Saudi Journal of Biological Sciences (2015) xxx, xxx–xxx
King Saud University
Saudi Journal of Biological Sciences
www.ksu.edu.sa
www.sciencedirect.com
ORIGINAL ARTICLE
Menadione (vitamin K) enhances the antibiotic
activity of drugs by cell membrane permeabilization
mechanism
Jacqueline C. Andrade a, Maria Flaviana B. Morais Braga a,
Gláucia Morgana M. Guedes a, Saulo R. Tintino a, Maria A. Freitas a,
Lucindo J. Quintans Jr. b, Irwin R.A. Menezes a, Henrique D.M. Coutinho a,*
a
b
Universidade Regional do Cariri, Crato (CE), Brazil
Universidade Federal de Sergipe, Aracaju (SE), Brazil
Received 25 June 2015; revised 28 August 2015; accepted 1 September 2015
KEYWORDS
Menadione;
Lipid solubility;
Microdilution;
Antibiotic-modifying;
Permeabilization
Abstract Menadione, vitamin K3, belongs to the class of lipid-soluble vitamins and lipophilic
substances as menadione cause disturbances in the bacterial membrane, resulting in damage to
the fundamental elements for the integrity of the membrane, thus allowing increased permeability.
Accordingly, the aim of this study was to evaluate in vitro the antibiotic-modifying activity of
menadione in multiresistant strains of Staphylococcus aureus, Pseudomonas aeruginosa and
Escherichia coli, with a gradual increase in its subinhibitory concentration. In addition, menadione
was compared with cholesterol and ergosterol for similarity in mechanism of drug modulatory
action. Antibiotic-modifying activity and antibacterial effect were determined by the broth
microdilution assay. Menadione, cholesterol and ergosterol showed modulatory activity at clinically
relevant concentrations, characterizing them as modifiers of bacterial drug resistance, since they
lowered the MIC of the antibiotics tested. This is the first report of the antibacterial activity of
menadione and its potentiation of aminoglycosides against multiresistant bacteria.
Ó 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is
an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
* Corresponding author at: Departamento de Quı́mica Biológica,
Universidade Regional do Cariri – URCA, Rua Cel. Antonio Luis
1161, Pimenta, Crato (CE) 63105-000, Brazil. Tel.: +55 (88)31021212;
fax: +55 (88)31021291.
E-mail address: hdmcoutinho@gmail.com (H.D.M. Coutinho).
Peer review under responsibility of King Saud University.
Production and hosting by Elsevier
1. Introduction
Menadione, vitamin K3, is a synthetic compound that belongs
to the class of lipid-soluble vitamins, which is converted to
vitamin K2 in the gut (Klack and Carvalho, 2006). Lipidsoluble vitamins are organic substances present in small
amounts in foods, and they are essential to the functioning
of the body as co-factors (Paixão and Stamford, 2004). Vitamin K is a biologically active substance found in functional
foods, which is required particularly in the mechanism of
http://dx.doi.org/10.1016/j.sjbs.2015.09.004
1319-562X Ó 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article in press as: Andrade, J.C. et al., Menadione (vitamin K) enhances the antibiotic activity of drugs by cell membrane permeabilization mechanism.
Saudi Journal of Biological Sciences (2015), http://dx.doi.org/10.1016/j.sjbs.2015.09.004
2
Figure 1
Structural formulae of menadione.
Staphylococcus aureus 358
number of events
4
MIC/8
MIC/4
MIC/2
3
2
1
0
VIT K
CHOLES
ERGOST
Pseudomonas aeruginosa 03
number of events
2.5
MIC/8
MIC/4
MIC/2
2.0
1.5
1.0
0.5
0.0
VIT K
CHOLES
ERGOST
Escherichia coli 27
2.5
number of events
blood coagulation, where it is essential for the synthesis of prothrombin, besides being involved in the synthesis of proteins
present in plasma, kidney and perhaps other tissues. Some
studies on vitamin K2 have demonstrated growth inhibitory
effects against various neoplastic cells and reduced risk of
mutagenic events in rapid cell proliferation in the fetus and
newborn (Klack and Carvalho, 2006). Some studies report
that lipid-soluble compounds modulate plasma membrane
permeability in bacteria (Pretto et al., 2004; Gibbons, 2004;
Nicolson et al., 1999). Therefore, menadione with its lipidsoluble nature may cause changes in the fluidity of the bacterial membrane, making it more permeable to substances,
including antibiotics.
Cholesterol is a lipid component that is necessary for
normal functioning of the body, and it plays an important role
in the structure and function of the plasma membrane as well
as organelle membranes. Also, it is involved in the synthesis of
bile acids required for the absorption of lipids and lipid-soluble
vitamins from the intestine, and participates in the synthesis of
steroid hormones and vitamin E (Ludke and López, 1999;
Leança et al., 2010).
Bacteria do not have cholesterol as part of their cytoplasmic membrane, nor ergosterol, a cholesterol derivative and
lipid component of fungal membranes. Both sterols were used
as complex lipid substances (Santos and Carvalho, 2001;
Thevissen et al., 2003; Loguercio-Leite et al., 2006) that can
act on the fluid mosaic of the bacterial membrane, modifying
its fluidity, for comparison with menadione with regard to
effect on the bacterial plasma membrane.
Bacteria are simple organisms found in most natural
environments, where the bacterial cell has several structures,
some present only in certain species. An essential structure is
the cytoplasmic membrane, which is responsible for numerous
functions including DNA replication, enzyme secretion,
biosynthesis of components, solute transport and energy production (Schaechter et al., 2002). The cell wall is a structure
that gives rigidity to many bacteria, and according to its constitution, bacteria are divided into two classes, Gram-positive
and Gram-negative bacteria, the difference being mainly due
to their permeability properties and surface components
(Tortora et al., 2008; Schaechter et al., 2002; Pretto et al.,
2005).
Bacterial infections are currently the focus of public health,
mainly due to the significant growth of bacterial resistance.
Infections caused by Staphylococcus aureus are the most
common, showing a greater difficulty in treatment due to its
resistance to various antibiotics (Tortora et al., 2008). The
species Pseudomonas aeruginosa is the leading cause of
nosocomial infections, attacking the skin, urinary tract, ear,
and eye (Murray et al., 2004). Escherichia coli are the most
common species of the genus Escherichia, associated with
severe urinary tract infections, meningitis and gastroenteritis
(Murray et al., 2004; Tortora et al., 2008).
The aim of this study was to evaluate in vitro the antibioticmodifying activity of menadione in multiresistant strains of S.
aureus, P. aeruginosa and E. coli, with gradual increase in its
subinhibitory concentration. Also, menadione was compared
to cholesterol and ergosterol with regard to mechanism of
modulating action (see Figs. 1 and 2).
J.C. Andrade et al.
MIC/8
MIC/4
MIC/2
2.0
1.5
1.0
0.5
0.0
VIT K
CHOLES
ERGOST
Figure 2 Comparison of the number of events modulator
concentrations subinhibitory MIC/8, MIC/4, MIC/2 between the
solutions of menadione, cholesterol and ergosterol. *MIC: minimum inhibitory concentration, VIT K: vitamin K.
Please cite this article in press as: Andrade, J.C. et al., Menadione (vitamin K) enhances the antibiotic activity of drugs by cell membrane permeabilization mechanism.
Saudi Journal of Biological Sciences (2015), http://dx.doi.org/10.1016/j.sjbs.2015.09.004
Menadione
Table 1
3
Bacterial resistance profile against antibiotics.
Bacterial strain
Source
Resistance profile
Staphylococcus aureus SA 358
Staphylococcus aureus ATCC 25923
Escherichia coli EC27
Escherichia coli ATCC 10536
Pseudomonas aeruginosa PA03
Pseudomonas aeruginosa ATCC 15442
Surgical wound
–
Surgical wound
–
Catheter tip
–
Oxa, Gen, Tob, Ami, Can, Neo, Para, But, Sis, Net
–
Ast, Ax, Amp, Ami, Amox, Ca, Cfc, Cf, Caz, Cip, Clo, Im, Can, Szt, Tet, Tob
–
Cpm, Ctz, Im, Cip, Ptz, Lev, Mer, Ami
–
Ast – Aztreonam; Ax – Amoxacillin; Amp – Ampicillin; Ami – Amikacin; Amox – Amoxicillin; Ca – Cefadroxil; Cfc – Cefaclor;
Cf – Cephalothin; Caz – Ceftazidime; Cip – Ciprofloxacin; Clo – Chloramphenicol; Im – Imipenem; Can – Kanamycin; Szt – Sulphametrophim,
Tet – Tetracycline; Tob – Tobramycin; Oxa – Oxacillin; Gen – Gentamicin; Neo – Neomycin; Para – Paramomicin; But – Butirosin;
Sis – Sisomicin; Net – Netilmicin; (–) absence of resistance or non-significant resistance.
Table 2 Minimum inhibitory concentration (MIC) of
menadione (vitamin K3) against bacterial strains.
Bactérias
S. aureus
P. aeruginosa
Klebsiella pneumoniae
E. coli
2 mL of DMSO/Tween 80 at a concentration of 200 mg/mL,
after which they were diluted to 1024 lg/mL in distilled water.
2.2.3. Antibiotics
MIC (lg/mL)
Menadiona
DMSO
128
64
128
128
128
256
128
128
Drugs used in the tests were the aminoglycosides amikacin,
neomycin and gentamicin (Sigma Co., St. Louis, USA). All
drugs were diluted in sterile water, to a concentration of
5000 lg/mL.
2.3. Antibacterial and modulatory activity
2. Experimental
2.1. Bacterial material
Bacteria used in the minimal inhibitory concentration (MIC)
test were the standard strains of S. aureus ATCC 25923,
P. aeruginosa ATCC 15442 and E. coli ATCC 10536. To evaluate the modulatory activity of the extract, the following
multi-resistant bacterial strains were used, isolated from clinical environments: P. aeruginosa 03, E. coli 27 and S. aureus
358, with the resistance profile demonstrated in Table 1 in
the MIC test. All strains were obtained from the Laboratory
of Clinical Mycology – UFPB. All strains were maintained
on heart infusion agar slants (HIA, Difco Laboratories.
Lawrence, USA) and prior to assay, the cells were grown
overnight at 37 °C in brain heart infusion (BHI, Difco
Laboratories, Lawrence, USA).
The minimal inhibitory concentration (MIC) was determined
by the broth microdilution assay. MIC is defined as the lowest
concentration at which no microbial growth is observed. MIC
was determined using a bacterial suspension of 105 CFU/mL
in 10% brain heart infusion (BHI) broth. In 96-well microdilution plates, 100 mL of inoculum were added to each well followed by 100 mL of a serially diluted solution of menadione,
cholesterol or ergosterol starting at a concentration of
1024 lg/mL. The final concentrations varied from 1024 to
8 lg/mL. The plates were incubated for 24 h at 35 °C
(Javadpour et al., 1996). The potential of the vitamin, cholesterol and ergosterol as modifiers of antibacterial resistance was
determined as proposed by Coutinho et al. (2008) with
modifications. The solution of vitamin was tested at three
subinhibitory concentrations (MIC/8, MIC/4 and MIC/2). In
a microdilution plate, 100 mL of BHI with bacterial inoculum
and liposoluble vitamins were added to each well, and 100 mL
of antimicrobial drugs were then serially diluted 1:2 with
concentrations varying 1024–0.5 lg/mL. The plates were
incubated for 24 h at 37 °C.
2.2. Drugs
2.2.1. Liposoluble vitamins
The vitamin K3 (Menadione) was obtained from Sigma Chemical Co., St. Louis, USA. Stock solutions were prepared in
1 mL of dimethylsulfoxide (DMSO), at a concentration of
100 mg/mL, after which they were diluted to a concentration
of 1024 lg/mL in distilled water, except menadione which
was diluted in DMSO. Thus, a DMSO control was included
to determine any possible interference with the results.
2.2.2. Sterols
Cholesterol and ergosterol were obtained from Sigma Chemical Co., St. Louis, USA. Stock solutions were prepared in
3. Results and discussion
This is the first report of antibacterial activity and potentiation
of menadione by the aminoglycosides, against multiresistant
bacteria. Until now, there had been no report on the use of
menadione as a modulator of antibiotics.
In view of the development of bacterial resistance to
antibiotics, which is responsible for the lack of efficacy in the
treatment of many existing infections, the pharmaceutical
industry, in recent years, has shown increased interest in
substances isolated from natural products that possess
antimicrobial properties (Köhler et al., 1999; Lee et al., 2003;
Taleb-Contini et al., 2003).
Please cite this article in press as: Andrade, J.C. et al., Menadione (vitamin K) enhances the antibiotic activity of drugs by cell membrane permeabilization mechanism.
Saudi Journal of Biological Sciences (2015), http://dx.doi.org/10.1016/j.sjbs.2015.09.004
4
J.C. Andrade et al.
Table 3 Antibiotic modulatory activity of menadione alone or associated with aminoglycosides in sub-inhibitory concentrations
(MIC/8, MIC/4 and MIC/2).
Menadione (vitamin K) (lg/mL)
Antibiotic
+ MIC/8
Staphylococcus aureus 358
Amikacin
78.1
Gentamicin
9.7
Neomycin
156.2
Pseudomonas
Amikacin
Gentamicin
Neomycin
aeruginosa 03
156.2
39.1
156.2
Escherichia coli 27
Amikacin
78.1
Gentamicin
19.5
Neomycin
78.1
MIC
DMSO
Antibiotic
alone
39.1
78.1
156.2
39.1
4.8
156.2
156.2
39.1
78.1
156.2
19.5
2.4
Antibiotic
+ MIC/4
MIC
DMSO
Antibiotic
alone
Antibiotic
+ MIC/2
MIC
DMSO
Antibiotic
alone
9.7
2.4
2.4
19.5
2.4
4.8
78.1
2.4
156.2
2.4
2.4
2.4
9.7
2.4
2.4
156.2
312.5
156.2
156.2
39.1
78.1
39.1
9.7
78.1
39.1
19.5
78.1
78.1
19.5
78.1
2.4
2.4
2.4
9.7
2.4
78.1
312.5
625
78.1
156.2
39.1
312.5
9.7
2.4
78.1
78.1
19.5
78.1
78.1
9.7
312.5
2.4
2.4
2.4
4.8
2.4
4.8
156.2
625
312.5
Table 4 Antibiotic modulatory activity of cholesterol alone or associated with aminoglycosides in sub-inhibitory concentrations
(MIC/8, MIC/4 and MIC/2).
Cholesterol (lg/mL)
Antibiotic + MIC/8
Antibiotic alone
Antibiotic MIC/4
Antibiotic alone
Antibiotic + MIC/2
Antibiotic alone
Staphylococcus aureus 358
Amikacin
78.1
Gentamicin
4.8
Neomycin
39.1
39.1
19.5
156.2
39.1
2.4
4.8
19.5
2.4
78.1
19.5
2.4
9.7
156.2
9.7
156.2
Pseudomonas aeruginosa 03
Amikacin
78.1
Gentamicin
19.5
Neomycin
156.2
39.1
39.1
312.5
156.2
39.1
156.2
156.2
39.1
312.5
39.1
4.8
156.2
78.1
19.5
156.2
Escherichia coli 27
Amikacin
39.1
Gentamicin
9.7
Neomycin
156.2
39.1
9.7
156.2
19.5
2.4
78.1
78.1
4.8
156.2
39.1
4.8
78.1
156.2
9.7
78.1
Menadione demonstrated antibacterial activity against
P. aeruginosa 03, with a MIC of 64 lg/mL, while DMSO, used
as a negative control, showed a much higher MIC of
256 lg/mL against the strain tested. Menadione showed no significant antibacterial activity against the other bacterial strains
analyzed, where MIC was the same as the DMSO control
(Table 2). Dimethylsulfoxide is versatile and has several
pharmacological and therapeutic properties, including antimicrobial action, showing in vitro bactericidal or bacteriostatic
activity at concentrations of 5–50% against various pathogenic
bacteria, including Staphylococcus spp., E. coli, Mycobacterium tuberculosis, Streptococcus spp., Salmonella spp. and
Proteus spp. (Brayton, 1986; Stone, 1993; Mangia, 2008).
Lipophilic substances and menadione cause disturbances in
the bacterial membrane, resulting in damage of the fundamental elements needed for membrane integrity, such as reduced
membrane potential and loss of ions, cytochrome C, proteins
and radicals, followed by the collapse of the proton pump
and ATP depletion (Sikkema et al., 1994; Turina et al., 2006;
Hirayama et al., 2006). Permeabilization of the outer and inner
membrane can subsequently occur and facilitate the entry of
antibiotics, causing cell lysis and death (Knowles et al., 2005).
When combined with the aminoglycoside class of antibiotics, menadione decreased the antibiotic MIC with increasing
subinhibitory concentration of vitamin K3, MIC/8 to MIC/2,
indicating a synergistic relationship (Table 3).
Menadione at the subinhibitory concentration of MIC/8
did not show antibiotic-modifying potential in any of the bacterial strains used. Subinhibitory concentration MIC/4 showed
a significant synergistic interaction in S. aureus 358 with amikacin and neomycin and E. coli 27 with all aminoglycosides.
Subinhibitory concentration MIC/2 was synergistic with all
antibiotics and strains tested, including P. aeruginosa 03.
Especially notable is that menadione was significantly
effective against S. aureus 358 and mainly E. coli 27, microorganisms with different morphologies. Gram-positive S. aureus
has a thick and rigid cell wall formed by layers of peptidoglycan. The cell walls of Gram-negative bacteria such as E. coli
Please cite this article in press as: Andrade, J.C. et al., Menadione (vitamin K) enhances the antibiotic activity of drugs by cell membrane permeabilization mechanism.
Saudi Journal of Biological Sciences (2015), http://dx.doi.org/10.1016/j.sjbs.2015.09.004
Menadione
5
Table 5 Antibiotic modulatory activity of ergosterol alone or associated with aminoglycosides in sub-inhibitory concentrations
(MIC/8, MIC/4 and MIC/2).
Ergosterol (lg/mL)
Antibiotic + MIC/8
Antibiotic alone
Antibiotic + MIC/4
Antibiotic alone
Antibiotic + MIC/2
Antibiotic alone
Staphylococcus aureus 358
Amikacin
78.1
Gentamicin
4.8
Neomycin
19.5
39.1
19.5
156.2
9.7
2.4
39.1
19.5
2.4
78.1
19.5
2.4
78.1
156.2
9.7
156.2
Pseudomonas aeruginosa 03
Amikacin
78.1
Gentamicin
4.8
Neomycin
312.5
39.1
39.1
312.5
39.1
9.7
625
156.2
39.1
312.5
19.5
4.8
156.2
78.1
19.5
156.2
Escherichia coli 27
Amikacin
39.1
Gentamicin
9.7
Neomycin
156.2
39.1
9.7
156.2
9.7
2.4
39.1
78.1
4.8
156.2
9.7
2.4
39.1
156.2
9.7
78.1
contain only a thin peptidoglycan layer (Tortora et al., 2008),
which suggests that menadione, due to its lipid-soluble nature
has a lipophilic action on the bacterial cell envelope, causing a
disruption of the fluid mosaic membrane (Nostro et al., 2004),
affecting E. coli more so than S. aureus.
According to Nicolson et al. (1999) Gram-positive and
Gram-negative bacteria are more sensitive to low-polarity
compounds due to the presence of polysaccharide chains in
the bacterial membrane that act as barriers to hydrophobic
substances.
Ergosterol and cholesterol are major components of biological membranes of eukaryotes, where they control permeability, but they are absent in the membrane of bacteria. The
cell can control its fluidity by regulating the level of cholesterol, or the saturation of phospholipid hydrocarbon chains
(Frézard and Schettini, 2005). Due to their lipophilic structure,
analogous to menadione, both were used as controls to check
and compare the mechanism of action of menadione in the
bacterial membrane.
Cholesterol and ergosterol had no antimicrobial activity,
showing MIC P1024 lg/mL, which was already expected.
However, the combination of either with antibiotics, against
multiresistant bacteria, reduced the antibiotic MIC significantly as the subinhibitory concentration of the sterols was
increased (Tables 4 and 5). There is no previous report on
the use of cholesterol and ergosterol as modifiers of the action
of antibiotics or any other drug, so this is the first study in this
area. Thus, it was possible to determine the similarity between
menadione between cholesterol, and ergosterol with regard to
antibiotic-modifying activity.
4. Conclusion
Menadione demonstrated clinically relevant results in the
modulation of aminoglycosides against multiresistant bacteria.
This represents an interesting alternative to increasing bacterial resistance, since menadione is present in the diet, and is
not toxic to humans. Pre-clinical and clinical studies are warranted to determine bioavailability and mechanisms of action
involved in this interaction.
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