Recent Advancements in Enhancing Antimicrobial Activity of Plant-Derived Polyphenols by Biochemical Means

Abstract

Plants are a reservoir of phytochemicals, which are known to possess several beneficial health properties. Along with all the secondary metabolites, polyphenols have emerged as potential replacements for synthetic additives due to their lower toxicity and fewer side effects. However, controlling microbial growth using these preservatives requires very high doses of plant-derived compounds, which limits their use to only specific conditions. Their use at high concentrations leads to unavoidable changes in the organoleptic properties of foods. Therefore, the biochemical modification of natural preservatives can be a promising alternative to enhance the antimicrobial efficacy of plant-derived compounds/polyphenols. Amongst these modifications, low concentration of ascorbic acid (AA)–Cu (II), degradation products of ascorbic acid (DPAA), Maillard reaction products (MRPs), laccase–mediator (Lac–Med) and horse radish peroxidase (HRP)–H2O2 systems standout. This review reveals the importance of plant polyphenols, their role as antimicrobial agents, the mechanism of the biochemical methods and the ways these methods may be used in enhancing the antimicrobial potency of the plant polyphenols. Ultimately, this study may act as a base for the development of potent antimicrobial agents that may find their use in food applications.

Antimicrobial Quantitative Relationship and Mechanism of Plant Flavonoids to Gram-Positive Bacteria

“…To better apply the antimicrobial quantitative relationship in practice, the main relationships between the lipophilicity (LogP) and the structure of the plant flavonoids, together with their consistency with some of the structure–activity relationships of the reported plant flavonoids [ 7 , 8 , 13 , 14 , 15 , 16 , 17 ], are presented in Table 4 , in which some novel structure–activity relationships are also proposed. As everyone knows, the lipophilicity is influenced by many factors, such as the molecular structure and the pH environment, and the former also includes various substituent groups and their positions, etc.…”

“…These are completely consistent with the experimental MICs reported [ 8 , 18 ] and can be considered as novel structure–activity relationships of plant flavonoids against Gram-positive bacteria ( Table 4 ). It is likely that the above are responsible for the confused, unsystematic, and even contradictory structure–activity relationships (SARs) of the plant flavonoids [ 7 , 8 , 13 , 14 , 15 ], especially for the effect of hydroxyls at the structural skeletons and their methylations on the antibacterial activities of the plant flavonoids. Moreover, the numbers and subclasses of plant flavonoids used for the establishments of most reported SARs are different and limited, which might be another reason for the confused and even contradictory SARs.…”

“…Among them, plant flavonoids have received close attention [ 8 , 9 , 10 , 11 , 12 ]. Some of their structure–activity relationships against bacteria were summarized in various degrees [ 7 , 8 , 13 , 14 ], together with some sporadic ones [ 15 , 16 ]. In addition, the quantitative structure–activity relationship (QSAR) analyses for 30 prenylated (iso)flavonoids against Listeria monocytogenes and Escherichia coli were performed, respectively, with an accuracy of 71–88% [ 17 ].…”

“…In addition, the quantitative structure–activity relationship (QSAR) analyses for 30 prenylated (iso)flavonoids against Listeria monocytogenes and Escherichia coli were performed, respectively, with an accuracy of 71–88% [ 17 ]. However, a universal and systematic conclusion remains unclear due to the extensive structural diversity of plant flavonoids, and some of the conclusions are even contradictory [ 7 , 8 , 13 , 14 ].…”

Antibacterial lignin-based nanoparticles and their use in composite materials

“…55 Their antibacterial activity has also been related to their capacity to suppress the activity of essential enzymes. 79,80 Other studies have reported their capacity to weaken the bacterial membrane, increasing the permeability of the cell. 56,57…”