Structure–Activity Relationship Studies on Derivatives of Eudesmanolides from Inula helenium as Toxicants against Aedes aegypti Larvae and Adults

An Aedes aegypti larval toxicity bioassay was performed on compounds representing many classes of natural compounds including polyacetylenes, phytosterols, flavonoids, sesquiterpenoids, and triterpenoids. Among these compounds, two eudesmanolides, alantolactone, and isoalantolactone showed larvicidal activities against Ae. aegypti and, therefore, were chosen for further structure–activity relationship study. In this study, structural modifications were performed on both alantolactone and isoalantolactone in an effort to understand the functional groups necessary for maintaining and/or increasing its activity, and to possibly lead to more effective insect‐control agents. All parent compounds and synthetic modification reaction products were evaluated for their toxic activities against Ae. aegypti larvae and adults. Structure modifications included epoxidations, reductions, catalytic hydrogenations, and Michael additions to the α,β‐unsaturated lactones. None of the synthetic isomers synthesized and screened against Ae. aegypti larvae were more active than isoalantolactone itself which had an LC₅₀ value of 10.0 μg/ml. This was not the case for analogs of alantolactone for which many of the analogs had larvicidal activities ranging from 12.4 to 69.9 μg/ml. In general, activity trends observed from Ae. aegypti larval screening were not consistent with observations from adulticidal screening. The propylamine Michael addition analog of alantolactone was the most active adulticide synthesized with an LC₅₀ value of 1.07 μg/mosquito. In addition, the crystal structures of both alantolactone and isoalantolactone were determined using CuK_α radiation, which allowed their absolute configurations to be determined based on resonant scattering of the light atoms.     

土木香化学成分的研究

采用硅胶柱色谱、制备薄层色谱、制备高效液相、葡聚糖凝胶SephadexLH-20等方法进行分离纯化,根据光谱数据进行结构鉴定。从乙醇提取物中分离得到了8个化合物,分别鉴定为：异土木香内酯（1）,11,13-二氢异土木香内酯（2）,土木香内酯（3）,β-谷甾醇（4）,3-hydroxy-11,13-dihydroisoalantolactone（5）,macrophyllilae-toneE（6）,HIS-12-en-18-H-3-O-β-D-glucopyranoside（7）,caffeic acid anhydride（8）。化合物7和8系首次从该属植物中分离得到。