Antibacterial activity of flavonoids and their structure–activity relationship: An update review

Abstract

Based on World Health Organization reports, resistance of bacteria to well-known antibiotics is a major global health challenge now and in the future. Different strategies have been proposed to tackle this problem including inhibition of multidrug resistance pumps and biofilm formation in bacteria and development of new antibiotics with novel mechanism of action. Flavonoids are a large class of natural compounds, have been extensively studied for their antibacterial activity, and more than 150 articles have been published on this topic since 2005. Over the past decade, some promising results were obtained with the antibacterial activity of flavonoids. In some cases, flavonoids (especially chalcones) showed up to sixfold stronger antibacterial activities than standard drugs in the market. Some synthetic derivatives of flavonoids also exhibited remarkable antibacterial activities with 20-to 80-fold more potent activity than the standard drug against multidrug-resistant Gram-negative and Gram-positive bacteria (including Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus). This review summarizes the ever changing information on antibacterial activity of flavonoids since 2005, with a special focus on the structure-activity relationship and mechanisms of actions of this broad class of natural compounds.

Antibacterial Activity of Some Flavonoids and Organic Acids Widely Distributed in Plants

“…Flavonoids have the C 6 -C 3 -C 6 carbon structure consisting of two phenyl rings (A and B) and a heterocyclic ring (C). Generally, it was observed that at least one hydroxyl group in the ring A (especially at C-7) is vital for the antibacterial activity of flavones, and in another position such as C-5 and C-6 can increase this biological effect [85]. In this context, it is interesting to compare our results regarding the antibacterial activity of flavones with the hydroxyl groups at C-5 and C-7 (chrysin, apigenin, luteolin, and their glycosides) and flavone devoid of them.…”

Towards a new treatment against polymicrobial infections: high antibacterial activity of lemon IntegroPectin againstPseudomonas aeruginosaandEscherichia coli

“…Finally, citrus flavonoids chiefly contained in the flavedo and in the albedo are well known antibacterials. [27] Only recently the mechanism through which they inhibit P. aeruginosa biofilm formation was identified. Flavonoids possessing dihydroxyl moieties in the flavone A-ring backbone prevent LasR DNA binding due to the inhibitory action of the two hydroxyl groups, with one of them that must be at position 7 on the A-ring for potent inhibition of the aforementioned binding.…”

Polyphenols: A concise overview on the chemistry, occurrence, and human health

“…Flavonoids are classified into the following subclasses: anthocyanins, flavanols, flavanones, flavonols, flavonones, and isoflavones (Amarowicz et al, ; Kabera et al, ; Kumar & Pandey, ). A wide range of pharmacological activities, including antioxidant, antibacterial, hepatoprotective, antinflammatory, and antihyperlipidemic effect, are attributed to flavonoids (Abenavoli et al, ; Azzini et al, ; Belwal, Nabavi, Nabavi, & Habtemariam, ; D'Evoli et al, ; Farhadi, Khameneh, Iranshahi, & Iranshahy, ; Farhat, Drummond, & Al‐Dujaili, ; Iriti et al, ; Miccadei et al, ; Ninfali, Antonini, Frati, & Scarpa, ; Rasouli, Mohammad‐Bagher Hosseini‐Ghazvini, & Khodarahmi, ; Rees, Dodd, & Spencer, ; Riccio et al, ; Tungmunnithum, Thongboonyou, Pholboon, & Yangsabai, ). The term flavonoid generally indicates a phenol compound having a phenylbenzopyran chemical structure with a carbon skeleton of a C6–C3–C6 joined to a chroman ring (Pereira, Valentão, Pereira, & Andrade, ).…”