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Antimicrobial effect of linalool and α-terpineol against periodontopathic and cariogenic bacteria


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Linalool and α-terpineol exhibited strong antimicrobial activity against periodontopathic and cariogenic bacteria. However, their concentration should be kept below 0.4 mg/ml if they are to be used as components of toothpaste or gargling solution. Moreover, other compounds with antimicrobial activity against periodontopathic and cariogenic bacteria should be used in combination.
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Antimicrobial effect of linalool and
-terpineol against periodontopathic and
cariogenic bacteria
Soon-Nang Park
, Yun Kyong Lim
, Marcelo Oliveira Freire
, Eugene Cho
, Dongchun Jin
Joong-Ki Kook
Department of Oral Biochemistry, School of Dentistry, Chosun University, 375 Seosuk-Dong, Dong-Gu, Gwangju 501-759, Republic of Korea
Herman Ostrow School of Dentistry, University of Southern California, 925 West 34th Street, Los Angeles, CA 90089, USA
Department of Veterinary Medicine, College of Agriculture, Yanbian University, Jilin Province 133002, China
article info
Article history:
Received 19 December 2011
Received in revised form
4 April 2012
Accepted 6 April 2012
Available online 17 April 2012
Antimicrobial effect
Mutans streptococci
Linalool and
-terpineol exhibited strong antimicrobial activity against periodontopathic and cariogenic
bacteria. However, their concentration should be kept below 0.4 mg/ml if they are to be used as
components of toothpaste or gargling solution. Moreover, other compounds with antimicrobial activity
against periodontopathic and cariogenic bacteria should be used in combination.
Crown Copyright Ó2012 Published by Elsevier Ltd. All rights reserved.
Dental caries and periodontal diseases are major oral infectious
diseases caused by bacteria colonizing the tooth surface. The major
causative bacteria of dental caries are mutans group streptococci
(MS), such as Streptococcus mutans and Streptococcus sobrinus,in
the case of humans [1]. The major causative agents of periodontal
diseases are gram negative anaerobic bacteria, such as Porphylo-
monas gingivalis,Prevotella intermedia,Aggregatibacter actimony-
cetemcomitans,Fusobacterium nucleatum [2,3]. Dental plaque
control is an essential strategy for preventing dental caries and
periodontal diseases. Tooth-brushing and gargling are the most
accepted and effective methods for controlling plaque. Recently,
many studies have attempted to identify effective chemical
compounds extracted from plants that can be used as antimicrobial
agents to prevent dental caries and periodontal diseases [4e6].
Essential oils are odorous, volatile products of plant secondary
metabolism found in many leaves and stems [7]. It has been
reported that essential oils possess antibacterial, antifungal, anti-
leishmanial, and antiviral activities [8e16]. Linalool (3,7-
dimethylocta-1,6-dien-3-ol) and
-terpineol [2-(4-Methyl- 1-
cyclohex- 3-enyl) propan-2-ol] are terpene alcohols that have
been shown to display broad spectrum antimicrobial activity
[7,9,17e19]. Nevertheless, there is only limited information on the
antimicrobial effect of linalool and
-terpineol against cariogenic
and periodontopathic bacteria [7,9]. In this study, the antibacterial
effects of linalool and
-terpineol against cariogenic and perio-
dontopathic bacteria and the cytoxicity of both essential oils on
human oral tissue cells were evaluated to test whether these
compounds can be used as candidates for pre-clinical and clinical
trials in future oral hygiene products.
The following bacterial strains were used: Porphyromonas
gingivalis ATCC 33277
,P. gingivalis ATCC 49417, P. gingivalis ATCC
53978, P. intermedia ATCC 25611
,P. intermedia ATCC 49046,
Prevotella nigrescens ATCC 33563
,P. nigrescens ATCC 25261,
F. nucleatum subsp. nucleatum ATCC 25586
,F. nucleatum
subsp. polymorphum ATCC 10953
,F. nucleatum subsp. vincentii
ATCC 49046
,F. nucleatum subsp. fusiforme ATCC 51190
F. nucleatum subsp. animalis ATCC 51191
,Aggregatibacter actino-
mycetemcomitans ATCC 33384
,A. actinomycetemcomitans ATCC
43717, A. actinomycetemcomitans ATCC 43718, S. mutans ATCC
and S. sobrinus ATCC 33478
. All reference strains were
purchased from the American Type Culture Collection (ATCC, USA).
The clinical strains of S.mutans (KCOM 1054, KCOM 1111, KCOM
*Corresponding author. Tel.: þ82 62 230 6877; fax: þ82 62 224 3706.
E-mail address: (J.-K. Kook).
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Anaerobe 18 (2012) 369e372
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1113, KCOM 1116, KCOM 1126, KCOM 1128, KCOM 1136, KCOM 1197,
KCOM 1202, KCOM 1207, KCOM 1217) and S.sobrinus (KCOM 1157,
KCOM 1196, KCOM 1221) were obtainedfrom the Korean Collection
for Oral Microbiology (KCOM, Gwangju, Korea).
With the exception of Streptococcus spp., the above strains were
cultured in Tryptic Soy broth supplemented with 0.5% yeast extract,
0.05% cysteine HCleH
O, 0.5 mg/ml of hemin and 2
g/ml of
vitamin K
at 37o
C in an anaerobic chamber (Bactron I, Sheldon
Manufacturing Inc., Cornelius, OR, USA) under an atmosphere
containing 10% H
and 85% N
. All Streptococcus spp. strains
were cultured in Todd Hewitt (TH) broth or on agar plates (Difco,
Lab., Detroit, MI, USA) in a 37o
C incubator that had an atmosphere
composition of 90% air and 10% CO
The MIC and MBC were determined using a microdilution assay
according to the NCCLS standard [20]. The bacterial strains were
cultured in the described above media at 37o
C in an incubator for
24 h, and added to a 96-well plate to a nal concentration of
CFU/ml. Solutions of linalool (Sigma, St. Louis, MO, USA) or
-terpineol (Sigma) dissolved in dimethyl sulfoxide (DMSO; Sigma)
were added to each well to a nal concentration of 0.1, 0.2, 0.4, 0.8,
1.6, 3.2 and 6.4 mg/ml. The nal concentration of DMSO in each
well was 1%. 1% DMSO in the medium was used as the negative
control and ampicillin (concentration of 100
g/ml) was used as
a positive control. After 24 h of incubation under the appropriate
conditions, the lowest concentration of essential oil that inhibited
visible growth was considered the MIC. To determine the MBC
values, 10
l of the bacterial culture solution from each well at the
MIC value determined above was diluted 100- or 10,000-fold and
plated onto an appropriate agar plate for each bacterial strain. The
agar plate was incubated in a 37o
C incubator for 24 h and the
number of bacterial colonies was then counted. The concentration
that killed 99.9% of the bacteria was considered the MBC value. All
experiments were carried out in triplicate.
The KB cell line, which is an oral epithelial carcinoma cell line,
was obtained from ATCC. The KB cells were grown in MEM medium
(Gibco, Grand Island, NY, USA) supplemented with 10% heat-
inactivated fetal bovine serum (PAA Laboratories, Etobicoke,
Ontario, Canada), 100 U/ml penicillin and 100
g/ml streptomycin
(Gibco) at 37o
C in a humidied atmosphere containing 5% CO
A MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide, a tetrazole) assay was used to assess cell toxicity of
linalool and
-terpineol on the KB cells as described previously [21]
at different linalool and
-terpineol concentrations (0.2, 0.4, 0.8,1.6,
3.2 and 6.4 mg/ml).
Linalool or
-terpineol showed remarkable antibacterial effects
against the periodontopathic and cariogenic bacteria. The MIC and
MBC values of linalool or
-terpineol against 5 species of perio-
dontopathogens ranged from 0.1 to 1.6 mg/ml or 0.1e0.8 mg/ml,
respectively (Table 1). Signicant toxicity was observed when
the KB cells were treated with 0.8 mg/ml of linalool or 0.8 mg/ml
-terpineol, and a mild decrease in cytotoxicity was observed
when 0.4 mg/ml of linalool (76.4%) or 0.2 mg/ml of
(73.7%) were used (Fig. 1(A) and (B)). Considering the cell cyto-
toxicity of linalool, all periodontopathogen strains were sensitive
to <0.4 mg/ml of linalool except for the P. gingivalis ATCC 33277
P. intermedia ATCC 49046, and two P. nigrescens strains. The
sensitivity of the P. gingivalis and P. intermedia strains to linalool
varied according to the strain, whereas the effects on the
P. nigrescens,F. nucleatum, and A. actinomycetemcomitans species
were similar. In addition,
-terpineol had a similar antimicrobial
effect on the periodontopathic strains (Table 1).
In this study, the bacterial model system [22] was used to
examine antimicrobial activity and determine the optimal linalool
-terpineol concentration. The MIC and MBC values of linalool
-terpineol against mutans streptococci of the bacterial model
system ranged from 0.1 to 3.2 mg/ml and 0.1e1.6 mg/ml,
respectively (Table 2). Of the strains included in the bacterial
model system, S. mutans KCOM 1113, S. mutans KCOM 1136, and
S. sobrinus KCOM 1221 strains were much more sensitive than the
other type strains. The remaining clinical isolates had the same or
lower MIC and MBC values compared to the type strains (Table 2).
In a previous study, the MBC value of the three natural extracts,
Phellodendron amurense,Coptidis rhizome and Galla rhois, against
the clinical strains of S. mutans and S. sobrinus was higher than that
against the type strains, which ranged from 7.5% to 90% and from
60% to 93.3%, respectively [22]. This suggests that the antimicrobial
efcacy of the chemical compounds is dependent on the mutans
streptococci strain.
Essential oils were previously shown to exert their antimicrobial
activity by disrupting bacterial cell walls, inhibiting bacterial
enzyme activity, and suppressing translation of certain regulatory
gene products [23e25]. These ndings suggest that the cytotoxic
effect of linalool and
-terpineol on human tissue cells occurs
through a similar mechanism. Considering the cytotoxicity to KB
cells, linalool or
-terpineol should not be used alone as compo-
nents of oral hygiene products at high concentration (Table 2) and
(Fig. 1). Various essential oils have been shown to display syner-
gistic activities when combined with chlorhexidine digluconate or
Table 1
Antimicrobial effects of essential oils against periodontopathogens.
Species and strains Linalool
MIC (mg/ml) MBC (mg/ml) MIC (mg/ml) MBC (mg/ml)
Porphylomonas gingivalis ATCC 33277
0.8 1.6 0.4 0.4
P. gingivalis ATCC 49417 0.1 0.2 0.1 0.2
P. gingivalis ATCC 53978 0.1 0.1 0.4 0.4
Prevotella intermedia ATCC 25611
0.2 0.4 0.4 0.4
P. intermedia ATCC 49046 1.6 1.6 0.8 0.8
Prevotella nigrescens ATCC 33563
0.8 0.8 0.4 0.4
P. nigrescens ATCC 25261 0.8 0.8 0.4 0.4
Fusobacterium nucleatum subsp. nucleatum ATCC 25586
0.2 0.4 0.4 0.4
F. nucleatum subsp. polymorphum ATCC 10953
0.2 0.4 0.4 0.4
F. nucleatum subsp. vincentii ATCC 49046
0.1 0.1 0.1 0.1
F. nucleatum subsp. fusiforme ATCC 51190
0.2 0.4 0.2 0.4
F. nucleatum subsp. animalis ATCC 51191
0.2 0.2 0.4 0.4
Aggregatibacter actinomycetemcomitans ATCC 33384
0.1 0.2 0.2 0.2
A. actinomycetemcomitans ATCC 43717 0.1 0.1 0.2 0.2
A. actinomycetemcomitans ATCC 43718 0.1 0.1 0.2 0.4
ATCC, America Type Culture Collection.
S.-N. Park et al. / Anaerobe 18 (2012) 369e372370
Author's personal copy
antibiotics [26,27]. A combinatorial approach might be used in
future studies, in which low concentrations of the compounds will
allow for the safe use of the material and enhance the antimicrobial
activity (Table 2) and (Fig. 1).
Based on the in vitro studies, linalool and
-terpineol not only
displayed strong antimicrobial activity but were also cytotoxic to
mammalian cells. In general, the effects of chemicals or natural
extracts on human cell viability are often examined in vitro.
However, human oral tissue cells might be more resistant to these
chemicals in vivo than in vitro because oral tissue cells in vivo are
continuously supplied with nutrients through the blood, which can
better support repair mechanisms than those in vitro [4].In
particular, the epithelium of the human oral mucosa is composed of
three to four layers. Although, the supercial layer of the epithe-
lium was detached due to the cytotoxicity of essential oils, in vitro
systems are limited and in vivo outer layers are recovered by the
growth of other layers, particularly epithelial cells of the germinal
layer. More studies will be needed to demonstrate the efcacy and
safety of these compounds.
This study was supported by a grant from the Korea Healthcare
technology R&D Project, Ministry for Health, Welfare & Family
Affairs, Republic of Korea (A100960).
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Fig. 1. Effects of (A) Linalool and (B)
-Terpineol on the cell viability of KB cells.
Table 2
Antimicrobial effects of essential oils against mutans streptococci.
Species and strains Linalool
Streptococcus mutans ATCC 25175
1.6 3.2 0.8 1.6
S. mutans KCOM 1054 1.6 3.2 0.8 0.8
S. mutans KCOM 1111 0.8 1.6 0.8 1.6
S. mutans KCOM 1113 0.4 0.4 0.4 0.4
S. mutans KCOM 1116 0.4 0.8 0.8 0.8
S. mutans KCOM 1126 0.8 0.8 0.4 0.4
S. mutans KCOM 1128 3.2 3.2 0.8 0.8
S. mutans KCOM 1136 0.1 0.1 0.1 0.1
S. mutans KCOM 1197 0.4 0.8 0.8 1.6
S. mutans KCOM 1202 1.6 1.6 0.8 0.8
S. mutans KCOM 1207 0.8 1.6 0.8 0.8
S. mutans KCOM 1217 1.6 1.6 0.8 0.8
Streptococcus sobrinus ATCC 33478
1.6 1.6 0.8 0.8
S. sobrinus KCOM 1157 1.6 1.6 0.4 0.8
S. sobrinus KCOM 1196 1.6 1.6 1.6 1.6
S. sobrinus KCOM 1221 0.4 0.8 0.8 0.8
ATCC, America Type Culture Collection; KCOM, Korean Collection for Oral
S.-N. Park et al. / Anaerobe 18 (2012) 369e372 371
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... thujone and camphor found in sage EO, menthone in peppermint EO, and cineol found in both sage and niaouli EOs) (Tariq et al. 2019). It has been illustrated in the literature that α-terpineol which is the major chemical component in T. satureioides has effective inhibitory activity against Bacillus coagulans, E. coli (Li L et al. 2014), Shigella flexneri (Huang et al. 2021), S. aureus, Streptococcus agalactiae (Zhang Yuetian et al. 2018), Streptococcus mutans (Park et al. 2012), Micrococcus luteus and Salmonella enteritidis (Kotan et al. 2007). The proposed mechanism of action involves the alteration of cell structure (Li et al. 2014). ...
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In the food industry, the development of microbial biofilms is a serious problem that leads to the contamination and deterioration of food products. To overcome that, our aim consists of searching for natural antimicrobial and non-toxic compounds (essential oils EOs), which might be used alone or adsorbed on natural biopolymer films (chitosan). In this work, the antioxidant activity of eight EOs was evaluated by DPPH radical-scavenging method while their antibacterial activity was determined by diffusion on agar and microdilution methods. Among all tested EOs, Eugenia caryophyllus, Cinnamomum zeylanicum Blume and Thymus satureioides Cosson showed high antioxidant activities at the concentration of 25.6 mg/mL, with respective values of (86.26%, 81.75%, and 76%), and strong antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Enterococcus hirae, with (MIC) values ≤ 4 µL/mL. At the concentration of 1 µL/mL, these EOs tested alone, showed values of antibiofilm-forming activity ranging from 79.43 to 99.33% and from 44.18 to 94.17%, when they are adsorbed onto chitosan film. These promising results confirm that these three EOs have a good potential for an eventual application in the food industry, as antimicrobial and antioxidant agents, or as active biodegradable food packaging, if combined with chitosan.
Background Nowadays, consumers increasingly prefer food with original, natural, and delicious flavors, which is closely linked to the content of volatile organic compounds (VOCs) in food. In recent years, the function of plant VOCs as natural food additives (flavoring and aromatizing agents, antibacterial agents) and their health benefits have attracted increased attention from the food industry. However, plant VOCs are quickly deteriorated because of their reactive molecular characteristics, which is the most critical bottleneck in their functions. Exploring the consequence, mechanism, sensor detection, and control technology of VOC deterioration can help to promote further advances in the protection of the food aroma and the application of plant VOCs in the food industry. Scope and approach Focusing on the highlighted roles of VOCs in the food industry and deterioration-prone characteristics, concluding the consequence, mechanism, sensor detection, and control technology of VOC deterioration. Key findings and conclusions The VOC deterioration in fresh food mainly results from composition variation induced by intracellular metabolism during storage, and metabolic loss induced by environmental factors. The leading causes inducing the VOC deterioration in processed food include physical loss by heating and chemical variations arising from the Maillard reaction, lipid oxidation, and other reactions. The biosensors assembled by proteins, peptides, or DNA showed excellent VOC sensitivity and selectivity performance. One technology cannot ideally protect every volatile component. Establishing the loss model and law of characteristic aroma components in specific technical treatment helps the component preservation of VOCs.
Lotus seed plumule (LP) is rich in a variety of antioxidant and anti-inflammatory secondary metabolites, making it a traditional food and medicine widely used in China. Physiological and histological evidences indicated that LP mainly accumulated metabolites in 15-24 days after pollination (DAP) during their development. To systematically investigate the dynamic accumulation of major secondary metabolites, the UPLC-HRMS-based widely targeted metabolomics analyses were performed on maturing LP at 15, 18, 21, and 24 DAP. In total, 767 metabolites were identified, including many secondary metabolites, e.g., 27% flavonoids and 8% alkaloids. Among them, 591 were identified as differentially accumulated metabolites (DAMs). The majority of secondary metabolites showed great accumulation after 18 DAP even at the late stage of LP maturation, such as hesperidin, neohesperidin, orobol, serotonin, and lotus special O-nornuciferine, endowing mature LP with effective pharmaceutical properties. The paralleled transcriptomic analysis identified 11,019 differentially expressed genes (DEGs). Based on the comprehensive data, several systematical metabolic regulation maps were established for different secondary metabolites, and 18 DAP was found as a switching point for LP maturing from active primary metabolism to massive secondary metabolites deposition. This study provides valuable information for understanding the mechanism of secondary metabolite accumulation in maturing LP and facilitates its pharmaceutical application.
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The safest and most effective and preventive method that inhibits the growth of phytotoxic fungi is the biological method using metabolic materials, which are environmentally friendly. The current study focusses on extracting bioactive compounds from some citrus peels, and evaluating antimicrobial activity against some pathogenic plant fungi, also detecting the active compound using GC-MS. The five extracts of peels citrus included, Citrus aurantifolia (key lime), Citrus singensis (orange), Citrus maxima (pomelo), Citrus limon (lemon), and Citrus reticulate (mandarin orange). The extracts were evaluated against seven fungal species, including Alternaria solani, Alternaria alternate, Rhizoctonia solani, Macrophomina phaseolina, Trichothecium roseum, Fusarium solani, and Fusarium equiseti. The results showed that peels extract of pomelo (PPE) is the most effective anti-fungal, which was clear for all types of fungi used in the examination, and which recorded the highest inhibitory diameter against the fungus F. equiseti, followed by peels extract of the orange (OPE) and lemon peels extract (LPE), respectively, while lowest antifungal activities have been recorded in peels extracts of mandarin orange (MOPE) and key lime peels extract (KPE), respectively. The diameters of inhibition that represent the antifungal activity of the other extracts ranged between 0 and 25 mm, which constitute significant differences between them and (PPE). The most active extract (PPE) was analysed using GC-MS, and the result included the detection of 50 different compounds. According to the GC-MS results, furfural (4.91%), auraptenol (1.38%), 2-methoxy-4-vinylphenol (0.92%) and hexadecanoic acid-, methyl ester (0.80%) were the major components in the essential oil obtained from peels extract of pomelo (PPE), in addition of ethyl oleate (0.65%), alpha-terpineol (0.32%), osthole (0.31%), which were known as antifungal compounds.
Hydrodistillation (HD), steam distillation (SD) and microwave-assisted hydrodistillation (MAHD) extraction methods were assessed for their effects on yield, chemical composition and antimicrobial activity of essential oils from Distichochlamys citrea M.F. Newman rhizomes. The greatest essential oil yields (v/w on dry weight basis) were obtained by MAHD (0.37%), followed by HD (0.27%) and SD (0.25%). The extraction time of MAHD was 1 h, compared to 4 h for HD and SD. Gas chromatography and gas chromatography-mass spectrometry were used to analyze the obtained oils. Geranial, neral, α-terpineol, 1,8-cineole, β-pinene and α-pinene were the major components in all oil samples. MAHD resulted in an increase in the content of oxygenated monoterpenes in the essential oil compared to HD or SD. Antimicrobial activity of essential oils was evaluated in terms of minimum inhibitory concentrations (MICs) by the microdilution broth method. All essential oils showed varying degrees of antimicrobial activity, with MICs ranging from 200 to 400 μg/mL. These results indicate that extraction method significantly influences the yield, chemical composition and antimicrobial activity of essential oils from D. citrea rhizomes. Compared with HD and SD methods, MAHD has the advantages of shorter extraction time, increased yield and increased oil quality. Therefore, MAHD is proposed as the preferred method for extracting essential oils from D. citrea rhizomes.
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Five aromatic constituents of essential oils (cineole, citral, geraniol, linalool and menthol) were tested for antimicrobial activity against eighteen bacteria (including Gram-positive cocci and rods, and Gram-negative rods) and twelve fungi (three yeast-like and nine filamentous). In terms of antibacterial activity linalool was the most effective and inhibited seventeen bacteria, followed by cineole, geraniol (each of which inhibited sixteen bacteria), menthol and citral aromatic compounds, which inhibited fifteen and fourteen bacteria, respectively. Against fungi the citral and geraniol oils were the most effective (inhibiting all twelve fungi), followed by linalool (inhibiting ten fungi), cineole and menthol (each of which inhibited seven fungi) compounds.
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Ursolic acid is a triterpenoid compound present in many plants. This study examined the antimicrobial activity of ursolic acid against mutans streptococci (MS) isolated from the Korean population. The antimicrobial activity was evaluated by the minimum inhibitory concentration (MIC) and time kill curves of MS. The cytotoxicity of ursolic acid against KB cells was tested using an MTT assay. The MIC 90 values of ursolic acid for Streptococcus mutans and Streptococcus sobrinus isolated from the Korean population were 2 µg/ml and 4 µg/ml, respectively. Ursolic acid had a bactericidal effect on S. mutans ATCC 25175 T and S. sobrinus ATCC 33478 T at > 2 × MIC (4 µg/ml) and 4 × MIC (8 µg/ml), respectively. Ursolic acid had no cytotoxic effect on KB cells at concentrations at which it exerted antimicrobial effects. The results suggest that ursolic acid can be used in the development of oral hygiene products for the prevention of dental caries.
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The aim of this study was to determine the optimal concentration of Korean propolis against clinical isolates of mutans streptococci (MS) from Koreans. The antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) and time-kill curves against mutans streptococci. The MIC90 values of propolis for MS were 35 μg/ml. Propolis had a bacteriostatic effect on Streptococcus mutans ATCC 25175T and bactericidal effects on Streptococcus sobrinus ATCC 33478T at > 2×MIC (70 μg/ml). These results suggest that the propolis can be used in the development of oral hygiene products for the prevention of dental caries.
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Bacterial resistance to multiple antibiotics is a health problem. Essential oils (EOs) possess antibacterial properties and have been screened as potential sources of novel antimicrobial compounds. Terpenes and terpenoids are components derived from EOs. Some of these EOs show inhibitory activity against Staphylococcus aureus. Carvacrol has specific effects on S. aureus and Staphylococcus epidermidis. Perilla oil suppresses expression of α-toxin, Staphylococcus enterotoxin A and B and toxic shock syndrome toxin. Geraniol shows good activity in modulating drug resistance in several gram-negative species. EOs could act as biopreservatives, reducing or eliminating pathogenic bacteria and increasing the overall quality of animal and vegetable food products. Although clinical studies are scarce, the uses of EOs for topical administration and as penetration enhancers for antiseptics are promising. Little information exists for oral administration.
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Tuberculosis, caused by Mycobacterium tuberculosis (MTB), is the most notified disease in the world. Development of resistance to first line drugs by MTB is a public health concern. As a result, there is the search for new and novel sources of antimycobacterial drugs for example from medicinal plants. In this study we determined the in vitro antimycobacterial activity of n-Hexane sub-fraction from Bridelia micrantha (Berth) against MTB H37Ra and a clinical isolate resistant to all five first-line antituberculosis drugs. The antimycobacterial activity of the n-Hexane sub-fraction of ethyl acetate fractions from acetone extracts of B. micrantha barks was evaluated using the resazurin microplate assay against two MTB isolates. Bioassay-guided fractionation of the ethyl acetate fraction was performed using 100% n-Hexane and Chloroform/Methanol (99:1) as solvents in order of increasing polarity by column chromatography and Resazurin microtiter plate assay for susceptibility tests. The n-Hexane fraction showed 20% inhibition of MTB H37Ra and almost 35% inhibition of an MTB isolate resistant to all first-line drugs at 10 μg/mL. GC/MS analysis of the fraction resulted in the identification of twenty-four constituents representing 60.5% of the fraction. Some of the 24 compounds detected included Benzene, 1.3-bis (3-phenoxyphenoxy (13.51%), 2-pinen-4-one (10.03%), N(b)-benzyl-14-(carboxymethyl) (6.35%) and the least detected compound was linalool (0.2%). The results show that the n-Hexane fraction of B. micrantha has antimycobacterial activity.