College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi Province, China.
School of Marine Sciences, Ningbo University, Ningbo 315211, Zhejiang Province, China.
J Agric Food Chem. 2020 Nov 4;68(44):12241-12251. doi: 10.1021/acs.jafc.0c05588. Epub 2020 Oct 26.
Globally, the citrus industry produces various wastes, which contain a great deal of limonoids. In order for the sustainable development of the citrus industry, and considering the diverse bioactivities of limonoids, a series of ester derivatives were constructed by structural modification of limonin in the B ring. Furthermore, two seven-membered lactone derivatives of limonin and obacunone with a novel skeleton in the B ring were obtained by the Baeyer-Villiger oxidation rearrangement. The steric structures of six key compounds , , , , , and were determined by X-ray crystallography. It demonstrated that the molar ratio of (7α-isomer) and (7β-isomer) depended on the mixed solvents in the reduction system. The anti-tobacco mosaic virus (TMV) activities under three different modes of action for most of the tested compounds were as the following sequence: inactivation effect > protection effect > curative effect. It was noteworthy that compound displayed the most potent anti-TMV/insect growth inhibitory activities, which indicated that the introduction of the phenylacryloyloxy group at the C-7β position of limonin could significantly improve its agricultural biological activities. This study will pave the way for future value-added application of citrus industrial wastes and provide strong evidence for the discovery of sustainable biopesticides based on limonoids.
全球范围内，柑橘产业产生了各种废物，其中含有大量的柠檬苦素。为了实现柑橘产业的可持续发展，同时考虑到柠檬苦素的多种生物活性，通过对 B 环中环型结构的修饰，合成了一系列柠檬苦素的酯类衍生物。此外，通过 Baeyer-Villiger 氧化重排反应，得到了 B 环中具有新型骨架的柠檬苦素和obacunone 的两个七元内酯衍生物。通过 X 射线单晶衍射确定了六个关键化合物 、 、 、 、 、 的立体结构。结果表明，（7α-异构体）和（7β-异构体）的摩尔比取决于还原体系中的混合溶剂。大多数测试化合物的三种不同作用模式下的抗烟草花叶病毒（TMV）活性顺序如下：失活作用>保护作用>治疗作用。值得注意的是，化合物 表现出最强的抗 TMV/昆虫生长抑制活性，这表明在柠檬苦素的 C-7β 位置引入苯丙烯酰氧基基团可以显著提高其农业生物活性。本研究将为柑橘工业废物的增值应用铺平道路，并为基于柠檬苦素的可持续生物农药的发现提供有力证据。
