There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Bacteriocins and their position in the next wave of conventional antibiotics.

Acacetin, a flavone with diverse therapeutic potential in cancer, inflammation, infections and other metabolic disorders.

A review of the biological activity and pharmacology of cryptotanshinone, an important active constituent in Danshen.

Isoliquiritigenin (ISL) and liquiritigenin (LTG) are structurally related flavonoids found in a variety of plants. Discovery of novel antimicrobial combinations for combating methicillin-resistant Staphylococcus aureus (MRSA) infections is of vital importance in the post-antibiotic era. The present study was taken to explore the in vitro and in vivo combination effect of LTG and ISL with β-lactam antibiotics (penicillin, ampicillin and oxacillin) against mec A-containing strains of MRSA. Minimum inhibitory concentration (MIC) of both LTG and ISL exhibited significant anti-MRSA activity (50-100 µg/mL) against clinical isolates of MRSA. The result of in vitro combination study showed that ISL significantly reduced MIC of β-lactam antibiotics up to 16-folds [∑ fractional inhibitory concentration (FIC) 0.312-0.5], while LTG reduced up to 8-folds (∑FIC 0.372-0.5). Time kill kinetics at graded MIC combinations (ISL/LTG + β-lactam) indicated 3.27-9.79-fold and 2.59-3.48-fold reduction in the growth of clinical isolates of S. aureus respectively. In S. aureus-infected Swiss albino mice model, combination of ISL with oxacillin significantly (p < 0.05, p < 0.01, p < 0.001) lowered the systemic microbial burden in blood, liver, kidney, lung and spleen tissues in comparison with ISL, oxacillin alone as well as untreated control. Considering its synergistic antibacterial effect, we suggest both ISL and LTG as promising compounds for the development of novel antistaphylococcal combinations. Copyright © 2016 John Wiley & Sons, Ltd.

Drug Resistance Reversal Potential of Isoliquiritigenin and Liquiritigenin Isolated from Glycyrrhiza glabra Against Methicillin-Resistant Staphylococcus aureus (MRSA).

Cryptotanshinone (CT), a major tanshinone of medicinal plant Salvia miltiorrhiza Bunge, demonstrated strong antibacterial activity against clinic isolated methicillin and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) in this experiment. The CT was determined against clinic isolated MRSA 1–16 with MIC and MBC values ranging from 4 to 32 and 8 to 128 μg/mL; for MSSA 1-2 from 16 to 32 μg/mL and 64 to 128 μg/mL; for VRSA 1-2 from 2 to 4 μg/mL and 4 to 16 μg/mL, respectively. The range of MIC50 and MIC90 of CT was 0.5–8 μg/mL and 4–64 μg/mL, respectively. The combination effects of CT with antibiotics were synergistic (FIC index ) against most of tested clinic isolated MRSA, MSSA, and VRSA except additive, MRSA 4 and 16 in oxacillin, MRSA 6, 12, and 15 in ampicillin, and MRSA 6, 11, and 15 in vancomycin (FIC index < 0.75–1.0). Furthermore, a time-kill study showed that the growth of the tested bacteria was completely attenuated after 2–6 h of treatment with the 1/2 MIC of CT, regardless of whether it was administered alone or with ampicillin, oxacillin, or vancomycin. The results suggest that CT could be employed as a natural antibacterial agent against multidrug-resistant pathogens infection.

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Synergistic Effect between Cryptotanshinone and Antibiotics against Clinic Methicillin and Vancomycin-Resistant Staphylococcus aureus

Methicillin-restitant Staphylococcus aureus (MRSA) is very dangerous bacteria and one of
the most feared nosocomial germs. In this study, acacetin was evaluated against
20 clinical isolates of MRSA, either alone or in combination with antibiotics.
The acacetin exhibited a good activity against isolates MRSA with MICs/MBCs
ranged between 10-80/20-160 μg/mL, for ampicillin 64-1024/128-2048 μg/mL, and for oxacillin 8-32/16-64 μg/mL. The combination of acacetin plus
oxacillin or ampicillin was reduced by ≥4-fold against isolates MRSA tested, evidencing a
synergistic effect as defined by a FICI of ≤0.5. Furthermore, a
time-kill study evaluating the growth of the tested bacteria was completely
attenuated after 2-5 h of treatment with the 1/2 MIC of acacetin,
regardless of whether it was administered alone or with oxacillin (1/2 MIC) or
ampicillin (1/2 MIC). In conclusion, acacetin exerted synergistic effects when
administered with oxacillin or ampicillin and the antibacterial activity and
resistant regulation of acacetin against clinical isolates of MRSA might
be useful in controlling MRSA infections.

/pdf/combination-of-acacetin-with-antibiotics-against-methicillin-2o08gv8pcl.pdf

Sung-Mi Choi

Papers

Synergistic Effect between Cryptotanshinone and Antibiotics against Clinic Methicillin and Vancomycin-Resistant Staphylococcus aureus

Combination of Acacetin with Antibiotics against Methicillin Resistant Staphylococcus aureus Isolated from Clinical Specimens