Legume and cereal defence metabolites as lead compounds for novel antimicrobials : production, analysis, and structural modification

Abstract

Secondary metabolites from plants include those that function as defence compounds, which often possess antimicrobial activity. These metabolites can be valuable for the food and pharmaceutical industries, as natural food preservatives and leads for new antimicrobial compounds, respectively. The main aim of this research was to explore the antimicrobial potential of defence metabolites from peanut and cereals. Prenylated stilbenoids can be produced by germination of peanuts with simultaneous fungal elicitation. We demonstrated that some of these compounds possess good antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The results also indicated that dimeric prenylated stilbenoids could be even more potent than their monomeric precursors. A systematic approach to the mass spectrometric characterisation of defence metabolites in wheat and oat led to a more complete overview of the chemical diversity in these species. This facilitates more accurate quantification of the total content of benzoxazinoids and avenanthramides in wheat and oat, respectively. Contrary to peanuts and other legumes, fungal elicitation did not enhance the quantity or diversity of metabolites formed in cereals during germination. A literature review revealed that monomeric natural benzoxazinoids lack antimicrobial potency. Synthetic derivatives with a 1,4-benzoxazin-3-one backbone were much more potent than natural analogues. QSAR studies on the antimicrobial activity of 1,4-benzoxazin-3-ones and in silico drug design showed the potential of this backbone for the development of novel antimicrobial drugs.