Combined toxicity influence of polypropylene microplastics and di-2-ethylhexyl phthalate on physiological-biochemical characteristics of cucumber (Cucumis sativus L.).

Microplastics and di-2-ethylhexyl phthalate (DEHP) are prevalent and emerging pollutants in agro-ecosystem, raising concerns due to their widespread co-presence. Nevertheless, their combined toxicity on terrestrial plants remains largely unexplored. This study investigated the impact of polypropylene microplastics (MPs), DEHP, and their mixture on the physiological and biochemical characteristics of cucumber seedlings. The changes of membrane stability index (MSI), antioxidase activities, photosynthetic pigments and chlorophyll fluorescence in cucumber seedlings were assessed. The results demonstrated that MPs alone significantly inhibited MSI, photosynthetic pigments (Chl a, Chl b, and Chl a + b), Fm and qp of cucumber seedlings, and significantly promoted the carotene content and antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) in cucumber seedlings. While DEHP alone significantly inhibited MSI and photosynthetic pigments of cucumber seedlings, and significantly promoted antioxidant enzyme activities in cucumber seedlings. Moreover, the combined toxicity of MPs and DEHP was found to be less pronounced than that of the single action of MPs and DEHP. The interaction between DEHP and MPs may contribute to the reduced toxicity. Abbott's modeling revealed that the combined toxicity systems were all antagonistic (RI < 1). Two-factor analysis and principal component analysis further confirmed that the treatment of MPs alone contributed the most to the toxicological effects of the physiological properties of cucumbers. In summary, this study highlighted the importance of understanding the combined effects of MPs and DEHP on plant physiology, providing insights for the development of effective treatments for emerging pollutants in agricultural ecosystems.

[Advance of studies on bioactivity of flavonoid-metal complexes].

The flavonoid-metal complexes showed obviously stronger bioactivities such as antibiosis, antivirus, anti-inflammatory, anti-tumor and anti-free-radical, possibly because of the stronger binding force caused by the change in complex structure and accessibility to target spots, or the synergy effect between flavonoids and metallic ions. This essay summarizes studies on bioactivity and mechanism of flavonoid-metal complexes, in order to provide reference for in-depth study and development on effective constituents contained in flavonoid traditional Chinese medicines.

[Synthesis of baicalin-copper and baicalin-aluminium complex and its bioactivity].

OBJECTIVE: To study synthesis of baicalin-copper and baicalin-aluminium complex and its antimicrobial, anti-tumor activity and anti-tumor effect against macrophages. METHOD: Baicalin was reacted with metallic salt under a weak base condition to produce baicalin-copper and baicalin-aluminium complex. Baicalin and its synthesized complex were detected for antimicrobial activity against Staphylococcus aureus, Hay bacillus, Escherichia coli, Salmonella and Candida albicans by twofold broth dilution technique. Their anti-tumor activity against A549 and IC50 of HepG2 cells and anti-tumor effect against macrophages were detected by the MTT. And their phagocytic effect on macrophages was determined by the neutral red assay. RESULT: The yields of baicalin-copper and baicalin-aluminium complex were 73.93% and 91.08%, respectively. The minimum inhibitory concentration (MIC) value against Staphylococcus aureus, Hay bacillus, Escherichia coli, Salmonella and Candida albicans was 0.0004, 0.0009, 0.0004, 0.0009, 0.000 4 mol x L(-1) for baicalin-copper complex and 0.0011, 0.0011, 0.0011, 0.0011, 0.0005 mol x L(-1) for baicalin-aluminium complex. The IC50 values against A549 and HepG2 cells were 89.6, 22.6 micromol x L(-1) for baicalin-copper complex, and 138.8, 97.2 micromol x L(-1) for baicalin-aluminium complex. The inhibitory ratio of macrophage on A549 cell was 43.52%, 80.89%, 52.66%, respectively, after the macrophages were stimulated by baicalin, baicalin-copper and baicalin-aluminium complex at a concentration of 160 micromol x L(-1). CONCLUSION: The acute toxicity test in mice showed that the complex was nontoxic to mice. Baicalin-copper complex showed the highest antimicrobial, anti-tumor activity, and the strongest effect on the anti-tumor activity of macrophage, while baicalin showed the lowest activities compared with baicalin-copper and baicalin-aluminium complex.