High Value-Added Use of Citrus Industrial Wastes in Agriculture: Semisynthesis and Anti-Tobacco Mosaic Virus/Insecticidal Activities of Ester Derivatives of Limonin Modified in the B Ring

Abstract

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 3a, 3b, 4m, 4n, 6, and 7 were determined by X-ray crystallography. It demonstrated that the molar ratio of 3a (7α-isomer) and 3b (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 4aa 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.

High Value-Added Application of Natural Plant Products in Crop Protection: Construction and Pesticidal Activities of Piperine-Type Ester Derivatives and Their Toxicology Study

“…36 Then, in the presence of NaBH 4 , aldehyde 2 was reduced to compound 3. 31 Finally, a series of piperine-type ester derivatives (4a−z and 4a′−c′) were obtained in 45−83% yields by a reaction of compound 3 with carboxylic acids RCO 2 H. 37 Their structures were all determined by mp, IR, 1 H NMR ( 13 C NMR), and high-resolution mass spectrometry (HRMS).…”

Construction, Pesticidal Activities, Control Effects, and Detoxification Enzyme Activities of Osthole Ester/Amide Derivatives

“…Recently, diverse sets of andrographolide esters ( I ), limonin esters ( II ), osthole-type esters ( III ), and podophyllotoxin amides ( IV ) were prepared as pesticide candidates (Figure ), some of which showed better insecticidal activity than their corresponding precursors. Especially, (2′ E ,4′ E )-( para -chlorophenylcarbonyl)­oximinylosthole, a derivative of C-8 oxime esters of osthole ( V , Figure ), displayed better insecticidal and acaricidal activities than osthole .…”

Semisynthesis and Pesticidal Activities of Novel Cholesterol Ester Derivatives Containing Cinnamic Acid-like Fragments

“…In addition, several cholesterol oxime esters containing cinnamic acid-like fragments ( 1′ ) have shown promising insecticidal activities [ 14 ]. Nowadays, due to the extensive and irrational use of chemical insecticides resulting in pest resistance and ecological environment problems, the research and development of new pesticides for crop protection is highly desirable [ 15 , 16 , 17 , 18 ]. Because of the characteristics of natural secondary metabolites as an unparalleled source of bioactive products, currently, the study of natural product-based insecticides as an important alternative to classic agrochemicals has received much attention [ 19 , 20 , 21 ].…”