Sulfur compounds in the diesel were selectively derived into methylsulfonium salts by reacting with iodomethane in the presence of silver tetrafluoroborate, and characterized by positive-ion electrospray ionization (ESI) fourier transform ion cyclotron resonance (FT-ICR MS). The conversion ratios and react selectivities of the methylation for various sulfur compounds were investigated by gas chromatograph coupled with pulse flame photometric detector (GC-PFPD). Result shows that the sulfur compounds in the diesel can react with iodomethane easily at room temperature, the most of sulfur compound derived into methylsulfonium salts;the homologue of benzothiophene get the higher conversion ratio and react selectivity than the homologue of dibenzothiophene (DBT). It is found that primarily sterically hindered alkylated DBT, for example, 4- or 4-, 6- DBT, is recalcitrant to be methylated. Other than benzothiophenes and dibenzothiophenes, one- and two-ring sulfides, as well as other sulfur compounds with a double bond equivalent (DBE) value ranged from 1 to 12 are identified in the diesel.

This study explores the potential antiepileptic mechanism of ursolic acid(UA)and its improvement of GABAergic interneuron damage induced by epilepsy based on transcriptome analysis.Hippocampal tissues from rats in the control group(NC group),epilepsy group(SE group),and epilepsy UA treatment group(UA group)were subjected to full-length transcriptome sequencing.The obtained sequencing data were analyzed,using gene ontology(GO),the Kyoto Encyclopedia of Genes and Genomes(KEGG),and protein-protein interaction(PPI)to perform the analysis of differential genes(DEGs).The expression levels of key differential genes were verified using RT-qPCR in hippocampal tissue.Finally,an epilepsy in vitro model was constructed on primary neurons,RT-qPCR was used to verify the expression levels of key differential genes,and the expression level of GABAA receptor γ2 subunit(GABRG2)on neurons was further examined using immunofluorescence and Western blot.The heatmap of pairwise sample expression correlation and the clustering analysis of differentially expressed genes showed that the SE group was farthest from the NC group,and that after UA treatment,the overall trend shifted towards the normal group.Compared with the SE group,a total of 220 differential genes were screened in the UA group,including 143 upregulated genes and 77 downregulated genes.GO enrichment analysis showed that it involved three processes in the primary classification:biological processes,cellular components,and molecular functions.KEGG pathway enrichment analysis showed that DEGs were involved in 36 biological pathways,including cAMP signaling pathway and calcium signaling pathway.PPI analysis showed that DEGs were closely related to GABA and inflammation.RT-qPCR results showed that UA treatment increased the expression levels of GABA receptor-related gene(Gng4),GABA synthesis-related gene(Camk2a,Vgf,and Npy)and inflammation-related gene(Timp1 and Spp1)in hippocampal tissue,and decreased the expression levels of GABA synthesis-related gene(Nptx2)and cAMP-related pathway gene(Gnas).It further confirmed that UA treatment increased the expression levels of Gng4 and Camk2a on neurons and decreased the expression level of Gnas.Immunofluorescence and Western blot results showed that,compared with the SE group,the expression level of GABRG2 on primary neurons increased after UA treatment.This study enriched the transcriptome data of UA's antiepileptic effect and laid a theoretical foundation for further research on UA's antiepileptic and neuroprotective effects.