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Bay Leaves have Antimicrobial and Antioxidant Activities

Authors:
  • Pharmacy school, University of Tripoli
Bay Leaves have Anmicrobial and Anoxidant Acvies
Sumia O Algabri1*, Basma M Doro2, Awatf M Abadi1, Mahmoud A Shiba1 and Almonder H Salem1
1Department of Pharmacognosy, University of Tripoli, Tripoli, Libya
2Department of Microbiology and Immunology, University of Tripoli, Tripoli, Libya
*Corresponding author: Algabri SO, Department of Pharmacognosy, Faculty of Pharmacy, University of Tripoli, Tripoli, Libya, Tel:
+218928629603; E-mail: mannaaljabri@yahoo.com
Received date: July 06, 2018; Accepted date: July 28, 2018; Published date: August 02, 2018
Copyright: © 2018 Algabri SO, et al. This is an open-access arcle distributed under the terms of the creave Commons Aribuon License,
which permits unrestricted use, distribuon and reproducon in any medium, provided the original author and source are credited.
Citaon: Algabri SO, Doro BM, Abadi AM, Shiba MA, Salem AH (2018) Bay Leaves have Anmicrobial and Anoxidant Acvies. J Pathogen Res
Vol.1 No.1:3.
Abstract
Background: Bay, Laurus nobilis L is a nave plant and is
one of the most frequently used cooking spices. The dry
Bay leaves are used to treat several digesve problems
with anconvulsive, narcoc and anbacterial properes.
Thus, this study was aimed to invesgate the in-vitro
anmicrobial and anoxidant acvies of dierent
extracts of Bay leaves.
Methods: The dried Bay leaves were extracted
sequenally with n-hexane, dichloromethane and
methanol by Soxhlet apparatus. The extracts were
concentrated and evaluated for anmicrobial acvity
against Staphylococcus aureus, Pseudomonas aeroginosa,
E. coli and Candida albicans using well diusion method
to determine the diameter of zone of inhibion. Also, Bay
leaves extracts were evaluated for anoxidant acvity
using qualitave DPPH assay.
Results: The ndings of anmicrobial assay showed that
methanolic extract of Bay leaves has an anbacterial
acvity against Staphylococcus aureus with zone of
inhibion of 18 ± 0.8 mm, which is higher than phenol
inhibion zone (10 ± 1.0 mm) whereas, no anbacterial
inhibion against other tested bacteria was detected. The
dichloromethane extracts inhibited E. coli growth with
zone of inhibion of 14 ± 0.6 mm and with Staphylococcus
aureus of 18 ± 0.8 mm, while, the n-hexane extract has no
anbacterial acvity with all of the tested organisms.
However, all of Bay leaves extracts displayed no anfungal
eect on Candida albicans. In terms of anoxidant
acvity, all of Bay leaves extracts exhibited anoxidant
acvity, but the methanolic extract displayed the most
prominent level.
Conclusion: The bay leaves extracts have anbacterial and
anoxidant acvity and further invesgaons to assess
these eects are recommended.
Keywords: Bay leaves; Staphylococcus; Qualitave DPPH;
Anmicrobial; Anoxidant
Introducon
One of the most well-known plants from the Lauraceae
family is Laurus nobilis L, which is also known as Bay or laurel
leaves. Bay is one of the most frequently used cooking spices
for avouring meat products, shes and soups. It is a nave
plant in the Southern Mediterranean area, found in warm
climate regions, but it is used as a decorave plant in Europe
and USA. In addion, it is commercially grown in, Algeria,
Morocco, Portugal, Spain, Italy, France, Turkey and Mexico
[1-3].
Tradionally, the dry Bay leaves and their infusions are used
to treat digesve dicules as epigastric pain, atulence,
bloang, and eructaon problems. Leaves and fruits of Bay
plant have been used as astringent, diaphorec, smulant and
emec as well as emmenagogue, aborfacient and insect
repellent. In addion, as it is an aromac plant, its essenal oil
is added in the cosmec products like soaps, creams and
perfumes [4].
Phytochemical studies on Bay leaves and its fruits have
indicated various secondary metabolites including alkaloids,
avonols (kaempferol, myricen, and quercin), avones
(apigenin and luteolin), glycosylated avonoids, sesquiterpene
lactones, monoterpene and germacrane alcohols [5-10].
Interesngly, there is a worldwide concern around that use
of anbiocs to treat bacterial and fungal infecons can lead
to the rise and spread of organisms resistant to broad-
spectrum anbiocs, opening ways to use plants as natural
sources for novel anmicrobial agents with a similar acvity
[11-13]. Natural medicinal plants, as L. nobilis, are rich sources
of bioacve compounds. Thus, the biological properes of Bay
extracts and its essenal oil are documented, specically their
anmicrobial, anfungal and anoxidant eect. A previous
study has reported that the aqueous decocon of bay leaf
showed 53.4% of bactericidal eect against 176 bacterial
isolates belonging to 12 dierent genera of bacterial
Research Article
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populaon isolated from oral cavity of 200 individuals [14].
Also, another study found that the bay leaf essenal oil (EO)
was able to decrease the populaon of total coliforms (2.8 log
CFU/g) and to prolong the shelf life of fresh Tuscan sausage
stored at 7°C for 14 days for two days [15]. In a Turkish
research, the in vitro anbacterial against three Gram-posive
(Bacillus sublis, Staphylococcus aureus and S. epidermidis)
and two Gram-negave bacteria (Escherichia coli and
Pseudomonas aeruginosa), using agar diluon methods was
assayed. Furthermore, its potenal toxicity to Candida albicans
and Aspergillus niger was examined by using both disc-
diusion and agar diluon methods. The ndings of this study
showed the minimum inhibion concentraon (MIC) of the L.
nobilis extract was 5 mg/mL for all the bacteria tested. Also,
the extract of L. nobilis, showed higher inhibitory acvity
against the yeast C. albicans and the fungus A. niger than the
standard anfungal nystan that used as a posive control
[16].
In addion, the potenal anoxidant eect bay leaves
extract has been reported. The methanolic extract of seed oil
exhibited anoxidant properes in both 2, 2-diphenyl-l-
picrylhydrazyl (DPPH) free radical scavenging and β-carotene/
linoleic acid test systems [17]. In another study, the
anoxidant possibility of ethanolic and aqueous extracts of
Hypericum perforatum, Ocimum basilicum and L. nobilis leaves
were assessed by DPPH assay. The aqueous extract of L. nobilis
showed the lowest radical scavenging capacity (RSC) as
compared to H. perforatum and O. basilicum. However, the
ethanolic extracts of L. nobilis showed more DPPH radical
scavenging eect than their aqueous extracts [18].
As in Libya the bay leaves commonly used in tradion meals,
the aim of this study was to explore the in-vitro anmicrobial
and anoxidant acvies of dierent extracts of Bay leaves
collected from local Libyan store.
Materials and Methods
Chemicals and reagents
2,2 diphenyl -1- picryl hydrazyl (DPPH) and ascorbic acid
(Vitamin C) were obtained from Sigma Aldrich (Germany),
Silica gel F254 TLC plates was obtained from Merck (Germany),
metathanol (MeOH), dichloromethane (DCM) and hexane are
of HPLC grade and obtained for Fisher Scienc.
Plant material
The dried Bay leaves were obtained from local market in
Tripoli, Libya, in 27 November 2014 ready for grinding and
extracon. The plant was idened and authencated as
Laurus nobilis. Dried leaves by Botanists in the Herbarium of
Sciences College, University of Tripoli, Libya where a voucher
specimen was deposited.
Preparaon of plant extracts
The dried Bay leaves were nely ground using a coee
grinder and 196 gm were placed in a cellulose thimble and
extracted with a Soxhlet apparatus sequenally with n-hexane,
dichloromethane (DCM) and methanol (MeOH) extracts were
concentrated using a rotary evaporator at 45°C and stored in
pre-weighed glass jars for further analysis.
Evaluaon of anmicrobial acvity
The anmicrobial acvity of Bay leaves extracts was tested
in vitro using the agar well-diusion assay. This method was
performed using freshly prepared Mueller Hinton agar
inoculated with an overnight culture of bacteria suspended in
sterile saline and adjusted to a 0.5 McFarland standard. Aer
solidicaon, 6 mm diameter wells were punched into the
Mueller Hinton agar plates [19]. Each well was lled with 100
μl of the extract soluon at concentraon 1 mg/ml and then
incubated for 24 h at 37°C. The inhibion zones were
measured in millimeters. 5% phenol was used as a standard.
The controls were prepared without extract. The experiment
was carried out in triplicate to ensure reproducible results.
Dimethylsulfoxide (DMSO) was used as a negave control
while phenol was used as a posive control.
Bacterial strains and media
The anmicrobial acvity of Bay leaves extracts was tested
against two Gram-negave bacteria Pseudomonas aeruginosa
(ATCC 29138) and Escherichia coli (ATCC 25922), and one
Gram- posive bacteria Staphylococcus aureus (ATCC 29213).
In addion, the same extracts were tested against the yeast
Candida albicans (ATCC 10231). The standard bacterial strains
were streaked onto nutrient agar, incubated for 24 hours at
37°C then stored at 4°C. The media used in this study were
nutrient broth (NB), nutrient agar (NA) and Mueller Hilton agar
(Oxoid). The media was prepared according to the
manufacturer’s instrucons.
Evaluaon of anoxidant acvity
Qualitave DPPH assay: Anoxidant acvity of dried Bay
leaves extracts was analyzed qualitavely by using 2,
2,diphenyl-1-picrylhydrazyl (DPPH) assay on thin layer
chromatography (TLC) plates [20]. DPPH assay was used as a
screening test for the radical scavenging ability of the
compounds present in dierent extracts of Bay leaves. Silica
gel F254 TLC plates were used to separate Bay leaves extracts
where 10 μl aliquots of each of the n-hexane, DCM and MeOH
extracts (10 mg/ml) were applied to Silica gel plates using
capillary tubes, le to dry, then; The plates were dried in the
fume hood for the detecon of anoxidant acvity,
chromatograms were sprayed with 0.2% DPPH in methanol, as
an indicator. It was allowed to develop for 30 min. The
presence of anoxidant compounds was detected by
observaon of yellow spots against a purple background on
TLC plates sprayed with 0.2% DPPH in methanol. Vitamin C (2
mg/100 ml methanol) was used as a posive standard [20,21].
Journal of Pathogen Research
Vol.1 No.1:3
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Results and Discussion
Anmicrobial acvity
In Table 1, the anmicrobial acvity of Bay leaves in terms
of zone of inhibion (in mm diameter) of n-hexane,
dichloromethane and methanolic extracts at concentraons
0.5 mg/ml against the tested microorganisms were shown. The
ndings indicated that the methanolic extract of Bay leaves
has an anbacterial acvity against Staphylococcus aureus
with zone of inhibion 18 ± 0.8 mm, which is much higher than
the posive control (phenol) inhibion zone (10 ± 1.0 mm),
whereas, there was no anbacterial inhibion against other
tested bacteria. The Dichloromethane extract inhibited E. coli
growth with an inhibion 14 ± 0.6 mm and Staphylococcus
aureus with 13 ± 0.5 mm, while the n-hexane extract has no
anbacterial acvity with all the tested organisms. However,
all of Bay leaves extracts displayed no anfungal eect on
Candida albicans (Table 1).
Table 1 Average diameter, in millimeters, of the bacterial inhibion zones of Bay leaves extracts at concentraon 0.5 mg per ml
against tested microorganism.
Microorganism Mean diameter of zone of inhibition (mm ± SE)
Extract (0.5 mg/ml)
n-hexane extract DCM Extract MeOH Extract 5% Phenol
Staphylococcus aureus 0.0 ± 0.0 13 ± 0.5* 18 ± 0.8* 10 ± 1.0
Pseudomonas aeruginosa 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 27 ± 0.5
E. coli 0.0 ± 0.0 14 ± 0.6 0.0 ± 0.0 12 ± 2.0
Candida albicans 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 11 ± 2.5
*Statistically significant difference by t-test.
In a previous study, the in vitro anmicrobial and
anoxidant acvies of the essenal oil, seed oil and
methanolic extract of seed oil of Bay leaves were showed that
the extract of seed oil has more eecve anbacterial acvity
compared with essenal oil and seed oil [22]. Furthermore,
GC-MS analysis of essenal oil resulted in idencaon of 25
compounds. 1.8-Cineol (44.72%), a-Terpinyl acetate (12.95%),
Sabinene (12.82%) were the main components. In addion,
other study reported that Laurus nobilis extract has
anbacterial acvity against Staphylococcus aureus where the
zone diameter of inhibion of Laurus nobilis extract was
comparable to zone diameter of the inhibion of tetracycline
[23]. That may support the ndings of this study in terms of
the anbacterial eect.
Anoxidant acvity
Qualitave DPPH assay: Various methods have been used
to evaluate anoxidant capacity of some compounds in
dierent plant extracts, one of the most widely used methods
are those involve the generaon of free radicals which then
neutralized by anoxidant compounds [24]. The DPPH
anoxidant assay is based on the ability of DPPH to decolorize
in the presence of anoxidants. The odd electron in the DPPH
radical is responsible for the deep purple color. When DPPH
accept an electron from anoxidant compound, the DPPH
decolorize [20].
In the present study, only TLC based qualitave DPPH assay
was performed to evaluate anoxidant acvity of bay leaves
extracts which provide a rapid, exible and ecient screening
method for anoxidant acvity [25]. The results showed the
presence of anoxidant acvity in all the tested Bay leaves
extracts as it is given in Figure 1. The acvity was indicated by
the presence of yellow spots against a purple background on
the chromatograms. The degree of acvity of all the samples
tested was also determined qualitavely from observaon of
the yellow color intensity. It is observed that methanolic
extract of Bay leaves displayed the most prominent level of
anoxidant acvity where it has an intense yellow color
compared with the control using vitamin C.
Figure 1 Chromatogram of Bay leaves extracts sprayed with
0.2% DPPH in methanol yellow zones indicate anoxidant
acvity.
Several previous studies assessed the quantave
anoxidant acvity of dierent extracts of Bay leaves by using
dierent models, all of them indicated that Bay leaves extracts
provide both In vitro and In vivo anoxidant eect [26-30].
Although, in this research only the qualitave anoxidant
eect was tested, and this eect may be related to the
presence of phenolic secondary metabolites like phenols.
Conclusion
The ndings of this study show that the bay leaves extracts
have anbacterial and anoxidant eects. However,
Journal of Pathogen Research
Vol.1 No.1:3
2018
© Copyright iMedPub 3
quantave DPPH assay is needed to conrm the obtained
results and more invesgaons on wide range of pathogen to
assess the spectrum of bay leaves extracts are recommended.
Acknowledgements
The authors would like to thank Prof. Fathi M Sherif,
Department of Pharmacology, for his help in crical reviewing
the manuscript and valuable comments. Also, thanks go to the
laboratory sta of Microbiology and Immunology for their
help.
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... The Eucalyptus and bay leaf extracts have found to have antibacterial activity. (Algabri, S. O. 2018) [1] . Hence, Herbal Dhoop stick is an effective way to prevent various air borne bacterial diseases. ...
... [8] indicated that the E. coli was less sensitive to bay leaf extracts compared to the positive S. aureus. He also indicated that bay leaf reduces E. coli and thus prolongs the shelf life of food products that bay leaves enter into their composition, due to the presence of many effective compounds that have the ability to inhibit bacteria, especially Gram positive bacteria [20]. ...
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The global demand for medicinal plants has increased recently as food source for functional, healthy and sensory properties. This study allows the identification of active compounds found in alcoholic bay leaf extracts by GC-MS technique that give the plant functional properties. The inhibitory activity of extracts at concentrations of 0.25, 0.50, 0.75 and 1 mg/ml were tested against four types of bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. The results found the emergence of a number of active compounds, volatile oils and flavor compounds with a retention time (RT) ranging between 4.861-40.551 minutes, including compounds that gave the highest area of 24.96% such as Eucalyptol and alpha.-Terpinyl acetate compound by Area 10.87%. The results also showed that S. aureus recorded the highest inhibitory diameter at a concentration of 1 mg / ml was 10.7 mm, while E. coli recorded the lowest inhibitory diameter compared to the rest bacteria at the same concentration was 9.5 mm. B. cereus and P. aeruginosa, showed the highest inhibitory diameter were 10.4 and 9.8 mm at a concentration of 1 mg / ml. Which indicates the possibility of introducing bay leaves in many diets, improving its health and functional properties and prolonging the storage period due to rich in biologically active compounds Highlights: 1. Active Compounds Identified: Eucalyptol (24.96%), α-Terpinyl Acetate (10.87%) via GC-MS. 2. Antibacterial Activity: S. aureus (10.7 mm), E. coli (9.5 mm) at 1 mg/ml. 3. Potential Applications: Functional food ingredient, health benefits, extended shelf life..
... [8] indicated that the E. coli was less sensitive to bay leaf extracts compared to the positive S. aureus. He also indicated that bay leaf reduces E. coli and thus prolongs the shelf life of food products that bay leaves enter into their composition, due to the presence of many effective compounds that have the ability to inhibit bacteria, especially Gram positive bacteria [20]. ...
Conference Paper
The global demand for medicinal plants has increased recently as food source for functional, healthy and sensory properties. This study allows the identification of active compounds found in alcoholic bay leaf extracts by GC-MS technique that give the plant functional properties. The inhibitory activity of extracts at concentrations of 0.25, 0.50, 0.75 and 1 mg/ml were tested against four types of bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. The results found the emergence of a number of active compounds, volatile oils and flavor compounds with a retention time (RT) ranging between 4.861-40.551 minutes, including compounds that gave the highest area of 24.96% such as Eucalyptol and alpha.-Terpinyl acetate compound by Area 10.87%. The results also showed that S. aureus recorded the highest inhibitory diameter at a concentration of 1 mg / ml was 10.7 mm, while E. coli recorded the lowest inhibitory diameter compared to the rest bacteria at the same concentration was 9.5 mm. B. cereus and P. aeruginosa, showed the highest inhibitory diameter were 10.4 and 9.8 mm at a concentration of 1 mg / ml. Which indicates the possibility of introducing bay leaves in many diets, improving its health and functional properties and prolonging the storage period due to rich in biologically active compounds Highlights: 1. Active Compounds Identified: Eucalyptol (24.96%), α-Terpinyl Acetate (10.87%) via GC-MS. 2. Antibacterial Activity: S. aureus (10.7 mm), E. coli (9.5 mm) at 1 mg/ml. 3. Potential Applications: Functional food ingredient, health benefits, extended shelf life..
... [8] indicated that the E. coli was less sensitive to bay leaf extracts compared to the positive S. aureus. He also indicated that bay leaf reduces E. coli and thus prolongs the shelf life of food products that bay leaves enter into their composition, due to the presence of many effective compounds that have the ability to inhibit bacteria, especially Gram positive bacteria [20]. ...
Article
Full-text available
The global demand for medicinal plants has increased recently as food source for functional, healthy and sensory properties. This study allows the identification of active compounds found in alcoholic bay leaf extracts by GC-MS technique that give the plant functional properties. The inhibitory activity of extracts at concentrations of 0.25, 0.50, 0.75 and 1 mg/ml were tested against four types of bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. The results found the emergence of a number of active compounds, volatile oils and flavor compounds with a retention time (RT) ranging between 4.861-40.551 minutes, including compounds that gave the highest area of 24.96% such as Eucalyptol and alpha.-Terpinyl acetate compound by Area 10.87%. The results also showed that S. aureus recorded the highest inhibitory diameter at a concentration of 1 mg / ml was 10.7 mm, while E. coli recorded the lowest inhibitory diameter compared to the rest bacteria at the same concentration was 9.5 mm. B. cereus and P. aeruginosa, showed the highest inhibitory diameter were 10.4 and 9.8 mm at a concentration of 1 mg / ml. Which indicates the possibility of introducing bay leaves in many diets, improving its health and functional properties and prolonging the storage period due to rich in biologically active compounds Highlights: 1. Active Compounds Identified: Eucalyptol (24.96%), α-Terpinyl Acetate (10.87%) via GC-MS. 2. Antibacterial Activity: S. aureus (10.7 mm), E. coli (9.5 mm) at 1 mg/ml. 3. Potential Applications: Functional food ingredient, health benefits, extended shelf life..
... It also contains flavonoids, tannins and glycosides that have been reported to reduce hyperlipidemia (Wahyuningsih et al., 2022). In the medicine this plant is used against gastrointestinal disorders (epigastric pain, bloating, eructation, flatulence), but it is also known that bay leaf possess antimicrobial, antioxidant, anticonvulsive, astringent (Algabri et al., 2018), analgesic, anti-inflammatory, anti-arthritic and anti-asthmatic properties (Boulila et al., 2015). ...
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The present study aimed to investigate the phytochemical composition, antioxidant potential and antimicrobial activity of five culinary plants – bay leaf, rosemary, juniper fruit, pitahaya fruit and black goji berry fruit, and their application as sources of bioactive compounds in development of prebiotic vegan mayonnaises. After the analyses of the plant materials, in the experimental procedure, a low-fat mayon¬naise (30% fat content) without animal products was prepared. The mayonnaise base was divided into three portions – the first portion was kept as a control; the second portion was additionally divided into five parts used for direct addition of 1% agave inulin + 1% ground plant material (bay leaf, rosemary, juniper fruit, pitahaya fruit and black goji berry fruit, respectively); the third portion was also divided into five parts used for incorporation of 10% calcium alginate microcapsules (containing 1% agave inulin + 1% bay leaf, rosemary, juniper fruit, pitahaya fruit and black goji berry fruit, respectively). The obtained mayonnaises were stored under refrigeration conditions (4°С) for 21 days and samples for physicochemical and micro¬biological analyses were taken once a week. The sensory evaluation was performed immediately after the mayonnaise preparation.
... These properties give them antioxidant, anti-inflammatory, antimicrobial, anticancer, and antidiabetic benefits, making them a valuable plant in both modern pharmacological research and traditional medicine. [1][2][3][4][5] Bay Leaf Extract: ...
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Introduction: Mediterranean-native bay leaves have long been utilized in traditional medicine because of their healing qualities. These consist of tannins, phenolic acids, flavonoids, and essential oils. Essential oils help to fight infections, to improve gastrointestinal problems, and to promote digestion. As antioxidants, flavonoids protect cells from oxidative damage and may reduce the chance of developing chronic diseases. Additionally, bay leaves help to control type 2 diabetes, to reduce blood sugar, and to support healthy skin. They boost the immune system, have neuroprotective properties, and have anticancer effects. Traditional systems such as Ayurveda and Unani value bay leaves. Materials and Method: Bay leaf extracts can be used as an anticancer agent, with concentrations based on research findings. The gel formulation includes natural and synthetic polymers, with penetration enhancers for enhanced absorption. Solubility requirements are determined, and solvents and buffer systems are chosen based on active compounds' solubility. The process involves drying, crushing, extracting solvent, and storing the extract. Research analysis validates anticancer properties, and the gel properties are optimized through pH adjustment, viscosity control, and stability testing. Results and Discussion: Bay leaf extract, rich in bioactive compounds like flavonoids, polyphenols, and essential oils, was extracted using ethanol and methanol as solvents. The extract was incorporated into a gel, tested for its anticancer properties using human cancer cell lines. The gel's stability and antioxidant activity support its potential as a topical anticancer product. Conclusion: A bay leaf extract-based anticancer gel, containing bioactive compounds like flavonoids, polyphenols, and essential oils, has shown potential for localized cancer treatment, but further in vivo research is needed.
... Some studies have also shown that laurel also has antiepileptic and anticonvulsant activity against experimental seizures [10] . Bay leaves exhibit a range of pharmacological and biological activities, including antioxidant activity [11,12] , antibacterial activity [13] , antiviral activity [14] , immunestimulant activity, anticholinergic activity [15] , antifungal activity [16] , insect repellant activity [17] , antimutagenic activity [18] , and analgesic and antiinflammatory activity [19] . ...
... In addition, bay leaf is also an aromatic plant, its essential oil is added to cosmetic products such as soap, cream, and perfume. 8 Bay leaves have chemical properties, namely tannins, flavonoids, and 0.05% essential oil consisting of eugenol and citral. The content of Eugenia polyantha Wight is an active ingredient that is thought to have pharmacological effects. ...
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Background: Many microorganisms can be found within the oral cavity, including Streptococcus mutans. The introduction of oral bacteria into the bloodstream can lead to the occurrence of bacteremia and subsequent development of systemic diseases. Traditional medicine uses specific ingredients or herbs employed over successive generations and is widely believed to possess medicinal properties. One example is the bay leaf, scientifically known as Eugenia polyantha Wight. Objective. This study aims to determine the effectiveness of bay leaf extract (Eugenia polyantha Wight.) in inhibiting Streptococcus mutans. Materials and Methods: This type of research is an experimental laboratory with Post-test Only Control Group Design. Testing the effectiveness of antibacterial in this study using the diffusion method by diluting bay leaf extract using DMSO solvent into five concentrations, namely 50%, 25%, 12.5%, 6.25%, and 3.125%, with a sample size of 4 for each concentration. Results: The results showed that bay leaf extract concentrations of 50%, 25%, 12.5%, 6.25%, and 3.125% showed a clear zone around the disc paper in Muller Hinton Agar as a medium for the breeding of Streptococcus mutans bacteria. The formation of a clear zone indicates that the ability of bay leaf extract inhibits the growth of Streptococcus mutans with a mean diameter of inhibition of 10.4 ± 0.2944 mm; 8.9 ± 0.7500 mm; 7.1 ± 0.3202 mm; 6.9 ± 0.2944 mm; and 6.4 ± 0.1826 mm. Conclusion: Eugenia polyantha Wight can inhibit the development of Streptococcus mutans. A concentration of 50% is the best in inhibiting the development of Streptococcus mutans based on the growth zone of bacteria.
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Microbial resistance to antibiotics and the shortage of efficient antimicrobial agent has necessitated the search for a better antimicrobial agent from various sources. Plants secondary metabolites are the major sources for discovery of new bioactive chemical compounds. The objective of this study was to determine the antibacterial and antioxidant activities of Laurus nobilis leaf extract and its essential oil against human pathogenic microorganisms and to analyse its chemical composition. The leaf of L. nobilis (500 g) was air-dried, powdered and extracted using four different solvents. The crude extract and the essential oil were tested against four Gram-negative and two Gram-positive bacterial strains. The radical scavenging activity of the crud extract was examined using DPPH assay. Bacterial inhibition activity of the crude extract increased with increased concentration from 25 mg/mL to 200 mg/mL. The maximum inhibition zone was recorded against Enterococcus faecalis 13.33±1.52 mm, Escherichia coli 14.33±1.53 mm and Salmonella typhimurium 16.00±1.00 mm, respectively. MeOH extract (1000 µg/mL) showed superior radical scavenging property (0.02) than ascorbic acid (0.05). The analysis of the oil using GC-MS indicated the presence of 48 chemical substances accounting for 91.4 % of the total compositions. The finding of this study showed that bay leaf has considerable antimicrobial and antioxidant activities. Further evaluation of this plant is recommended with particular focus on the mechanisms of action of the antimicrobial substance.
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OBJECTIVE In this study, we aimed to determine the phenolic compounds, the antibacterial activity of extract from Laurus nobilis leaves, and its possible effect on transforming growth factor-β1 expression level in peripheral blood mononuclear cells. METHODS The phenolic components of Laurus nobilis were identified by the high-performance liquid chromatography method. The antibacterial activity of this extract was determined by disk diffusion and broth microdilution methods. The transforming growth factor-β1 expression was analyzed using the RT-qPCR method. RESULTS Epicatechin was found in the highest amount and o-coumaric acid in the lowest amount. The half-maximal inhibitory concentration (IC50) was determined to be 55.17 μg/mL. The zones of inhibition and minimum inhibitory concentration for Staphylococcus aureus, Enterococcus faecalis, and Klebsiella pneumoniae were 15, 14, and 8 mm and 125, 250, and 1000 μg/mL, respectively. The change in transforming growth factor-β1 expression levels was found to be statistically significant compared with the control groups (p<0.0001). CONCLUSION Laurus nobilis extract was found to be effective against bacteria and altered the expression level of transforming growth factor-β1 in peripheral blood mononuclear cells.
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In this study, the components of the volatile oil obtained from Laurus nobilis leaves by steam distillation were determined using Agilent 6890 Gas Chromatography (GC) - 5975 Mass Spectrometry (MS). The antioxidant activities of different extracts of L. nobilis leaves were determined by using DPPH•(2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity, β-carotene-linoleic acid bleaching assay and ABTS•+(2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) cation radical decolorization assay. Determination of the total phenolic contents of L. nobilis leaf extracts were performed using the Folin-Ciocalteau procedure and total flavonoid contents were measured using a spectrophotometric assay. According to the GC/MS results, 1,8-cineole (46.16%), alpha-terpinyl acetate (10.62%), alpha-pinene (6.27%), terpinen-4-ol (5.07%) and sabinene (4.99%) were found to be the major compounds in volatile oil. The obtained volatile oil was used to make skin care lotion. Stability tests and organoleptic analyses of final product were performed after 1, 5, 30 and 90 days of production. The highest amounts of total flavonoid content were found to be 5.48 ± 0.65 and 8.60 ± 0.12 μg QEs/mg in ethyl acetate and ethanol extracts, respectively. The highest amounts of total phenolic compounds were found to be 54.42 ± 0.14 and 25.32 ± 0.10 μg PEs/mg in ethyl acetate and ethanol extracts, respectively. According to the results of ABTS•+, DPPH•and β-carotene linoleic acid assays, ethyl acetate extract was found to be the most active extract (24.98±0.87 μg mL-1, 75.65±0.77 μg mL-1 and 19.32±1.04 μg mL-1)
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In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat the emergence of the microbial resistance. Therefore, a greater attention was paid on antimicrobial activity screening and evaluating methods. Several bioassays are well known and commonly used such as disk-diffusion, well diffusion and broth or agar dilution, but others are not widely used such as flow cytofluorometric and bioluminescent methods because they require specified equipment and further evaluation for reproducibility and standardization, even if they can provide a rapid results of the antimicrobial agent’ effects and a better understood of their impact on the viability and cell damage inflicted to the tested microorganism. In this present review article, an exhaustive list of in vitro antimicrobial susceptibility testing methods and detailed information on their advantages and limitations are reported.
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The present study deals with the supercritical carbon dioxide (SC-CO2) extraction and hydrodistillation (HD) of dried bay leaves (Laurus nobilis L.). The chemical composition and antibacterial activity of the SC-CO2 extract and essential oil (EO) from dried leaves of bay were compared to each other and literature data. Qualitative and quantitative analyses of the SC-CO2 extract and EO were performed using GC-FID and GC-MS analytical methods. A significant difference in the chemical composition of the SC-CO2 extract and EO was observed. The EO comprised high contents of monoterpcnes and their oxygenated derivates (98.4 %), principally 1,8-cineole (33.4 %), linalool (16.0 %) and alpha-terpinyl acetate (13.8 %), sabinene (6.91 %) and methyl eugenol (5.32 %). The SC-CO2 extract comprised twice less monoterpenes and their oxygenated derivates (43.89 %), together with sesquiterpenes (12.43 %), diterpenes (1.33 %) and esters (31.13 %). The major components were methyl linoleate (16.18 %), alpha-terpinyl acetate (12.88 %), linalool (9.00 %), methyl eugenol (8.67 %), methyl arachidonate (6.28 %) and eugenol (6.14%) An investigation of the antibacterial activity of bay SC-CO2 extract and EO was completed on different Staphylococcus strains using the broth macrodilution method. Staphylococcus intermedius strains were the most susceptible to both the SC-CO2 extract and EO (MIC = 640 mu g/ml).
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The presence of foodborne pathogens in fresh Tuscan sausage has been reported and these contaminations pose a potential risk to consumers. The objective of the present study was to evaluate the antimicrobial activity of bay leaf essential oil (EO) in vitro and in fresh Tuscan sausage stored at 7 °C for 14 d. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against foodborne pathogens were determined in vitro. The lowest MIC and MBC were found for Escherichia coli (MIC = MBC = 2.5 g/L) and Yersinia enterocolitica (MIC = 1.25 g/L, MBC = 2.5 g/L). Fresh Tuscan sausages were treated with bay leaf EO at 0.05 g/100 g or 0.1 g/100 g and their shelf life was compared to a non-treated control. All groups presented low levels of rancidity (TBARS < 0.5 mg MDA/kg). The EO was able to reduce the population of total coliforms (2.8 log CFU/g) and to extend the product shelf life for two days. Although the presence of the EO affected the sensory characteristics of the sausage, it was considered acceptable by consumers at both concentrations tested. Overall, the results of this study indicate that bay leaf essential oil can be applied in fresh Tuscan sausage to improve its safety and shelf life.
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