ABSTRACT
Aims@#Many plants and their derivatives are widely used in food manufacturing because of their biological activities. They play a significant role as food additives to control microbial growth and the occurrence of oxidation reactions. Syzygium malaccense L. is a well-known plant with biological activities such as antimicrobial and antioxidant activities. Thus, the aims of this study were to evaluate the toxicity of the ethanolic leaves extract of S. malaccense and to study its antibacterial mode of action.@*Methodology and results@#The toxicity assessment of S. malaccense leaves extract was determined using the brine-shrimp larvae model. The action mechanisms against bacterial membrane were determined by studying the intracellular material leakage by means of nucleic acid (DNA and RNA) release, crystal violet dye uptake and cellular protein leakage. The present findings proved the extract's safety as indicated by a high dose of 7.402 mg/mL for lethal concentration (LC50) against brine-shrimp larvae. On the other hand, the ethanolic extract caused a severe membrane permeability towards all the tested bacteria as indicated by the increased intracellular material leakage in a concentration-dependent manner.@*Conclusion, significance and impact of study@#The current study provides valuable information regarding the safety and antibacterial action mechanism of S. malaccense ethanolic leaves extract, thus paving the way for its utilization as a natural preservative in a wide range of food products.