Cinmethylin

DCPA inhibits the growth of grass species by dismpting the mitotic sequence, probably at entry (190). DCPA influences spindle formation and function (181) and causes root-tip swelling (182) and britde shoot tissue (191). It has been reported that DCPA, like colchicine and vinblastine, attests mitosis at prometaphase and is associated with formation of polymorphic nuclei after mitotic arrest (192). Pronamide also inhibits root growth by dismpting the mitotic sequence in a manner similar to the effect of colchicine and the dinitroanilines (193,194). Cinmethylin and bensuhde prevent mitotic entry by unknown mechanisms (194). 

Cinmethylin and cloma2one [81777-89-1] are used for selective pre-emergence control and etholumesate [26225-79-6] for selective pre- and post-emergence weed control (2,296). 

Endothall is a structural analogue of cantharidin (Fig. 20). Its mode of action is apparently inhibition of protein phosphatase(s). A struc-ture/activity relationship study demonstrated that the presence of the oxygen bridge and the location of the two carboxylic groups play important roles in the activity of the molecules. The unusual 7-oxabicyclo[2.2.1]heptane ring of endothal is similar to that of cinmethylin, another natural product-like herbicide for which the mode of action has also eluded scientists for many years. 

GraysonBT, Webb JD, Factors offecting the performance and crop phytotoxicity of a new rice herbicide, cinmethylin. 1. Effects of water depth and soil type on the distribution and uptake of anmethylin by transplanted and direct-seeded rice,... 

The rice herbicides cinmethylin (Figure 2.23), mefenacet (Figure 2.24) and daimuron and methyldymron (Figure 2.25) also interfere with meristematic activity in susceptible species. 

DiTomaso, J. M. and Duke, S. O. 1991. Is polyamine biosynthesis a possible site of action of cinmethylin and artemisinin . Pestic. Biochem. Physiol. 39, 158-167... 

Figure 2. Effect of 1,4-cineole (circles), cis-2-hydroxy-1,4-cineole (triangles) and the commercial herbicide cinmethylin (squares) on the activity of asparagine synthetase from lupin. The dotted line represents 50% inhibition of enzyme activity.

Figure 5. Gene expression of cinmethylin-treated vs. control arabidopsis seedlings. The gray spots in the center of the plot represent genes which remain unchanged in the control and treated samples. Darker spots indicate genes that are at least 2-fold induced or repressed by 0.0165 pM cinmethylin.

The herbicide cinmethylin has been reported to be derived Irom the monoterpene backbone of the cineole class of natural products. Indeed, cinmethylin is identical to 1,4-cineole, with the addition of a benzyl ether moiety that was added to lower the volatility of the natural product. Cinmethylin was in fact developed by Shell Chemical during a biorational synthetic program to discover new insecticides that targeted the glycerol-3-phos-phate shuttle. A phytotoxic dioxalane intermediate was identified. Optimization of the monocyclic structures led to rigid bicyclic structures with improved herbicidal activity. Some of the bicyclic structures possessed the basic backbone of the monoterpene cineoles found in nature. 

Vaughn, S.F. and Spencer, G.F. (1996) Synthesis and herbicidal activity of modified monoterpenes structurally similar to cinmethylin. Weed Sci. 44, 7-11... 

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