Bibenzyls and flavone glycosides from Dendrobium nobile as potential plant-derived insecticides against Acyrthosiphon pisum and Sitobion avenae.

BACKGROUND

Plant-derived natural product insecticides exhibit notable advantages over traditional chemical insecticides, including high target selectivity, enhanced biodegradability with no residual accumulation, and minimal environmental impact. These properties align with the developmental imperatives of green agriculture, establishing this field as a priority area in insecticide research and development.

RESULTS

Phenolic compounds are a crucial source of plant-derived insecticides. Twenty-four compounds, including two new bibenzyls, dendronosides A - B (1-2) and three novel flavone C-glycosides, dendronosides C - E (3-5) were isolated from Dendrobium nobile. Their structures were elucidated by spectroscopic data analysis, ECD calculations, and HPLC characterization of acid-hydrolyzed and derivatized monosaccharides. The insecticidal activity of these compounds was evaluated against Acyrthosiphon pisum and Sitobion avenae. Compound 5 not only demonstrated notable oral toxicity against A. pisum, with an LC50 value of 181.6 μg mL-1, but also exhibited remarkable repellency against A. pisum, achieving a repellency index of 1.0 at 400 μg mL-1. In A. pisum exposed to compound 5, epidermal shrinkage and mouthpart retraction are the dominant toxic symptoms observed. The insecticidal activity of compound 5 is presumably attributable to its interference with the activities of chitinase and GST. Molecular docking analyses revealed that compound 5 binds tightly to OfChtI via multiple stable hydrogen bonds, indicative of a strong binding affinity between this compound and the target enzyme.

CONCLUSION

These findings demonstrate that flavone glycosides isolated from D. nobile, especially dendronoside E (5), hold great potential as candidates in developing plant-derived insecticidal lead compounds. © 2026 Society of Chemical Industry.