Biomedical Engineering Reference
In-Depth Information
TABLE 25.4
Cephalosporins
O
X
R
1
C
NH
N
O
R
2
COOH
R
1
R
2
HOOC
CH
(CH
2
)
3
CH
2
OC
3
O
Cephalosporin C
NH
2
CH
2
OC
3
O
Cefalotin
CH
2
S
N
N
N
N
N
2
Cefazolin
CH
2
S
CH
3
N
S
N
CH
2
Cefaloridine
CH
2
S
N
N
CH
2
S
N
CH
OH
Cefamandole
N
CH
3
C
N
OC
O
NH
2
CH
2
O
Cefuroxime
OCH
3
N
N
CH
2
S
N
CH
N
Cefonicid
OH
SO
3
H
N
N
CH
2
CH
2
S
N
Ceforanide
N
NH
2
COOH
In 1971 b-lactams with a methoxy group on C
7
, cephamycins, were discovered in certain
Strep tomyces
strains. This substituent is responsible for a greater resistance to b-lactamase (Table 25.5).
In the Takeda laboratories, it was discovered in 1977 that reaction of a chloracetylcephalosporin
with thiourea leads to a product with an aminothiazolylacetic acid side chain, e.g., cefotiam, which
had a very good activity especially against Gram-negative bacteria. On the other hand, the pres-
ence of an oxime group in nocardicin was the guide for the introduction of this group in cefu-
roxime, which has a good resistance against b-lactamase. These two observations were combined
in the preparation of cefotaxime. A whole series of cephalosporins with an aminothiazol side chain
are now available (Table 25.6).
