Although antibiotics have saved many lives and are an essential contribution to medicine, bacteria have developed a strong resistance to them. This resistance will put many more patients at risk of death due to bacterial infection from serious, common procedures such as organ transplants and chemotherapy. The antibiotic resistance crisis is only becoming more dire due to several causes. Antibiotics are overused immensely and this increases the resistance to them. The administration and distribution of antibiotics have also greatly contributed to the antibiotic resistant strains of bacteria that are seen today, such as tuberculosis and MRSA. Antibiotics are often used agriculturally to increase yields of meat produced by livestock, but these antibiotics are transferred to humans through the consumption of these products. One solution to decrease the rate at which bacteria are growing resistant to the only method we have to fight them is to create new antibiotics. However, new antibiotics have not been developed in the last thirty-five years. Antibiotics are no longer the most profitable drug, so companies do not want to invest in the development of them. For companies that do want to invest in this, it is still a challenge, as obtaining approval for antibiotic development is difficult.
One way to combat the resistance is to use naturally derived substances, such as honey. Honey is known to contain antibacterial properties. There are many different kinds of honey and each one possesses different antimicrobial properties. In general, they can be separated into two categories, peroxide honeys and non-peroxide honeys. Hydrogen peroxide is a result of the glucose oxidase enzyme, which plays a role in the bee’s digestion of the nectar, which when treated with heat, or light may be inactive. The gluconic acid, also a result of this enzyme, contributes to the low pH of the honey, along with other acids in the substance. The low pH is also a factor in the antimicrobial property. Due to different activity levels of this enzyme, the amount of hydrogen peroxide varies by type of honey, which could account for the varying antimicrobial efficiency in peroxide honeys (Nanda, 2015). Non-peroxide honeys have other properties that make up for the lack of this property. They contain the compound methylglyoxal in very high concentrations. All honeys have this compound, but most contain a very low concentration of it, aside from non-peroxide honeys. Methylglyoxal is antibacterial and is formed from sugars when heated or stored for long periods of time. This compound is derived, specifically, from dihydroxyacetone, which is heavily concentrated in the nectar of the flowers from which non-peroxide honey is derived (Kwakman, 2011). The antibacterial component of this compound comes from the fact that it alters the structure of the bacteria, so that it cannot survive under the conditions.(Rabie, 1).
Essential oils are also known to be antibacterial. Many of the antimicrobial properties of essential oils are due to their structural components, which are largely characterized as phenols. These compounds are also found in honey. A mixture of honey and essential oils would presumably work synergistically to provide a stronger antimicrobial agent than either of the two alone, which is what this project aimed to show.
Over the course of this project, it was shown that honey and oil do, in fact, show greater antimicrobial properties when mixed. Many different types of honey and oil were tested in varying concentrations. Before mixing any substances, the honey samples were tested alone. Both peroxide and non-peroxide honeys were tested. Non-peroxide honeys exhibited a much greater inhibition of bacterial growth. This was determined through examining the zone of inhibition when the bacteria were placed on plates with the honey samples. Various oils were also tested. The oil that was shown to have the highest antibacterial resistance was cinnamon cassia. Once the best honey and oil samples were determined, they were mixed in varying concentrations in efforts to find the best antibacterial surface.
At first, when mixing the honey and oil, it was determined that another substance would have to be added in order to make a homogeneous mixture. In efforts to keep the substance natural, aloe vera gel was used to do so. Once added, the substances were able to mix due to the hydrophilic head and hydrophobic tail of the aloe. The non-peroxide honey used, which was Manuka honey, and the cinnamon cassia oil showed the most resistance to bacterial growth, so they were mixed together and showed the highest resistance out of all of the formulations. Once this was determined, the concentration of the oil was increased to see if the bacterial effect would be greater, which it was.
Now that it has been determined which surfaces work the best, we will examine various types of Manuka honey and cinnamon cassia oil. Manuka honey has something called a “manuka factor” which varies among different types/brands. This factor will be examined to determine whether a higher manuka factor will exhibit a higher resistance to bacterial growth. Cinnamon cassia oil is relatively similar among different brands, but may still vary slightly in its properties, so future elaborations of this project will examine this. Lastly, plant powders will also be added to the formulations. These powders will add to the antibacterial effect of the surfaces. The most effective pairings of all three substances will be examined.
The opportunity to conduct this research has allowed me to gain experience that I could not otherwise have obtained. I will be able to take the skills I have developed over the course of this project and apply them in my career. In the beginning of April I was able to present this research in Orlando at the American Chemical Society National Conference, which allowed me to present in a professional setting. I was also able to develop a close relationship with my mentor, Dr. Jaimelee Rizzo, as I had to consult her about my results often. Although it took a lot of time and dedication, I am grateful that I was able to conduct this research.