Table 4.
Antimicrobial activity of quercetin 3,4′-diglucoside and quercetin 4′-monoglucoside.
| Species | Strain Origin | Quercetin 4′-Monglucoside b | Quercetin 3,4′-Diglucoside b | ||
|---|---|---|---|---|---|
| Gram-Positive Bacteria | MIC | MBC | MIC | MBC | |
| Staphylococcus aureus | ATCC 29213 | >300 | >300 | >200 | >200 |
| Staphylococcus aureus | Clinical/MRSA | >300 | >300 | >200 | >200 |
| Enterococcus faecalis | ATCC 29212 | 150 | >300 | 200 | >200 |
| Streptococcus pyogenes | ATCC 19615 | >300 | >300 | >200 | >200 |
| Listeria monocytogenes | ATCC 19111 (1/2a) | >300 | >300 | >200 | >200 |
| Bacillus cereus | Food | >300 | >300 | >200 | >200 |
| Gram-Negative Bacteria | |||||
| Escherichia coli | ATCC 25922 | >300 | >300 | >200 | >200 |
| Klebsiella pneumoniae | ATCC 13883 | >300 | >300 | >200 | >200 |
| Yeast | MIC50 | MIC90 | MIC50 | MIC90 | |
| Candida albicans | ATCC 90029 | 300 | >300 | >200 | >200 |
| Mould | |||||
| Aspergillus niger | Food | 150 | >300 | 200 | >200 |
b Quercetin 4′-monoglucoside (c = 1.5 mg/mL) was tested in the concentration range of 300 to 0.3 µg/mL, while in the case of quercetin 3,4′-diglucoside (c = 1 mg/mL) the concentration range was 200 to 1.9 µg/mL. MIC—minimum inhibitory concentration, MBC—minimum bactericidal concentration.