# Morphological and Chemical Changes in the Trophozoites and Cysts of Acanthamoeba Castellanii Induced by Camellia Sinensis Extracts

## TL;DR

This study shows that Camellia sinensis extracts can kill Acanthamoeba castellanii by disrupting its cell structure and inhibiting protein and nucleic acid synthesis.

## Contribution

The study provides new insights into the amoebicidal effects of Camellia sinensis through detailed morphological and chemical analysis.

## Key findings

- Camellia sinensis extract disrupts nuclear membrane integrity and causes chromatin degradation in Acanthamoeba trophozoites.
- FTIR analysis indicates inhibition of protein synthesis in treated Acanthamoeba castellanii.
- Exposure to Camellia sinensis reduces DNA and RNA levels, leading to trophozoite death.

## Abstract

Acanthamoeba castellanii is an important opportunistic human protozoal pathogen that can cause both skin, ocular and brain infections. Recent studies have established that brews and solvent extract (SE) of green tea (Camellia sinensis) can inhibit the growth and encystation of A. castellanii. Here we characterized those growth and encystation inhibitions.

Herein, we characterize of the morphological and chemical changes that occur in the trophozoites and the encysting stage of A. castellanii after exposure to C. sinensis SE and brew using Transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) microspectroscopy and fluorescence-based assays.

TEM showed ultrastructural changes in both A. castellanii stages. FTIR microspectroscopy revealed modifications of amide I and II band peaks in the C. sinensis-treated trophozoites, suggesting an inhibition of protein synthesis. Assessment of the nucleus integrity of trophozoites exposed to SE and brew revealed disruption of the nuclear membrane integrity, nuclear fragmentation, and chromatin degradation, and reduction in the quantity of DNA and RNA, indicating trophozoite death. These results are consistent with C. sinensis acting as a membrane-active anti-acanthamoebic, exhibiting amoebicidal activity against growing and encysting A. castellanii. This work underlines the importance of characterizing the effect of C. sinensis constituents, individually or in combinations, to clarify which ones are the primary components responsible for its action and the observed alterations in the structure and function of A. castellanii.

These results demonstrated that exposure to C. sinensis SE or brew alters the synthesis of protein, DNA, RNA and disrupts the cell wall integrity.

The online version contains supplementary material available at 10.1007/s11686-024-00941-9.