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Antibacterial activity of essential oils and their active components from Thai spices against foodborne pathogens

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As the popularity of organic food especially fresh vegetables is increasing, it is a common practice to replace chemical fertilizers by manure which leads to high bacterial contamination. Some essential oils such as Thymus vulgaris (thyme) and Ocimum basilicum (basil) oils reduce spoilage flora and foodborne pathogens when used in washing water. This information prompted us to search for effective essential oils from Thai spices for vegetable washing products. Seven out of nine essential oils; fingerroot (Boesenbergia pandurata (Roxb.) Schltr.), galanga (Alpinia galanga (L.) Willd.), holy basil (Ocimum tenuiflorum L.), makrut leaf, makrut peel (Citrus hystrix DC.), sweet basil (O. basilicum L.), and turmeric (Curcuma longa L.) oils showed antibacterial activity. The active components were identified by thin layer chromatography (TLC) bioautography, preparative TLC, and gas chromatography-mass spectrometry. The results indicated that the active components were major components of the oils. The essential oils exhibited higher potency than their active components suggesting that the whole essential oils were more suitable than the pure compounds for product development.
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R
ESEA RCH ARTI CLE
doi: 10.2306/scienceasia1513-1874.2013.39.472
ScienceAsia 39 (2013): 472476
Antibacterial activity of essential oils and their active
components from Thai spices against foodborne
pathogens
Phanida Phanthonga, Pattamapan Lomarata, Mullika Traidej Chomnawangb,
Nuntavan Bunyapraphatsaraa,
aDepartment of Pharmacognosy, Faculty of Pharmacy, Mahidol University, Sri Ayudhya Road, Rajathevi,
Bangkok 10400 Thailand
bDepartment of Microbiology, Faculty of Pharmacy, Mahidol University, Sri Ayudhya Road,
Rajathevi Bangkok 10400 Thailand
Corresponding author, e-mail: nuntavan.bun@mahidol.ac.th
Received 15 Nov 2012
Accepted 25 Jun 2013
ABSTRACT: As the popularity of organic food especially fresh vegetables is increasing, it is a common practice to replace
chemical fertilizers by manure which leads to high bacterial contamination. Some essential oils such as Thymus vulgaris
(thyme) and Ocimum basilicum (basil) oils reduce spoilage flora and foodborne pathogens when used in washing water.
This information prompted us to search for effective essential oils from Thai spices for vegetable washing products. Seven
out of nine essential oils; fingerroot (Boesenbergia pandurata (Roxb.) Schltr.), galanga (Alpinia galanga (L.) Willd.), holy
basil (Ocimum tenuiflorum L.), makrut leaf, makrut peel (Citrus hystrix DC.), sweet basil (O. basilicum L.), and turmeric
(Curcuma longa L.) oils showed antibacterial activity. The active components were identified by thin layer chromatography
(TLC) bioautography, preparative TLC, and gas chromatography-mass spectrometry. The results indicated that the active
components were major components of the oils. The essential oils exhibited higher potency than their active components
suggesting that the whole essential oils were more suitable than the pure compounds for product development.
KEYWORDS: TLC bioautography, GC-MS, active compounds, citral, biological guided separation
INTRODUCTION
Diarrhoea, a disease which causes high morbidity and
mortality, caused at least two million deaths world-
wide in year 2000. Besides, each year 30% of people
in industrialized countries suffer from this foodborne
disease1. The bacteria which are foodborne pathogens
including Escherichia coli,Salmonella Enteritidis,
Salmonella Typhimurium, Salmonella Typhi, Shigella
flexneri,Bacillus cereus, and Staphylococcus aureus,
often contaminate food particularly fresh vegetable2.
At present, the popularity of organic foods, especially
fresh vegetables is increasing and it is a common
practice to use manure instead of chemical fertilizers
which leads to high bacterial contamination. Hence to
control bacterial contamination, an effective and safe
vegetable washing product is needed. Currently, veg-
etable washing products available in the Thai market
are used to remove pesticides, therefore it is necessary
to have the vegetable washing products with antibac-
terial agent in order to decrease the contamination of
the foodborne pathogens.
Some essential oils such as thyme and basil oils
are effective against spoilage flora and foodborne
pathogens when used in washing water3,4. This
information prompted us to search for the active com-
pounds of essential oils from Thai spices. Previous
studies indicated that some essential oils of Thai
spices such as lemongrass, holy basil, turmeric, and
galanga oils had antibacterial properties57. However,
an extensive study to identify the active components
has only been done on lemongrass oil, in which citral
was identified as the active compound5,8.
The aims of this study were to determine the
efficacy of nine commercially available essential oils
of Thai spices as antimicrobial against foodborne
pathogens (E. coli,S. Enteritidis, S. Typhimurium,
S. Typhi, S. flexneri,B. cereus, and S. aureus),
and to identify the active components of each oil.
Biological guided separation was used along with
gas chromatography-mass spectrometry (GC-MS) to
identify active components of the tested oils. Since
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ScienceAsia 39 (2013) 473
the essential oils selected for this study were obtained
from edible plants and were volatile, it is likely that
they will be safe and easy to remove. With proper
research and development, essential oil products may
be an alternative for cleaning fresh vegetables to
eliminate microbial contamination.
MATERIALS AND METHODS
Essential oils
Nine essential oils of Thai spices; black pepper fruit
(Piper nigrum L.), fingerroot rhizome (Boesenbergia
pandurata (Roxb.) Schltr.), galanga rhizome (Alpinia
galanga (L.) Willd.), holy basil leaf (Ocimum tenui-
florum L.), lemongrass stem (Cymbopogon citratus
Stapf), makrut leaf and peel (Citrus hystrix DC.),
sweet basil leaf (O. basilicum L.), and turmeric rhi-
zome (Curcuma longa L.) oils were obtained from
Thai-China flavour & fragrances industry Co., Ltd.
(Bangkok, Thailand).
Reference compounds
The major compounds of essential oils; (+)-camphor,
()-trans-caryophyllene, 1,8-cineole, citral, citronel-
lal, citronellol, eugenol, geraniol, α-humulene, D-lim-
onene, (±)-linalool, methyl chavicol, ()-α-terpineol,
and terpinen-4-ol were obtained from Sigma-Aldrich
Chemical Co. Inc. (St. Louis, MO). Camphene was
obtained from Carl Roth Co. (Schoemperlenstr, Karl-
sruhe). Methyl cinnamate and methyl eugenol were
obtained from Tokyo Chemical Industry (Tokyo).
Bacterial cultures
Bacterial strains used in this study, E. coli (ATCC
25922), S. Enteritidis (DMST 15676), S. Typhimu-
rium (ATCC 13311), B. cereus (ATCC 11778), S. au-
reus (ATCC 25923), S. flexneri, and S. Typhi were
inoculated and maintained on tryptic soy agar (TSA).
All bacteria were obtained from the Microbiology
Laboratory Culture Collection, Department of Micro-
biology, Faculty of Pharmacy, Mahidol University,
Bangkok, Thailand.
Identification of the components in the essential oil
The components of the essential oils were identified
by GC-MS on GCMS-QP 2010 GC-MS (Shimadzu)
using a DB-5MS bonded phase fused silica capil-
lary column (30 m ×0.25 mm i.d., 0.25 µm film
thickness; J&W Scientific, Folsom, CA). Purified
helium was used as carrier gas at constant flow rate
of 0.68 ml/min. The oven temperature program for
essential oil was modified from method of previous
studies912. The injector temperature and ion source
temperature were 200 °C and 250 °C, respectively.
Electron impact mass spectra were obtained at 70 eV
by operating in the full scan acquisition mode in
the range of m/z 40–400. The identification of the
active compounds were performed by comparing the
obtained mass spectra with those from the Wiley and
NIST spectral library and their retention time and
mass spectral with those of the reference compounds.
Determination of minimum inhibitory
concentration (MIC) and minimum bactericidal
concentration (MBC)
The broth macrodilution method was used to deter-
mine the MICs of oils and reference compounds.
Stock solutions of oils were initially dissolved in
tween 80 and 95% ethanol then a series of two-
fold dilutions of each oil (ranging 200 µg/ml to
1.5625 µg/ml) was prepared in tryptic soy broth
(TSB). Freshly grown bacterial suspensions in TSB
were adjusted to approximately 106CFU/ml. For MIC
determination, a set of 10 assay tubes in duplicate was
employed per sample. The first test tube contained
1.8 ml of the seeded broth and the remaining tubes
had 1 ml each. The solution of the test agent (0.2 ml)
was added to the first tube to bring the volume to
2 ml. One ml of this was transferred to the next tube
and the process was repeated giving a two-fold serial
dilution. The tubes were incubated at 37 °C for 24 h.
The first assay tube with no apparent growth of the
microorganism containing the lowest dilution of the
test essential oil represented the MIC. The bactericidal
effect was assessed by MBC determination. Samples
were removed from tubes that showed no turbidity
and were dropped onto TSA plate. After incubation
at 37 °C for 24 h the minimum concentration without
visible growth was reported as MBC13 .
Determination of the active components by thin
layer chromatography (TLC) bioautography
The TLC bioautographic method was used to detect
the active components. After application of oils and
reference standards on three silica gel G60 F254 alu-
minium plates (A, B, C), the plates were developed us-
ing toluene-ethyl acetate (93:7) as the solvent. Plate A
was visualized under UV light at 254 nm and sprayed
with anisaldehyde sulphuric acid. Then, it was heated
at 110 °C for 5 min to detect the separated components
and used as reference chromatogram. Plate B was
prepared for the isolation of active compounds of
essential oil.
The TLC bioautography method was modified
from the method of Chomnawang et al14 . The TLC
plate (C) was developed as described above. The
TLC plate (C) was placed on the top of agar base
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474 ScienceAsia 39 (2013)
and inocula of bacterial strains in TSA media (agar
seed) was distributed over TLC plate (C). The plate
(C) was incubated at 37 °C for 24 h. The active
compounds were identified by the spots within the
inhibition zones. Rf of the corresponding spots were
compared with Rf of reference standard on plate A.
Plate B was compared with plates A and C. The areas
on the TLC plate which corresponded to the inhibition
zones were scraped from the plate and the substances
were eluted from the adsorbent with hexane. Eluted
samples were filtered with filter paper (Whatman
No 1), concentrated by removing the solvent under
vacuum. Then, the active components were confirmed
by gas chromatography-mass spectrometry (GC-MS).
RESULTS AND DISCUSSION
GC analysis of the components of the essential
oils from Thai spices revealed that the major com-
ponents of black pepper, fingerroot, galanga, holy
basil, lemongrass, makrut leaf and peel, sweet basil,
and turmeric oils, were δ-3-carene, trans-β-ocimene,
1,8-cineole, eugenol, E-citral, β-citronellal, limonene,
methyl chavicol, and ar-tumerone, respectively
(Table 1). The antibacterial testing against foodborne
pathogens showed that seven essential oils of Thai
spices exhibited the activity with MIC lower than
125 µg/ml (Table 1). In this study, the cut off limit was
set up as recommended by UNIDO for commercially
potential agents, which were 125 µg/ml and 10 µg/ml
for crude extract and pure compound13, respectively.
Since lemongrass oil has been well known to contain
citral as active component, it was used as a positive
control in this study. As a result of the activity
against the tested bacteria, none of the tested oils
were comparable to lemongrass oil. However, among
seven essential oils, holy basil and sweet basil oils
showed the widest spectrum (6 strains) followed by
makrut leaf and fingerroot oils (4 strains), galanga,
makrut peel, and turmeric oils (1 strain), in that order
(Table 1). The holy basil, makrut leaf, and sweet
basil oils also showed the highest potency (25 µg/ml).
The results suggest that besides lemongrass oil, sweet
basil oil showed the highest potential for commercial
products followed by holy basil and makrut leaf oils.
Some of our results were in agreement with previous
reports6,7.
Preliminary identification by TLC autobiography
found positive bands on TLC chromatogram of each
oil (Table 1). However, the identification by TLC
was limited. The large amount of the oil required to
produce antibacterial activity resulted in overlapping
of the adjacent components and prevented a precise
identification. Hence the identification was confirmed
by GC-MS. Most of the active components were
found to be the major constituents of essential oils.
The major active components of fingerroot, galanga,
holy basil, makrut leaf, makrut peel, sweet basil, and
turmeric oils were 1,8-cineole/camphor, 1,8-cineole,
eugenol, citronellal, terpinen-4-ol/α-terpineol, methyl
chavicol, and ar-tumerone, respectively. All other
active components are shown in Table 1. The at-
tempt to isolate active components by preparative
TLC was not successful due to the instability of each
component. Hence all the commercially available
active compounds were used and subjected to an-
tibacterial testing and all of the compounds showed
the MICs over 50 µg/ml which is over the cut-off
limit recommended by UNIDO13. Thus the oils are
recommended for product development rather than the
active components.
Some of the antibacterial components found
in Thai spices were reported to be active including
trans-α-bergamotene, camphor, trans-caryophyllene,
1,8-cineole, citronellal, eugenol, α-humulene,
(±)-linalool, methyl eugenol, methyl chavicol, neral,
α-terpineol, and terpinen-4-ol 1521 . In this study,
new active components against foodborne pathogen,
citronellol, ar-curcumene, β-farnesene, cis-farnesol,
trans-farnesol, and turmerone, were found. None of
these active compounds showed a potency comparable
to that of citral (5 µg/ml). They exhibited the activity
with MICs over the UNIDO cut off limit (10 µg/ml)13 .
Based on the results, the oils were more appropriate
than active components for product development.
The potential role of essential oil as food preser-
vatives has been recognized but the concentration nec-
essary to inhibit foodborne pathogens is high which
leads to the undesirable organoleptic effect22 . Only
few articles reported on the use of essential oil in
the washing solution for decontamination of fresh
vegetable3,4,15 . Based on the antibacterial activity
and the flavour of the essential oils, lemongrass, sweet
basil, holy basil, and makrut leaf oils were suggested
to be used in washing solution for fresh vegetables.
In this study, sweet basil oil contained methyl
chavicol (estragol) as active components against
S. flexneri,S. Typhi, and S. aureus which was in agree-
ment with previous study15. Methyl chavicol has been
reported to exhibit weaker activity against Shigella
spp. than carvacrol and thymol which is probably
due to the substitution of phenolic hydroxyl group
with methyl group15. However, Thai sweet basil oil
which contained 90% methyl chavicol showed the
inhibitory activity against E. coli with the MIC of
25 µg/ml. Hence it was considered to be potential for
the vegetable washing products.
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ScienceAsia 39 (2013) 475
Table 1 The constituents, minimum inhibitory concentration (MIC), maximum bactericidal concentration (MBC), and
active components of essential oils from Thai spices identified by TLC-bioautography and GC-MS.
Essential oil Constituents MIC MBC Bacterial Active Identification by TLC and GC-MS
(µg/ml) (µg/ml) strainsaband
Black pepper δ-3-carene (37%), >200 >200 All 7 bacteria ND ND
limonene (32%),
β-pinene (17%),
caryophyllene (8%)
Fingerroot trans-β-ocimene (27%), 100 200 B. cereus 3 geraniol, α-terpineol, 1,8-cineole, camphor,
camphor (24%), neral, and unidentifiedb
1,8-cineole (17%), 100 100 S. Typhi 5 geraniol, α-terpineol, (±)-linalool,
geraniol (11%), 1,8-cineole, camphor, neral, and unidentifiedb
camphene (8%), 100 >200 S. flexneri 3 geraniol, α-terpineol, (±)-linalool, and unidentifiedb
cis-ocimene (3%), 100 >200 E. coli 2 geraniol, α-terpineol, and unidentifiedb
methyl-cis-cinnamate (3%)
Galanga 1,8-cineole (34%) 50 50 B. cereus 6 1,8-cineole,tau-muurolol, and unidentifiedb
β-farnesene (15%),
trans-caryophyllene (12%),
zingiberene (4%)
Holy basil eugenol (42%), 25 50 B. cereus 2 eugenol, methyl eugenol, and unidentifiedb
caryophyllene (26%), 50 >200 S. aureus 3 eugenol, methyl eugenol, and unidentifiedb
methyl eugenol (15%), 50 100 S. Typhi 1 eugenol, methyl eugenol
()-β-elememe (12%) 100 >200 S. Typhimurium 2 eugenol, methyl eugenol, and unidentifiedb
100 200 S. flexneri 2 eugenol, methyl eugenol, and unidentifiedb
100 200 E. coli 2 eugenol, methyl eugenol, and unidentifiedb
Makrut leaf β-citronellal (78%), 25 25 B. cereus 5 citronellol, cis-farnesol, trans-farnesol, citronellal,
citronellyl acetate (6%), and unidentifiedb
β-citronellol (5%) 50 50 S. Typhi 4 citronellol, cis-farnesol, citronellal, and unidentifiedb
50 >200 S. Typhimurium 1 unidentifiedb
50 >200 S. flexneri 5 citronellol, cis-farnesol, citronellal, and unidentifiedb
Makrut peel limonene (46%), 100 100 S. Typhi 3 α-terpineol, terpinen-4-ol, and unidentifiedb
α-terpineol (19%),
β-pinene (18%),
terpinen-4-ol (17%)
Sweet basil methyl chavicol (90%), 50 100 B. cereus 2 2 unidentifiedb
α-bergamotene (3%) 100 >200 S. aureus 4 methyl chavicol and 3 unidentifiedb
50 50 S. Typhi 3 methyl chavicol and 2 unidentifiedb
50 >200 S. Typhimurium 1 unidentifiedb
25 50 S. flexneri 3 methyl chavicol and 2 unidentifiedb
25 50 E. coli 2 2 unidentifiedb
Turmeric Ar-tumerone (45%), 50 >200 S. Typhi 2 tumerone, Ar-curcumene, and trans-caryophyllene
curlone (14%),
tumerone (12%),
α-curcumene (7%),
β-sesquiphellandrene (6%)
Lemongrass E-citral (53%), 25 25 S. aureus 1 citral
Z-citral (38%), 12.5 12.5 B. cereus 1 citral
geraniol (4%) 100 100 S. Typhi 1 citral
*Positive control 100 100 S. Typhimurium 1 citral
50 50 S. flexneri 1 citral
100 100 S. Enteritidis 1 citral
50 50 E. coli 1 citral
aThe bacterial strains not present in this table exhibited MIC and MBC of oils higher than 200 µg/ml.
bLack of reference compound.
ND: Not determined.
Holy basil, one of the active oils contained
eugenol (42%) and methyl eugenol (15%) which was
found to be active against S. Typhimurium, S. Ty-
phi, S. flexneri,E. coli,S. aureus, and B. cereus.
The results from this study supported previous report
which indicated that eugenol was active. Eugenol
exerted the activity not only at the membrane but also
inhibited the production of amylase and protease by
organisms21,23. However, the unpleasant flavour of
eugenol may not be accepted by consumers. Another
potential oil, makrut leaf oil contained different active
compounds. The major active components were cit-
ronellal (78%) and citronellol (5%). The activities of
citronellal and citronellol were due to aldehyde and
alcohol functional groups, respectively22 .
CONCLUSIONS
In conclusion, four essential oils of Thai spices,
lemongrass, holy basil, makrut leaf, and sweet basil
oils showed the inhibitory activity against foodborne
pathogens with the MICs 25–100 µg/ml. The major
active components were identified along with other
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476 ScienceAsia 39 (2013)
components using TLC-bioautography and GC-MS
techniques. Since most of the components are less
active than the whole oils, it is recommended to
use the whole oil for vegetable washing solution.
This study also identified the new antibacterial agents
against foodborne pathogens including citronellol, ar-
curcumene, and turmerone.
Acknowledgements:The authors are grateful to the Co-
ordinating Centre for Research and Development to increase
value of the Plants Indigenous to Thailand, Mahidol Univer-
sity and the Thailand Research Fund for financial support.
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... Surprisingly, B. cereus TISTR 035 was inhibited by guava EO at the same level (P > 0.05) by the lemongrass, kaffir lime, fingerroot but plai EO (Table 1). Some antibacterial compounds found in Thai spices such as lemongrass, holy basil, makrut leaf, fingerroot and sweet basil were investigated (Phanthong et al., 2013). The results showed that none of the active compounds were as effective to citral. ...
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Multidrug resistant bacterial infections can kill 700,000 individuals globally each year and is considered among the top ten global health threats faced by humanity as the arsenal of antibiotics is becoming dry and alternate antibacterial molecule is in demand. Nanoparticles of curcumin exhibit appreciable broad spectrum antibacterial activity using unique and novel mechanisms and thus the process deserves to be reviewed and further researched to clearly understand the mechanisms. Based on the antibiotic resistance, infection and virulence potential, a list of clinically important bacteria was prepared after extensive literature survey and all recent reports on the antibacterial activity of curcumin and its nanoformulations as well as their mechanism of antibacterial action have been reviewed. Curcumin, nanocurcumin and its nanocomposites with improved aqueous solubility and bioavailability are very potential, reliable, safe and sustainable antibacterial molecule against clinically important bacterial species that uses multi‐target mechanism such as inactivation of antioxidant enzyme, ROS mediated cellular damage and inhibition of acyl‐homoserine‐lactone synthase (AHL‐synthase) necessary for quorum sensing and biofilm formation thereby bypassing the mechanisms of bacterial antibiotic resistance. Nanoformulations of curcumin can thus be considered as a potential and sustainable antibacterial drug candidate to address the issue of antibiotic resistance. This article is protected by copyright. All rights reserved
... Evolvement in research technologies uncovers multiple important bioactivities of C. hystrix leaves, such as antioxidant, antibacterial, anticancer, and antiviral properties [7,8]. C. hystrix EO has been reported to possess notable antibacterial and antimicrobial properties against foodborne pathogens [9], respiratory tract pathogens [10], and a group of bacteria that are linked to periodontal diseases [11]. Pronounced antimicrobial properties shown by C. hystrix leaves EO renders it as a convincing natural food preservative. ...
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Subcritical water extraction (SWE) of essential oil (EO) from Citrus hystrix DC. leaves was optimized using response surface methodology (RSM), involving factors of particle size (0.5-1) mm, sample-to-solvent ratio (0.025-0.175) g/mL, extraction temperature (140-180) ºC, and extraction time (20-40) minutes. Thus, an optimal EO yield of (2.14 ± 0.03) % (w/w) was obtained at 0.75 mm, 0.025 g/mL, 174 ºC, and 29 minutes. SWE was found to yield significantly higher EO than the conventional hydrodistillation, within a shorter time. The regression model was established, presenting a significant quadratic correlation (R² = 0.97) and adequate for predictions. SWE at 160 ºC and 180 ºC yielded 36 compounds, with isopulegol-dominant, exceeding SWE at 140 ºC (21 compounds) and hydrodistillation (25 compounds). SWE with tunable temperatures not only improved the quantity of EO but was also capable of enhancing the quality because more EO compounds were extracted, offering diverse functionalities to nutraceutical sectors.
... activity of inhibiting the growth of microbes found in foods such as S. aureus (Oonmetta-aree, Suzuki, Gasalucka & Eumke, 2006). Alpinia galanga contains 1,8-cineole essential oil, β-farnesene, trans-caryophyllene, zingiberene inhibits the growth Bacillus cereus (Phanthong, Lomarata, Chomnawang & Bunyapraphatsar, 2013). ...
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The sayur asem is one of the traditional Indonesian dishes, especially the Betawi ethnic group. This study aims to document the local knowledge of vegetable traders in the Kranggan Mas market, the diversity of plants used as an ingredient in sayur asem. The method used in this research was a survey. Data were analyzed qualitatively and descriptively. The sayur asem is a soup-like vegetable that has a sour taste with the main ingredients of melinjo (Gnetum gnemon) leaves and seeds and tamarind fruit (Tamarindus indica). The total of 13 species belonging 12 genera and 10 families used to process of making sayur asem. The part of used to process of making sayur asem is dominated by fruits (8 species), followed leaves and tubers (each 2 species). The melinjo (G. gnemon) is the main ingredient in the making of sayur asem, while Alphinia galanga, Syzygium polianthum and Tamarindus indica are the main spices with a larger volume. The main ingredients and seasonings used mostly have antioxidant and antimicrobial activity and are therefore very good at supporting digestive tract health and providing healthful effects.Keywords: Antioxidant, antimicrobial, gnetum gnemom, tamarindus indica
... Flowers of A. galanga showed high dietary fiber and fat (Rachkeeree et al., 2018). It was found that rhizome oil is used to against foodborne pathogens (Phanthong et al., 2013), moreover, bisabolene and trans-caryophyllene in galangal oil showed slimming aromatherapy in rats (Damayanti et al., 2015). Galangin from galangal has antiaflatoxic, antiinflammatory, antimutagenic, anticancer, antioxidant, antiviral, aromatase inhibitor and tyrosinase inhibitor properties (Duke, 2003). ...
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Flowers are used as food ingredients and decoratives in many countries. A growing awareness of consumer health benefits is leading to a new product research from edible flowers to be other options for natural food and beverage markets. Hot and cold tea formulations were developed from two gingers commonly used in Thailand, Alpinia galanga Willd. flower buds and Etlingera elatior R. M. Sm. inflorescenses, mixed with Ficus auriculata Lour. for health benefits and distinct flavour properties. These plants are rich source of natural antioxidants. Evaluations of their phytochemicals (alkaloids, flavonoids, anthocyanins, saponins, tanins and polyphenol, steroids, terpenoids) were done. Total phenolics and flavonoids contents were obtained for both water and ethanol extracts of each plant sample. Antioxidant activities of water, ethanol extracts and formulations were estimated using DPPH o + radical scavenging activity and ABTS o + radical scavenging activity compared to Camellia sinensis (L.) Kuntze as a positive control. Sensory evaluation was done using a 9-point hedonic scale with thirty trained panelists for three formulations. Rainy Season formulations, 'Floral infusion' was achieved with impartment for colour, aroma, flavour, astringency and overall acceptability to mixtures and several health benefits.
... Consequently, the combined GEO+HBEO (1:1 v/v) was potentially a strong antimicrobial inhibitor because HBEO contributed a large percentage of eugenol and caryophyllene as inhibitory agents, and DATTS was a key fraction of GEO. Phanthong et al. (2013) reported that eugenol, caryophyllene and methyl eugenol in HBEO were key compounds to inhibit B. cereus, E. coli, S. aureus and S. Typhimurium. Furthermore, many studies suggested that DATTS provided a potent antimicrobial activity (Rattanachaikunsopon & Phumkhachorn, 2008). ...
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Chitosan–pectin hydrogel beads that trap and release the maximal amount of combined garlic and holy basil essential oils to inhibit food microorganisms were developed based on the central composite design, with chitosan (0.2–0.7% w/v), pectin (3.5–5.5% w/v) and calcium chloride (CaCl2) (5.0–20.0% w/v) contents. The optimal bead consisted of 0.3–0.6% w/v chitosan, 3.9–5.1% w/v pectin and 8.0–17.0% w/v CaCl2, which had a high encapsulation efficiency (62.16–79.06%) and high cumulative release efficiency (31.55–37.81%) after storage at 5 °C for 15 days. Optimal hydrogel beads were packed into a cellulose bag to evaluate antimicrobial activity by the disc volatilisation method. The beads inhibited Bacillus cereus, Clostridium perfringens, Escherichia coli, Pseudomonas fluorescens, Listeria monocytogenes and Staphylococcus aureus but did not affect Lactobacillus plantarum and Salmonella Typhimurium. The oil‐containing beads could potentially be applied in food packaging to inhibit the mentioned microorganisms. Microencapsulated oils beads were developed. Antimicrobial activity of beads was analysed in volatile phase in order to apply in food packaging.
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Ethanopharmacological importance Alpinia galanga (L.) Willd, belonging to Zingiberaceae family is used as a spice and condiment in various culinary preparations of Indonesia, Thailand and Malaysia.It has been also used as a key ingredient in various traditional systems of medicine for the treatment of throat infection, asthma, urinary ailments, inflammation and rheumatism amongst other conditions. A. galanga (AG) is widely used as a functional food and included in various preparations to obtain its nutraceutical and pharmacological benefits of its phytoconstituents such as phenyl propanoids, flavonoids and terpenoids. Over the past decades, several researchers have carried out systematic investigation on various parts of AG. Numerous studies on AG rhizomes have shown positive pharmacological effects such as anti-inflammatory, anticancer, antipsoriasis, antiallergic, neuroprotective and thermogenesis. Till date, no comprehensive review summarizing the exploitation of AG into nanomedicine has been published. Aim of the review This comprehensive review aims to briefly discuss cultivation methods, propagation techniques, extraction processes for AG. The ethnopharmacological uses and pharmacological activities of AG extracts and its isolates are discussed in detail which may contribute well in further development of novel drug delivery system (NDDS) i.e. future nanomedicine. Materials and methods Information about AG was collected using search engine tools such as Google, Google Scholar, PubMed, Google Patent, Web of Science and bibliographic databases of previously published peer-reviewed review articles and research works were explored. The obtained data sets were sequentially arranged for better understanding of AG's potential. Results More advanced genetic engineering techniques have been utilized in cultivation and propagation of AG for obtaining better yield. Extraction, isolation and characterization techniques have reported numerous phytoconstituents which are chemically phenolic compounds (phenyl propanoids, flavonoids, chalcones, lignans) and terpenes. Ethnopharmacological uses and pharmacological activity of AG are explored in numerous ailments, their mechanism of action and its further potential to explore into novel drug delivery system are also highlighted. Conclusions The review highlights the importance of plant tissue culture in increasing the production of AG plantlets and rhizomes. It was understood from the review that AG and its phytoconstituents possess numerous pharmacological activities and have been explored for the treatment of cancer, microbial infection, gastrointestinal disorders, neuroprotective effects, obesity and skin disorders. However, the use of AG as alternative medicine is limited owing to poor solubility of its bioactive components and their instability. To overcome these challenges, NDDS have been utilized and found good success in overcoming its aforementioned challenges. Furthermore, efforts are required towards development of scalable, non-toxic and stable NDDS of AG and/or its bioactives.
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In this research, the antibacterial activity and the interaction mechanisms of the major chemical constituent present in the Alpinia galanga rhizomes essential oil (AGREO) were investigated. Ethyl cinnamate, methyl cinnamate and n-pentadecane were the major components of AGREO. The antibacterial mechanism of AGREO on Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) was evaluated and the results proved that the potent antibacterial activity of AGREO was due to higher passive permeability of bacterial cell membrane, followed by crucial intracellular components efflux. Additionally, AGREO disrupted the intracellular physiological metabolism of EHEC O157, including inhibition of P-type ATPases activity and down-regulation expression of four virulence genes associated with EHEC infections. Notably, molecular docking studies suggested that ethyl cinnamate probably competed with the structural NAD(P)⁺ for the binding sites of glucose-6-phosphate dehydrogenase (G6PD), resulting in a decrease in G6PD activity with subsequent suppression of respiratory metabolism. The spectroscopic techniques and molecular docking studies proved that the AGREO major components were prone to bind to the minor groove of DNA.
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Cinnamon plants (Cinamomum burmannii) besides being used as a spice in cooking, it also has benefits as a medicine. Essential oil is an active ingredient found in cinnamon plants (Cinnamomum burmannii) and can be found in parts of cinnamon bark. The content of the cinnamaldehyde and eugenol compounds contained in cinnamon essential oil is known to have antibacterial properties. Staphylococcus aureus is a pathogenic bacterium that can cause infectious diseases in humans and animals. The purpose of this study was to determine the antibacterial effect of essential oils of cinnamon bark (Cinnamomum burmannii) on Staphylococcus aureus isolated from the dairy cows milk. This study was an experimental laboratory study with the three repetitions, and consisted of 6 treatments with positive control of tetracycline, the negative control of 70% ethanol and essential oil concentration of 1%, 2%, 4%, and 8% on Staphylococcus aureus bacteria using the disc diffusion method. The finding showed that at a concentration of 2%, 4%, and 8% the essential oil of cinnamon bark (Cinnamomum burmannii) showed the zone of inhibition on Staphylococcus aureus. Based on the result, it can be concluded that the essential oil of cinnamon bark (Cinnamomum burmannii) has an antibacterial effect on Staphylococcus aureus
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Kaffir lime (Citrus hystrix DC) is a tropical plant with aromatic leaves. It produces fruits that are used in Asian cuisines as a flavoring agent. Essential oil from the leaves and peel of kaffir lime is a complex mixture of volatile and semi‐volatile compounds. It is rich in bioactive molecules that act synergistically to improve the well‐being of an individual. The method of extraction is important as it affects the quality and quantity of essential oil significantly. Kaffir lime oil is used as raw material in many fields, some of which include pharmaceutical, agronomic, food, sanitary, cosmetic, and perfume industries. It is also used extensively in aromatherapy and as an essential ingredient of various cosmetic and beauty products. Hydrodistillation, steam distillation, pressurized liquid extraction, and soxhlet extraction are some of the commonly used methods for extracting essential oil from kaffir lime as they are cost‐effective, environment friendly, and easy to implement on commercial scale. This review discusses about the condition's of extraction, merits, and demerits of various extraction methods used for kaffir lime oil and their application in healthcare products to induce positive effect in humans. Different extraction methods for extracting essential oil from the leaf and peel of kaffir lime and its application in health care products is critically reviewed.
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Eugenol, the major essential oil of clove, in sublethal concentrations (0.02–0.03%, v/v) inhibited the production of alpha-amylase, protease, and subtilisin by Bacillus subtilis in laboratory media. Microscopic observations revealed that at these eugenol concentrations, B. subtilis cells appeared swollen and distorted and/or appeared as very long and thin filaments (> 100 μm). Of 20 amino acids investigated, only L-glutamic or L-aspartic acid (>5.0 mg/ml) prevented such morphogenic distortions when added to eugenol-containing media before inoculation. Addition of these amino acids also resulted in an increase in biomass and protease production. In contrast, the addition of serine (> 1.0 mg/ml) enhanced filamentous growth but reduced the production of protease and subtilisin.
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Chemical composition, antioxidant and antimicrobial activities of the essential oils from aerial parts of basil (Ocimum basilicum L.) as affected by four seasonal, namely summer, autumn, winter and spring growing variation were investigated. The hydro-distilled essential oils content ranged from 0.5% to 0.8%, the maximum amounts were observed in winter while minimum in summer. The essential oils consisted of linalool as the most abundant component (56.7-60.6%), followed by epi-α-cadinol (8.6-11.4%), α-bergamotene (7.4-9.2%) and γ-cadinene (3.2-5.4%). Samples collected in winter were found to be richer in oxygenated monoterpenes (68.9%), while those of summer were higher in sesquiterpene hydrocarbons (24.3%). The contents of most of the chemical constituents varied significantly (p<0.05) with different seasons. The essential oils investigated, exhibited good antioxidant activity as measurements by DPPH free radical-scavenging ability, bleaching β-carotene in linoleic acid system and inhibition of linoleic acid oxidation. Evaluation of antimicrobial activity of the essential oils and linalool, the most abundant component, against bacterial strains: Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pasteurella multocida and pathogenic fungi Aspergillus niger, Mucor mucedo, Fusarium solani, Botryodiplodia theobromae, Rhizopus solani was assessed by disc diffusion method and measurement of determination of minimum inhibitory concentration. The results of antimicrobial assays indicated that all the tested microorganisms were affected. Both the antioxidant and antimicrobial activities of the oils varied significantly (p<0.05), as seasons changed. Copyright © 2007 Elsevier Ltd. All rights reserved.
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The effect of autoxidation of lemon-grass oil on its antibacterial activity has been studied. Using the Active Oxygen method, the oil was found to undergo rapid oxidation under accelerated test conditions. The oxidized oil samples were found to have reduced activity against bacteria. This activity was completely lost in extensively oxidized oil samples. Inclusion of antioxidants in the oil samples reduced the rate of oxidation and enhanced the antibacterial activity of the oil. The effects of the antioxidants were concentration dependent, and at their effective concentrations, oxidation was completely prevented for the period of the test.
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Gas chromatography-mass spectrometry was applied to the cyclohexane extract of Curcuma longa L. The chromatographic conditions generated retention indices very close i.e., greater than 99.9%, to those reported for structures in the Sadtler Standard Gas Chromatography Retention Index Library. In addition to the extensively reported sesquiterpene ketones, this essential oil extract contained a series of saturated and unsaturated fatty acids. Wiley mass spectra library matching for the free fatty acids, their trimethylsilyl esters and methyl esters narrowed their identity down to a few candidates. Combining this information with the retention indices of the fatty acid methyl esters in the Sadtler library allowed the identification of some of the double bond positions.
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Chlorine dioxide (ClO2), ozone, and thyme essential oil has been found to be effective in reducing pathogens, including Escherichia coli O157:H7, on selected produce. The efficacy of these sanitizers was evaluated, alone or through their sequential washing to achieve a 3 or more log reduction of mixed strains of E. coli O157:H7 on shredded lettuce and baby carrots. Samples sprinkle inoculated with mixed strains of E. coli O157:H7 were air-dried for 1 h at 22±2°C in a biosafety cabinet, stored at 4°C for 24 h, and then treated with different concentrations of disinfectants and exposure time. Sterile deionized water washing resulted in approximately 1log reduction ofE. coli O157:H7 after 10 min washing of lettuce and baby carrots. Gaseous treatments resulted in higher log reductions in comparison to aqueous washing. However, decolorization of lettuce leaves was observed during long exposure time. A logarithmic reduction of 1.48–1.97log10 cfu/g was obtained using aqueous ClO2 (10.0 mg/L for 10 min) ozonated water (9.7 mg/L for 10 min) or thyme oil suspension (1.0 mL/L for 5 min) on lettuce and baby carrots. Of the three sequential washing treatments used in this study, thyme oil followed by aqueous ClO2/ozonated water, or ozonated water/aqueous ClO2 were significantly (P<0.05) more effective in reducing E. coli O157:H7 (3.75 and 3.99log, and 3.83 and 4.34 log reduction) on lettuce and baby carrots, respectively. The results obtained from this study indicate that sequential washing treatments could achieve 3–4log reduction of E. coli O157:H7 on shredded lettuce and baby carrots.
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There are a few reports on the antimicrobial activity of essential oils or their major constituents towards Shigella sp. The antimicrobial effect of basil and thyme essential oil and its major constituents thymol, p-cymene, estragol, linalool, and carvacrol was determined using the agar well diffusion assay. Thyme essential oil and thymol and carvacrol showed inhibition of Shigella sp. in the agar well diffusion method. The potential of thyme essential oil, thymol and carvacrol at 0.5% and 1.0% v/v for decontamination of lettuce was evaluated. A decrease of the shigellae was observed after washing with 0.5% while at 1% Shigella numbers dropped below the detection limit. However, the antimicrobial effect on a subsequent lettuce sample in the same decontamination solution was significantly decreased. In addition, application of thyme essential oil or thymol or carvacrol for decontamination is hampered by sensoric properties of the lettuce (browning, strong odour).
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Fifteen essential oil components were evaluated for antifungal activity towards five spoilage-causing fungi. In liquid shake cultures, unsaturated aldehydes (citral, cinnamic aldehyde and cittronellal) followed by geraniol, an unsaturated alcohol were most inhibitory to Aspergillus niger, Fusarium oxysporum and Penicillium digitatum; their minimal inhibitory concentrations (MIC) was 100 μg ml−1. Menthol, a terpene alcohol was most inhibitory to Rhizopus stolonifer and Mucor sp. with a MIC of 200 μg ml−1. Hydrocarbons like camphene, limonene and α-terpinene were least inhibitory. When incorporated in agar medium different patterns of activity were found. Thus citral, cinnamic aldehyde, citronellal, geraniol and menthol not only failed to completely inhibit A. niger, F. oxysporum and P. digitatum but were more active against R. stolonifer and Mucor sp. than in liquid medium. The differences were due to the vapour of the volatile test compounds which accumulated over the agar medium. The growth inhibition due to the vapours alone was measured by using structurally modified petri-plates. The vapours were more active against R. stolonifer and Mucor sp. than against A. niger, F. Oxysporum and P. digitatum. Fungal growth inhibition by volatile compounds in agar medium reflects the combined activity of the vapour and the compound incorporated in the medium and the inhibition is different from that obtained in liquid medium. Regarding the structure-activity relationship of citral, the-CHO group in conjugation with a carbon to carbon double bond (CC) was found to be responsible for the antifungal activity of the molecule.
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Antibacterial activity of 11 essential oil constituents against Escherichia coli, E. coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, and Vibrio vulnificus was tested at 5, 10, 15, and 20% in 1% Tween 20 using a paper disk method. Eight constituents were then tested in liquid medium to determine minimum inhibitory and minimum bactericidal concentrations (MIC and MBC, respectively). V. vulnificus was most susceptible using disk assay. Carvacrol showed strong bactericidal activity against all tester strains, while limonene, nerolidol, and β-ionone were mostly inactive. Carvacrol was highly bactericidal against S. typhimurium and V. vulnificus in liquid medium (MBC 250 μg/mL). Citral and perillaldehyde had MBCs of 100 and 250 μg/mL against V. vulnificus. Terpineol and linalool were least potent against tester strains, with MBCs of 1000 μg/ mL. Citral, geraniol, and perillaldehyde at 500 μg/mL completely killed E. coli, E. coli O157:H7, and S. typhimurium, while citronellal at 250 μg/mL killed V. vulnificus. Therefore, these compounds could serve as potential antibacterial agents to inhibit pathogen growth in food.
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To evaluate the antibacterial activity of eugenol and its mechanism of bactericidal action against Salmonella typhi. The antibacterial activity was checked by disc-diffusion method, MIC, MBC, time course assay and pH sensitivity assay. The chemo-attractant property of eugenol was verified by chemotaxis assay. The mode of action of eugenol was determined by crystal violet assay, measurement of release of 260 nm absorbing material, SDS-PAGE, FT-IR spectroscopy, AFM and SEM. Treatment with eugenol at their MIC (0.0125%) and MBC (0.025%) reduced the viability and resulted in complete inhibition of the organism. Eugenol inactivated Salmonella typhi within 60 min exposure. The chemo-attractant property of eugenol combined with the observed high antibacterial activity at alkaline pH favors the fact that the compound can work more efficiently when given in vivo. Eugenol increased the permeability of the membrane, as evidenced by crystal violet assay. The measurement of release of 260 nm absorbing intracellular materials, SDS-PAGE, SEM and AFM analysis confirmed the disruptive action of eugenol on cytoplasmic membrane. The deformation of macromolecules in the membrane, upon treatment with eugenol was verified by FT-IR spectroscopy. The results suggest that the antibacterial activity of eugenol against Salmonella typhi is due to the interaction of eugenol on bacterial cell membrane.