Scientific Research in School Volume 3 Issue 1 2021
Antibacterial activity and degradation pathways of methallyl isothiocyanate Ollie Bacon Barker College Methallyl isothiocyanate is an analogue of the well-researched antibacterial agent allyl isothiocyanate, found in plants belonging to the Brassicaceae family. Candidacy of methallyl isothiocyanate as an alternative antibacterial agent was investigated. The antibacterial activity of methallyl isothiocyanate was determined by testing multiple concentrations of the compound against K-12 E. coli achieved through serial dilutions. The compound was found to not display activity at the experimental concentrations. Multiple explanations for this are provided including an insufficient range of concentrations used for testing and structural differences between methallyl isothiocyanate and allyl isothiocyanate. Chemical degradation pathways of methallyl isothiocyanate are proposed based on literature inquiring into the decomposition of allyl isothiocyanate in water. Literature review Between 2001 and 2013, 107 bacterial toxin-mediated outbreaks were confirmed in Australia, affecting 2,219 people with 47 hospitalisations and 13 deaths occurring (May, Polkinghorne & Fearnley, 2016). The true number of outbreaks is likely higher due to underreporting which is common for bacterial infections. From this incident, 48% of outbreaks resulted from commercial food services inadequately controlling the temperature of environments where food was stored and handled (May, Polkinghorne & Fearnley, 2016), making conditions favourable for bacterial growth. Bacterial infections which are contracted by humans from eating or handling contaminated food are treated with the use of antibiotics. Over time, bacterial strains can develop favourable DNA mutations which render currently used antibiotic drugs ineffective, demonstrating the natural process of antibiotic resistance. The misuse of antibiotics through unnecessary or incorrect consumption is causing the rapid development of antibiotic resistance, thus reducing the ability to treat common bacterial infections (World Health Organisation, 2020). This will likely lead to a significant increase in global deaths if new antibacterial agents are not developed. Antibiotic resistance is therefore one of the largest threats to global health and as such, more effective methods of treating bacterial infections must be explored (World Health Organisation, 2020). One cause of bacterial infection is Escherichia coli (E. coli) which presents a significant danger to public health despite certain strains being used in laboratories. This is
due to the wealth of knowledge surrounding this organism, the ability to be easily genetically modified and being considered as biologically safe vehicles for propagation of various genes and vectors (Kuhnert, Nicolet & Frey, 1995). In 2011, Shiga toxin-producing E. coli strains (STEC) were the cause of an outbreak in Germany in which 3,842 cases of human infections were recorded (Beutin & Martin, 2012) with person to person and foodborne transmission being the most effective mode of pathogen spread. Other unrelated STEC outbreaks highlight the ability of a wide variety of wild, domestic and captive animals to act as reservoirs for zoonotic pathogens (Kim, Lee & Kim, 2020).
Figure 1:General chemical structure of isothiocyanate functional group. R represents the glucosinolate side chain which varies between each ITCs.
As technological advances and the trend of mass production for maximised profit continue, human activities which result in the contamination of water sources and animal products will require new methods to mitigate the effects of these pathogens (Kim, Lee & Kim, 2020). One such method will include the development of novel antibacterial agents (Munita & Arias, 2016) in order to combat a future with increased antibiotic resistance.
Science Extension Journal • 143
