Quantitative analysis of PAH compounds in DWH crude oil and their effects on Caenorhabditis elegans germ cell apoptosis, associated with CYP450s upregulation

Evaluation of surfactant-aided polycyclic aromatic hydrocarbon biodegradation by molecular docking and molecular dynamic simulation in the marine environment

Marine oil spills directly cause polycyclic aromatic hydrocarbons (PAHs) pollution and affect marine organisms due to their toxic property. Chemical and bio-based dispersants composed of surfactants and solvents are considered effective oil spill-treating agents. Dispersants enhance oil biodegradation in the marine environment by rapidly increasing their solubility in the water column. However, the effect of dispersants, especially surfactants, on PAHs degradation by enzymes produced by microorganisms has not been studied at the molecular level. The role of the cytochrome P450 (CYP) enzyme in converting contaminants into reactive metabolites during the biodegradation process has been evidenced, but the activity in the presence of surfactants is still ambiguous. Thus, this study focused on the evaluation of the impact of chemical and bio-surfactants (i.e., Tween 80 (TWE) and Surfactin (SUC)) on the biodegradation of naphthalene (NAP), chrysene (CHR), and pyrene (PYR), the representative components of PAHs, with CYP enzyme from microalgae Parachlorella kessleri using molecular docking and molecular dynamics (MD) simulation. The molecular docking analysis revealed that PAHs bound to residues at the CYP active site through hydrophobic interactions for biodegradation. The MD simulation showed that the surfactant addition changed the enzyme conformation in the CYP-PAH complexes to provide more interactions between the enzyme and PAHs. This led to an increase in the enzyme's capability to degrade PAHs. Binding free energy (ΔG‌‌Bind) calculations confirmed that surfactant treatment could enhance PAHs degradation by the enzyme. The SUC gave a better result on NAP and PYR biodegradation based on ΔG‌‌Bind, while TWE facilitated the biodegradation of CHR. The research outputs could greatly facilitate evaluating the behaviors of oil spill-treating agents and oil spill response operations in the marine environment.

Environmental dose of 16 priority-controlled PAHs mixture induce damages of vascular endothelial cells involved in oxidative stress and inflammation

Epidemiological studies have shown that cardiovascular diseases caused by PM_2.5 pollution account for the second death rate in China. Polycyclic aromatic hydrocarbons (PAHs) are one important group of persistent organic pollutants absorbed on PM_2.5. Though individual PAH is related to vascular disease, the relationship between environmental PAHs exposure and vascular damages is still unclear. To explore the effect of PAHs on blood vessel, human umbilical vein endothelial cells (HUVECs) are treated with 16 priority-controlled PAHs at various concentrations to study their cytotoxicity and morphological alteration. Results showed that, after 48 h treatment, PAHs mixture generally attenuated the ability of wound healing, transwell migration and tube formation of HUVECs (p < 0.01) except for 1 × PAHs in transwell migration. Moreover, PAHs increased the levels of ROS and 8-hydroxy-2'-deoxyguanosine (p < 0.05), indicating that it exceeded the scavenging ability of superoxide dismutase activity. However, PAHs mixture did not increase apoptosis rate, which may be attribute to the difference of PAH concentration and composition between this study and previous reports. Downstream signaling cascades significantly and generally upregulated the relative expression of proteins in Nrf2/HO-1 and NF-ƙB/TNF-α pathway with the activation of oxidative stress, including HO-, TNF-α and Nrf2. In summary, this study suggests that environmental mixture of 16 priority-controlled PAHs can induce the damages of vascular endothelial cells involved in cellular oxidative stress and inflammation.