農藥化學結構與生物活性關係之探討

The Structure-activîty Relationship (SAR) between Pesticides and Their Biological Efficacies

陳家鐘(C. C. Chen)

《中華民國雜草學會會刊》 17卷2期 (1996/12) Pp. 89-100

https://doi.org/10.6274/WSSROC-1996-017(2)-089

摘要

農藥之主成份化學結構與其生物活性之間的關係相當地重要也引起廣泛的注意，生物學家和化學家們均在想從其中的道理做出更具高藥效的農藥。對於農藥的水溶解性、酸鹼性、吸附脫附性及官能基變異性已有大量的研究報告發表，其中殺蟲劑裡的除蟲菊精便是已被研究得相當透徹。除蟲菊精的基本化學類別是酯類，亦即其可以分為酸類部份及醇類部份來討論。酸類部份通常含有一個環丙烷，其上帶有甲基、不飽和取代基及羧基，有一些除蟲菊精可以不必含有環丙烷的基本結構而能維持良好的生物活性，但一般而言，在酸類部份上加上鹵素有助於生物活性之提高。醇類部份通常為酚基苯甲基醇，在甲基上附上氰基可大幅提高生物活性，酚基也必須固定在苯甲基之第三位置上。整個除蟲菊精的酯類結構上，可以有三個不對稱之碳中心，因而混合了八個立體異構物，這八個異構物中僅有一個具有高藥效，其他七個皆屬低藥效或無藥效之分子，可見立體之排列在生物活性上佔著重要的地位。除蟲菊精分子中間銜接的部份若由酯類轉為酮類、醚類或醯胺類，會使生物活性降低，所牽涉的因素，包括了分子兩部份之間的間距，分子極性的變化和分子內部電子密度分佈之不同，均足以使除蟲菊精改變其生物活性。化學結構與生物活性之關係，雖然已有很多的研究，但是因為生物系統的複雜性，使得必須加入的因子比科學家所能做的要多。到如今，現有的數據及心得仍不足以使科學家從面資料去準確地預測新分子的生物活性，人們仍然須從事傳統式的溫室或田間生物試驗去肯定一個藥劑的生物活性。

關鍵字

除蟲菊精 ； 殺蟲劑 ； 立體異構物 ； 生物活性 ； 取代基 ； 酯類 ； 酸類 ； 醇類 ； 酮類 ； 醚類 ； 醯胺類

並列摘要

The structure-activity relationship (SAR) between pesticides and their biological efficacies has been an important subject in the past decades. Many works were done on the study of water-octanol partition, acidity and functional group variation of pesticides. Special attention on the SAR review of the synthetic pyrethroids is brought up in this paper to emphasize its importance as an insecticide. The basic structure of pyethroid as an ester is consisted of a carboxylic acid moiety and an alcohol moiety which can be considered separately. The acid moiety usually includes a cyclopropyl unit connecting to an olefinic group. Variations of functional groups on this moiety results in largely different bioefficacy of the pyrethroids. The alcohol moiety usually involves a phenoxybenzyl alcohol. Change in functional group on this moiety also alter the biological activity, but not as drastically as the acid moiety. Enantiomeric nature on these two moieties is very important. Only the isomer of the right configuration shows-high biological activity. Other structural isomers usually have very low bioefficacy. The center link between these two moieties is also critical. Alternation from ester functional group into others may result in lower activity. It is believed that linkage such as ketone, ether and amide causes decreased activity due to the change of the spatial arrangement of the pyrethroid molecule. The SAR study provides some assistances for chemists and biologists to understand the biological performance of chemical substances. It will help researchers reduce the effort and time in the discovery of new pesticide compounds. However, the SAR still can not completely explain and predict the complicated biological nature among the plants, insects, fungi and chemical compounds. The traditional green house screenings and the field tests are still needed to confirm the biological activity of a chemical compound.

並列關鍵字

SAR ； pyrethroid ； insecticide ； moiety ； enantiomer ； bioefficacy ； functional group ； configuration ； ester ； acid ； alcohol ； ketone ； ether ； amide