Assessing the Efficiency of Antimicrobial Plant Extracts from Artemisia afra and Eucalyptus globulus as Coatings for Textiles

Abstract

This study aimed to assess the antimicrobial activities of plant extracts from <i>Artemisia afra</i> and <i>Eucalyptus globulus</i> when used as coatings for textiles. A pulsed ultrasound-assisted extraction method (PUAE) was employed to obtain methanolic and hexanoic extracts from both plants. <i>Eucalyptus globulus</i> methanol extraction exhibited the highest yield at 22.76% (±0.61%), while <i>Artemisia afra</i> demonstrated lower yields. Phytochemical screening identified various secondary metabolites in the extracts, including phenols, quinones, and steroids. Antimicrobial tests against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> revealed varying degrees of susceptibility, with <i>Eucalyptus globulus</i> hexanoic extracts showing the highest activity against <i>Staphylococcus aureus</i> at an average percentage growth of 18.74% (±0.26%). Minimum inhibitory concentration (MIC) values were determined for the extracts, but complete inhibition did not occur at concentrations below 500 μg/mL. The extracts exhibited varying effects on <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> growth, with some extracts promoting bacterial growth. Coating textiles with <i>Eucalyptus globulus</i> methanolic extracts demonstrated antibacterial activity against <i>Staphylococcus aureus</i> with the highest zone of inhibition observed in cotton-coated samples (258.4 mm²). Polyester-coated samples exhibited smaller inhibition zones, with the lowest observed in <i>Eucalyptus globulus</i> methanolic extract coating (65.97 mm²). Scanning electron microscope (SEM) analysis revealed visible surface morphology changes in coated fabrics, depicting fine, cluster, lumpy, flaky, and fragment-like morphologies. Laundering effects on coated fabrics were investigated, showing a significant decrease in antimicrobial activity after washing. Fourier-transform infrared spectroscopy (FTIR) identified functional groups in the extracts associated with antimicrobial properties. The complexity of the bioactive compounds suggests potential antimicrobial efficacy, resting on factors such as geographical location, climate, and extraction methods. Notwithstanding the limitations, this study contributes valuable insights into the use of plant extracts as antimicrobial coatings for textiles.