Antimicrobial Activity of Natural Polyphenols

This paper deals with the antimicrobial activity of different polyphenols in fruits, vegetables, herbs, spices, and honey. Polyphenols are secondary metabolites which protect plants from different pathogens, such as viruses, bacteria, fungi, insects, and herbivores. They are divided into two main groups: simple phenols and phenolic acids. Flavonoids represent one of the most abundant groups of polyphenols. Polyphenols are usually metabolized in the human liver but can also remain unaffected as they pass through the gastrointestinal tract. They undergo certain biochemical transformations in the colon under the action of specific lactobacilli and bi¬fidobacteria. Polyphenols are detected in numerous plants - olives, tomatoes, peppers, parsley, onion, garlic as well as in honey. Their amount differs significantly across different species and varieties. This landscape anal¬ysis of scientific literature summarizes the antibacterial, antiviral and antifungal activity of polyphenols. Poly¬phenolic extracts obtained at 80ºC show higher antibacterial activity compared to those extracted at 100ºC, while methanolic extracts possess greater activity than ethanolic ones. Selected herbs, fruits and vegetables rich in antimicrobial polyphenols are a source of highly effective novel antimicrobial substances.