Synthesis and antibacterial activity evaluation of octapeptin derivatives / 药学学报

Octapeptin has strong antibacterial activity against Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii, while it also has activity against some Gram-positive bacteria. This study used natural octapeptin A3 and B3 as lead compounds for structural modification. Twenty-one peptide derivatives (including A3 and B3) containing eight amino acid residues were prepared by solid-phase synthesis, and evaluated for antibacterial activity and renal cytotoxicity. Among them, three compounds 6, 7 and 17 exhibited broad-spectrum antibacterial activity and significantly enhanced the activity for Gram-positive bacteria while maintaining the activity of Gram-negative bacteria. Several compounds improved the activity for Pseudomonas aeruginosa. Compound 7 was active against all test strains and had relatively low renal cytotoxicity. The results provide a basis for the further development of novel polypeptide antibiotics.

Berberine inhibits autophagy and promotes apoptosis of fibroblast-like synovial cells from rheumatoid arthritis patients through the ROS/mTOR signaling pathway / 南方医科大学学报

OBJECTIVE@#To evaluate the regulatory effect of berberine on autophagy and apoptosis balance of fibroblast-like synoviocytes (FLSs) from patients with in rheumatoid arthritis (RA) and explore the mechanism.@*METHODS@#The inhibitory effect of 10, 20, 30, 40, 50, 60, 70, and 80 μmol/L berberine on RA-FLS proliferation was assessed using CCK-8 method. Annexin V/PI and JC-1 immunofluorescence staining was used to analyze the effect of berberine (30 μmol/L) on apoptosis of 25 ng/mL TNF-α- induced RA-FLSs, and Western blotting was performed to detect the changes in the expression levels of autophagy- and apoptosis-related proteins. The cells were further treated with the autophagy inducer RAPA and the autophagy inhibitor chloroquine to observe the changes in autophagic flow by laser confocal detection of mCherry-EGFP-LC3B. RA-FLSs were treated with the reactive oxygen species (ROS) mimic H2O2 or the ROS inhibitor NAC, and the effects of berberine on ROS, mTOR and p-mTOR levels were observed.@*RESULTS@#The results of CCK-8 assay showed that berberine significantly inhibited the proliferation of RA-FLSs in a time- and concentration-dependent manner. Flow cytometry and JC-1 staining showed that berberine (30 μmol/L) significantly increased apoptosis rate (P < 0.01) and reduced the mitochondrial membrane potential of RA-FLSs (P < 0.05). Berberine treatment obviously decreased the ratios of Bcl-2/Bax (P < 0.05) and LC3B-II/I (P < 0.01) and increased the expression of p62 protein in the cells (P < 0.05). Detection of mCherry-EGFP-LC3B autophagy flow revealed obvious autophagy flow block in berberine-treated RA-FLSs. Berberine significantly reduced the level of ROS in TNF-α-induced RA-FLSs and upregulated the expression level of autophagy-related protein p-mTOR (P < 0.01); this effect was regulated by ROS level, and the combined use of RAPA significantly reduced the pro-apoptotic effect of berberine in RA-FLSs (P < 0.01).@*CONCLUSION@#Berberine can inhibit autophagy and promote apoptosis of RA-FLSs by regulating the ROS-mTOR pathway.

Structure modification and antimicrobial activity of novel cationic melittin analogues / 药学学报

Melittin exhibits high antibacterial potency against drug-resistant bacteria. However, the clinical utility of melittin is limited by its serious hemolytic activity. Thus, the need for developing novel melittin analogues with high antimicrobial activity and low hemolytic activity has grown. We designed, synthesized, and evaluated 20 novel melittin analogues with varying hydrophobic, polar or positively charged amino acids. The results showed that 8 compounds had antimicrobial activity (MIC: 1-4 μg·mL-1) against gram-positive pathogens equal to or better than that of melittin, and 16 compounds had low hemolytic activity (HC50 ≥ 11.9 μg·mL-1). Compounds 13 (MIC: 2-4 μg·mL-1) and 15 (MIC: 1-2 μg·mL-1) showed equal or better antimicrobial activity against both susceptible and resistant strains of Staphylococcus aureus and Enterococcus faecium compared to melittin (MIC: 4 μg·mL-1). Compound 13 (HC50: 24.0 ± 4.3 μg·mL-1) displayed noticeably decreased hemolytic activity compared to melittin (HC50: 5.3 ± 0.4 μg·mL-1). This work established a base for further study on the structure-activity relationships and structure-toxicity relationships of melittin.

Research advances on the virulence factors of Corynebacterium pseudotuberculosis / 中国人兽共患病学报

Zoonotic pathogen Corynebacterium pseudotuberculosis is the etiological agent of Caseous lymphadenitis (CLA),a chronic infectious disease throughout almost the whole world,which is extremely difficult to control.The pathogenesis of C.pseudotuberculosis is closely related to its virulence factors.In this paper,the virulence factors of C.pseudotuberculosis are reviewed,and it is proposed to further identify and analyze the roles and correlations of other different virulence factors in the pathogenesis of C.pseudotuberculosis infection,which is important for understanding the pathogenic mechanism and identify candidate vaccine of C.pseudotuberculosis.

Early conservative eschar-scraping and delayed skin graft to cure deep burn on the face caused by coal-dust burning and blasting / 中华全科医师杂志

Objective To study effective treatment for deep burn on the face caused by coal-dust burning and blasting to prevent severe disfigurement.Methods Early conservative eschar-scraping, delayed skin graft,early strain-diminution for the eyelids in both sides,and wound expansion with skin graft were used to treat 12 patients with deep burn on their faces caused by coal-dust burning and blasting. Results Facial wound of all the 12 patients healed within three weeks after burn.No significant cicatricial hyperplasia and deformity were found on their faces during three-month follow-up,with natural facial expression and abundant emotion.Conclusions Early eschar-scraping and delayed skin graft for deep facial burn can promote fast repair of burn-wound,diminish cicatricial hyperplasia and prevent deformity on the face.