Rice–rape rotation is a widely practiced cropping system in China. However, changes in soil properties and management could change the bioavailability of Cd, In order to explore the occurrence state, transportation and transformation characteristics of heavy metals Cd and Zn in rice-rape rotation system in Guizhou karst area with high background value of Cd. In the karst rice–rape rotation area, the physical and chemical properties of soil, chemical specifications and activities of Cd and Zn at different soil depths and during various crop growth stages, and the bioaccumulation of Cd and Zn in different tissues of rice and rape were studied by field experiment and laboratory analysis. The bioaccumulation of Cd and Zn and the effects of physical and chemical soil properties on the activities and bioavailabilities of Cd and Zn during rice–rape rotation were explored. The findings revealed that soil particle size, composition, pH, redox potential, soil organic matter, and Cd and Zn contents varied dramatically, especially in deep soils. The physical and chemical properties of the deep and surface soils were significantly related to the bioaccumulation of Cd and Zn. Cd and Zn are activated during crop rotation. Cd was easier to be enriched in rice, while Zn was easier to be enriched in rape. The correlation between Cd and Zn contents in Brassica campestris L and their enrichment abilities were not significant, but that in Oryza sativa L were significant. During rice-rape rotation, the chemical speciations and activities of Cd and Zn changed with the changes of soil properties and waterlogging environment. This study had important basic guiding significance for the evaluation, prevention and control of heavy metal pollution, and improving soil quality in different rotation systems in karst areas, and was conducive to promoting the safe production of rape and rice.

Aberrant expression of the phosphatidylinositol 3-kinase (PI3K) signalling pathway is often associated with tumourigenesis, progression and poor prognosis. Hence, PI3K inhibitors have attracted significant interest for the treatment of cancer. In this study, a series of new 6-(imidazo[1,2-a]pyridin-6-yl)quinazoline derivatives were designed, synthesized and characterized by ¹H NMR, ¹³C NMR and HRMS spectra analyses. In the in vitro anticancer assay, most of the synthetic compounds showed submicromolar inhibitory activity against various tumour cell lines, among which 13k is the most potent compound with IC₅₀ values ranging from 0.09 μΜ to 0.43 μΜ against all the tested cell lines. Moreover, 13k induced cell cycle arrest at G2/M phase and cell apoptosis of HCC827 cells by inhibition of PI3Kα with an IC₅₀ value of 1.94 nM. These results suggested that compound 13k might serve as a lead compound for the development of PI3Kα inhibitor.

Arable land resources in karst regions are relatively scarce. The original crop rotation pattern can no longer meet the requirements of productivity development, while different crop rotation patterns have different impacts on the physicochemical properties of the soil. Through field experiments and laboratory analysis, the physicochemical properties and pollution characteristics of the soil during different crop growing stages in rice–rape rotation were investigated systematically. The main results are as follows. During the rice–rape rotation, fine sand in the topsoil experienced the greatest variation. During the rotation, pH variation in the subsoil was greater than that in the topsoil. The soil in paddy fields was poorly ventilated, and the rotation could reduce the redox potential of the soil. In the rotation process, the soil organic matter in the topsoil was higher than that in the subsoil, but the variation of soil organic matter in the topsoil was lower than that in the subsoil. The worst Cd pollution of the topsoil occurred in the seedling stage of rice, while that of the subsoil occurred in the flowering stage of rape; the comprehensive pollution index of Cr and Cd in the subsoil was higher than that in the topsoil. It is of great significance to investigate efficient crop rotation patterns under the conditions of the current productivity for promoting sustainable increases of rape and rice yield, maintaining soil fertility, and improving the soil.

The effect of calcium (Ca)-cadmium (Cd) interactions on the plant Cd bioaccumulation process may be closely related to the ecological Ca/Cd stoichiometry in the substrate. However, owing to the complexity of plant absorption, accumulation mechanisms and influencing factors, the mechanism of Ca-mediated Cd bioaccumulation and Cd tolerance in Capsicum is still unclear. In this study, the bioaccumulation, subcellular distribution and chemical forms of Cd in Capsicum were analysed via pot experiments to reveal the Ca-mediated Cd bioaccumulation process and its detoxification mechanism under different Ca/Cd stoichiometric ratios. The results revealed that an increase in the substrate Ca/Cd ratio promoted the accumulation of Cd in the roots; restricted the transport of Cd to the stems, leaves and peppers; and promoted the accumulation of Cd in the aboveground leaves but decreased its accumulation in edible parts. Cd was enriched mainly in the cell wall and cell-soluble fraction in each tissue and was enriched in only 1 %-13 % of the organelles. The accumulation of Cd in the cell wall and cell-soluble fractions of roots treated with different Ca concentrations increased by 56.57 %-236.98 % and 64.41 %-442.14 %, respectively. The carboxyl, hydroxyl and amino groups on the root cell wall play important roles in binding and fixing Cd2+. Moreover, the increase in the Ca content also increased the proportion of pectin and protein-bound Cd (F-(NaCl)), insoluble phosphate-bound Cd (F-(C)) and insoluble oxalate-bound Cd (F-(HCl)) in the roots, stems and leaves and reduced the proportion of highly active chemical forms such as inorganic acid salt-bound Cd (F-(E)) and water-soluble phosphate-bound Cd (F-(W)). Our study revealed that the bioaccumulation of Cd in Capsicum was influenced by the Ca/Cd ratio and that Ca could alleviate Cd stress by regulating the subcellular distribution and chemical form ratio of Cd in different tissues where the cell wall plays an important role in Cd tolerance and detoxification.

Andrographis paniculata (Burm. f.) and its products have a long history of medicinal use in Asia. A. paniculata products are mainly made from the root extraction of stems, leaves and parts, but there may be differences in the proportion of different parts and different harvest times, which ultimately leads to certain differences in product quality. In this study, the chemical components and non-targeted metabolomics were characterized, and the characteristic compounds in different parts of A. paniculata at various growth stages were analyzed. By utilizing polygonal mass defect filtering, precursor ion lists, and a self-built compound library, a total of 225 components were identified in A. paniculata. Notably, spermidine derivatives and phosphatidylcholines were reported for the first time in this plant species. In total, 41 differential components were identified in different parts of A. paniculata. These findings provide scientific evidence for the selection of quality markers in A. paniculata and its products.