Interaction between Six Waxy Components in Summer Black Grapes (Vitis vinifera) and Mancozeb and Its Effect on the Residue of Mancozeb

Abstract

Mancozeb, an antifungal typically used for the growth of fruits, has the characteristic of non-internal absorption, and has a risk of binding to the waxy components of fruits. This work investigated the interaction of pesticide molecules with the waxy layer on the grape surface and their effects on pesticide residues in grapes. The study observed significant changes in the compositions of the waxy layer on the grape surface after soaking in a mancozeb standard solution. The six substances—oleanolic acid, ursolic acid, lupeol, octacosanol, hexacosanal, and γ-sitosterol—with discernible content differences were chosen for molecular docking. Docking results were further visualized by an independent gradient model based on Hirshfeld partition (IGMH). Hydrogen bonds and van der Waals forces were found between mancozeb and the six waxy components. Moreover, the negative matrix effects caused by the presence or absence of wax for the determination of mancozeb were different through the QuEChERS-HPLC-MS method. Compared with the residue of mancozeb in grapes (5.97 mg/kg), the deposition of mancozeb in grapes after dewaxing was significantly lower (1.12 mg/kg), which further supports that mancozeb may interact with the wax layer compositions. This work not only provides insights into the study of the interaction between pesticides and small molecules but also provides theoretical guidelines for the investigation of the removal of pesticide residues on the surface of fruits.

Multi-stimulus Response Behavior of Biomimetic Autocrine Waxy Materials for Potential Self-Constructing Surface Microstructures

“…Biomimetic autocrine waxy materials (AWMs), inspired by the renewable solid epidermal waxes of terrestrial plants, are attracting increasing attention. − Scientists have found that the waxy layer is an organic mixture consisting mainly of C 20 -C 34 aliphatic substances , and usually exhibits hydrophobic properties. , By mimicking the waxy layer in leaves, Wang et al reported a solid organogel material with a regenerable sacrificial alkane surface layer and demonstrated an important role in combating solid deposition . Some scholars have exploited the rapid autocrine ability and hydrophobicity of AWMs, and the as-prepared materials quickly and spontaneously recovered their superhydrophobicity even after being subjected to severe plasma etching .…”