Synthesis And Insecticidal Activity Of Celangulin Analogues

Various secondary metabolites are produced in the process of botanic self-defendingagainst harmful organs,even of co-evoluting between plants and their pests.Novelenvironment-friendly botanical insecticides may be derived from these secondary metabolites.Celastrus angulatus Max. has been used as folk pesticides for a very long time in China.Insecticidal component of this plant was studied deeply and widely and found to beβ-dihydroagarofuran poly-ester sesquiterpenes by the Chinese researchers since1980’s. Thetarget of these insecticidal β-dihydroagarofuran sesquiterpenes was be found in midgutepithelia of tested insect and suggested this type of sesquiterpenes may be novel digestivepoison.In this thesis Celangulin analogues were prepared with β-dihydroagarofuransesquiterpenes from Celastrus angulatus Max. as start material and the structures of all thenew compounds were confirmed by1H-NMR,13C-NMR,MS,IR spectral data or2DNMRand single crystal X-ray spectral data analyses. Insceticidal activities against3rdMythimnaseparata of these Celangulin analogues were tested. These helpful studies may lead to novelhighly active and environment-friendly botanical insecticides. The primary results are asfollows:1.Celangulin-V was isolated from the benzene extract of Celastrus angulatus Max.barkand the structure was confirmed by single crystal X-ray spectral data and corrected the wrongstructure was reported in1994by our group.70Celangulin-V derivatives including twelve6-ether derivatives,fourteen6-ester derivatives, twelve6-amino acid ester derivatives,twenty6-triazole derivatives,six twin-drug derivatives and seven others were prepared and amongthem67were the first synthesized. Insecticidal activities assayed indicated that some of themshowed the same stomach toxic effects as Celangulin-V.Compounds2-2-2,2-2-3,2-2-6,2-2-7,2-3-1,2-3-2and2-4-7showed higher activity than the possitive control Celangulin-V withKD50of135.9，101.3，169.0，219.2，266.5，217.3，231.2μg.g-1respectively and compounds2-5-14and2-7-6showed similar activity to Celangulin-V with KD50of367.5and369.7μg.g-1.2.Three sesquiterpene polyols from the hydrolysis of benzene extract of Celastrusangulatus Max. and the structures were confirmed as1β,2β,4α,6α,8β,9α,12-heptahydroxy- β-dihydroagarofuran,1β,2β,4α,6α,8α,9β,12--heptahydroxy-β-dihydroagarofuran and1β,2β,4α,6α,9α,12-hexahydroxy-β-dihydroagarofuran,Bio-assay guided diversity-orientedsynthesis lead to a insecticidal compounds library and eight new Celangulin analogues wasgotten from this library. Insecticidal activities assayed indicated that compounds3-2-2,3-2-3and3-2-4showed similar activity to Celangulin-V with KD50of912.6，521.5and593.2μg.g-1respectively.3.Thirty five β-dihydroagarofuran derivatives were prepared from the startmaterial1β,2β,4α,6α,8β,9α,12-heptahydroxy-β-dihydroagarofuran and33of them werethe new compounds. Insecticidal activities were assayed and indicated that compounds3-4-25and3-4-26showed higher activity than Celangulin-V with KD5038.2and27.6μg.g-1respectively.The results suggested that β-dihydroagrofuran should be a new lead compound for abotanical insecticide.