Characterization of gelsevirine metabolites in rat liver S9 by accurate mass measurements using high-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry.

RATIONALE: Gelsemium elegans Benth. belongs to the family Loganiaceae and is widely distributed in northern America, east Asia, and southeast Asia. It has attracted wide attention for its diverse biological effects and complex architectures. Gelsevirine is one of the major components in G. elegans. Compared with other alkaloids from G. elegans, gelsevirine exhibits equally potent anxiolytic effects but with less toxicity. However, the metabolism of gelsevirine has not been clearly elucidated. METHODS: The metabolism of gelsevirine was investigated using liver S9 fractions derived from rat liver homogenates by centrifugation at 9000 g. A rapid and accurate high-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (HPLC/QqTOF-MS) method was applied to characterize the gelsevirine metabolites. RESULTS: We discovered a total number of four metabolites of gelsevirine. The metabolic pathways of gelsevirine consisted of hydrogenation, N-demethylenation and oxidation in rat liver S9. CONCLUSIONS: This is the first study on the metabolism of gelsevirine. We proposed possible metabolic pathways of gelsevirine. These findings may warrant future studies of the in vivo metabolism of gelsemine in animals.

Metabolomic profiling for identification of potential biomarkers in the protective effects of modified Sinisan against liver injury in dimethylnitrosamine treated rats.

Metabolomics is a new platform based on the comprehensive analysis of low molecular weight metabolites and provides a powerful approach to discover biomarkers in biological systems. Modified Sinisan (MSNS), a traditional Chinese medicine formula, displayed bright prospects in the prevention and therapy of liver injury. However, its molecular mechanism of hepatoprotective effects remains unclear. This paper was designed to explore the effects and potential mechanisms of MSNS against dimethylnitrosamine-induced liver injury. Global metabolic profiling was performed by ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-Q-TOF-MS) in conjunction with multivariate data analysis and pathway analysis. Eleven serum biomarkers were identified and pathway analysis results showed that phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, tryptophan metabolism, retinol metabolism, tyrosine metabolism were perturbed by liver injury. More importantly, MSNS has showed satisfactory pharmacological effect on liver injury through partially regulating the perturbed pathways, correlates well to the biochemical and histopathological detection results. The present study proved that the robust metabolomics approach is promising for unraveling hepatoprotective effects of MSNS and these findings provide new insights into mechanisms of the liver injury, and its pathophysiologic processes.

[Species-abundance distribution patterns of Quercus aliena var. acutiserrata forest in Taibai Mountain, China.] / å¤ªç™½å±±é”é½¿æ Žæž—ç‰©ç§-å¤šåº¦åˆ†å¸ƒæ ¼å±€.

The statistical model (log-normal model), niche models (Zipf model, broken stick mo-del, niche preemption model), and neutral model were used to fit the species-abundance distribution patterns based on the measurements of environmental factors and inventory data of trees with DBH≥1 cm in a 1.5 hm2 plot in the primary forest (PF) and a 1.5 hm2 plot in the secondary forest (SF). The results showed that species-abundance distribution was affected by habitat heterogeneity in Q. aliena var. acutiserrata forest. Topography had a predominant impact on the species-abundance distribution in PF. Species distribution was affected by both neutral and niche processes, with neutral process having a less prominent effect in large convexity habitats. While the neutral model was rejected by the K-S and Chi-square test in low convexity habitats, the species-abundance distribution satisfied the assumption of niche theory. Niche process and neutral process were equally important in the community in areas with steep slopes, while niche differentiation was the dominant in flat areas. In SF, the main factors affecting species distribution were soil nutrients. The niche process was the mainly ecological process affected species-abundance distribution in habitats with high soil available phosphorus, while the niche and neutral processes existed simultaneously in habitats with low soil phosphorus availability. There was a significant scale effect on the species-abundance distribution pattern of Q. aliena var. acutiserrata forests in Taibai Mountain. The niche and neutral processes could protect the species-abundance distribution at the 20 m×20 m scale in PF, while the niche process could explain the species-abundance distribution at the 40 m×40 m and 70 m×70 m scales. The niche and neutral processes combined acted on the species abundance distribution at the 20 m×20 m, 40 m×40 m and 70 m×70 m scales in SF, with niche process being more important than neutral process. Moreover, besides the scale and habitat heterogeneity, the species-abundance distribution patterns of Q. aliena var. acutiserrata forests differed significantly between primary forest and secondary forest under anthropogenic disturbance.

The metabolism of gelsevirine in human, pig, goat and rat liver microsomes.

Gelsemium is a small genus of flowering plants from the family Loganiaceae comprising five species, three of which, Gelsemium sempervirens (L.) J. St.-Hil., G. elegans Benth and G. rankinii Small, are particularly popular. Compared with other alkaloids from G. elegans, gelsemine, gelsevirine and koumine exhibit equally potent anxiolytic effects and low toxicity. Although the pharmacological activities and metabolism of koumine and gelsemine have been reported in previous studies, the species differences of gelsevirine metabolism have not been well studied. In this study, the metabolism of gelsevirine was investigated by using liver microsomes of humans, pigs, goats and rats by means of HPLC-QqTOF/MS. The results indicated that the metabolism of gelsevirine in liver microsomes had qualitative and quantitative species differences. Based on the results, the possible metabolic pathways of gelsevirine in liver microsomes were proposed. Investigation of the metabolism of gelsevirine will provide a basis for further studies of the in vivo metabolism of this drug.

[Community structure of Quercus aliena var acuteserrata forest in the Taibai Mountain, China].

Qinling Mountains are biodiversity hotspots in China, with rich vegetation resources and species diversity. To clarify the mechanism underlying biodiversity maintenance during vegetation restoration in this area, we established two permanent plots with each area of 100 m×150 m in the Q. aliena var. acuteserrata secondary forest (SF) and primary forest (PF) in the northern slope of Taibai Mountain in 2016, following the standardized protocols by CTFS (the Center for Tropical Forest Science). We analyzed community composition and structure with measuring all trees with DBH ≥ 1 cm. 2839 and 2840 trees were recorded in the SF and PF plots, respectively. Trees in those two plots belong to 29 families, 45 genera, 65 species and 21 families, 37 genera, 47 species, respectively. The proportions of occasional species and rare species were 38.4% and 24.6% in the SF plot, and 40.4% and 19.2% in the PF plot. Most of the trees were distributed in northern temperate zones, and the proportions of genera were 46.6% and 48.7% in the SF and PF plots, respectively. The diameter of Q. aliena var. acuteserrata in both plots followed a unimodal distribution (more young trees than old ones). The diameter distributions of companion species (e.g., Sorbus alnifolia, Acer davidii, Cornus kousa, and Staphylea holocarpa) were inverted "J" shapes, indicating that those populations could have complete life history. In the pair correlation function g(r) analyses, the aggregation of dominant species were the strongest at 0-2 m scale in the two plots when r=10 m. The degree of aggregation gradually weakened with increasing scale. The population distribution patterns of the dominant species were random or uniform when the scale increased to certain value. The average uniform angle index (W) were 0.56 and 0.58 in the SF and PF, respectively. Trees in the communities followed an aggregated distribution. The average W of the community and dominant species in the SF were smaller than that in the PF, indicating weaker species aggregation in the SF. The average dominance in the SF and PF was both 0.47, indicating that the stands were in a co-dominant state. The average mingling was 0.70 and 0.57 in the SF and PF, respectively, which belonged to high and moderate mingling. Species richness, community stability and spatial distribution patterns of forest community could be affected by human disturbance. The role of interspecific interaction, effects of habitat heterogeneity on species coexistence, and variation of community structure should be considered during vegetation restoration of disturbed forest community.

Seasonal Changes in Pinus tabuliformis Root-Associated Fungal Microbiota Drive N and P Cycling in Terrestrial Ecosystem.

In terrestrial ecosystems, mycorrhizal roots play a key role in the cycling of soil carbon (C) and other nutrients. The impact of environmental factors on the mycorrhizal fungal community has been well studied; however, the seasonal variations in the root-associated fungal microbiota affected by environmental changes are less clear. To improve the understanding of how environmental factors shape the fungal microbiota in mycorrhizal roots, seasonal changes in Pinus tabuliformis root-associated fungi were investigated. In the present study, the seasonal dynamics of edaphic properties, soil enzymatic activities, root fungal colonization rates, and root-associated fungal microbiota in P. tabuliformis forests were studied across four seasons during a whole year to reveal their correlations with environmental changes. The results indicate that the soil functions, such as the enzymatic activities related to nitrogen (N) and phosphorus (P) degradation, were varied with the seasonal changes in microclimate factors, resulting in a significant fluctuation of edaphic properties. In addition, the ectomycorrhizal fungal colonization rate in the host pine tree roots increased during warm seasons (summer and autumn), while the fungal colonization rate of dark septate endophyte was declined. Moreover, the present study indicates that the fungal biomass increased in both the pine roots and rhizospheric soils during warm seasons, while the fungal species richness and diversity decreased. While the Basidiomycota and Ascomycota were the two dominant phyla in both root and soil fungal communities, the higher relative abundance of Basidiomycota taxa presented in warm seasons. In addition, the fungal microbial network complexity declined under the higher temperature and humidity conditions. The present study illustrates that the varieties in connectivity between the microbial networks and in functional taxa of root-associated fungal microbiota significantly influence the soil ecosystem functions, especially the N and P cycling.

[Changes of soil physical properties during the conversion of cropland to agroforestry system]. / 农田向农林复合系统转变过程中土壤物理性质的变化.

To provide theoretical basis for modeling and managing agroforestry systems, the influence of conversion of cropland to agroforestry system on soil physical properties was investigated via a walnut (Juglans regia)-wheat (Triticum aestivum) intercropping system, a wide spreading local agroforestry model in northern Weihe River of loess area, with the walnut and wheat monoculture systems as the control. The results showed that the improvement of the intercropping system on soil physical properties mainly appeared in the 0-40 cm soil layer. The intercropping system could prevent soil bulk density rising in the surface soil (0-20 cm), and the plow pan in the 20-40 cm soil layer could be significantly alleviated. The intercropping system had conti-nuous improvement on soil field capacity in each soil layer with the planting age increase, and the soil field capacity was higher than that of each monoculture system in each soil layer (except 20-40 cm soil layer) since the 5th year after planting. The intercropping system had continuous improvement on soil porosity in each soil layer, but mainly in the 0-20 and 20-40 cm soil layer, and the ratio of capillary porosity was also improved. The soil bulk density, field capacity and soil porosity obtained continuous improvement during the conversion of cropland to agroforestry system, and the improvement on soil physical properties was stronger in shallow soil layer than in deep soil.

[Light competition and productivity of agroforestry system in loess area of Weibei in Shaanxi].

Agroforestry is the most effective way for the restoration of disturbed land on Loess Plateau and the development of poorly local economy. Taking the tree-based intercropping systems of walnut or plum with soybean or pepper in the loess area of Weibei as test objects, the photosynthesis, growth, and yield of soybean (Qindou 8) and pepper (Shanjiao 981) in the systems were studied. The results showed that the photosynthetic active radiation (PAR), net photosynthetic rate (Pn), growth, and yield of individual soybean or pepper plants were significantly decreased, with the effects increased with decreasing distance from tree rows. Leaf water potential was not significantly or poorly correlated with the Pn, growth, and yield of the two crops. However, there were significant positive correlations between the soil moisture content in 10-20 cm layer and the biomass and yield of soybean, and the above-ground biomass of pepper. PAR was highly correlated with the yield of both crops, which indicated that light competition was one of the key factors leading to the decrease of crop yield.