Antimicrobial Properties of Chili Peppers

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Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Omolo et al., J Infect Dis Ther 2014, 2:4
http://dx.doi.org/10.4172/2332-0877.1000145
Review Article Open Access
Infectious Diseases & Therapy
Antimicrobial Properties of Chili Peppers
Morrine A Omolo, Zen-Zi Wong, Amanda K Mergen, Jennifer C Hastings, Nina C Le, Holly A Reiland, Kyle A Case and David J Baumler*
Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN, USA
Abstract
Chili peppers are used worldwide in foods for their pungent avor, aroma, and to prolong food spoilage. With
capsaicin contents ranging from zero to millions of Scoville heat units, the different varieties offer a wide range of options
for people all over the world. In addition to their use in cuisines, chili peppers have been explored for their antimicrobial
and antifungal properties. Consequently, research is underway to determine the potential for the application of chili
pepper extracts in the food industry in place of articial preservatives. As new antibiotic-resistant food borne pathogens
emerge, the discovery of natural antimicrobials in chili peppers will be invaluable to food scientists. This review goes
over some relevant research that has already been done in this area. In addition it lays the ground for the new research
that is emerging testing new varieties of chili peppers for nutrient content, avor proles, and for antimicrobial activities
against numerous human pathogens.
*Corresponding author: David J Baumler, Department of Food Science and
Nutrition, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA, Tel:
612-624-3086; E-mail: dbaumler@umn.edu
Received March 28, 2014; Accepted May 27, 2014; Published June 06, 2014
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014)
Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145. doi:10.4172/2332-
0877.1000145
Copyright: © 2014 Omolo MA, et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
Keywords: Chili peppers; Chile peppers; Antimicrobial; Foodborne
pathogen
Introduction
Human use of chili peppers dates back to prehistoric times.
Preserved peppers have provided evidence that South Americans
ate and grew aji, (chili in English), in 2500 B.C. e peppers became
increasingly common and integrated into the diet of particular
cultures. However, chili peppers and similar spices remained isolated
in these cultures until the 13th century, when they became available to
civilizations throughout the world [1]. e pungency of chili peppers
is due to the accumulation of capsaicinoids (also known as capsinoids,
a group of naturally produced compounds that are unique to the
Capsicum genus [2,3]. e chili pepper is a member of the Solanaceae
family. It is a diploid, facultative, self-pollinating crop, and closely
related to potato, tomato, eggplant, tobacco and petunia. It is one of
the oldest domesticated crops in the Western hemisphere, the most
widely grown spice in the world, and is a major ingredient in most
global cuisines. Capsicum species are commonly grown in warm humid
regions such as the tropics and subtropics and their fruits are mainly
used in local cuisine.
Chili peppers are widely used as spices in traditional Mexican
foods. e avor and pungent power of these peppers varies widely
and so do their contents of capsaicin and its capsaicinoid analogs [2].
When eaten, many chili peppers evoke a sensation of heat and/or pain
to the neurological systems in mammals, and these adverse eects can
be overcome through the consumption of foods containing casein such
as milk, cheese, or yogurt. Studies of the botanical pharmacopoeia of
the indigenous Mayan inhabitants of Mesoamerica have shown that
chili peppers (Capsicum species) are incorporated into a number of
medicinal preparations. ese preparations were applied for a variety of
ailments including respiratory problems, bowel complaints, earaches,
and sores. Early European observers noted the omnipresent nature
of chili peppers in the Mayan diet, reporting that nothing was eaten
without them. While typically regarded as a spice, the substantial role
that chili peppers occupy in this culture’s diet may have important
nutritional consequences for these people [4,5].
Chili peppers have a wide range of uses, including pharmaceutical,
natural coloring agents and cosmetics, as an ornamental plant, and as the
active ingredient in most defense repellants (i.e. pepper sprays) .Capsaicin,
a well-studied chemical component of the Capsicum species and one of the
pungent capsaicinoids found in chili peppers, has already demonstrated
a high degree of biological activity aecting the nervous, cardiovascular,
and digestive systems [5]. Chemical analysis has demonstrated that
Capsicum fruits contain relatively high concentrations of several
essential nutrients, including vitamin C (up to 6 times the concentration
of an orange) [5].
Strong consumer demand for safe and high-quality foods can
be attributed in part to the wide spread availability and accessibility
of quality health data and information. ere are also new concerns
about food safety due to increasing occurrences of new food-borne
disease outbreaks caused by pathogenic microorganisms. is
raises considerable challenges, particularly since there is increasing
unease regarding the use of chemical preservatives and articial
antimicrobials to inactivate or inhibit growth of spoilage and
pathogenic microorganisms [6]. In addition, currently available
treatment options for food-borne pathogen infections have drug-
related side eects, bacterial resistance to antimicrobials, and in some
cases no medical treatment exists for organisms such as Escherichia coli
O157:H7. erefore, newer treatments which are safe, cost eective,
and simple to administer are urgently needed. In light of this, the
use of nutritional agents is an attractive alternative to conventional
therapeutics and warrants further investigation [3]. Consequently,
natural antimicrobials, such as chili peppers, are receiving a good deal
of attention for a number of microorganism-control issues [6]. Recent
reports state that the Capsicum genus, among other plant genera, is a
good source of antimicrobial and antifungal compounds [7].
Top 14 Food-borne Pathogens
According to the U.S Food and Drug and Administration (FDA),
there are several food-borne pathogens that are of concern and harmful
to the general public, and are particularly harmful to pregnant women
(Table 1) [8].
Aside from these 14, there are other well-known pathogens
some of which are foodborne, including Bacillus cereus, Bacillus
subtilis, Enterobacter aerogenes [5], Pseudomonas aeruginosa [5,9]

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 2 of 8
Pathogen Basics Sources Symptoms Incubation Duration
Campylobacter
jejuni
A bacterium that's the most common
bacterial cause of diarrhea in the U.S.
Must-Know: Children under age 1 have
the highest rate of Campylobacter
infections. Unborn babies and infants
are more susceptible on rst exposure
to this bacterium. In addition, there's a
low threshold for seeking medical care
for infants.
Raw milk, untreated water, raw
and undercooked meat, poultry,
or shellsh
Diarrhea (sometimes bloody),
stomach cramps, fever, muscle
pain, headache, and nausea.
Generally 2 to 5
days after eating
contaminated food
7 to 10 days
Clostridium
botulinum
A bacterium that can be found in moist,
low-acid food. It produces a toxin that
causes botulism, a disease that causes
muscle paralysis.
Must-Know: Don't feed a baby honey - at
least for the rst year. Honey can contain
Clostridium botulinum spores. Infant
botulism is caused by consuming these
spores, which then grow in the intestines
and release toxin.
Home-canned and prepared
foods, vacuum-packed and
tightly wrapped food, meat
products, seafood, and herbal
cooking oils
Dry mouth, double vision
followed by nausea, vomiting,
and diarrhea. Later, constipation,
weakness, muscle paralysis, and
breathing problems may develop.
Botulism can be fatal. It's
important to seek immediate
medical help.
4 to 36 hours after
eating contaminated
food
Recovery can
take between
1 week to a full
year.
Clostridium
perfringens
A bacterium that produces heat-stable
spores, which can grow in foods that
are undercooked or left out at room
temperature.
Meat and meat products Abdominal pain, diarrhea, and
sometimes nausea and vomiting.
8 to 12 hours after
eating contaminated
food
Usually 1 day
or less
Pathogenic
Escherichia coli
(E. coli)
A group of bacteria that can produce a
variety of deadly toxins.
Meat (undercooked or raw
hamburger), uncooked produce,
raw milk, unpasteurized juice,
and contaminated water
Severe stomach cramps, bloody
diarrhea, and nausea. It can also
manifest as non-bloody diarrhea
or be symptomless.
Must-Know: It can cause
permanent kidney damage
which can lead to death in young
children.
Usually 3 to 4 days
after ingestion, but
may occur from 1 to
10 days after eating
contaminated food.
5 to 8 days
Listeria
monocytogenes
A bacterium that can grow slowly at
refrigerator temperatures.
Must-Know: Listeria can cause serious
illness or death in pregnant women,
fetuses, and newborns.
Refrigerated, ready-to-eat foods
(meat, poultry, seafood, and
dairy - unpasteurized milk and
milk products or foods made
with unpasteurized milk)
Fever, headache, fatigue,
Muscle aches, nausea, vomiting,
diarrhea, meningitis, and
miscarriages.
48 to 72 hours after
ingestion, but may
occur from 7 to 30
days after eating
contaminated food.
1 to 4 days.
Norovirus
(Norwalk-like
Virus)
A virus that's becoming a health threat. It
may account for a large percent of non-
bacterial foodborne illnesses.
Raw oysters, shellsh, coleslaw,
salads, baked goods, frosting,
contaminated water, and ice. It
can also spread via person-to-
person.
Diarrhea, nausea, vomiting,
stomach cramps, headache, and
fever.
24 to 48 hours after
ingestion, but can
appear as early as 12
hours after exposure.
1 to 2 days
Salmonella
enteritidis
A bacterium that can infect the ovaries
of healthy-appearing hens and internally
infect eggs before the eggs are laid.
Raw and undercooked eggs,
raw meat, poultry, seafood,
raw milk, dairy products, and
produce
Diarrhea, fever, vomiting,
headache, nausea, and stomach
cramps
Must-Know: Symptoms can be
more severe in people in at-
risk groups, such as pregnant
women.
12 to 72 hours after
eating contaminated
food
4 to 7 days
Salmonella
typhimurium
Some strains of this bacterium, such
as DT104, are resistant to several
antibiotics.
Raw meat, poultry, seafood,
raw milk, dairy products, and
produce
Diarrhea, fever, vomiting,
headache, nausea, and stomach
cramps
Must-Know: Symptoms can be
more severe in people in the
at-risk groups, such as pregnant
women.
12 to 72 hours after
eating contaminated
food
4 to 7 days
Shigella
A bacterium that's easily passed from
person-to-person via food, as a result
of poor hygiene, especially poor hand
washing.
Only humans carry this bacterium.
Salads, milk and dairy products,
raw oysters, ground beef,
poultry, and unclean water
Diarrhea, fever, stomach cramps,
vomiting, and bloody stools
1 to 7 days after
eating contaminated
food
5 to 7 days
Staphylococcus
aureus
This bacterium is carried on the skin
and in the nasal passages of humans.
It's transferred to food by a person, as a
result of poor hygiene, especially poor
hand washing.
When it grows in food, it makes a toxin
that causes illness.
Dairy products, salads,
cream-lled pastries and other
desserts, high-protein foods
(cooked ham, raw meat and
poultry), and humans (skin,
infected cuts, pimples, noses,
and throats)
Nausea, stomach cramps,
vomiting, and diarrhea
Usually rapid - within
30 minutes to 8
hours after eating
contaminated food
24 to 48 hours

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 3 of 8
Vibrio cholerae
A bacterium that occurs naturally in
estuarine environments (where fresh
water from rivers mix with salt water from
oceans).
It causes cholera, a disease that can
cause death if untreated.
Raw and undercooked seafood
or other contaminated food and
water.
Often absent or mild. Some
people develop severe diarrhea,
vomiting, and leg cramps.
Loss of body uids can lead to
dehydration and shock. Without
treatment, death can occur within
hours.
6 hours to 5
days after eating
contaminated food
7 days
Vibrio
parahaemolyticus
A bacterium that lives in saltwater and
causes gastrointestinal illness in people.
Raw or undercooked sh and
shellsh
Diarrhea, stomach cramps,
nausea, vomiting, headache,
fever, and chills
4 to 96 hours after
eating contaminated
food
2.5 days
Vibrio vulnicus
A bacterium that lives in warm seawater.
It can cause infection in people who eat
contaminated seafood or have an open
wound exposed to seawater.
Raw sh and shellsh,
especially raw oysters
Diarrhea, stomach pain, nausea,
vomiting, fever, and sudden chills.
Some victims develop sores on
their legs that resemble blisters.
Usually within 16
hours after eating
contaminated food or
exposure to organism
2 to 3 days
Yersinia
enterocolitica
A bacterium that causes yersiniosis, a
disease characterized by diarrhea and/
or vomiting.
Raw meat and seafood,
dairy products, produce, and
untreated water
Fever, diarrhea, vomiting, and
stomach pain
Must-Know: Symptoms may be
severe for children.
1 to 2 days after
eating contaminated
food
1 to 2 days
Adopted from the FDA website [8]
Table 1: Top 14 food-borne pathogens.
and Helicobacter pylori [10] which seem to be of interest to research
scientists.
Species of the Genus Capsicum Presently Known
Capsicum species are small perennial herbs native to tropical
South America. e majority of researchers believe that this genus
is comprised of more than 20 species. e 5 most common ones
believed to be a result of domestication are C. annuum, C. baccatum, C.
frutescens, C. chinense and C. pubescens [5], (Figure 1).
e other species are exotic and not as widely distributed as these
ve. Below is a list of the other presently known species [11].
• Capsicum buforum
• Capsicum campylopodium
• Capsicum cardenasii
• Capsicum ceratocalyx
• Capsicum chacoense
• Capsicum coccineum
• Capsicum cornutum
• Capsicum dimorphum
• Capsicum dusenii
• Capsicum eximium
• Capsicum exuosum
• Capsicum friburgense
• Capsicum galapagoense
• Capsicum geminifolium
• Capsicum havanense
• Capsicum hookerianum
• Capsicum hunzikerianum
• Capsicum lanceolatum
• Capsicum leptopodum
• Capsicum lycianthoides
• Capsicum minutiorum
• Capsicum mirabile
• Capsicum mositicum
• Capsicum parvifolium
• Capsicum pereirae
• Capsicum ramosissimum
• Capsicum recurvatum
• Capsicum rhomboideum
• Capsicum schottianum
• Capsicum scolnikianum
• Capsicum spina-alba
• Capsicum stramoniifolium
• Capsicum tovarii
• Capsicum villosum
Figure 1: Courtesy of Dr. D. J. Baumler.

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 4 of 8
Studies on Antimicrobial Eects of Chili Pepper-
extracts on Some Foodborne and/or Human Pathogens
Bacillus subtilis (not typically associated with foodborne illness)
According to Molina-Torres et al. [12], capsaicin (pure, purchased
from Sigma Aldrich), had a strong inhibitory eect towards B. subtilis
starting from 25 µg/ml (minimum concentration assayed).
Escherichia coli
Molina-Torres et al. [12] determined that capsaicin (pure,
purchased from Sigma Aldrich), at concentrations up to 200 or 300 µg/
ml only retarded the growth of E. coli.
Salmonella typhimurium
Careaga et al. [9] investigated the antimicrobial eect of Capsicum
extract on S. typhimurium inoculated in minced beef. e minimum
lethal concentration of the pepper extract was 1.5 ml/100 g of meat.
e combination of sodium chloride and C. annum extract tested was
not successful to eliminate Salmonella. is could be explained by the
fact that Salmonella is tolerant to salt. e researchers proposed using
a combination that had less salt and more pepper extract, because any
more salt would be too much to eat.
Pseudomonas aeruginosa
In the same study, Careaga et al. [9] investigated the antimicrobial
eect of Capsicum extract on P. aeruginosa inoculated in minced beef.
A reduction of P. aeruginosa growth was observed between 0.06-0.1 ml/
100 g meat, with a bacteriostatic eect between 0.5-1.5 ml/100 g meat.
As the extract concentration increased, a drastic bactericidal eect was
observed, particularly between 4-5 ml/100 g meat. e combination of
sodium chloride and C. annum extract tested eliminated P. aeruginosa
aer 3 days of storage.
Staphylococcus aureus
Nitin et al. [12] evaluated the possibility of capsaicin acting as an
inhibitor of the NorA eux pump of S. aureus. e minimum inhibitory
concentration (MIC) of ciprooxacin was reduced 2 to 4 fold in the
presence of capsaicin. is reduction was more prominent for S. aureus
SA-1199B (NorA overproducing) as compared with S. aureus SA-1199
(wild-type) up to 25 mg/L capsaicin. Beyond that, no concentration
dependent eect was observed. S. aureus SA-K1758 (norA knockout)
showed no reduction in the MIC of ciprooxacin. Table 2 shows in
vitro ciprooxacin/ capsaicin combination studies. Table 3 shows post-
antibiotic eect (PAE) of ciprooxacin alone and in combination with
capsaicin against S. aureus SA-1199B aer exposure of 2 h. Ciprooxacin
at 4 mg/L, at which no mutant was selected, was dened as the mutant
prevention concentration (MPC). When tested in combination with
capsaicin at 12.5 and 25 mg/L, the MPC of ciprooxacin was reduced
to 2 and 1 mg/L, respectively. e MPC of the combination was found
to be lower than the Cmax of the ciprooxacin (3-4 mg/L), indicating the
clinical relevance of these combinations in restricting the selection of
resistant mutants. Ethidium bromide uoresces only when it is bound
to nucleic acids inside cells. Only the control cells without capsaicin
extruded ethidium bromide, resulting in a signicant decrease in
orescence over the assay period. In the presence of capsaicin, the loss
of orescence was signicantly reduced, reecting a strong interference
with ethidium bromide eux by capsaicin [2]. Table 4 shows the
mutation frequency of S. aureus ATCC 29213 [13].
Vibrio cholerae
is study examines common spices to determine their inhibitory
capacity against virulence expression of V. cholera (Table 5). Among
them methanol extracts of red chili, sweet fennel and white pepper
could substantially inhibit cholera toxin (CT) production (Table 6). As
these species act against virulence expression rather than viability of V.
cholerae, there is a lesser chance of developing resistance [13].
In a dierent study, Chatterjee et al. [15] determined that the
methanol extract of red chili, and puried capsaicin could inhibit
cholera toxin (CT) production in recently emerged V. cholerae O1 El
Tor variant strains without aecting their viability. All 23 strains of
V. cholerae used in the study (Table 7), were grown in the lab. Crude
methanol extract of the red chili pepper was used (individual ingredients
MIC (mg/ml of ciprooxacin for respective strain with/without test molecule (fold reduction)
Capsaicin (mg/L) MIC of capsaicin SA-1199 SA-1199B SA-1758
Capsaicin (50) >100 0.12/0.25 (2) 2/8 (4) 0.125/0.125 (0)
Capsaicin (25) >100 0.12/0.25 (2) 2/8 (4) 0.125/0.125 (0)
Capsaicin (12.5) >100 0.25/0.25 (0) 4/8 (2) 0.125/0.125 (0)
Reserpine (25) >100 0.12/0.25 (2) 2/8 (4) 0.125/0.125 (0)
Table adopted from Kalia et al. [13].
Table 2: In vitro ciprooxacin/capsaicin studies.
Mean PAE (h) ± S.D
Regimen 0.25×MIC (2 mg/L) 0.5×MIC (4 mg/L) MIC (8 mg/L)
Ciprooxacin 0.3 ± 0.1 1.0 ± 0.1 1.3 ± 0.17
Ciprooxacin + Capsaicin (25mg/L) 1.0 ± 0.2 1.5 ± 0.17 2.4 ± 0.2
PAE = Post Antibiotic Effect
Table adopted from Kalia et al. [13]
Table 3: PAE of ciprooxacin alone and in combination with capsaicin against S. aureus SA-1199B after exposure of 2 h.
Capsaicin (mg/L) 2×MIC (0.5 mg/L) 4×MIC (1 mg/L) 8×MIC (2 mg/L) 16×MIC (4 mg/L)
0 1.47×10-9 7.7×10-9 4.3×10-9 <10-9
12.5 13.5×10-9 3.9×10-9 <10-9 <10-9
25 2.5×10-9 < 10-9 <10-9 <10-9
MIC = Minimum Inhibitory Concentration
Table adopted from Kalia et al. [13]
Table 4: Mutation frequency of S. aureus ATCC 29213.

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 5 of 8
not isolated). Capsaicin was purchased from LKT laboratories Inc.,
MN. RNA isolation and real-time transcription-PCR (qRT-PCR) assay
revealed that capsaicin eectively repressed the transcription of ctxA,
tcpA, and toxA genes, but not the toxR and toxS genes. It enhanced the
transcription of the gene hns (Table 8).
Based on the experimental results, the researchers proposed a
mechanism by which capsaicin and the red chili methanol extract
represses the virulence genes of V. cholerae. Briey, the activation of
toxR, toxS, tcpP, and tcpH is caused by environmental factors such as
pH, temperature, and osmolarity. is activation subsequently activates
ctxAB and tcpA transcriptions via activation of transcriptional activator
toxT. HN-S is a basal repressor of toxT, ctxAB and tcpA genes under
nonpermissive conditions. In the presence of capsaicin, while ctxAB,
Plant Scientic name Specic compound Target Mechanism
Wasabi Wasabi japonica Allyl isothiocynate V. parahemolyticus Inhibit growth
Green tea Camellia sinensis Catechins V. cholera Inhibit growth and CT activity
Guazuma Guazuma ulimifolia Procyanidins V. cholera CT activity
Daio (Kampo formulation) Rhei rhizome Gallate analogues V. cholera CT activity
Apple Malus spp. Aplephenon V. cholera CT activity
Hop Humulus lupulus Procyanides V. cholera CT activity
Neem Azadirachta indica Unknown V. cholera Inhibit growth
Elephant garlic Allium ampleloprasum Oil (diallyl suldes) V. cholera Inhibit growth
Red bayberry Myrica rubra Unknown V. cholera Inhibit CT production
Red chili Capsicum annum Capsaicin V. cholera Inhibit CT production
CT = Cytotoxin
Table adopted from Yamasaki et al. [14]
Table 5: Natural compounds identied to act against diarrhoeagenic Vibrio spp.
Stain ID Isolation year Red chili Sweet fennel White pepper Red pepper Cassia bark Star anise
CO 533 1994 97 95 86 68 45 50
CRC27 2000 97 92 99 80 79 66
CRC41 2000 90 96 94 53 86 6.0
CRC87 2000 94 85 87 56 78 29
Table adopted from Yamasaki et al. [14]
Table 6: % Inhibition of CT production in V. cholerae O1 E1 Tor variant strains (isolated from cholera patients in India) with methanol extracts of 6 different commonly used
spices (100 μg/ml).
Serial no. Strain Serogroup/biotype ctxB genotype Country Isolation Year
1 NICED-1 O1 El Tor El Tor India 1970
2 NICED-10 India 1970
3 NICED-3 India 1980
4 P130 Peru 1991
5 VC190 India 1993
6 VC301 O1 El Tor Classical India 1992
7 Al-091 variant Bangladesh 1993
8 CO533 India 1994
9 CRC27 India 2000
10 CRC41 India 2000
11 CRC87 India 2000
12 B33 Mozambique 2004
13 1’/05 India 2005
14 2’/05 India 2005
15 5’/05 India 2005
16 2680713 Bangladesh 2006
17 2684269 Bangladesh 2006
18 SG24 O139 El Tor India 1992
19 CRC142 Classical India 2000
20 VC82 Non-O1/ El Tor India 1989
21 VC259 Non-O139 India 1991
22 569B O1 classical Classical India 1948
23 O395 India 1964
Table adopted from Chatterjee et al. [14]
Table 7: Vibrio cholerae strains used in the study.

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 6 of 8
tcpA, and toxT transcriptions were repressed, the transcription of hns
was enhanced. Capsaicin may probably repress the virulence genes
transcriptions in a direct manner or via modulation of the global
regulator hns gene. e higher inhibitory impact of red chili methanol
extract than capsaicin (43- and 23- fold respectively) indicates the
possibility of other unidentied compound(s) in red chilis that can
directly inhibit or synergistically act with capsaicin [15].
Helicobacter pylori
In their experiment, Jones et al. [3] determined that capsaicin
inhibited growth of H. pylori strain LC-11 in a dose-dependent manner
at concentrations above 10 µg/ml (ANOVA, P<0.05). is bactericidal
eect was evident within 4 h of incubation. Aer 24 h, growth of the
bacteria was completely inhibited. e eect of capsaicin was maximal
at a concentration of 50 µg/ml. is bactericidal eect was not limited
to H. pylori LC-11. Growth of LC-32 and LC-28 were inhibited to a
similar extent at 500 µg/ml [3].
To examine the possible inuence of pH on the bactericidal activity
of capsaicin, the growth of H. pylori strain LC-11 was compared in
broth culture at pH 4.5, 5.4, and 6.4 in the presence and absence of
capsaicin. At each of these pH values, the growth of H. pylori was
inhibited compared to bacterial growth in standard broth culture at pH
Primer/probe Primer and probe sequence (5’ – 3’) Amplicon size (bp)
ctxA F GGA GGG AAG AGC CGT GGA T
ctxA P CAT CAT GCA CCG CCG GGT TG 66
ctxA R CAT CGA TGA TCT TGG AGC ATT C
tcpA F GGG ATA TGT TTC CAT TTA TCA ACG T
tcpA P TGC TTT CGC TGC TGT CGC TGA TCT T 82
tcpA R GCG ACA CTC GTT TCG AAA TCA
toxT F TGA TGA TCT TGA TGC TAT GGA GAA A
toxT P TAC GCG TAA TTG GCG TTG GGC AG 107
toxT R TCA TCC GAT TCG TTC TTA ATT CAC
toxR F GCT TTC GCG AGC CAT CTC T
toxR P CTT CAA CCG TTT CCA CTC GGG CG 65
toxR R CGA AAC GCG GTT ACC AAT TG
toxS F TGC CAT TAG GCA GAT ATT TCA CA
toxS P TGA CGT CTA CCC GAC TGA GTG GCC C 72
toxS R GCA ACC GCC CGG CTA T
tcpP F TGG TAC ACC AAG CAT AAT ACA GAC TAA G
tcpP P TAC TCT GTG AAT ATC ATC CTG CCC CCT GTC 100
tcpP R AGG CCA AAG TGC TTT AAT TAT TTG A
tcpH F GCC GTG ATT ACA ATG TGT TGA GTA T
tcpH P TCA ACT CGG CAA AGG TTG TTT TCT CGC 82
tcpH R TCA GCC GTT AGC AGC TTG TAA G
hns F
hns TCG ACC TCG AAG CGC TTA TT
hns P CTG CGC TAT CAG GCG AAA CTA AAA CGA AA 70
hns R GGT GCA CGT TTG CCT TTT G
recA F CAA TTT GGT AAA GGC TCC ATC AT
recA P CTT AGG CGA CAA CCG CGC 71
recA R CCG GTC GAA ATG GTT TCT ACA
Table adopted from Chatterjee et al. [15]
Table 8: Primers and probes used for qRT-PCR.
Compound Retention Time (min)* % Acetonitrile at which the separation was achieved
L-phenylalanine 6.55 ± 0.66 27.91
Caffeic Acid 7.00 ± 0.76 28.83
p-coumaric acid + ferulic acid 8.56 ± 0.52 32.03
m-coumaric acid 9.32 ± 0.52 33.59
o-coumaric acid 11.21 ± 0.70 37.46
Trans-cinnamic acid 18.99 ± 094 53.41
Capsaicin 25.72 ± 0.90 67.20
Dihydrocapsaicin 27.33 ± 0.74 70.50
*Data represent an average of ten replicates (± S.D.).
Table adopted from Dorantes et al. [2]
Table 9: HPLC prole of standard phenylpropanoid compounds, capsaicin, and dihydrocapsaicin from chili extracts.

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 7 of 8
Capsinoid Habanero Serrano Morron
o-coumaric acid 0.089 ± 0.01 0.90 ± 0.01 0.18 ± 0.01
m-coumaric acid - 0.31 ± 0.01 0.21 ± 0.01
Trans-cinnamic acid - 0.47 ± 0.01 0.21 ± 0.01
Capsaicin 5.88 ± 0.03 0.63 ± 0.01 -
Dihydrocapsaicin 0.86 ± 0.01 0.059 ± 0.01 -
*Data represent an average of three replicates (± S.D.).
Table adapted from Lidia et al. [2]
Table 10: Content of some capsinoids in the habanero, serrano, and pimiento
moron extracts (mg/ml).
Bacteria o-coumaric m-coumaric Cinnamic
acid Capsaicin Dihydro-
capsaicin
B. cereus Neg 10.0 ± 0.0 8.0 ± 0.8 Neg Neg
S. aureus Neg 10.0 ± 0.8 6.0 ± 0.8 Neg Neg
L. monocytogenes Neg 6.0 ± 0.6 5.0 ± 0.8 Neg Neg
S. typhimurim Neg 2.0 ± 0.8 2.0 ± 0.0 Neg Neg
*Data represents an average of three replicates (± S.D.)
Table adopted from Lidia et al. [2]
Table 11: Zone of growth produced by some phenylpropanoids identied in serrano
chili peppers (mm)*.
7.38. Capsaicin exerted a growth inhibitory eect of 92 ± 3.7% at pH
5.4 and 72 ± 11% at pH 6.4. At pH 4.5, bacterial growth did not diering
the presence (93.5 ± 2.4%) and absence (88.4 ± 7.8%) of capsaicin [3].
Listeria monocytogenes
Reverse-phase HPLC analysis was performed to determine the
capsinoid-content of the pepper extracts of habanero, serrano, and
pimiento chili peppers. Table 9 shows the HPLC prole of standard
phenylpropanoid compounds, capsaicin, and dihydrocapsaicin from
chili extracts, while Table 10 shows the content of some capsinoids
in the habanero, serrano, and pimiento moron extracts (mg/ml) [2].
Lidia et al. do not specify what serotypes of the peppers they used.
e following pictures show the most readily available varieties in the
market (Figure 2).
e capsinoid compositions of the three pepper extracts are
dierent, and this may inuence their antimicrobial eect. e
concentration of capsaicin and capsaicinoids used in this study did
not show an inhibitory eect on L. monocytogenes. Habanero which
has the highest content of capsaicin was the least eective as a bacterial
inhibitor. e pimiento morron extract, which contains m-coumeric
acid and cinnamic acid but no capsaicin, showed a good inhibitory
eect on the bacteria [2] (Table 11).
Conclusions
As more food scientists, consumers, and members of the medical eld
gain interest in chili peppers, it is certain that through ethnobotanical
observations, Capsicum species harbor many economically signicant
benets awaiting ‘discovery’ [6]. ere are a variety of methods for
testing the antimicrobial activities of chili peppers. ese methods
strongly aect the observed levels of inhibition. Various reasons may
contribute in the dierences between results, including inconsistency
between analyzed plant materials [7].
In these experiments, crude extracts of chili peppers were used; no
separation of pepper components was done, except by Dorantes et al.
[2]. Based on the data, it seems that capsaicin had a lesser antimicrobial
eect compared to other components of chili pepper extracts.
erefore, future studies should try to determine what compounds in
the chili pepper gives the spice its antimicrobial properties, and to do so
purication of the extracts is necessary. Caps aicin gives chili peppers the
‘hot’ sensation, which some people might not like. It would, therefore,
be benecial if there is another substance in the pepper that could be
used in the food industry as a preservative without the pungent taste
and hotness.
e studies examined herein were done in vitro. However, more
tests need to be conducted to determine the antimicrobial eects of chili
peppers in vivo, especially because such a large number of people eat
peppers. is could be a potential means through which to minimize
the eect of foodborne pathogens when there is an outbreak. Graham
et al. [10] were unable to conrm the hypothesis that capsaicin has an
inhibitory eect on H. pylori in vivo. ey believe that natural substances
and folk remedies should undergo testing in vivo before publication of
the in vitro results to reduce the possibility of misinforming the public
regarding the potential usefulness of these agents.
Varied as these studies may be, they open the doors to greater
research on chili peppers. e data already collected and methods
of testing oer new directions for future experiments. To obtain
more conclusive data, the number of pepper varieties used should be
increased since hundreds of thousands of dierent types of chili pepper
plants exist worldwide. e following picture shows some of the most
common varieties, including many exotic types sourced from all over
the world (Figure 3).
For example the six hottest chili peppers in the world, Bhut
Jolokia, Trinidad 7-pot, Trinidad Scorpion ButchT, Trinidad Doughlah,
Trinidad Moruga Scorpion (shown in the next photo), and Carolina
Reaper (not shown), have not been tested and may possessun discovered
antimicrobial compounds and activity [15].
Our lab will be working with over 700 varieties of chili peppers
to determine the antimicrobial eects the extracts of leaves and fruits
Figure 2: Courtesy of Dr. D. J. Baumler.
Figure 3: Courtesy of Dr. D. J. Baumler.

Volume 2 • Issue 4 • 1000145
J Infect Dis Ther
ISSN: 2332-0877 JIDT, an open access journal
Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al. (2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145
Page 8 of 8
have on selected foodborne pathogens (Figure 4). ese varieties will
include peppers with and without capsaicin from all over the world.
Also, purication of the extracts will be done to determine the most
eective component of the extract for antibacterial usage. Finally, as
mentioned earlier, peppers have vitamins and other nutrients. Our lab
will carry out assays to determine the contents of vitamins A, C, E, and
folic acid in many of these exotic types of chili peppers. is data will be
useful when using peppers as an additive to value added foods.
References
1. Mortensen JM, Mortensen JE (2009) The Power of Capsaicin. J Cont Ed 11:
8-13.
2. Dorantes L, Colmenero R, Hernandez H, Mota L, Jaramillo ME, et al. (2000)
Inhibition of growth of some foodborne pathogenic bacteria by Capsicum
annum extracts. International Journal of Food Microbiology 57: 125-128.
Figure 4: Courtesy of Dr. D. J. Baumler.
3. Jones NL, Shabib S, Sherman PM (1997) Capsaicin as an inhibitor of the
growth of the gastric pathogen Helicobacter pylori. FEMS Microbiol Lett 146:
223-227.
4. Seugill K, Minkyu P, Seon-In Y, Yong-Min K, Je ML, et al. (2014) Genome
sequence of the hot pepper provides insights into the evolution of pungency in
Capsicum species. Nature 1: 1-10.
5. Brito-Argáez L, Moguel-Salazar F, Zamudio F, González-Estrada T, Islas-Flores
I (2009) Characterization of a Capsicum chinense Seed Peptide Fraction with
Broad Antibacterial Activity. Asian Journal of Biochemistry 4: 77-87.
6. Cichewicz RH, Thorpe PA (1996) The antimicrobial properties of chile peppers
(Capsicum species) and their uses in Mayan medicine. J Ethnopharmacol 52:
61-70.
7. Tajkarimi MM, Ibrahim SA, Cliver DO (2010) Antimicrobial herb and spice
compounds in food.J Food Control 21:1199-1218.
8. (2013) Food Safety for Moms-to-Be: Medical Professionals-Foodborne
Pathogens
9. Careaga M, Fernández E, Dorantes L, Mota L, Jaramillo ME, et al. (2003)
Antibacterial activity of Capsicum extract against Salmonella typhimurium and
Pseudomonas aeruginosa inoculated in raw beef meat. Int J Food Microbiol 83:
331-335.
10. Graham DY, Anderson SY, Lang T (1999) Garlic or jalapeno peppers for
treatment of Helicobacter pylori infection. Am J Gastroenterol 94: 1200-1202.
11. http://en.wikipedia.org/wiki/Capsicum
12. Molina-Torres J, Garcıa-Chávez A, Ramırez-Chávez E (1999) Antimicrobial
properties of alkamides present in avouring plants traditionally used in
Mesoamerica: afnin and capsaicin. J Ethnopharmacol 64: 241-248.
13. Kalia NP, Mahajan P, Mehra R, Nargotra A, Sharma JP, et al. (2012) Capsaicin,
a novel inhibitor of the NorA efux pump, reduces the intracellular invasion of
Staphylococcus aureus. J Antimicrob Chemother 67: 2401-2408.
14. Yamasaki S, Asakura M, Neogi SB, Hinenoya A, Iwaoka E, et al. (2011)
Inhibition of virulence potential of Vibrio cholerae by natural compounds. Indian
J Med Res 133: 232-239.
15. Chatterjee S, Asakura M, Chowdhury N, Neogi SB, Sugimoto N, et al. (2010)
Capsaicin, a potential inhibitor of cholera toxin production in Vibrio cholerae.
FEMS Microbiol Lett 306: 54-60.
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Citation: Omolo MA, Wong Z, Mergen AK, Hastings JC, Le NC, et al.
(2014) Antimicrobial Properties of Chili Peppers. J Infect Dis Ther 2: 145.
doi:10.4172/2332-0877.1000145