*2.1. Flavonoids*

Flavonoids, such as catechins, flavones, and flavonols, have antifungal, antiviral, and antibacterial activities [21]. The antimicrobial activity of the flavonoid quercetin is attributed to the inhibition of the enzyme DNA gyrase and (-)-epigallocatechin gallate, which was reported to inhibit the energy metabolism [21]. Flavonoids, especially catechins and proanthocyanidins (due to antioxidant properties), have been proposed to neutralize bacterial toxic factors originating from *Vibrio cholerae*, *Staphylococcus aureus, Vibrio vulnificus, Bacillus anthracis, Clostridium botulinum* [22]. The citrus flavonoids, such as apigenin, kaempferol, quercetin, and naringenin, are effective antagonists of cell–cell signaling [23]. Recent reviews have provided lines of evidences on the antimicrobial activity of plant flavonoids along with their mechanism of actions [24,25].
