Screening and enhancement of the antimicrobial activity of some plant oils using liposomes as nanoscale carrier

Background Liposomes have the ability to enclose hydrophilic or lipophilic materials. Bioactive macromolecules become more stable when they are entrapped within liposomes resisting environmental changes, allowing maintenance of the antimicrobial molecules and increasing their effectiveness and constancy thus can be used for food preservation. The aim of this study was to screen food samples for microbial contamination and to examine the antimicrobial activity of selected six ready-made plant oils which were; clove, black seed, thyme, garlic, rosemary and green tea against the isolated microbes from food samples and other selected microbes. Also to examine the possible enhancement of the antibacterial property of clove oil and tetracycline versus Escherichia coli when they were encapsulated into distearoyl phosphatidylcholine (DSPC) liposomes as a nanoscale carriers. Results of the antimicrobial action measured by minimum inhibitory concentration revealed that all six oils had antimicrobial action when facing at least one of the tested microbes. However only clove oil could inhibit the growth of all tested microbes. Moreover encapsulation of clove oil into DSPC liposomes enhanced its antibacterial action by 10 times when examined to inhibit the growth of E. coli. Also the antibacterial activity of liposome encapsulated tetracycline was improved by 8 times. Results of characterization of formulated clove oil liposomes by measuring their Zeta potential and their sizes implying that clove oil might be enclosed within the hydrophobic portion of the two layers of the liposome. Analyzing data of Fourier Transform Infrared Spectroscopy showed that clove oil was detected in the interfacial area of the liposome. Analyzing results of Differential scanning calorimetry and measuring phase transitions suggested that liposomes encapsulating clove oil had a membrane fluidization effect. Conclusion Some plant oils like clove has antimicrobial activity which enhanced with liposomal encapsulation and thus reduces the needed concentration to give the desired actions.