structure and among penicillin derivatives of identical side-chain but different nuclear structure. inverse relation to their molecular weights. The penicillins and biological activity also have R2 side chains attached to the thiazine ring. Factors .. [14C JPG isotope for at least 7 months (Table 4). Analysis of. The cephalosporins are a class of β-lactam antibiotics originally derived from the fungus Only the frequency of these reactions vary, based on the structure. of the side chains (e.g., first generation cephalosporins are similar to penicillins), Fourth-generation cephalosporins, however, have true broad-spectrum activity. penicillin antibiotics, SAR of Penicillins, Classification, Degradation.
Has gram positive potency against susceptible Staphylococci, Streptococci. More acid stable then Penicillin G. Administered by oral route.
SAR of PENICILLIN |authorSTREAM
Has electronegative oxygen on the acyl side chain with electron withdrawing effect which has the ability to solve acid sensitivity.
Has no electron withdrawing group on the side chain. Acid sensitive and has to be injected. Steric shields can be added to penicillins to protect from penicillinase enzyme.
Cephalosporin - Wikipedia
Bulky groups on the side chain prevent the penicillinase enzyme to reach the penicillinase active site. The isoxazolyl ring acts as the steric shield but It is also electron-withdrawing giving the Structure acid stability.
Ring acts as steric shield and also a electron withdrawing group giving acid stability to the structure. Susceptable to degradation of penicillins. Better absorbed through gut wall due to presence of hydroxyl goup.
Same spectrum of activity as that of penicillin G but more active against gram— ve bacteria.
Acid resistant hence given orally. Synthesis of Penicillins from 6-APA: Peptidoglycan cell wall N-acetylglucosamine N-acetylmuramic acid Transpeptidases located within the cell membrane are responsible for cross linking the Peptidoglycan chains Transpeptidases Penicillin Binding Proteins In order to make the rigid grid, There is an enzyme called Transpeptidase,which connects the Little peptide strings perpendicular to the NAM and NAG chains.
Has negligible antibacterial activity. Given with Penicillins which increases spectrum of activity.
Microbial resistance to beta lactam antibiotics. Isolated from Streptomyces clavuligerus. Prepared by partial chemical synthesis from penicillins. Has little or no antibacterial activity.
Diphtheria, tetanus, gas gangrene. Intra abdominal infection, syphilis. E ar, nose, lungs infections. Drug of choice for Anthrax, Trench mouth, Rat bite fever, Actinomycosis. Currently, some Citrobacter freundiiEnterobacter cloacaeNeisseria gonorrhoeaeand Escherichia coli strains are resistant to cephalosporins.
Some Morganella morganiiProteus vulgarisProvidencia rettgeriPseudomonas aeruginosaand Serratia marcescens strains have also developed resistance to cephalosporins to varying degrees.
Cephalosporins are sometimes grouped into "generations" by their antimicrobial properties. The first cephalosporins were designated first-generation cephalosporins, whereas, later, more extended- spectrum cephalosporins were classified as second-generation cephalosporins. Each newer generation has significantly greater Gram-negative antimicrobial properties than the preceding generation, in most cases with decreased activity against Gram-positive organisms.
Fourth-generation cephalosporins, however, have true broad-spectrum activity.
For example, the fourth generation of cephalosporins is not recognized as such in Japan. Cefmetazole and cefoxitin are classed as third-generation cephems. Flomoxef and latamoxef are in a new class called oxacephems. This continues to be the preferred spelling in the United States, Australia, and New Zealand, while European countries including the United Kingdom have adopted the International Nonproprietary Nameswhich are always spelled "cef-".