Antibacterial Activity of Plant Polyphenols

Abstract

This chapter focuses on methods of polyphenol isolation and on the antibacterial activity of different polyphenols found in herbs, spices, fruits and vegetables. Polyphenols are secondary metabolites which protect plants from different pathogens, such as viruses, bacteria, fungi, insects, and herbivores. Currently, about 9000 polyphenols found in more than 480 plants are known. Their amount fluctuates across different species and varieties. This chapter describes conventional and novel methods for extraction, the influence of the type of solvents, solvent concentration and temperature on the yield. The highest yield is obtained at 70% of methanol and ethanol, and at 90% of acetone. Extraction at 80°C leads to higher amounts of polyphenols than extraction at 100°C. Polyphenols are usually metabolized in the human liver but can also remain unaffected as they pass through the gastrointestinal tract. The main location for their uptake is the colon. They exhibit a wide range of antibacterial activity against Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus epidermidis, Klebsiella pneumoniae, E. coli, Listeria monocytogenes, Acinetobacter sp., Proteus sp., Micrococcus sp., and Bacillus sp. All these plants, rich in antimicrobial polyphenols, represent a promising and powerful source of highly effective novel antibacterial substances in the current era of ubiquitous antibiotic resistance.

Biosensors Based on Phenol Oxidases (Laccase, Tyrosinase, and Their Mixture) for Estimating the Total Phenolic Index in Food-Related Samples

“… Some types of biological (pharmacological) activities of plant phenolic compounds [ 2 , 3 , 5 , 6 , 7 , 8 , 9 , 10 ]. …”

“…Flavonoids are the largest class of phenolic compounds and include major flavonoids (2-phenylbenzopyrans), isoflavonoids (3-benzopyrans), neoflavonoids (4-benzopyrans), and minor flavonoids [ 4 ]. Currently, the number of phenolic substances is about 9000 [ 5 ], of which more than 6500 compounds fall on the share of flavonoids, and it is assumed that the number of the latter may exceed 8000 [ 4 ].…”

“…Phenolic compounds of plant origin have antioxidant, anti-inflammatory, anticancer, antiviral, antibacterial, antifungal, antidiabetic, cardioprotective, hepatoprotective, neuroprotective, and other effects in vitro and/or in vivo [ 2 , 3 , 5 , 6 , 7 , 8 , 9 , 10 ] ( Figure 1 ). This enables us to look at plant phenolic compounds as potential therapeutic agents against pathological conditions and human diseases caused by oxidative stress, pathogens, inflammation, and aging.…”

“…There are two analytical approaches to characterize the phenolic status of a sample: (1) measuring the concentration of individual phenolic compounds, and (2) estimating the total phenolic content (TPC). The first approach is a complex task, since about 9000 plant phenolic compounds have been identified so far [ 5 ]. The second approach is less laborious and can be recommended for the qualimetric evaluation of complex multicomponent samples in routine analyses.…”

Diversity and Mechanisms of Action of Plant, Animal, and Human Antimicrobial Peptides

“…Antibacterial activity of AMP/polyphenol-containing vegetables (inhibition zone d in mm) against B. subtilisand E. coli-type strains[52].…”