This study was conducted to reveal the antibacterial effect of selected medicinal plants from Western Ghats against dental caries bacteria and aware the populace about the importance of using phytomedicines. In this study, the antibacterial effects of nine well known medicinal plants were checked against the dental caries bacteria using well diffusion method. The highest zonation was reported in acetone and methanol extracts. The Chloroform and ethanol extracts revealed sensible activity and water extracts were produced least inhibitory activity. Acetone extract of Eucalyptus gained high inhibitory activity against Bacillus megaterium. While Pseudomonas aeruginosa showed resistance to all the extracts of Syzygium aromaticum

Ashok, Arunima

K, Sukesh

Thalikunnil, Shafi Thompson

English

Advanced Research Journals

International Journal of Phytomedicine 3 (2011) 416-421 
http://www.arjournals.org/index.php/ijpm/index 
 
Original Research Article 
              
               
A study on the antibacterial effect of selected medicinal plants of Western 
Ghats against dental caries bacteria 
Shafi Thompson T1*, Arunima Ashok2, Sukesh K2 
 
*Corresponding author: 
 
Shafi Thompson T 
1 Department of  Biotechnology, 
Mar Ivanios College, 
Thiruvananthapuram Dist-695 015, 
Kerala, India 
2 Department of Microbial 
Technology, Malankara Catholic 
College, Kanyakumari Dist- 629 
153,Tamilnadu, India 
 
 
 
 
Abstract 
This study was conducted to reveal the antibacterial effect of selected 
medicinal plants from Western Ghats against dental caries bacteria and aware 
the populace about the importance of using phytomedicines. In this study, the 
antibacterial effects of nine well known medicinal plants were checked 
against the dental caries bacteria using well diffusion method. The highest 
zonation was reported in acetone and methanol extracts. The Chloroform and 
ethanol extracts revealed sensible activity and water extracts were produced 
least inhibitory activity. Acetone extract of Eucalyptus gained high inhibitory 
activity against Bacillus megaterium. While Pseudomonas aeruginosa 
showed resistance to all the extracts of Syzygium aromaticum.  
Keywords: Dental caries, Western Ghats, Medicinal plants, Antibacterial 
activity, Phytochemical investigation 
 
. 
Introduction 
Dental decay is the most prevalent disease 
affecting humanity. Teeth get decayed due to a 
combination of causes that include bad oral 
hygiene, stagnation of food on or around the 
teeth, presence of plaque on the tooth structure 
and the presence of caries causing 
microorganisms [1]. The presence of a certain 
types of microorganism was discovered during 
the last decade in dental plaques. The nucleating 
role of the microorganisms in the formation of 
dental calculus shows similarities to that of 
nanobacteria in calcification [2]. Periodontal 
disease has long been recognized as a chronic 
disease, but literature describes it as a disease 
derived entirely from the effects of a microbial 
colonization of the gingival crevice. If this were 
so, it would mean that periodontal disease is 
unique among chronic diseases, all of which 
represent the long-term cumulative effects of 
interaction between a host biologic system and 
the surrounding environment [3]. Antibiotic 
resistance is the ability of a microorganism to 
withstand the effects of an antibiotic. It is a 
specific type of drug resistance. Antibiotic 
resistance evolves naturally via natural selection 
through random mutation, but it could also be 
engineered by applying an evolutionary stress on 
a population. Once such a gene is generated, 
bacteria can then transfer the genetic information 
in a horizontal fashion (between individuals) by 
plasmid exchange. The patterns of antibiotic 
usage greatly affect the number of resistant 
organisms which develop. Overuse of broad-
spectrum antibiotics, such as second- and third-
generation greatly hastens the development of 
ISSN: 0975-0185 
Shafi et al. International Journal of Phytomedicine 3 (2011) 416-421 
 
417 
 
resistance. Other factors contributing towards 
resistance include incorrect diagnosis, 
unnecessary prescriptions, improper use of 
antibiotics by patients [4]. Antibiotic resistance in 
microorganisms recovered from the acute dental 
abscess has been reported to be increasing (with 
the exception of Metronidazole) in some 
populations studied over the last few decades. 
The resistance problem demands that a renewed 
effort be made to seek antibacterial agents 
effective against pathogenic bacteria resistant to 
current antibiotics. One of the possible strategies 
towards this objective is the rational localization 
of bioactive phytochemicals. Plants have a 
limitless ability to synthesize aromatic 
substances, most of which are phenols or their 
oxygen substituted derivatives such as tannins. 
Many of the herbs and spices used by humans to 
season food yield have useful medicinal 
compounds including those having antibacterial 
activity [5]. Plant derived drugs remain an 
important resource especially in developing 
countries to combat serious diseases.  
Materials and Methods 
Selection of Bacterial Strains 
Bacterial strains of six different species 
(Pseudomonas aeruginosa, Streptococcus 
salivarius, Streptococcus viridans, Streptococcus 
mutans, Bacillus megaterium, and Neisseria 
catarrhalis) were selected from Microbial 
Technology Laboratory, Malankara Catholic 
College, Mariagiri, Kaliakkivilai, Tamil Nadu. 
Collection of Medicinal Plants  
The medicinal plant samples were collected from 
the Maruthuvarmalai region of Western Ghats of 
Kanyakumari district. The different parts such as 
root, stem, leaves and inflorescence of nine well-
known plants were selected for testing its 
antibacterial studies and characterization of 
secondary metabolites of effective ones. 
Preparation of Plant Extracts 
Plant samples were shade dried and ground well. 
10 gram of powdered sample was filled in screw 
cap bottles with 10 ml of different solvent 
systems (acetone, ethanol, chloroform, methanol 
and water). It was kept at 220 c for fifteen days. 
Antibacterial Effect Checking of Medicinal 
Plant Extracts 
Antibacterial effect of medicinal plant extracts 
were checked by Well- diffusion method.  
Well Diffusion Method 
The bacterial isolates were effectively swabbed 
on the Mueller-Hinton agar plates. After allowing 
the inoculums to dry at room temperature and six 
millimeter wells were bored on it. The extract 
was introduced (50 µl of a 100mg/ml 
concentration) into three duplicate wells. The 
plates were allowed to stand at room temperature 
for one hour for the extract to diffuse into the 
agar and then they were incubated at 370 c for 18 
hours. After incubation the plates were observed 
for the results. 
Results 
Antimicrobial Effect of Medicinal Plant 
Extracts 
The antimicrobial activity of nine selected 
medicinal plant’s  (Syzygium aromaticum, Piper 
betle, Areca catechu, Camellia sinensis, 
Eucalyptus globules , Zingiber officinale, 
Gymnema sylvestre, Azadirachta indica, and 
Chrysopogon zizanioides) ethanol, acetone, 
chloroform, methanol and water extracts against 
bacterial isolates (Pseudomonas aeruginosa, 
Streptococcus salivarius, Strptococcus viridans, 
Strptococcus mutants, Bacillus megaterium, 
Neisseria catarrhalis) were tabulated. 
The acetone extract of Eucalyptus globulus 
showed high inhibitory activity against 
Streptococcus mutans, Streptococcus viridans and 
Bacillus megaterium with 30mm, 31mm and 
36mm respectively. Whereas the ethanol extract 
revealed activity against Bacillus megaterium and 
Streptococcus salivarius.. It was observed that  
Shafi et al. International Journal of Phytomedicine 3 (2011) 416-421 
 
418 
 
  
Table.1. Zone of Inhibition of Different Extracts of Eucalyptus globulus against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
18 
30 
18 
31 
36 
11 
10 
12 
10 
10 
13 
9 
25 
23 
25 
_ 
26 
13 
17 
17 
17 
22 
20 
_ 
13 
_ 
_ 
27 
14 
_ 
 
Table.2. Zone of Inhibition of Different Extracts of Zingiber officinale against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
25 
21 
12 
16 
12 
_ 
16 
15 
15 
14 
16 
13 
23 
20 
15 
20 
16 
11 
17 
17 
16 
14 
11 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
 
Table.3.Zone of Inhibition of Different Extracts of Syzygium aromaticum against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
30 
23 
22 
21 
22 
_ 
18 
20 
15 
18 
17 
_ 
23 
24 
21 
22 
18 
_ 
25 
24 
20 
18 
20 
_ 
_ 
24 
11 
11 
12 
_ 
 
Table.4. Zone of Inhibition of Different Extracts of Camellia sinensis against Bacteria 
Bacteria Acetone 
  (mm) 
Chloroform 
    (mm) 
Ethanol 
  (mm) 
Methanol 
   (mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
25 
20 
20 
22 
18 
15 
_ 
_ 
_ 
_ 
_ 
8 
15 
_ 
18 
30 
25 
18 
18 
_ 
15 
24 
23 
9 
_ 
_ 
_ 
_ 
_ 
_ 
 
 
 
 
Shafi et al. International Journal of Phytomedicine 3 (2011) 416-421 
 
419 
 
Table.5. Zone of Inhibition of Different extracts of Piper betle against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
10 
12 
11 
10 
22 
18 
11 
21 
9 
23 
15 
20 
17 
13 
18 
15 
23 
14 
11 
12 
9 
20 
20 
18 
_ 
_ 
7 
_ 
_ 
_ 
 
Table.6. Zone of Inhibition of Different extracts of Gymnema sylvestre against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
10 
13 
10 
13 
20 
16 
8 
_ 
10 
_ 
14 
_ 
13 
13 
13 
15 
14 
10 
_ 
9 
18 
11 
20 
_ 
_ 
_ 
_ 
13 
_ 
_ 
 
Table.7. Zone of Inhibition of Different extracts of Azadirachta indica against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
17 
7 
15 
12 
15 
_ 
9 
12 
14 
9 
9 
6 
13 
10 
11 
15 
8 
6 
20 
9 
11 
10 
_ 
_ 
_ 
_ 
_ 
_ 
7 
_ 
 
Table.8. Zone of Inhibition of Different extracts of Chrysopogon zizanioides against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
12 
18 
15 
32 
25 
12 
8 
_ 
_ 
_ 
10 
8 
18 
13 
_ 
18 
25 
13 
12 
10 
11 
18 
25 
9 
11 
_ 
_ 
_ 
7 
_ 
 
 
 
Shafi et al. International Journal of Phytomedicine 3 (2011) 416-421 
 
420 
 
Table.9. Diameter of Zone of Inhibition of Different extracts of Areca catechu against Bacteria 
Bacteria Acetone 
(mm) 
Chloroform 
(mm) 
Ethanol 
(mm) 
Methanol 
(mm) 
Water 
(mm) 
Neisseria catarrhalis 
Streptococcus mutans 
Streptococcus salivarius 
Streptococcus viridans 
Bacillus megaterium 
Pseudomonas aeruginosa 
20 
18 
17 
20 
18 
12 
11 
9 
9 
_ 
9 
19 
11 
12 
12 
12 
16 
11 
18 
13 
12 
12 
19 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
 
water extract inhibited the growth of 
Streptococcus viridans with a zone of 27mm.  
The acetone extract of Zingiber officinale 
inhibited the growth of Neisseria catarrhalis and 
produced zone of 25mm. it was observed that the 
ethanol extract has the ability to inhibit the 
growth of Neisseria catarrhalis and Streptococcus 
mutans.  
The chloroform extract of Syzygium aromaticum 
showed activity against both Neisseria catarrhalis 
and Streptococcus viridans with a clear zone of 
18mm each. Whereas its acetone extraction 
revealed high activity against Neisseria 
catarrhalis with a zone of 30 mm. The methanol 
extract produced high activity against 
Streptococcus mutans with a zone of 24mm. It 
was observed that the water extract inhibited the 
growth of Streptococcus mutans with a clear zone 
of 24mm. 
Neisseria catarrhalis was sensitive to acetone 
extract of Camellia sinesis with a growth 
inhibitory zone of 25mm. whereas the chloroform 
extract showed activity only against 
Pseudomonas aeruginosa with a zone of 8mm. 
Water extract did not showed activity on any 
organism. 
The crude acetone extract of Piper betle showed 
high inhibitory activity against Bacillus 
megaterium and Pseudomonas aeruoginosa with a 
zone of 22mm, 18mm respectively. Chloroform 
extract revealed activity against Streptococcus 
viridans with a clear zone of 23mm. Whereas 
ethanol extract showed inhibitory activity against 
Bacillus megaterium with zone of 23mm. it was 
observed that water extract  has ability to inhibit 
Streptococcus salivarius with a zone of 7mm. 
 
The acetone extract of Gymnema sylvestre 
showed highest activity against Bacillus 
megaterium and Pseudomonas aeruginosa with 
20mm, 16mm respectively. Whereas the water 
extract showed the maximum activity only 
against Streptococcus viridans with a clear zone 
of 13mm. 
Acetone extract of Azardirachta indica showed 
maximum inhibitory activity against Neisseria 
catarrhalis and Streptococcus salivarius with 
17mm, 15mm respectively. Whereas the 
methanol extract showed high activity of 20mm 
zone against Neisseria catarrhalis and 11mm on 
Streptococcus salivarius. It was observed that 
water extract has activity against Bacillus 
megaterium alone. 
Acetone extract of Chrysopogon zizanioides 
showed high activity against Streptococcus 
viridans (32mm) and ethanol extract expressed 
high activity against Bacillus megaterium 
(25mm). Whereas the methanol extract showed 
high inhibitory activity against Bacillus 
megaterium and Streptococcus viridans with 
25mm, 18mm respectively. 
The crude acetone extract of Areca catechu 
showed maximum inhibitory activity against 
Neisseria catarrhalis (20mm) and chloroform 
extract was highly inhibited Pseudomonas 
aerugonisa with a zone of 19mm.  The methanol 
extract expressed high activity against Bacillus 
megaterium and Neisseria catarrhalis with 19mm, 
18mm respectively. 
Discussion 
Shafi et al. International Journal of Phytomedicine 3 (2011) 416-421 
 
421 
 
Nowadays the degree of dental caries and related 
problems are increasing with severe effects. As 
part of search for effective phytoderivatives 
against dental pathogens, nine medicinal plants 
(Syzygium aromaticum, Piper betle, Areca 
catechu, Camellia sinensis, Eucalyptus globules, 
Zingiber officinale, Gymnema sylvestre, 
Azadirachta indica, Chrysopogon zizanioides) 
were collected from the Maruthuvar Malai region 
of Western Ghats in Kanyakumari district and its 
solvent extracts were applied against bacterial 
isolate. The result evidenced that all the selected 
plants are with acceptable levels of bactericidal 
activity. The highest zonation was reported in 
acetone and methanol extracts. The Chloroform 
and ethanol extracts showed moderate activity 
and water extracts were showed relatively least 
inhibitory activity. Perhaps the variations may be 
due to the polarity of solvents which determines 
the type of reaction and solubility of compounds.  
The acetone and methanol have better extracting 
capacity which may be attributed to the ability to 
extract the natural antimicrobial compounds such 
as alkaloids, flavanoids, terpinoids and phenolic 
compounds from the plant. Acetone extract of 
Eucalyptus showed high inhibitory activity 
against Bacillus megaterium. Whereas 
Pseudomonas aeruginosa was resistant to all the 
extracts of Syzygium aromaticum. These results 
strengthen the possibility of application of 
phytoderivatives against human oral flora.  
Acknowledgement 
The authors are thankful to Rev Fr. Prem Kumar, 
MSW, The Correspondent and Secretary of 
Malankara Catholic College, for providing 
facilities and moral support. 
References 
[1]. J. Kirkham, R. C. Shore, S. J. Brookes 
and C. 2002.  Robinson. FEMS 
Microbiology Ecology,  39, Issue 3, 239-
244  
[2]. Turgut Demir. 1990.  Archives of Oral 
Biology,  35, Supplement 1, S177-S180 
[3]. V R Dowell, Jr, S Offenbacher, W 
Snyder, and T Hersh .2006. Archives of 
Oral Biology,  47, Issue 6, 491-498  
[4]. Parekh J, Karathia N, Chanda S. 2006.  
Screening of some traditionally used    
medicinal plants for potential antibacterial 
activity. Indian J Pharm Sci; 68:832-4 
[5]. Bhavnani, S.M. and Ballow, C.H. 2000. 
Curr. Opin. Microbiol., 3: 528 
 
 
 


A study on the antibacterial effect of selected medicinal plants of Western Ghats against dental caries bacteria

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A study on the antibacterial effect of selected medicinal plants of Western Ghats against dental caries bacteria

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