Configurational Relationship between Substituents on Cyclopropane Ring of Pyrethroids and Their Insecticidal Toxicity

Several methyl-substituted cyclopropanecarboxylates were prepared and their steric configurations were established. The insecticidal activity against the housefly of their 5-benzyl-3-furylmethyl esters were tested. Among the substituents on cyclopropane ring, cis-methyl group to ester linkage has been found to be the most essential part for toxicity and trans-methyl and trans-isobutenyl groups greatly enhance its toxic activity.     

A New Cytotoxic Carbazole Alkaloid and Two New Other Alkaloids from Clausena excavata

One new carbazole alkaloid, excavatine A ( 1 ), and two additional new alkaloids, excavatine B ( 2 ) and excavatine C ( 3 ), were isolated from the stems and leaves of Clausena excavata Burm .f. (Rutaceae). Their structures were determined on the basis of detailed spectroscopic analyses, especially 2D‐NMR and HR‐EI‐MS data. Compounds 1 – 3 were tested for their cytotoxic activities against A549, HeLa, and BGC‐823 cancer cell lines, and for their antimicrobial activities against Candida albicans and Staphylococcus aureus. Only 1 exhibited cytotoxicity against A549 and HeLa cell lines with the IC₅₀ values of 5.25 and 1.91 μg/ml, respectively.