Suppressing Alpha-Hemolysin as Potential Target to Screen of Flavonoids to Combat Bacterial Coinfection.

The rapid emergence of bacterial coinfection caused by cytosolic bacteria has become a huge threat to public health worldwide. Past efforts have been devoted to discover the broad-spectrum antibiotics, while the emergence of antibiotic resistance encourages the development of antibacterial agents. In essence, bacterial virulence is a factor in antibiotic tolerance. However, the discovery and development of new antibacterial drugs and special antitoxin drugs is much more difficult in the antibiotic resistance era. Herein, we hypothesize that antitoxin hemolytic activity can serve as a screening principle to select antibacterial drugs to combat coinfection from natural products. Being the most abundant natural drug of plant origins, flavonoids were selected to assess the ability of antibacterial coinfections in this paper. Firstly, we note that four flavonoids, namely, baicalin, catechin, kaempferol, and quercetin, have previously exhibited antibacterial abilities. Then, we found that baicalin, kaempferol, and quercetin have better inhibitions of hemolytic activity of Hla than catechin. In addition, kaempferol and quercetin, have therapeutic effectivity for the coinfections of Staphylococcus aureus and Pseudomonas aeruginosa in vitro and in vivo. Finally, our results indicated that kaempferol and quercetin therapied the bacterial coinfection by inhibiting S. aureus α-hemolysin (Hla) and reduced the host inflammatory response. These results suggest that antitoxins may play a promising role as a potential target for screening flavonoids to combat bacterial coinfection.

[Study on the effects of curcumin on angiogenesis].

OBJECTIVE: The effects of curcumin on angiogenesis were studied. METHODS: Proliferation of bovine aortic endothelial cells (BAECs) and cells of human cancerous cell line SGC-7901 were measured by MTT colorimetric assay after treated by various concentrations of curcumin. The effects of curcumin on BAECS proliferation promoted by tumor conditioned medium were observed by MTT colorimetric assay. The effects of various concentration of curcumin on the migration of BAECs and migration promoted by tumor conditioned medium were investigated by agorose assay. RESULTS: Curcumin can obviously inhibit the proliferation of BAECs induced by fetal bovine serum (FBS) and tumor conditioned medium. Curcumin can also obviously inhibit the migration of BAECs induced by FBS and tumor conditioned medium. CONCLUSION: Curcumin can inhibit angiogenesis by preventing proliferation and migration of endothelial cells. It also suggestes that curcumin is one kind of specific inhibitors of angiogenesis.