p-tyrosol in rat plasma samples. Samples were analyzed by LC-MS/MS on a reverse-phase xTerra MS C18 column which was equilibrated and eluted with an isocratic mixture of acetonitrile-water (1:9, v/v) at a flow rate of 0.3 mL/min. The analytes were monitored by multiple reaction monitoring (MRM) under the negative electrospray ionization mode. The precursor/product transitions (m/z) were 299.0→118.8 for salidroside, 137.0→118.9 for p-tyrosol and 150.1→106.9 for the internal standard (IS), paracetamol, respectively. The calibration curve was linear over the concentration ranges of 50-2,000 ng/mL for salidroside and 20-200 ng/mL for p-tyrosol. The inter- and intra-day accuracy and precision were within ±15%. The method has been successfully applied to the pharmacokinetic study and the oral bioavailability was calculated. [ABSTRACT FROM AUTHOR]