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Abstract

Antibiotics have been effective in treatment of infectious diseases, but resistance to these drugs has led to the severe infectious diseases. In recent years, medicinal herbals have been used for the prevention and protection against infectious diseases. Thymol and carvacrol are active ingredients of family lamiaceae. These components have antibacterial and antifungal effects. In this review, we survey antimicrobial properties of, carvacrol and thymol. Available data from different studies (microbiological, retrieve from PubMed and Scopus databases) about antimicrobial affects carvacrol and thymol was evaluated. carvacrol and thymol can inhibit growth of both Gram positive and Gram negative bacteria. These compounds have antifungal and antibiofilm effects. Thymol and carvacrol can be applied as an alternative antimicrobial agent against antibiotic-resistant pathogenic bacteria. Thus, it is recommended potential medical use of thymol and carvacrol, but more research must be done on toxicity and side effects issue.
Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
Carvacrol and thymol: strong antimicrobial agents
against resistant isolates
Mohammad Y. Memar
a,b
, Parisa Raei
c
, Naser Alizadeh
b,d
,
Masoud Akbari Aghdam
a
and Hossein Samadi Kafil
d
Antibiotics have been effective in treatment of infectious diseases, but resistance to
these drugs has led to the severe consequences. In recent years, medicinal herbs have
been used for the prevention and protection against infectious diseases. Thymol and
carvacrol are active ingredients of family Lamiaceae; these components have anti-
bacterial and antifungal effects. In this review, we survey antimicrobial properties of
carvacrol and thymol. Available data from different studies (microbiological, retrieve
from PubMed, and Scopus databases) about antimicrobial affects carvacrol and thymol
was evaluated. Carvacrol and thymol can inhibit the growth of both gram-positive and
gram-negative bacteria. These compounds have antifungal and antibiofilm effects.
Thymol and carvacrol can also be applied as an alternative antimicrobial agent against
antibiotic-resistant pathogenic bacteria. Thus, thymol and carvacrol are recom-
mended for potential medical use; however, more research is required on toxicity
and side-effects of the compounds.
Copyright ß2017 Wolters Kluwer Health, Inc. All rights reserved.
Reviews in Medical Microbiology 2017, 28:6368
Keywords: antibacterial, antibiofilm, antifungal, carvacrol, thymol
Introduction
Infectious diseases are common reasons of morbidity and
mortality in the world [1]. Introduction of antibiotics
have had a consequence not only on the management of
infections but also on society by changing morbidity and
mortality [2]. However, the abuse of these compounds has
led to the emergence and increasing of multidrug-
resistant pathogens [3]. The situation is deteriorated by
the increasing the number of antibiotic-resistant patho-
gens and potential to endure after exposure to
antimicrobial agents [4]. As no new drugs have been
introduced to manage antibiotic-resistant pathogens, and
as it seems doubtful that any novel agents will be
established presently, clinicians may become obliged to
administrate some drugs regardless of their complications
[5]. Hence, antibiotic-resistant pathogens are public
health crisis and the need to explore and identify new
compounds with antibacterial properties without toxic
effects on human cells is obvious [6].
Plants are one source of the compounds with anti-
microbial activity that provides options of novel
alternative drugs for microbial disease [7]. Essential oils
derived from plants are one of the most important
agricultural products with antimicrobial property [8].
About 3000 essential oils produced by at least 2000 plant
species, which about 300 of them are significant from the
marketing viewpoint [9]. Essential oils and their
constituent small molecules exhibit excellent medicinal
properties and hence may be used against infectious and
noninfectious diseases [10]. Essential oils are definite as
any volatile oil(s) that have strong aromatic components
and that give characteristic odor, flavor, or smell to a
plant. These are the byproducts of plant metabolism and
are frequently referred to as volatile plant secondary
metabolites. Essential oils are found in glandular hairs or
secretory cavities of plant-cell wall and are present as
droplets of juice in the leaves, stems, bark, flowers, roots,
and/or fruits in different plants [11]. Carvacrol and
thymol are the major constituents of the essential oils,
a
Infectious and Tropical Disease Research Center,
b
Student Research Committee,
c
Drug Applied Research Center, and
d
Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
Correspondence to Hossein Samadi Kafil, PhD, Assistant Professor, Drug Applied Research Center, Tabriz University of Medical
Sciences, Tabriz, Iran.
Tel: +98 9127184735; fax: +98 4133364661; e-mail: Kafilhs@tbzmed.ac.ir
Received: 21 October 2016; revised: 2 February 2017; accepted: 7 February 2017
DOI:10.1097/MRM.0000000000000100
ISSN 0954-139X Copyright Q2017 Wolters Kluwer Health, Inc. All rights reserved. 63
Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
which belong to the Lamiaceae family of plants including
oregano and thyme [12]. In this study, we review
antimicrobial effects of carvacrol and thymol.
Traditional application
The ancient Egyptians used thymol and carvacrol as
protective agents to preserve the mummies [13]. They
were also used as an active additive in food flavoring,
perfumes, cosmetics, mouthwash, and some of them have
been made for massaging the joints and to treat nail fungi
as topical ointments. Drugs formulated from these
compounds were administered to care for infections of
the mouth and throat and prevent of gingivitis [14].
Thymol
Thymol (also known as 2-isopropyl-5-methylphenol)
(Fig. 1), a phenolic compound present in essential oils, is a
natural monoterpene and carvacrol isomer that extracted
from thyme and the other kinds of plants [15]. Thymol is
less water soluble at neutral pH, but it is as well soluble in
some organic solvents and alcohols [16]. It has been
observed its antioxidant, antispasmodic, antimicrobial,
and anti-inflammatory property [17]. It is a p-cymene
derivative compound and is also identified for the
antiseptic and antimicrobial effects [18]. Some studies
have reported the usage of thymol for anticancer property
[19]. The antioxidant effects of thymol and carvacrol have
been confirmed in several studies, suggesting their
administration as nutritious elements in the improvement
of novel functional foods [20]. Thymol protective
nature against caries and plaques allures the field of
dental drugs [21].
Carvacrol
Carvacrol (5-isopropyl-2-methylphenol), (Fig. 1), is also
monoterpene that found in many plant species such as
thyme and with greater amount in oregano [22].
Carvacrol is significant component of essential oils and
recently has attracted much attention as a result of its
biological properties, such as a wide spectrum of
antimicrobial activity. Because carvacrol exhibits strong
antioxidative properties and both hydrophobic properties
associated with the substituted aromatic ring and
hydrophilic properties associated with the phenolic
OH group, numerous studies report its antioxidative,
anti-inflammatory, antibacterial, antifungal, antiproto-
zoal, anticarcinogenic, antidiabetic, antinociceptive,
cardioprotective, and neuroprotective properties [23].
Antibacterial effect of thymol and
carvacrol
Several studies were reported antibacterial effects of
thymol alone or in combination with other substance
such as carvacrol [24]. These compounds can inhibit
growth of both gram-positive and gram-negative bacteria
[24]. Low toxicity and pleasant smell as well as taste of
thymol show that this material can be used as an additive
to prevent bacterial spoilage [25]. Trombetta et al. [26]
report the antimicrobial efficacy of thymol against
Staphylococcus aureus and Escherichia coli. Some researchers
speculated that the antibacterial mechanism of thymol
may consequence, at least partly, from a perturbation of
the lipid fraction of the bacterial plasma membrane,
resulting in changes of membrane permeability and in the
escape of intracellular content [27,28]. Lambert, et al.
exhibited antibacterial effect of thymol and carvacrol
against Pseudomonas aeruginosa and S. aureus as a result of
disruption in membrane integrity, which further affects
the pH homeostasis and balance of inorganic ions [27].
Therefore, antibacterial property of carvacrol and thymol
is dependent to their capability to permeabilize,
depolarize, and disruption of the cytoplasmic membrane.
Gas chromatographic mass spectrometric examination
indicated thymol is major essential oil of Monarda punctata.
The results of study carried by Li et al. [29] indicated that
Streptococcus pyogenes,E. coli, and Streptococcus pneumonia
were the most susceptible to thymol, whereas methicillin-
resistant S. aureus was reported to be the most resistant
to the essential oil with relatively higher Minimum
Inhibitory Concentration (MIC) and Minimum
bactericidal concentration (MBC) values. The disk
diffusion method data show thymol is most effective
against Brochothrix thermosphacta (Inhibition Zone:
39.7 mm) followed by Listeria monocytogenes and Salmo-
nella thyphimurium (Inhibition Zone: 35.6 and 33.3 mm,
respectively). The MIC and MBC values (0.25 and
0.5 mg/ml, respectively) were the same for L. mono-
cytogenes,S. thyphimurium, and E. coli O157:H7.
Pseudomonas fluorescens was the least inhibited by thymol
(MIC and MBC ranging from 1 to 1.5 mg/ml). These
components could be probable options to be applied as
64 Reviews in Medical Microbiology 2017, Vol 28 No 2
Fig. 1. Chemical structure of thymol and carvacrol.
Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
natural alternatives for further usage in food conservation
to hold up or inhibit the bacterial increase and for
protection and to expand the shelf existence of the food
products. However, the verification of antibacterial
effects and organoleptic impact of these essential oils in
foodstuffs require assessing [30]. Results of several studies
were confirmed bactericidal effects of thymol and
carvacrol against of pathogens and food spoilage bacteria
(Table 1) [24,3139].
The antibacterial efficacy of carvacrol and thymol in
combination with other antibacterial compounds on
gram-negative and gram-positive organism were eval-
uated in some studies. The results of these studies will be
affected by the methods for detection of synergy effects.
For example Hamoud et al. [40], reported checkerboard
data indicate indifferent interaction against gram-positive
and synergy against gram-negative bacteria, whereas
time-kill analyses advocate synergistic achievement in
diverse combinations against both types of bacteria.
Combinations of thymol and carvacrol with antibacterial
(azithhromycin, clarithromycin, minocycline, and tige-
cycline) using checkerboard indicted achievement a
synergism in the great majority of cases [41]. Thymol and
carvacrol were found to be highly efficient in increasing
the susceptibility of S. typhimurium to ampicillin,
tetracycline, penicillin, bacitracin, erythromycin, and
novobiocin and resistance of S. pyogenes to erythromycin
[24]. On the basis of these data, the authors recommended
that thymol in combination with specific antimicrobial
drugs may be an efficient alternative option to treat
infections.
Effect of thymol and carvacrol on biofilm
formation
Biofilm biomass is a mixture of exopolysaccharides,
proteins, DNA, and extracellular matrix that has the
stabilizing role of biofilm construction [42]. Bacteria in a
biofilm are much more resistant to antibiotics than to
planktonic status [43]. The plant derivatives can effect on
microbial biofilms [44]. Several studies described thymol
and carvacrol inhibited growth of preformed biofilm and
interfered with biofilm formation during planktonic
growth [45,46]. Nostro et al. [46] reported carvacrol and
thymol attenuated biofilm formation of S. aureus and
Staphylococcus epidermidis strains on polystyrene microtitre
plates and they suggested these oils repressed expansion of
Carvacrol and thymol: strong antimicrobial agents Memar et al. 65
Table 1. Results of varies study that assessed antimicrobial effects of thymol and carvacrol.
Compound Microorganism Main findings References
Thymol, carvacrol,
cinnamaldehyde, and
eugenol alone or
combined
Streptococcus mutans
ATCC25175
Use of eugenol and thymol or eugenol and carvacrol
combinations would be suitable in the management of
oral infections
[31]
S. sanguis,S. mitis, and S. milleri
Peptostreptococcus anaerobius
ATCC 4956, Prevotella buccae,
P. oris, and P. intermedia
Cinnamaldehyde,
thymol, and carvacrol
alone or their
combinations
S. typhimurium MIC of cinnamaldehyde, thymol, and carvacrol for
S. typhimurium were 200, 400, and 400 mg/l,
respectively. By their paired combinations, MIC of
cinnamaldehyde, thymol and carvacrol could be
decreased from 200, 400, and 400 mg/l to 100, 100, and
100 mg/l, respectively
[32]
Oregano oil, carvacrol,
and thymol
Methicillin-susceptible and
methicillin-resistant
staphylococci (MSS and MRS)
All S. aureus and S. epidermidis strains reported susceptible
to these compound with no significant difference
between MRS and MSS strains
[33]
Carvacrol and thymol E. coli Carvacrol and thymol could inhibit the growth of E. coli.
The antibacterial property was related to their capacity to
permeabilize and depolarize the bacterial membrane
[34]
Lippia sidoides and
thymol
Enterococcus faecalis Thymol kill microorganisms present in biofilms [35]
Thymol L. monocytogenes Thymol could potentially be applied to control L.
monocytogenes biofilms in food processing
[36]
Carvacrol and thymol Shigella sonnei and S. flexneri Antibacterial effects of thymol and carvacrol against
Sheigella spp.
[37]
Thymol C. albicans Thymol may be used as a potential antifungal therapy in the
future
[38]
Carvacrol and thymol P. digitatum and P. italicum The application of these essential oils in the citrus packing
lines could be considered as appropriate alternatives to
reduce the use of synthetic fungicides
[39]
Eugenol, carvacrol,
thymol and
cinnamaldehyde
Tetracycline-resistant S.
Typhimurium and E. coli,
penicillin-resistant S. aureus
and erythromycin-resistant S.
pyogenes
Natural antimicrobials were able to significantly reduce the
MIC of antibiotics in a different group of resistant bacteria
[24]
Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
preformed biofilm and obstructed with the biofilm
development during planktonic phase. El Abed et al. [47]
also described anti-adherence and antibiofilm effects of
terpenes and pointed out the excellent effectiveness of
eugenol, carvone, and carveol, which could characterize
candidates in the management of P. aeruginosa biofilm.
Thymol can also prevent the first stages of biofilm
formation and interfering with the formation of mature
biofilms as a result of the inhabitation of metabolic
activity for biofilms. All of these events may lead to major
membrane and blockage the production of viable
filamentous forms during the early steps of biofilm
formation. As biofilms are multifactorial event, the several
mechanisms of thymol (terpenes) perhaps effect on
diverse stages in their development [48].
Antifungal effect by thymol and carvacrol
Direct antifungal agents resistance is still a chief unease
when antifungal treatment failure is considered [49].
There are limits antifungal drugs available for treatment,
drug-resistant strains are also evidence of biofilm
infections and side-effects of prescription drugs will have
problems in the prevention and treatment of fungal
infections [50]. Several studies described antifungal effects
of thymol and carvacrol against fungal pathogens.
Antifungal effect of thymol and carvacrol investigated
against Penicillium digitatum and Penicillum italicum. Both
essential oils were effective in inhibiting fungal growth;
thymol was more effective than carvacrol [39].
Guo et al. [51] indicated antifungal activity of thymol
against clinical isolates of fluconazole susceptible and
nonsusceptible Candida albicans and high percentage of
synergism effects of thymol in combination with
amphotericin B.
Thymol and carvacrol because of the restrain of ergosterol
biosynthesis and the disturbance of membrane totality
shows potent fungicidal efficacy against Candida isolates
[52]. Effective fungicidal properties of carvacrol and
thymol against different plant pathogens were also
formerly reported by Kordali et al. [53].
Development of herbicides helps reduce factors such as
pollution and environmental degradation; in this regard,
natural herbicides can be effective. Essential oils and
monoterpenes compounds showed antifungal activity in
the treatment of mucormycosi [54,55].
Thymol is lipophilic compound, that alone or with
carvacrol, can change the cell membrane fluidity and
permeability [56]. In addition to this, the compound can
changes the cell membrane in fungi such as C. albicans by
the affect the function of the cell membrane enzymes that
catalyzes the synthesis of the cell wall polysaccharide
compounds such as b-glucan and inhibit the growth of
cells [57,58]. The results of electron microscopy showed
that thymol and carvacrol change the morphogenesis of
the envelope of C. albicans [58].
Carvacrol was also effective in reducing the growth of
Botrytis cinerea in berry and grapes; in grapes, 97%
inhibition was related to the higher doses of carvacrol
[59,60]. In addition to this, carvacrol was effective in
reducing the spore germinates and mycelium growth of
B. cinerea inoculated in grapes [59].
Other researchers showed the effect of monoterpenoid-
son the conidial germination and mycelial growth of B.
cinerea [61]. Also, Tsao and Zhou [61] reported that
0.25 mg/ml of thymol had an inhibitory effect on the
increase of mycelium of Monilinia fructicola, also on the
solid media, was 100% inhibited conidial germination of
the bacteria.
Toxicity issue
Essential oils affect the various active molecules in the cell
for different purposes, that, main purpose is the
cytoplasmic membrane [62]. Disruption of the per-
meability of the cell membrane leads to the loss of cell
function such as the electron transport chain, also affected
the eukaryotic cells [63]. Toxicity to eukaryotic cells is
responsible for undesirable side-effects for a host, such as
inflammation, corrosion, cell sensitivity, acute toxicity to
organs, and limits the use of essential oils as medicinal use
[52]. It is difficult to detect the toxicity of essential oils
because the toxicity varies based on the compounds and
depends on various factors [64]. A study showed that
thymol and carvacrol had the most toxic in concen-
trations of 36 –49 mg/l, which are less toxic than some
combination of essential oils [65]. There is less risk of
accumulation of body tissues. Therefore, it is suggested
possible medical use thymol and carvacrol, but more
research must be done on this issue.
Conclusion
Several studies have shown antibacterial and antifungal
property of the thymol and carvacrol. Thymol and
carvacrol can be applied as an alternative antimicrobial
agent against antibiotic-resistant pathogenic bacteria and
C. albicans. It is necessary for further precise detection of
thymol and carvacrol safety to determine the optimal dose
of these substances for human cells. Results of various
studies proposed replace of traditional medicines instead
of synthetic drugs, which has more side-effects. In this
review, reported information about the effects of
antibacterial, antifungal, and antibiofilm thymol and
66 Reviews in Medical Microbiology 2017, Vol 28 No 2
Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
carvacrol that provides a better view about the thymol and
carvacrol. More studies using bacterial strains isolated
from patients treated with these compounds needs to
be done.
Acknowledgements
This study was supported by Drug Applied Research
Center, Tabriz University of Medical Sciences, Tabriz,
Iran.
Conflicts of interest
The authors declare no conflicts of interest.
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68 Reviews in Medical Microbiology 2017, Vol 28 No 2
... •Thymol [250] •Carvacrol [251] • Methanolanddichloromethane extracts [252] • Essentialoil [253,254] • Thymol [254] • Extracts [246,252] •Essentialoil [255,256] • Thymol [257][258][259] •Carvacrol [258,259] NA NA * = data not available Alasbahi and Groot and B (isolated from the gel) with IC 50 value of 58 µM and 13.6 µM, respectively [36]. A dual inhibition of pure lipoxygenase (LOX) and COX-2 was shown by a purified protein (MW 14 kDa) isolated from A. vera gel [35]. ...
... •Thymol [250] •Carvacrol [251] • Methanolanddichloromethane extracts [252] • Essentialoil [253,254] • Thymol [254] • Extracts [246,252] •Essentialoil [255,256] • Thymol [257][258][259] •Carvacrol [258,259] NA NA * = data not available Alasbahi and Groot and B (isolated from the gel) with IC 50 value of 58 µM and 13.6 µM, respectively [36]. A dual inhibition of pure lipoxygenase (LOX) and COX-2 was shown by a purified protein (MW 14 kDa) isolated from A. vera gel [35]. ...
... has not been yet illustrated. However, the antimicrobial mechanisms of action of the compounds ,carvacrol and thymol, which are also the major constituents of essential oils of Yemeni T. laevigatus Vahl leaves, growing in different areas, [252,253] were demonstrated by their ability to permeabilize, depolarize, and disrupt the cytoplasmic membrane, and inhibitory effect on biofilm formation (inhibiting the growth of preformed biofilm and interfering with biofilm formation during planktonic growth) as well as by their antifungal activity (changing cell membrane fluidiy and permeability, and changing the morphogenesis of the envelope of C. albicans) [259]. ...
... [15]. It exhibits both hydrophobic (associated with the aromatic ring) and hydrophilic (associated with the phenolic OH group) properties, which lead to different biological activities [16]. Thymol has been reported to possess antibacterial activity against various bacterial strains including S. aureus, Escherichia coli, Bacillus cereus, and Pseudomonas aeruginosa, attributed to its hydrophobicity. ...
... Thymol has been reported to possess antibacterial activity against various bacterial strains including S. aureus, Escherichia coli, Bacillus cereus, and Pseudomonas aeruginosa, attributed to its hydrophobicity. Once it reaches the membrane, it could insert into and disrupt its lipid ordering, change permeability, and lead to depolarization [16][17][18]. It has also been suggested to bind the minor groove of the genomic DNA and alter DNA morphology [19]. ...
Article
A plethora of natural products emerges as attractive molecules in the struggle against antibiotic resistance. These molecules impose their bioactivities not only alone but also in combinations as well, which further enhances their effects. Berberine is a well-known isoquinoline alkaloid with antibacterial activity. Unfortunately, it is readily extruded, which significantly reduces its efficacy and restricts its potential. Thymol is a monoterpenic phenol that exhibits different biological activities but its major effect is observed only at relatively high concentrations, which raises concern on cytotoxicity. The aim of the study was to potentiate the antibacterial activity of berberine, in a combination treatment with thymol in the opportunistic pathogen Staphylococcus aureus and understand the antibacterial mechanism of the combination treatment. The synergism of berberine and thymol was first established by the checkerboard assay. Then the antibacterial mechanism of the synergistic combination was explored by growth curves, biofilm formation assay, SEM observation, and RNA-Seq based transcriptomic profiling. Checkerboard assay showed that 32 μg mL − 1 berberine and 64 μg mL − 1 thymol was a synergistic combination, both concentrations below their cytotoxicity limits for many cells. 32 μg mL − 1 berberine and 32 μg mL − 1 thymol was sufficient to inhibit biofilm formation. SEM images confirmed the morphological changes on the structure of combination treated cells. The major finding of the combination treatment from the tran-scriptomic analysis was the repression in the expression of virulence factors or genes related to virulence factors. Apart from the particular changes related to the cell envelope, the majority of expressional changes seemed to be similar to berberine-treated cells or to be resulting from general stress conditions. The findings of this work showed that when thymol was used in combination with berberine, it enhanced the antibacterial activity of berberine in a synergistic manner. Furthermore, thymol could be considered as an antivirulence agent, disarming S. aureus cells.
... 13,34,35 Natural Compounds Natural-originated compounds are always taken into consideration in medical fields, because they are biodegradable and usually very useful, so they serve as a convenient compound for the inhibition of biological infection. Several studies have shown that the use of natural eukaryotic or prokaryotic derived compounds can reduce the bacterial virulence and modulates QS. 4,[36][37][38][39][40] In this regard, natural compounds are assumed to be better than other QSIs, so for this reason, they can be used more confidently for a prolonged time and can reach the situation of GRAS (generally recognized as safe). 41 ...
... 14,[44][45][46][47][48][49] Prokaryotes have three types of enzymes that target the AHLs and play an essential role in QQ including AHL lactonases, AHL acylases, and AHL oxidoreductases. 40,41 ...
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Abstract: There has been excessive rate of use of antibiotics to fight Pseudomonas aeruginosa (P. aeruginosa) infections worldwide, which has consequently caused the increased resistance to multiple antibiotics in this pathogen. Due to the widespread resistance and the current poor effect of antibiotics consumed to treat P. aeruginosa infections, finding some novel alternative therapeutic methods are necessary for the treatment of infections. The P. aeruginosa biofilms can cause severe infections leading to the increased antibiotic resistance and mortality rate among the patients. In this regard, there are no approaches that can efficiently manage these infections; therefore, novel and effective antimicrobial and antibiofilm agents are needed to control and treat these bacterial infections. Quorum sensing inhibitors (QSIs) or quorum quenchings (QQs) are now considered as potential therapeutic alternatives and/or adjuvants to the current failing antibiotics, which can control the virulence traits of the pathogens, so as a result, the host immune system can quickly eliminate bacteria. Thus, the aims of this review article were presenting a brief explanation of the research reports on the natural and synthetic QSIs of P. aeruginosa, and the assessment of the current understanding on the QS mechanisms and various QQ strategies in P. aeruginosa.Keywords: Pseudomonas aeruginosa, quorum quenchings, quorum sensing, nanoparticle, natural compounds, synthetic compounds
... The EOs rich in phenolic compounds such as carvacrol, oxygenated derivatives (thymol methyl ether) and its precursors p-cymene and c-terpinene were reported in all investigated cultivars and have described to possess high levels of antimicrobial activity (Memar et al. 2017). Moreover, studies reported that oxygenated terpenoids such as phenolic terpenes and alcoholic isolated and confirmed in this study have been approved to have marked antimicrobial activity than the other components due to their highly lipophilic nature and low molecular weight that induce it capable of disrupting the cell membrane, causing inhibiting the microbial and cell death (Kuspradini et al. 2018). ...
... The most active monoterpenoid phenols of essential oils are known thyme oil and lavender oil (Dhifi et al., 2016), which found useful to increase the vase life of some cut flowers (Thakur et al., 2014). These results may be due to the role of thyme oil and lavender oil as antimicrobial agents (Memar et al., 2017), and they might have reduced xylem blockage and increased solution uptake, which may improve the vase life and relatively fresh weight. A positive correlation is stated between vase life, solution uptake, and relatively fresh weight in any kind of researches (Alaey et al. 2011;Amini et al., 2016). ...
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This study was carried out on the flowers of 'Le Castel' Dahlia (starflower) cultivated in Tokat Gaziosmanpaşa University Agricultural Research and Application Center in 2019. The study aimed to prolong the vase life of Dahlia flowers used as cut flowers. Deionized water (control), sucrose + deionized water, thyme oil, lavender oil, carvacrol, thymol, sodium hypochlorite, and gibberellic acid were used as vase solutions. The total vase solution uptake (g/stem), daily vase solution uptake (g/day fresh weight (FW)), proportional FW (%) and vase life (day) parameters were determined based on Dahlia flowers that harvested at different harvest stages (3, 4 and 5 layers). As a result; the most extended vase life was measured in the gibberellic acid treatment (8.22 days), the highest proportional fresh weight was measured in the carvacrol in the 6th day (139.78%), the highest daily solution uptake was measured in the thyme oil in 0-2 days (11.7 g/day FW) and the highest total solution uptake was measured in the thyme oil (27.5 g/stem). It was concluded that the vase life of earlier harvested flowers was longer than of late harvested.
... ; deMoraes et al. 2014;Rahman et al. 2014;Vinholes et al. 2014;Memar et al. 2017;Tyagi and Agarwal 2017;Singh and Chaturvedi 2019;Kim et al. 2020).Based on the literature, other compounds profiled from GC-MS analysis might show their association with other biological activities. Phthalic acid, di(2-propylpentyl) ester(Khatiwora et al. 2012;Ahsan et al. 2017;Shobi and Viswanathan 2018), which was detected the highest in the stem, is reported to have antimicrobial properties. ...
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Polyalthia bullata is a woody medicinal plant that contains antioxidant compounds. Finding a suitable solvent is important to obtain a high yield of antioxidants in the phenolic, flavonoid, and terpenoid families. In this study, from different solvent extracts, the leaf methanolic extract exhibited the highest total phenolic content (TPC), total flavonoid content (TFC), total terpenoid content (TTC), and total antioxidant activity. For woody parts of stem and roots, methanol was the best solvent for all phytochemicals except for phenolics, which accumulated in the roots and were extracted more efficiently using ethanol. However, the methanolic extracts from both tissues displayed the best antioxidant capacity. Gas chromatography-mass spectrometry (GC-MS) profiling data showed the presence of antioxidant compounds such as thymol, phytol, and neophytadiene in the leaf; trans-farnesol, n-hexadecanoic acid, and 9-Octadecenamide in the stem; and fatty acid (cis-vaccenic) and its methyl ester (11-Octadecanoic acid, methyl ester and [1,1'-bicyclopropyl]-2-octanoic acid, 2'-hexyl-methyl ester) in the roots. These findings reveal important compounds that are present in different plant parts of P. bullata.
... The EOs rich in phenolic compounds such as carvacrol, oxygenated derivatives (thymol methyl ether) and its precursors p-cymene and c-terpinene were reported in all investigated cultivars and have described to possess high levels of antimicrobial activity (Memar et al. 2017). Moreover, studies reported that oxygenated terpenoids such as phenolic terpenes and alcoholic isolated and confirmed in this study have been approved to have marked antimicrobial activity than the other components due to their highly lipophilic nature and low molecular weight that induce it capable of disrupting the cell membrane, causing inhibiting the microbial and cell death (Kuspradini et al. 2018). ...
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The sterols, hydrocarbons and fatty acids constituents of the leaves of five mango cultivars locally implanted in Egypt were identified. The effect of their essential oils (EOs) against food borne microorganisms was studied as preservative materials. The chemical constituents of the EOs isolated from mango leaves were identified by Gas Chromatography–Mass spectrometry (GC–MS) technique. Trans-caryophyllene, α–humulene and α–elemene were identified as terpene hydrocarbons, while 4-hydroxy-4-methyl-2-pentanone as oxygenated compounds were recorded in all tested cultivars with variable amounts. Results showed that Staphylococcus aureus and Escherichia coli were the most sensitive microorganisms tested for Alphonso EOs. On the other hand, Salmonella typhimrium was found to be less susceptible to the EOs of the studied cultivars. The EOs of different mango cultivars induced a steady decrease in the activity of amylase, protease and lipase at the minimum inhibitory concentration (MIC). The treatment of the tested bacteria with the EOs of mango cultivars caused a steady loss in enterotoxins even when applied at the sub-MIC. Bacteria-inoculated apple juice treated with minimum bactericidal concentration of Alphonso oil was free from the bacteria after 5 days of incubation at 25 °C. Eighteeen volatile compounds were found to reduce the activity of the amylase enzyme and the most active was cedrelanol (−7.6 kcal mol−1) followed by alpha-eudesmol (−7.3 kcal mol−1) and humulene oxide (−7 kcal mol−1). The binding mode of both of cedrelanol and alpha-eudesmol with amylase enzyme was illustrated.
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This study was designed to investigate the chemical composition and the antimicrobial activity of liquid and vapor phase of Algerian Saccocalyx satureioïdes essential oil (EO) against twenty-two foodborne pathogens. EO is obtained by hydrodistillation with a yield of 0.92 % and analyzed by gas chromatography coupled to mass spectrometry (GC/MS) where 53 compounds representing 98.36% of the total essential oil composition were identified. α-terpineol (38.47%), borneol (23.63%), thymol (20.90%) and terpinen-4-ol (2.61%) were the major compounds. The antimicrobial efficiency of the vapor phase of S.satureioïdes essential oil, which was never presented in the relevant literature yet, was carried out by disc volatilization method. Vapors showed a potent activity against the majority of pathogenic fungal (22.78 ± 0.70-43.25 ± 0.41 mm) and bacterial (13.27 ± 1.88-47.53 ± 0.91 mm) tested strains. The antimicrobial activity of the liquid phase was investigated using disc diffusion and agar dilution methods. EO exhibited a strong antimicrobial activity against all tested strains except P.aeruginosa, and was more effective than all the antibiotics tested against methicillin-resistant S.aureus, B.cereus, K.pneumoniae, S.typhimurium and Y.enterocolitica strains. Both minimum bactericidal (MBC) and fungicidal (MFC) concentrations values vary from 2.5 to 10µl/ml. These promising results suggest the possibility of using S. satureioïdes HE and vapors in anti-infectious aromatherapy against food poisoning or as antimicrobial agents in food industry.
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Vase life is one of the most important factors determining the marketability of cut flowers and influenced by water balance strongly. In recent years, the consumption of hydrangeas as a cut flower has gradually increased. However, the vase life of cut hydrangea flowers is short depends on wilting. Thus, this study was conducted to determine the effects of different treatments [thymol (100, 150 and 200 mgL–1), 8-hydroxyquinoline sulfate (8-HQS) (200 mgL–1)], and their combination with and without 1% sucrose on the vase life, relative fresh weight, daily (solution uptake for 3 days) and total solution uptake of hydrangeas (Hydrangea macrophylla ‘Green Shadow’) harvested freshly. Distilled water was used as the control. Compared to the control, thymol 150 mgL–1 treatment with 1% sucrose significantly increased the vase life of hydrangeas flowers in 5.80 days (from 10.7 to 16.5 days). It was also determined that same treatment increased the total solution uptake and delayed relative fresh weight loss. These results indicated that thymol treatments in combination with sucrose can be used to extend the vase life of cut hydrangea.
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The Caenorhabditis elegans model can be used to study Candida albicans virulence and host immunity, as well as to identify plant-derived natural products to use against C. albicans. Thymol is a hydrophobic phenol compound from the aromatic plant thyme. In this study, the in vitro data demonstrated concentration-dependent thymol inhibition of both C. albicans growth and biofilm formation during different developmental phases. With the aid of the C. elegans system, we performed in vivo assays, and our results further showed the ability of thymol to increase C. elegans life span during infection, inhibit C. albicans colony formation in the C. elegans intestine, and increase the expression levels of host antimicrobial genes. Moreover, among the genes that encode the p38 MAPK signaling pathway, mutation of the pmk-1 or sek-1 gene decreased the beneficial effects of thymol's antifungal activity against C. albicans and thymol's maintenance of the innate immune response in nematodes. Western blot data showed the level of phosphorylation of pmk-1 was dramatically decreased against C. albicans. In nematodes, treatment with thymol recovered the dysregulation of pmk-1 and sek-1 gene expressions, the phosphorylation level of PMK-1 caused by C. albicans infection. Therefore, thymol may act, at least in part, through the function of the p38 MAPK signaling pathway to protect against C. albicans infection and maintain the host innate immune response to C. albicans. Our results indicate that the p38 MAPK signaling pathway plays a crucial role in regulating the beneficial effects observed after nematodes infected with C. albicans were treated with thymol.
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Pseudomonas aeruginosa has a high propensity to develop biofilms that are resistant to exogenous deleterious agents. The aim of this study was to investigate whether carvacrol and thymol can interfere with adherence phenomena as well as acting on biofilm formation. Tests of P. aeruginosa strains showed that carvacrol and thymol interferes with the starting phases of adherence as well as with P. aeruginosa biofilms. Carvacrol and thymol (2MIC) inhibition was 97 +/- 8.5 and 89 +/- 6.3% for P. aeruginosa (ATCC 27853) and 72 +/- 4.6 and 69 +/- 6.8% for P. aeruginosa (CIP A22) adherence respectively. Carvacrol (2MIC) inhibition exceeds 90% for P. aeruginosa (ATCC 27853) and P. aeruginosa (IL5) biofilm. Thymol (2MIC) inhibition is 86 +/- 2.1, 54 +/- 5.9 and 70 +/- 4.3% for P. aeruginosa (ATCC 27853) P. aeruginosa (CIP A22), P. aeruginosa (IL5), respectively.
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Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
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The aim of the current research work was to study the chemical composition of the essential oil of Monarda punctata along with evaluating the essential oil and its major components for their antibacterial effects against some frequently encountered respiratory infection causing pathogens. Gas chromatographic mass spectrometric analysis revealed the presence of 13 chemical constituents with thymol (75.2%), p-cymene (6.7%), limonene (5.4), and carvacrol (3.5%) as the major constituents. The oil composition was dominated by the oxygenated monoterpenes. Antibacterial activity of the essential oil and its major constituents (thymol, p-cymene, limonene) was evaluated against Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Haemophilus influenzae and Escherichia coli. The study revealed that the essential oil and its constituents exhibited a broad spectrum and variable degree of antibacterial activity against different strains. Among the tested strains, Streptococcus pyogenes, Escherichia coli and Streptococcus pneumoniae were the most susceptible bacterial strain showing lowest MIC and MBC values. Methicillin-resistant Staphylococcus aureus was the most resistant bacterial strain to the essential oil treatment showing relatively higher MIC and MBC values. Scanning electron microscopy revealed that the essential oil induced potent and dose-dependent membrane damage in S. pyogenes and MRSA bacterial strains. The reactive oxygen species generated by the Monarda punctata essential oil were identified using 2', 7'-dichlorofluorescein diacetate (DCFDA).This study indicated that the Monarda punctata essential oil to a great extent and thymol to a lower extent triggered a substantial increase in the ROS levels in S. pyogenes bacterial cultures which ultimately cause membrane damage as revealed by SEM results.
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We describe the in vitro activities of the combinations of carvacrol and thymol with antibiotics (azithromycin, clarithromycin, minocycline and tigecycline) and antifungal agents (amphotericin B, caspofungin, itraconazole and terbinafine) against 23 isolates of the oomycete Pythium insidiosum. The assays were based on the M38-A2 technique and checkerboard microdilution. Based on the mean FICI values, the main synergies observed were combinations of carvacrol+itraconazole and thymol+itraconazole (96%), thymol+clarithromycin (92%), carvacrol+clarithromycin (88%), thymol+minocycline (84%), carvacrol+minocycline (80%), carvacrol+azithromycin (76%), thymol+azithromycin (68%), carvacrol+tigecycline (64%) and thymol+tigecycline (60%). In conclusion, we found that combinations of carvacrol or thymol with these antimicrobial agents might provide effective alternative treatments for cutaneous pythiosis due to their synergistic interactions. Future in vivo experiments are needed to elucidate the safety and therapeutic potential of these combinations.