Chemistry Reference
In-Depth Information
72
73
3.7.2 Monobactams
Tabtoxin (
72
) is a simple monobactam biotoxin produced by
Pseudomonas
syringae
var.
tabaci
. This compound acts by inhibiting glutamine synthetase
activity; however, the toxin is a less potent herbicide than is bialaphos.
Antibiotic 1233A (
73
) is a monobactam produced by
Scopulariopsis candida,
Cephalosporium
sp., and
Fusarium
sp. It is a potent phytotoxin that inhibits the
3-hydroxy-3-methylglutaryl coenzyme A synthetase.
3.7.3 Herbicidal Lactones
Cyanobacterin (
74
) (diaryl-substituted
γ
-lactone) has a chlorine in one of its
aromatic rings. It is produced by the cyanobacterium
Scytonema hofmanni
and
is a potent inhibitor of cyanobacteria, green algae, and higher plants. The her-
bicide functions via an inhibition of the Hill reaction when p-benzoquinone,
K3[Fe(CN)6], dichlorophenolindophenol, or silicomolybdate are used as electron
acceptors. Cyanobacterin inhibits O
2
-evolving photosynthetic electron transport
in all plants. The most probable site of action is photosystem II.
3.7.4 Herbicidal Macrolides
Herbimycin (
75
) is a new benzaquinoid ansamycin herbicidal agent produced by
S. hygroscopicus
. It is a broad-spectrum herbicide against both monocotyledonous
and dicotyledonous weeds and is particularly effective against
Cyperus microiria
STEUD. Herbimycin irreversibly and selectively inhibits tyrosine kinases by
74
