Influence of Pyranose and Spacer Arm Structures on Phloem Mobility and Insecticidal Activity of New Tralopyril Derivatives.

Yu Zhou,Zhi Lei,Ying Zhang,Wen Yang,Hui Liu,Mao Yang,Yao Chen

doi:10.3390/molecules22071058

Abstract

Six new conjugates were designed and synthesized by introducing glucose, methyl glucuronate or glucuronic acid moieties on tralopyril. Phytotoxicity and phloem mobility results demonstrated that the introduction of glucose, methyl glucuronate or glucuronic acid moieties can simultaneously solve the tough phytotoxicity problem and phloem mobility transformation of tralopyril. Conjugates 12 and 18 containing the glucuronic acid moiety exhibited higher phloem mobility than conjugates 9, 11, 15 and 17. Conjugates 15, 17 and 18 with methoxymethyl groups on the tralopyril pyrrole nitrogen atom showed activity against Plutella xylostella, while conjugates 9, 11 and 12 with a methene group on the pyrrole N showed no activity. Cabbage roots were incubated in a buffered solution containing conjugates 15, 17 and 18 at 4 mM for 72 h. Only 18 showed systemic insecticidal activity with 100% mortalityagainst P. xylostella, while 15 and 17 showed lower activity andchlorfenapyr showed no activity. The glucuronic acid promoiety imparted more phloem mobility to tralopyril than glucose and methyl glucuronate. The methoxymethyl group bond on the tralopyril skeleton was the key factor in determining the insecticidal activity of the conjugates. A promising systemic proinsecticide containing glucuronic acid and tralopyril moieties was proposed.

Highlights

For various practical reasons insecticides with phloem mobility are preferred for pest species hidden on unpredictable non-exposed plant parts, such as growing tips, roots, inside leaf deformations, and galls
Conjugates that share structural similarities should be designed and synthesized in order to accurately compare the differences in phloem mobility impartedby glucose, methyl glucuronate and glucuronic acid moieties to tralopyril
These results indicated that the introduction of the three different sugar promoieties could impart. These results indicated that the introduction of the three different sugar promoieties could impart phloem mobility to tralopyril

Summary

Introduction

For various practical reasons insecticides with phloem mobility are preferred for pest species hidden on unpredictable non-exposed plant parts, such as growing tips, roots, inside leaf deformations, and galls. There are very few existing synthetic insecticides with phloem mobility. Attempts have been made to achieve phloem-mobile insecticides by introducing a carboxyl group [2,3], amino acid [3], or sugar [4,5] into the parent compounds of existing non-phloem-mobile types. Three research groups have focused on the addition of a sugar moiety [4,5,6,7,8,9]. In 1995, Hsu et al described a phloem-mobile pronematicide to solve the inherent incompatibility between phloem mobility transformation and activity loss by structural modification of pesticides [4]

Methods

Results

Conclusion