5. ANTIBIOSIS AND ANTIBIOTICS
279
relations between molecular structure and biological activity
(161,162a).
The biosynthesis of cephalosporin C is stimulated, rather specifically, by
D-methionine (162b).
Alazopeptin is an anticancer agent produced by Streptomyces griseoplanus in which two moles of DON (XXXIV) are associated with one of
alanine.
Other antibiotics of low molecular weight involving one or more
amide bonds are, for example, netropsin (XXXIX), produced by several
streptomycetes; lycomarasmine (XL) (162c) which is an analog and
antagonist (produced by Fusarium lycopersici) of the growth factor
H 2 N.
^NH
^C—NH—CH 2 — C'
HN'
V
NH
LJ-CO-NH
"N
I
CH.
1
i
I
CH 3
-CO—NH—CH 2 —CH 2 —C'
Λ*Η 2
H 2 N V
O^
HO v
>C—CH 2
Netropsin
(XXXIX)
CH a
I
C- CH—NH—CO - CH 2 —NH- C— COOH
I
OH
a-hydroxyg ^
alanine
Lycomarasmine
(XL)
Ο Ν
HN^ Ν
C—Ν
Η
I
CH,
CH 2
I
HN^NH,
asparagine
Noformicin
(XLI)
streptogenin, a tripeptide containing glutamic acid and glycine; noformicin (XLI) from Nocardia formica; nocardamine (XLII) from a species
of Nocardia resembling N. flavescens (163a); eulicin (XLIII) from a species of Streptomyces resembling S. parvus; and amidinomycin (XLIV)
from Streptomyces sp.
The four closely related streptomycete-produced antibiotics: holomycin (S. griseus), thiolutin (S. albus, S. celluloflavus), aureothricin (S.
thioluteus, S. farcinicus, S. celluloflavus, S. cyanoflavus), and isobutyropyrrothine (Streptomyces sp.) have a common nucleus, holothin (XLV),
which is obtainable from acid hydrolysis of holomycin and has some