| Andrographolide,a naturally diterpene lactone,is isolated from the roots and rhizomes of Andrographis paniculata.It shows antitumor,anti-inflammatory,antimicrobial,and insecticidal activities.To explore the relationship between the structures and insecticidal/acaricidal activities of andrographolides,a series of 12-amino substituted derivatives of 14-deoxyandrographolide were prepared.Their insecticidal/acaricidal activities were tested against Mythimna separata and Tetranychus cinnabarinus.Some results were obtained as follows:1.Thirty compounds（23 new compounds）were synthesized,including 10 intermediates and 20 target compounds,and characterized by 1H NMR,HRMS,mp and optical rotation.2.The insecticidal activity was evaluated at 1 mg/m L against the pre-third-instar larvae of M.separata by the leaf-dipping method.Compounds 2b,2c,3a,IIb-d and IIIc exhibited more promising activity with the final mortality rates（FMRs）greater than 50%（andrographolide:37.9%;toosendanin:44.8%）.Some treated larvae appeared poisoning symptoms such as dehydration and curled up,some malformed and dead pupae also appeared,and some malformed moths were also found.3.The acaricidal activity was evaluated at 0.5 mg/m L against the female adult of T.cinnabarinus.Compounds 3a,Ic and IVb exhibited more promising activity with 72 h MRs greater than 35%（MR of andrographolide:14.4%）.Especially compound Ic(LC50:0.4513mg/m L)showed more than 10 times potent than andrographolide(LC50:5.1451 mg/m L).The preliminary structure-activity relationship showed introduction of the aldehyde acetal at its C-3 and C-19 positions could improve the insecticidal/acaricidal activities;especially introduction of butyraldehyde acetal improved the insecticidal activity;and introduction of benzylamine or 4-chlorobenzylamine on its C-12 position improved the acaricidal activity.It will lay the foundation for structural modification o f andrographolide as pesticidal agents. |
PDF Full Text Request