# Molecular Aspects of Tannin-Anthelmintic Interactions as Revealed by NMR Spectroscopy

## TL;DR

This study uses NMR to explore how plant tannins interact with anthelmintic drugs, revealing differences in binding mechanisms.

## Contribution

The study reveals novel molecular interaction patterns between polyphenols and anthelmintics using NMR spectroscopy.

## Key findings

- Flavan-3-ols and tannins interact with anthelmintics via hydrogen bonding and hydrophobic effects.
- Polyphenols showed stronger interactions with thiabendazole than with ivermectin.
- NMR chemical shift changes indicate specific interaction sites on the compounds.

## Abstract

The interactions
between plant polyphenols and commercial anthelmintics
remain largely unexplored, despite the benefits of understanding these
interactions for mitigating anthelmintic resistance. This study investigated
the interactions of flavan-3-ols, dimeric proanthocyanidins, and selected
hydrolyzable tannins with two anthelmintics, ivermectin (IVM) and
thiabendazole (TBZ), at various polyphenol to anthelmintic molar ratios
using nuclear magnetic resonance (NMR) spectroscopy. Chemical shift
changes (Δδs), indicating interaction,
were observed for specific regions of the compounds and at all polyphenol
to anthelmintic molar ratios. For IVM interactions with polyphenols,
downfield Δδs were observed and were
primarily associated with hydroxyl groups within the structures of
the anthelmintic and polyphenols, suggesting that the interactions
involved hydrogen bond formation. For TBZ interactions with polyphenols,
however, both upfield and downfield Δδs were observed, suggesting that both hydrogen bonding and hydrophobic
interactions were involved. All of the studied polyphenols interacted
more strongly with TBZ than with IVM.