| Coriaria lactone is a kind of sesquiterpene lactones extracted from plant Coriaria sinica.It has a unique picrotoxin scaffold and significant neurotoxicity. It is known as insectbehavior disruptor, antifeedant and stomach poison. Tutin is the main representative and mostactivated compound in coriaria lactone. The structure-activity relationships analyze of tutin,its toxic mechanism and structural modification have been areas of intense investigation ofcoriaria lactone. Mythimna separata is a world-wide agricultural pests with highly migratory.In this study, tutin extraction method was optimized, the derivatives of tutin and its analogueswere synthesized, and the optimal compounds were screened through the determination oftheir bioactivity. The mechanism of paralysis and growth blocking of tutin against Mythimnaseparata larva were preliminary analyzed. The SEM ultrastructure and the effect of tutinagainst Dastarcus helophoroides pericardial cells morphological analysis were carried out.The main results are as follows:1. The extraction method of tutin was optimized. This is the first time to use ultrasonicassisted extraction technology to extract tutin with ethanol as solvent from12.45Kg dryCoriaria seeds, the extraction ratio is0.53‰. The results of quadrature analysis showed that,the the optimum extraction condition is solid-liquid ratio as1︰15, in120min and50°C.The extraction temperature is the key factors to influencing the tutin ultrasonic extractionmethod.2. Structural modificationof tutin. Seven novel tutin acylation derivatives weresynthesized through addition reaction on the hydroxy at C-2of tutin. The result checkedthrought SicFinder Scholar showed that the seven derivatives are all new substances. Theantifeedant and insecticidal activity of tutin and their derivatives against M. separata weredetermined through non-chice leafdisc assay. T7,2-(2,4-dichlorobenzoyloxy)-tutin showedthe best activity among all the new compounds. The structure-activity relationship analysisshowed that, different moiety add in parent compound have different influence to theirbioactivity, and in which dichlorobenzoyl> chloronicotinoyl> methoxybenzoyl>chlorobenzoyl> nitrobenzoyl> sulfonyloxy> dinitrobenzoyl.3. Structural modification of tutin analogues. Twenty three derivatives with the lactonemoiety similar as tutin were synthesized through dehydration, addition and acylation reaction, in which contain9andrographis lactone derivatives, seven7-hydroxyl coumarin derivativesand7homoserine lactone derivatives. Novelty search through SicFinder Scholar showed thatthere are9new substances in them, while five compounds only have a CAS registry number,but have yet to be published. The activity analysis showed that15-fluorobenzylidene-14-Deoxy-11,12-didehydroandrographolide (A4d) and15-Bromoacylbenzylidene-14-deoxy-11,12-didehydroandrographolide (A4e) are the optimalcompounds of andrographolide derivatives;7-methane-sulfonyloxy-coumarine (C4) is theoptimal compound of7-hydroxycoumarin derivatives; N-(4-nitrobenzoyl)-homoserinelactone(H1) is the optimal compound of homoserine lactone derivatives.4. The growth blocking, paralysis and antifeedant activity of tutin against M. separatawere studied. The results showed that, tutin exhibited conspicuous antifeedant, paralysis andpoison activity to M. separate, and reduced the growth of larva. The growth blocking activitywas positively correlated with the toxin concentration. In vitro test, tutin significantlyaffected stretching activity of the plasma cell, and induced the immune response to testinsects. The increase of GBP gene expression may be respond for the tutin’s paralysis activityand immune response to test insects.5. The effect of tutin on the peritrophic membrane morphological features of M.separata was invealed by field emission scanning electron microscope. The results show that,tutin and its structural analogues have different levels of damaging on peritrophic membraneof M. separate in sublethal concentrations. Different compounds exhibited significantdifferences damage on peritrophic membrane. SDS-PAGE analysis showed that, tutin totallydegraded the peritrophic matrix proteins upper44.3kD in12h, while T7and A4d abundancethe proteins bands in different level. The ALDI-TOF-MS study identified6proteins thatexpressed differentially among tutin effect in12h. they are1Carboxypeptidase precursor,1troponin,2tropomyosins and2actins.6. Morphological features of pericardial cells of the different instars Dastarcushelophoroides revealed by field emission scanning electron microscopy analysis. The resultsshowed that, the dorsal vessel belongs to the straight tube, no obvious enlargement of parts andbranches, and embryonic differentiation and development, with the full functionality. |
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