SYNTHESIS AND PHYTOTOXIC PROFILE OF A NEW TETRAOXANE DESIGNED FROM A COMMERCIAL AUXIN

Modern agriculture relies on the massive use of agrochemicals, including herbicides. Despite their effectiveness, a continuous use of herbicides sharing the same target has resulted in the selection of weed biotypes resistant to such chemicals. To cope with this problem, the development of new herbicides is an urgent requirement. In this work we applied the Active compound Derivatization Method (ADM) strategy to develop a new tetraoxane (5), derived from the synthetic auxin 2-(naphtalen-1-yl)acetic acid (NAA). Greenhouse bioassays showed that 5 caused chlorosis, necrosis and leaf epinasty in Cucumis sativa. Furthermore, this compound, at the concentration of 1.25 x 10-5 mol L-1, inhibited the growth of important weeds such as Bidens pilosa, Iponomea acuminate, Solanum americanum and Althernantera ficoidea. For some weeds, the compound effect was higher or comparable to those caused by commercial glyphosate and imazethapyr. In addition, degradation studies revealed that 5 is transformed into NAA. The results also showed that 5 could act as photosynthesis inhibitor and as an auxin herbicide. In summary, we have discovered a new compound that may be a useful lead for the development of a commercial herbicide.现代农业高度依赖包括除草剂在内的农用化学品的大规模施用。尽管此类药剂除草效果显著，但持续使用作用靶点相同的除草剂，已筛选出对这类化学品具有抗药性的杂草生物型。为应对这一抗药性难题，开发新型除草剂已是迫切需求。本研究采用活性化合物衍生法（Active compound Derivatization Method, ADM）策略，以合成生长素2-(萘-1-基)乙酸（NAA）为母核结构，开发出一种新型四氧烷类化合物（编号5）。温室生物测定结果表明，化合物5可使栽培黄瓜（Cucumis sativa）出现褪绿、坏死及叶片偏上性生长等典型症状。此外，在1.25×10^-5 mol·L^-1浓度下，该化合物可显著抑制多种重要杂草的生长，包括三叶鬼针草（Bidens pilosa）、尖叶打碗花（Ipomoea acuminata，原文为Iponomea acuminate）、美洲龙葵（Solanum americanum）以及莲子草属物种（Alternanthera ficoidea，原文为Althernantera ficoidea）。针对部分杂草，该化合物的除草效果优于或等同于商用除草剂草甘膦（glyphosate）与咪唑乙烟酸（imazethapyr）的防治效果。此外，降解代谢研究表明，化合物5可在生物体内转化为NAA。研究结果同时显示，化合物5可兼具光合作用抑制剂与生长素类除草剂的双重作用机制。综上，本研究发现了一种新型化合物，其有望成为商业化除草剂开发的优质先导化合物。