Cytotoxic 8,9-seco-ent-kaurane diterpenoids from Croton kongensis.

Chemical study on the ethanolic extract generated from the aerial parts of Croton kongensis led to the isolation of three new 8,9-seco-ent-kaurane diterpenoids, kongeniods A‒C (1‒3), together with seven known analogs (4-10). The structures of these compounds were assigned by spectroscopic data analysis. The vitro cytotoxic tests showed that compounds 1-3 exhibited strong activities against HL-60 cell lines with IC50 values of 0.47, 0.58, and 1.27 µM, respectively.

Effects of chronic cold exposure on murine central nervous system.

Recently, cold-adaptation medicine has gotten more and more attention because of its specific significance to health care, military activities, sports performance, and so on. Although numerous studies have focused on respiratory, immune, and circulatory systems as well as skin damage upon cold exposure, the impacts on central nervous system are not well understood. This study explores the effects of chronic cold exposure on the murine central nervous system. To establish a chronic cold-exposure animal model, adult male mice from postnatal days 40-50 (P40-50) were housed at 0-4°C for 20 days. During the study period, estrogen receptors were labeled via immunohistochemistry, the dendritic spines of visual cortical pyramidal cells were labeled with DiI diolistic assay, and synaptic ultrastructure was observed by transmission electron microscopy. The results showed that cold exposure could inhibit neural proliferation significantly, with an increase of G-protein-coupled receptor 30 (GPR30) expression. Chronic cold exposure could also induce a decrease in the dendritic spines of pyramidal cells in visual cortex, along with a decrease in the number of synaptic formations. The ultrastructure of synapses after cold exposure was observed. It was found that pre- and postsynaptic membranes were fused, with a vague synaptic cleft. Furthermore, neuronal cytoplasmic and organelle swellings were also observed, along with microtubule disintegration. In conclusion, chronic cold exposure can cause structural and functional changes in the mouse central nervous system, possibly by direct participation of estrogen and its receptor, GPR30, in response to chronic cold exposure.

Crokonoids A-C, A Highly Rearranged and Dual-Bridged Spiro Diterpenoid and Two Other Diterpenoids from Croton kongensis.

Crokonoid A (1), a highly rearranged diterpenoid featuring a dual-bridged tricyclo[4.4.1.11,4]dodecane-2,11-dione ring system and its two possible ent-kaurene diterpenoid precursors (2 and 3), was isolated and structurally characterized by solid data from Croton kongensis. Compound 1 exhibited significant cytotoxicity against HL-60 and A-549 cell lines with IC50 values of 1.24 ± 0.56 and 1.92 ± 0.60 µM, respectively.

[Spatio-temporal variability of habitat quality in Beijing-Tianjin-Hebei Area based on land use change].

Land use change is the core content of global change. To achieve sustainable land use planning, it is necessary to evaluate the habitat quality pattern and its spatio-temporal variation resulted from land use change, which can provide basis for the formulation of land management policy. Based on the analysis of land use change from 2000 to 2010, this study investigated the spatio-temporal variation of habitat quality pattern of Beijing-Tianjin-Hebei Area. We used the watershed profile sampling points and spatial autocorrelation analysis based on watershed subdivision. The results showed that the main land use change types from 2000 to 2010 in this area included the transition from cultivated land to construction land, the transition between forest and grassland, and the transition from water bodies to cultivated land. This land use/cover change process led to the decrease of heterogeneity of landscape structure and increase of fragmentation. The overall spatial pattern of habitat quality was that southeast and south areas were relatively lower, while north and west areas were relatively higher. The analysis based on watershed profile showed that the habitat quality of each watershed presented significant difference in each part. Habitat quality of most sampling points degraded in a way, while some improved compared with 2000. In general, the habitat quality of the bottom part of Luanhe River basin, the medium part of Bai-Chaobai-Chaobaixin River basin, the medium and the bottom part of Yongding River basin and medium part of Laozhang-Fudongpai- Beipai River basin were poor and volatile, while other parts were relatively good. There was a decreasing agglomeration characteristic of distribution of habitat quality in Beijing-Tianjin-Hebei Area under the disturbance of human activities. Areas of high habitat quality in 2000 were mainly located in Luanhe River basin and top part of Baihe basin. Areas of low habitat quality were mainly located in medium and bottom part of Yongding River basin and some parts of Chaobai River basin. However, the areas of high habitat quality and areas with low habitat quality of 2010 had both expanded towards southwest.