Research On Synthesis And Properties Of Isothiocyanates And Their Biologyical Activity Against The Harmful Pests

This paper took isothiocyanates compounds which were isolated and identified from the horseradish plant as the starting target compounds, and modified and designed their structure of side-chain, synthesized 5 series 42 isothiocyanates compounds, then studied their spectroscopy characters and activities against the pests. Specific studies are as follows:1, The types of target compounds are as follows:I) Aliphatic isothiocyanates and thiocyanates(12)II) Aromatic isothiocyanates (10)III) Isothiocyanate-N-phenyl-propylene imine (7)IV) Acyl isothiocyanates (5)V) Substituted pyrazole aminopropionitrile isothiocyanates (8)Among them,15 compounds of types III and V are the first reported new compounds.2, The fumigation activities of the two types compounds (I and II) were tested on stored-product pests and the stomach and contact toxicity activities of the four types compounds (Ⅰ,Ⅱ,ⅢandⅣ). were tested on Plutella xylostella(L.). The results are as follows:(a) EITC and AITC, which have strongest fumigation activity on the main storage pests such as Sitophilus zeamais, Rhizopertha dominica and Tribolium castaneum, were selected from the aliphatic and aromatic isothiocyanates compounds. Under the concentration of 3μg/ml the indoor rearing warehouse pests can be fully controlled by AITC or EITC such as Sitophilus zeamais, Rhizopertha dominica, Tribolium castaneum(b)The fumigation results of AITC on grain pests are as follows:Under the concentration of 22g/m3 (weight/volume), pests(Sitophilus zeamais, Rhizopertha dominica, Tribolium castaneum, Cryptolestes ferrugineus) can effectively be controlled by airtight fumigation warehouse for 30 days, which were existing in the different layers of wheat; Under the concentration of 5 g/m3AITC(weight/volume), the storage pests which were existing in space above the wheat layers can effectively be controlled by airtight fumigation for 30 days.(c)In a simulated empty warehouse, different proportions of AITC and EITC mixtures were used to fumigate pests, the results showed that when a combination of the mixtures in a ratio of 5:1, The CTC values for Rhizopertha dominica, Sitophilus zeamais, Tribolium castaneum were respectively 307.84,163.39,174.82. The LC50 values were significantly lower than those treated by either AITC or EITC alone. In the simulant laden warehouse with the depth of 18cm, the optimal proportion composition was applied from the bottom of the simulant laden warehouse. As a result, the CTC values for Sitophilus zeamais, Rhizopertha dominica, Tribolium castaneum were different in different depths, where Sitophilus zeamais and Rhizopertha dominica were more sensitive than Tribolium castaneum. The CTC values for Sitophilus zeamais and Rhizopertha dominica were about 200 and for Tribolium castaneum was about 150.(d) The stomach toxicity activities and contact toxicity activities of four types compounds (Ⅰ,Ⅱ,ⅢandⅣ) were tested on Plutella xylostella(L.) (3rd generaion larvae). The activties of these compounds was not very high, when a base compound with the isothiocyanate group and the adjacent electron transfer capacity group, its biological activity on Plutella xylostella was significantly reduced, such as acyl isothiocyanate, p-nitrophenyl isothiocyanate, and so on. When combined with the adjacent isothiocyanate-based group with a strong electron-donating group of compound, its biological activity on Plutella xylostella was enhanced, such as p-toluene isothiocyanate, ethyl isothiocyanate and so on.3, Biological activity of the isothiocyanates compounds against the root-knot nematode in vitro and efficiency of the isothiocyanates compounds in vivo were researched. According to the elementary trials, Allyl isothiocyanate, propylene acyl isothiocyanate and ethyl isothiocyanate were selected from above compounds, which all show strong fumigation activities on 2nd generation nematodes. In pot experiments efficiency of AllylITC or AcITC on M. javanica were similarly to, or better than metam sodium, at their recommended doses.4, Biological activity of the isothiocyanates compounds against plant pathogens in vitro and efficiency of the isothiocyanates compounds against Penicillium and Botrytis cinerea in vivo were studied. Isothiocyanates compounds demonstrated strong fumigation activties against the nine kinds of pathogens. Overall, the optimal compound was AITC. When ratio of AITC:EITC was 3:1, the combination of the mixtures was more efficient at controlling P. expansum and B. cinerea than other combinations or either AITC or EITC alone. The optimized combination showed the lowest EC50 values, at 0.08 and 0.14μg/ml air, for P. expansum conidial germination and mycelial growth, respectively, and 0.07 and 0.12μg/ml air for B. cinerea conidial germination and mycelial growth, respectively. Artificially infected apples were exposed for 4 days to an ITC-enriched atmosphere. Among the ITCs tested, AITC, EITC, and their combinations reduced mildew by more than 85% after 3-4 days of apple incubation at 20℃. 5, Biological activities of typeⅤon weed were studied. It was the first report that eight substituted pyrazole aminopropyl isothiocyanates compounds were synthesized by combining substituted pyrazole ring with ammonia propyl isothiocyanates. Biological activities Eight compounds above and other two kind isothiocyanates compounds were tested on the weeds. Substituted pyrazole ring aminopropyl isothiocyanates have shown a certain extent of herbicidal activity on the four kinds of weeds, but the effect of AITC with fumigation activity on weeds is not obvious.Finally, toxicity tests of AITC were studied by Pesticide Toxicology Medical College Center, Huazhong University of Science and Technology.1) 95% AITC active compound acute toxicity test results:SD rats on the acute oral toxicity are moderate poisoning;SD rats on the acute dermal toxicity are low toxicity;Rabbit skin irritation/corrosion test, a moderate irritant;Rabbit eye irritation/corrosion test, not eyewash circumstances, a moderate irritant, eyewash circumstances, mild irritation;Guinea pig skin sensitization (allergic reaction) their sensitization rate is 0%, skin allergic reaction I level, is a weak allergen.2) 20%AITC preparation acute toxicity test resultsSD rats on the acute oral toxicity are low toxicity;SD rats on the acute dermal toxicity are low toxicity;Rabbit skin irritation/corrosion test, are mildly irritating;Rabbit eye irritation/corrosion test belong to moderate irritant;Guinea pig skin sensitization (allergic reaction) their sensitization rate is 0%, skin allergic reaction I level, is a weak allergen.