# Structural Alterations of Human Erythrocytes Induced by Minocycline

## TL;DR

Minocycline causes structural changes in red blood cells, which may affect their oxygen transport function and should be considered in long-term use.

## Contribution

The study reveals minocycline's effect on erythrocyte morphology and hemoprotein stability, suggesting new insights into its non-antibacterial side effects.

## Key findings

- Minocycline induces surface structure changes in erythrocytes, including spherulation and outgrowths.
- The antibiotic stabilizes hemoprotein spatial organization without increasing methemoglobin formation.
- Molecular docking confirms minocycline binds to heme pocket amino acid residues.

## Abstract

The non-antibacterial effects of the tetracycline antibiotic minocycline on human erythrocytes are currently under investigation. Our data indicate alterations in the surface structure of erythrocytes; the antibiotic promotes the redistribution of cellular transformational forms during preliminary in vitro incubation (1 h and 24 h) with the modifier. The degree of surface relief changes increases over time, leading to the formation of erythrocytes displaying outgrowths and ridges, spherulation, and “deflated ball”-shaped cells (after 1 day). These alterations are largely reversible, as washing the erythrocyte suspensions with a 1% bovine serum albumin solution reduces the number of echinocytes and irreversibly transformed spherocytes with spikes. Spectrophotometric analysis has shown that minocycline stabilizes the spatial organization of hemoprotein molecules, as it does not lead to increased methemoglobin formation in the samples over time. The antibiotic appears to bind primarily to amino acid residues within heme pockets, as confirmed by molecular docking. Our findings suggest a potential risk of reduced oxygen transport function in red blood cells when taking this antibiotic, highlighting the need to consider potential erythrocyte-related side effects during long-term minocycline therapy.