Tetracyclines 四环素andChloramphenicol氯霉素
Tetracyclines 四环素 and Chloramphenicol 氯霉素
1.TETRACYCLINESThe first tetracycline was obtained in 1948 from a StreptomycesbacteriumTetracyclines are broad-spectrum antimicrobial drugsThey enter into cells by a mechanism not present in the cells ofmammals2
2 1. TETRACYCLINES The first tetracycline was obtained in 1948 from a Streptomyces bacterium Tetracyclines are broad-spectrum antimicrobial drugs They enter into cells by a mechanism not present in the cells of mammals
Mechanism of Action of TetracvclinesaminoAAribosomeacidAAAAtransferantiRNAAAcodon(tRNA)anticodoncodoncodonPAmessengerRNA(mRNA)Tetracyclines四环素类bindreversiblytothe3ossubunit,andcompetewithtRNAfortheAsite.Theyarethereforebacteriostatic细菌抑制的drugs3
3 Mechanism of Action of Tetracyclines Tetracyclines 四环素类 bind reversibly to the 30S subunit, and compete with tRNA for the A site. They are therefore bacteriostatic 细菌抑制的 drugs
Entry into BacteriaTetracyclines enter intogram(-) bacteria by passivediffusionthroughtheporinsGram +ofthe outermembrane,thickcellwallandbyactivetransport主动扩散throughtheinnermembrane of both gram(+)Gram-and gram(-) bacteriathin cell wallcomplexoutermembraneATP国ADPporinsOur cells do not have that transport mechanism
4 Entry into Bacteria Tetracyclines enter into gram(-) bacteria by passive diffusion through the porins of the outer membrane, and by active transport 主动 扩散 through the inner membrane of both gram(+) and gram(-) bacteria Our cells do not have that transport mechanism
Molecular Structures of TetracyclinesCHaCH3OHN(CH3)2HCH.OHOHHOHCONH,OHICONH20OHOHOOH00OHOHdoxycyclineTetracyclineTetracyclines arebig,fluorescent,lipophilic,moleculesDoxycycline强力霉素andminocycline二甲胺四环素aremorelipophilicthantetracycline5
5 Molecular Structures of Tetracyclines Tetracyclines are big, fluorescent, lipophilic, molecules Doxycycline 强力霉素 and minocycline 二甲胺四环素 are more lipophilic than tetracycline