In vitro Antibacterial Activity of Mentha spicata Essential Oil against Some Pathogenic Bacteria

Abstract

Mentha spicata (M. spicata) is within family Lamiaceae that spreads mainly in the temperate and subtemperate zones of the world. It is considered as a good source of essential oils (EOs), which is widely used in food production and pharmaceutical industries. The aim of the current study is to evaluate antibacterial activities associated with the EO of M. spicata cultivated in Iraq-Erbil city. The aerial parts of M. spicata were subjected to hydro distillation to extract the oil. Antimicrobial potential was tested against many microorganisms, signifying Gram-negative and Gram-positive bacteria. EO of M. spicata demonstrated antimicrobial activities with best susceptibility observed for Gram-negative bacteria toward the oil. The results suggest that EO of M. spicata may have potential value as antibacterial activities.

Full text

Polytechnic Journal ● Vol 11 ● No 1 ● 2021 | 13 ©2011-2021, Erbil Polytechnic University, Erbil, Kurdistan Region - F.R. Iraq
In vitro Antibacterial Activity of Mentha spicata
Essential Oil against Some Pathogenic Bacteria
Sara I. Othman*, Fouad H. Kamel
Department of Medical Laboratory Techniques, Erbil Health Technical College, Erbil Polytechnic University, Erbil, Kurdistan Region, Iraq
Polytechnic Journal. 2021. 11(1): 13-15
ISSN: 2313-5727
http://journals.epu.edu.iq/index.php/polytechnic
RESEARCH ARTICLE
Mentha spicata (M. spicata) is within family Lamiaceae that spreads mainly in the temperate and
subtemperate zones of the world. It is considered as a good source of essential oils (EOs), which is
widely used in food production and pharmaceutical industries. The aim of the current study is to evaluate
antibacterial activities associated with the EO of M. spicata cultivated in Iraq-Erbil city. The aerial parts
of M. spicata were subjected to hydro distillation to extract the oil. Antimicrobial potential was tested
against many microorganisms, signifying Gram-negative and Gram-positive bacteria. EO of M. spicata
demonstrated antimicrobial activities with best susceptibility observed for Gram-negative bacteria toward
the oil. The results suggest that EO of M. spicata may have potential value as antibacterial activities.
Keywords: Antibacterial activities; Ciprooxacin; Essential oil; Mentha spicata; Pathogenic bacteria
*Corresponding author:
Sara I. Othman, Department
of Medical Laboratory
Techniques, Erbil Health
Technical College, Erbil
Polytechnic University, Erbil,
Kurdistan Region, Iraq.
E-mail: sara.othman@epu.
edu.iq
Received: 15 June 2020
Accepted: 26 October 2020
Published: 30 June 2021
DOI
10.25156/ptj.v11n1y2021.pp13-15
antioxidant, antiseptic, and antifungal properties (Kumar
et al., 2011) and (Telci et al., 2010).
M. spicata is distinguished by its characteristic EO of
commercial and therapeutic importance. It is broadly
cultivated in many regions worldwide to commercially
produce its EO (İşcan, 2002).
Plant EOs have several biological uses, for example,
antimicrobial, antioxidant, and antispasmodics, in good
correlation with the high contents of phenolic compounds
(Shahbazi and Shabisi, 2019).
The aim of the current study was to evaluate antibacterial
activities associated with the EO of M. spicata cultivated
in Iraq-Erbil city.
MATERIALS AND METHODS
Materials
All chemicals that used in this research were in analytical grade
and most of them were obtained from Erbil Polytechnic
University/Research Centers – Erbil. All reagents and
standard solutions were prepared using distilled water.
Collection of Plant Material
The fresh aerial parts of Mentha plant were gathered
from Erbil City at the full owering stage on July 2018.
INTRODUCTION
The spread of drug-resistant pathogenic microorganisms
is one of the most serious threats to successful treatment
of microbial diseases. Essential oils (EOs) of plants
have evoked interest as sources of natural products
(Prabuseenivasan et al., 2006). Especially, the anti-
oxidant and antimicrobial activities of EOs as well as
their potential anti-cancer activity have been investigated
(Zu et al., 2010).
EO have antimicrobial properties that make them suitable
alternatives to antibiotics. Recently, the in vitro experiments
have demonstrated that EOs or their components could
be used favorably to modulate rumen microbial activities
(Busquet et al., 2011; McIntosh et al., 2003).
Mentha spicata (spearmint) is within Lamiaceae family grows
in throughout the world and this plant is widely employed
as a flavoring agent in several foods, also cosmetic,
confectionary, and pharmaceutical industries (Kumar et al.,
2011) and (Tyagi and Malik, 2011).
Historically, the genus of M. spicata has been applied to
treat gastro-intestinal disorders (Tyagi and Malik, 2011).
Carvone and limonene the main components of the EO
of M. spicata have been reported to have antibacterial,
ABSTRACT

Othman and Kamel
Polytechnic Journal ● Vol 11 ● No 1 ● 2021 | 14
Authentication of the botanical of the plant was conducted
by Faculty of Agriculture, Salahaddin University, Erbil,
Iraq. The specimen of the collected plant materials was
identied as M. spicata.
Isolation of the EO
EO was extracted from the dried aerial parts of M. spicata
by hydro-distillation using an instrument of Clevenger type.
The extraction was carrying out for 4 h to mix 200 gram of
plants in 1500 mL of distilled water. The extracts were dried
with anhydrous sulfate and concentrated under reduced
pressure by rotatory evaporator to evaporate water. The
pure oil was stored at –4°C until used. The EOs yield is
demonstrated by the oil quality (in ml) obtained for 100 g
of dried weight of plant sample.
Stock Antimicrobials Solution
Stock solution of 1% Ciprooxacin in peptone broth media
prepared after sterilizing the media by autoclave for 45 min
at 121°C and used as positive control.
Test Organism
Common pathogenic bacterial isolates including
Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus
saprophyticus, Streptococcus oralis, Listeria monocytogenes,
Pseudomonas aeruginosa, and Pseudomonas uorescens which
isolated from patients were referred to medical lab of
Rezgary Hospital-Erbil obtained after diagnosis (Kamel
et al., 2014). Bacterial isolates identied by vitek 2 system
(Biomerieux company). The cultures of bacteria were
maintained on nutrient agar slants at 4°C throughout the
study.
Microbial suspension with a bacterial count of 1.5 × 108
CFU/ml was prepared with normal saline solution (Kamel
and Jarjes, 2015). The microbial suspension for each
bacterial isolate was cultured on plates containing Brain
Heart Infusion Agar and then wells with 6 mm diameter
were created (Kamel et al., 2014).
Four different concentrations of the spearmint EO
prepared with Dimethyl Sulfoxide (DMSO) at ratio (2.5%,
5%, 10%, and 20%). The tests were done in two replicates
and all plates were stored at 37°C overnight. The effective
concentration of diluted extracted oil against pathogenic
bacteria was determined by measuring the inhibition zone
of growth comparing to positive control.
RESULTS AND DISCUSSION
The traditional use of plants as medicines, increasing
antibiotic resistance of pathogens, and undesirable side
effects of antibiotics suggested the use of Mentha EOs
as antibiotics or alternatives for the treatment of various
infectious diseases (Zaidi and Dahyia, 2015).
In this research, primary antibacterial effect evaluation of
the of M. spicata EO was done utilizing the well diffusion
method (Kamel et al., 2013). For each bacterial strain
subjected to distinct extract levels, the mean diameter (mm)
of the growth inhibition area is shown in Table 1.
The EO of M. spicata was examined for its antibacterial
activity potential against a panel of pathogenic
microorganisms including Gram-positive and Gram-
negative pathogens. M. spicata oil demonstrated variable
level of antimicrobial activity against all examined
microorganisms. Results obtained by determination zone
of inhibition which indicated that the EO was active
especially in concentration (20%) of Spicata oil against all
of them except S. saprophyticus.
Our results are in fair correlation with the studies in which
spearmint and peppermint oil both showed antibacterial
activities against Gram-negative and Gram-positive
bacteria (Pattnaik et al., 1997; Singh et al., 2013). The oil
also possesses antifungal activity against Aspergillus spp.
and Candida albicans. The differences in the antimicrobial
activities with the reported one may be due to different
geographical environment, age of the plant, different
method followed for solation of oil, cultivar type,
seasonality, etc.
The results of the current research revealed that the
EO exhibited moderate antibacterial effect against the
microorganisms. In general, the results of the present study
showed that Gram-negative bacteria were more susceptible
to M. spicata EO than Gram-positive bacteria. Gram-
positive bacteria, including Staphylococcus aureus, surround
Table 1: Presented effect of EO of M. spicata on microbial growth
Mentha spicata
essential oil dilution
with DMSO
Inhibition zone measured in mm
S. aureus S. epidermidis S. saprophyticus S. oralis Listeria
monocytogens
Pseudomonas
aeruginosa
Pseudomonas
uorescens
20% 6 6.5 6 7 7 7 7
10% 6.7 7.5 6.5 7.5 7 8 7.5
5% 8 8.5 7 8.5 8 9 9
2.5% 6 6 6 6 6 6 6
Ciprooxacin 8 8.5 8 9 8 8.5 8

Othman and Kamel
Polytechnic Journal ● Vol 11 ● No 1 ● 2021 | 15
themselves with a thick cell wall that is essential to cell
survival and growth and is a major target of antibiotics
(Zu et al., 2010).
S. saprophyticus was noted with the highest resistance to
the EO, these observations were recently reported by
other researchers. Whatever the oil dilution with DMSO
(2.5%) did not showed activity because of smallest zone
of inhibition of S. saprophyticus comparing to others.
CONCLUSION
In summary, results of the current study revealed that
the EO of M. spicata demonstrated moderate bioactivity
obtained by its antibacterial potential. These results suggest
that the bioactive oil can be benecially employed in
pharmaceutical industries as well as in food production
technologies. The discovery of new antibacterial agents
was mainly based on natural products that can be obtained
from different sources including plants, bacteria, algae,
fungi, and animals.
EOs account for a source of very promising natural
compounds for producing new antibacterial drugs.
Numerous studies have reported a strong antibacterial
effect for some EOs. Among these EOs, the potential
antibacterial of M. spicata has been documented frequently
(Vasconcelos et al., 2018).
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