Condensed tannins act as anthelmintics by increasing the rigidity of the nematode cuticle

Abstract

Tannins and tanniferous plant extracts have been discussed as sustainable means for helminth control in the past two decades in response to a dramatic increase of resistances towards standard anthelmintics. While their bioactivities have been broadly investigated in vitro and in vivo, less is known about their mode of action in nematodes, apart from their protein binding properties. In the current study we therefore investigated the impact of a phytochemically well characterized plant extract from Combretum mucronatum, known to contain procyanidins as the active compounds, on the model organism Caenorhabditis elegans. By different microscopic techniques, the cuticle was identified as the main binding site for tannins, whereas underlying tissues did not seem to be affected. In addition to disruptions of the cuticle structure, molting defects occurred at all larval stages. Finally, an increased rigidity of the nematodes’ cuticle due to binding of tannins was confirmed by force spectroscopic measurements. This could be a key finding to explain several anthelmintic activities reported for tannins, especially impairment of molting or exsheathment as well as locomotion.

Anthelmintic Activity of Ethanolic and Aqueous Extracts of Khaya grandifoliola Stem Bark against Heligmosomoides polygyrus: In Vitro and In Silico Approaches

“…Subedi [ 42 ] suggests that the tannins in K. senegalensis extract may be the cause of the anthelmintic activities observed in vitro. According to Greiffer et al [ 43 ], tannin binding caused an increase in the stiffness of the worms' cuticle. This could be a crucial discovery to explain a number of anthelmintic behaviours linked to tannins, including inhibition of motility and molting or exsheathing.…”

Environmental impact of phytobiotic additives on greenhouse gas emission reduction, rumen fermentation manipulation, and performance in ruminants: an updated review

“…Phytobiotic additives, particularly those with high polyphenol content (e.g., tannins and flavonoids), triterpenoids, and saponin, have anthelmintic effects by forming complexes with protein in the rumen and increasing amino acid absorption by the small intestine (Tchetan et al 2022 ), which improves host homeostasis and immunomodulatory of the host against various parasites (Min et al 2003 ). Given their protein-binding capability, it appears probable that tannins possess a broad-spectrum action rather than targeting specific components, enabling them to effectively combat various structures within nematodes (Greiffer et al 2022 ). In addition to their nematicidal effects, tannins also demonstrate other anthelmintic activities, such as the inhibition of egg hatch, suppression of larval motility, and prevention of larval exsheathment (Spiegler et al 2017 ).…”

Promising Anthelmintic Properties of Papaya (Carica Papaya) Extract: A Literature Study

“…In helminths, the cuticle is an easy target for macromolecules, such as tannins. The activity of tannins decreased worm motility due to reduced cuticle flexibility and a direct effect on components of the extracellular matrix and muscles (18). In addition, tannins caused lysis of the worm membrane due to the destruction of membrane proteins (16).…”