After reading “Antimicrobial activity of flavonoids extracted from bergamot(Citrus bergamia Risso) peel, a byproduct of the essential oil industry”
Before I went on my vaccation, I read this paper and I found some interesting information about flavonoids. The result of this study is that flavonoids from bergamot have antimicrobial activty agains Gram–negative bacteria but also against other microorganisms including Gram-positive bacteria, fungi and viruses.
At the intro of this paper, it says that most of flavonoids are generally glycosylated forms in plants. There were lots of flavonoids but it focused on eriodictyol, naringenin, and hesperetin which exist O-glycosylated form in bergamot but our body cannot absorb them if they are glycosylated(e.g. rutinoside forms). So to use them, we first need to deglycosylate them.
They conducted the experiment with Escherichia coli K-12 MG1655, Salmonella enterica var. Typhimurirum LT2, Pseudomonas ptida ATCC795, Bacillus subtilis ATCC6633, Listeria innocua ATCC33090, Lactococcus lactis MG1614, Staphylococcus aureus FI10139 and Saccharomyces cerevisiae NCYC505. The MICs of the bergamot extracts were determined using a Bioscreen C(Labsystems, Helsinki, Finland) and also, had experiments for FIC(to now how effective a drug is when 2 different drugs are used together; FICa= MIC of a with b/MIC of a, FIC index= FICa+FICb).
Anyway, the 3 key point of this paper is; 1) aglycones of flavonoids are more effective as antimicrobial agents(need to know why flavonoids are effective) 2) combination of flavonoids can increase antimicrobial activity but rather it could reduce it due to reactions between them 3) the most effective flavonoids were Eriodictyol, Naringenin and Hesperetin and they are usually effective to gram-negative bacteria. With these information, I found chemical structure of these compounds and right below here is how they look like.
The structure that they are sharing looks like this.
I guess this structure is related to the pharmacological effect of flavonoids above. I think I need to study more about antimicrobial agents and especially more about antibiotics but for now, my hypothesis is they can affect the synthesis of cell walls of gram-negative bacteria.