Table 3 Antimicrobial (MIC) and hemolytic (MHC) activities of AR-23 and its analogues against Gram-negative bacteria and human erythrocytes.

From: Design of an α-helical antimicrobial peptide with improved cell-selective and potent anti-biofilm activity

Peptides

MIC (μM)a

GMb (μM)

MHCc (μM)

TId

Folde

E. coli

P. aeruginosa

K. pneumoniae

melittin

12.5

6.25

6.25

7.87

0.78

0.1

 

RV-23

6.25

6.25

6.25

6.25

6.25

1

 

AR-23

25

12.5

12.5

15.75

3.12

0.2

1

A(A1R)

12.5

6.25

12.5

9.92

3.12

0.31

1.55

A(A8R)

12.5

12.5

12.5

12.5

3.12

0.25

1.25

A(I17K)

25

25

50

31.5

50

1.59

7.95

A(I17R)

12.5

12.5

25

15.75

25

1.59

7.95

A(A1R, A8R)

6.25

6.25

6.25

6.25

6.25

1

5

A(A1R, I17K)

25

12.5

25

19.84

100

5.04

25.2

A(A8R, I17K)

25

25

25

25

100

4

20

A(A1R, A8R, I17K)

12.5

12.5

12.5

12.5

200

16

80

A(A1R, A8R, I17R)

12.5

12.5

12.5

12.5

100

8

40

  1. aMinimum inhibitory concentrations (MIC) were determined as the lowest concentration of peptide that prevented visible turbidity.
  2. bThe geometric mean (GM) of the peptide MICs against all four bacterial strains was calculated.
  3. cMHC is the minimum haemolytic concentration that caused 10% haemolysis of human red blood cells (hRBC). When no detectable haemolytic activity was observed at 100 μM, a value of 200 μM was used to calculate the therapeutic index.
  4. dTherapeutic index (TI) is the ratio of the MHC to the geometric mean of MIC (GM). Larger values indicate greater cell selectivity.
  5. eFold is the TI of analogue changes compared with AR-23.
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