Antibacterial properties of the methanol extract from the flower of Cassia auriculata L

 

P. Shanmuganathan and P. Muthukumaran

Meenakshi Chandra Sekaran College of Arts and Science, Pattukkottai -614 626, Tamil Nadu, India

 

ABSTRACT:

Antibacterial properties of methanol extract of Cassia auriculata  flower was studied on three Gram positive and seven Gram negative bacteria by disc diffusion method. The extract showed zone of inhibition against Gram positive bacteria (Bacillus cereus, B. subtilis and B. megaterium) and Gram negative bacteria [Streptococcus aureus, E. Coli, Salmonella typhae, S. paratyphae, Pseudomonous sp (I), Pseudomonous sp (II) and Shigella sonnei].

YWORDS:

 

 

INTRODUCTION:

Cassia auriculata L. commonly known as tanners cassia, also known as “avaram” in Tamil language is a shrub belongs to the Caesalpiniaceae family. The shrub is especially famous for its attractive yellow flowers which are used in the treatment of skin disorders and body odour. It is widely used in traditional medicine for rheumatism, conjunctivitis and diabetes. It has many medicinal properties. Its bark is used as an astringent, leaves and fruits anthelminthic, seeds used to treat in eye troubles and root employed in skin diseases1. It is also used for the treatment of ulcers, leprosy and liver disease2. The antidiabetic, hypolipidemic3 and antioxidant4 and hepatoprotective5 effects of Cassia auriculata have been reported. It was also observed that flower and leaf extract of Cassia auriculata shown to have antipyretic activity6

 

However, a few scientific evaluations of this plant have been documented. This study interests to evaluate the antibacterial activity of Cassia auriculata methanol extract.

 

MATERIALS AND METHODS:

Plant material

The flowers of Cassia auriculata were collected from Thanjavur, Tamilnadu, India .The flowers were examined carefully and old, infected, and fungus damaged flowers were removed. Extracts were prepared from dried and also from fresh flower. Healthy flowers were spread out and dried at room temperature for about ten days and ground into fine powder using electric blender.

 

Preparation of crude extract: The fresh flower of Cassia auriculata were washed with distilled water immediately after collection. The collected stems were chopped into small pieces, air dried at room temperature for about 20 day sand ground into powder to store in an airtight container. 790 g powder was macerated in 8 liters pure methanol (99% Anal-R) for 7 days at room temperature with occasional stirring.


Methanol extract, 7 days later, was filtered off through a cotton plug and finally with a Whatman No. 1 filter paper. The extract was concentrated under reduced pressure below 50ºCthrough rotatory vacuum evaporator. The concentrated extracts were collected in an eggplant flask and allow to air dry for complete evaporation of methanol. The whole process was repeated three times and finally, 15g greenish colored, concentrated stem extract was obtained (1.89% w/w) which was kept in refrigerator to40C.

 

 

Bacterial strains: Three Gram positive (Bacillus cereus, B.subtilis and B. megaterium) and seven Gram negative(Streptococcus aureus, E. Coli, Salmonella typhae, S.paratyphae, Pseudomonous sp (I), Pseudomonous sp (II) and Shigella sonnei) bacterial species were used.

 

Preparation of flower extracts solution: A measured amount of 200 mg Cassia auriculata flower extract was dissolved in 2mL of methanol to give a solution of known concentration (100 μg/μL). Methanol was chosen as solvent because, in addition to the complete dissolution of the crude extracts, it has no inhibitory effect on the cultures.

 

Preparation of sample discs: The sample discs of about 4mm in diameter were cut by punching machine from What man No. 1 filter paper. The discs were taken in a Petri dish and sterilized by autoclave, dried in oven at180°C.

 

Standard antibiotic disc: Kanamycin antibiotic disc with concentrations of 30 μg/disc was used as standard to compare with the sample.

 

Assay for antibacterial activity: Antibacterial activity of plant extract was determined by disc diffusion method7. All the test bacterial species were collected from the Research Laboratories of the Department of Microbiology, Meenakshi chandrasekaran arts and science college, Pattukkottai, Thanjavur.Dried filter paper discs (4 nm in diameter) impregnated in known amount of test substances (500 μg/discs)were placed on Mueller-Hinton agar medium uniformly seeded with the test organisms. Kanamycin discs (30 μg/disc) soaked in respective solvent were used as positive control. These plates were then kept at low temperature (4ºC) for 2-4 hours to allow maximum diffusion of compound. The diffusion occurred according to the physical law that controls the diffusion of molecules through agar gel. The plates were the incubated at 37ºC for 24 hours to allow maximum growth of the microorganisms. If the test materials have any antibacterial activity, it will inhibit the growth of the microorganisms giving the clear distinct zone around the disc called “zone of inhibition”. The antibacterial activity of the test material was determined by measuring the diameter of the zones of inhibition in millimeter with transparent scale.

 

RESULTS:

Table I showed that 1,000 μg/disc of extract exhibited13, 14 and 10 mm zone of inhibition against three Gram positive bacteria Bacillus cereus, B. subtilis and B. megaterium, respectively, and 15, 14, 13, 10, 14, 12 and 12mm zone of inhibition against seven Gram negative bacteria namely Streptococcus aureus, E. coli, Salmonelatyphi, Salmnela paratyphi (Fig 1a), Pseudomonous spI(Fig 1b), Pseudomonous sp (II) (Fig 1c) and Shigella sonnei (Fig 1d), respectively. On the other hand, standard antibiotic kanamycin (30 μg/disc) showed more significant antibacterial activity against all tested Gram positive and Gram negative bacteria showing the larger zone of inhibition in every case. This result indicates that Cassia auriculata flower extract has promising antibacterial activity.

 

 

Table I: Diameter of Zone of Inhibition (mm) against some Gram positive bacteria and Gram negative bacteria

 

Bacteria

Diameter of zone of inhibition (mm)

Kanamycin

(30 μg/disc)

Cassia auriculata flower   extract

(1,000 μg/disc)

Gram positive bacteria

 

 

Bacillus cereus

28 mm

13 mm

Bacillus subtilis

32 mm

14 mm

Bacillus megatarium

26 mm

10 mm

Gram negative bacteria

 

 

Streptococcus aureus

30 mm

15 mm

E. Coli

30 mm

14 mm

Salmonella typhae

30 mm

13 mm

Salmonella para typhae

30 mm

10 mm

Pseudomonous Sp (1)

29 mm

14 mm

Pseudomonous Sp (11)

30 mm

12 mm

Shigella sonnei

28 mm

12 mm

 

Figure 1: Zone of inhibition showed by the Cassia auriculata flower extract (a-c) against the bacterial strains a. Salmonella para typhae; b.Pseudomonous Sp (1); c. Pseudomonas SP (II) and d. Shigella sonnei (inhibition zone in presence of kanamycin)

 

DISCUSSION:

Plants produce a huge variety of secondary compounds as natural protection against microbial and insect attack. Some of these compounds are toxic to animals, but others may not be toxic. Indeed, many of these compounds have been used in the form of whole plants or plant extracts for food or medical applications in human8 because plants are the natural reservoir of many antimicrobial, anticancer agents, analgesics, anti-diarrheal, antifungal as well as various therapeutic activities9.Acceptance of medicines from such plant origin as an alternative form of healthcare is increasing because they are serving as promising sources of novel antibiotic prototypes10-11 . Some of the phytochemical compounds e.g. glycoside, saponin, tannin, flavonoids, terpenoid, alkaloids, have variously been reported to have antimicrobial activity12-13.

 

In the current study, the results of testing the flower extracts for antimicrobial activities against 10 bacterial and 6 fungal species might be due to the presence of some sorts of bioactive or inhibitory compounds or factors in the extract or synergism by the existence of some compounds or factors in the extract of Cassia auriculata flower  .

 

In conclusion, this demonstrates that the methanol extract of Cassia auriculata flower extract exhibits antibacterial effect in experimental models which therefore offer a scientific basis for using this plant as a good source of traditional microbiological references.

 

REFERENCES:

1.       Siva, R. and Krishnamurthy, K.V. 2005. Isozyme diversity in Cassia auriculata L, African J of Biotechnology  4: 772-775.

2.       Kumar, R.S., Ponmozhi, M. and Nalini, M. 2002. Effect of Cassia auriculata leaf extract on lipids in rats with alcoholic liver injury, Asia Pacific J of Clinical Nutrition  11: 157-163.

3.       Umadevi, P., Selvi, S., Suja, S., Selvam, K. and Chinnaswamy, P. 2006. Antidiabetic and hypolipidemic effect of Cassia auriculata in alloxan induced diabetic rats, International J of Pharmacology 2: 601-607.

4.       Kumaran, A., Joel Karunakaran, R. 2007. Antioxidant activity of Cassia auriculata flowers, Fitoterapia 78: 46-47

5.       Kumar, R.S., Ponmozhi, M., Viswanathan, P. and Nalini, N. 2003. Activity of Cassia auriculata leaf extract in rats with alcoholic liver injury, J of Nutritional Biochemistry 14: 452-458.

6.       Vedavathy, S. and Rao, K.N. 1991. Antipyretic activity of six indigenous medicinal Plants of Tirumala hills, J of Ethanopharmacology 33: 193-196.

7.       Bauer AW, Kirby E, Sherris JC, Turck M. 1966.  Antibiotic susceptibility testing by a standardized single disk method. Am J Clin Pathol 45: 493-96.

8.       Wallace RJ. 2004. Antimicrobial properties of plant secondary metabolites. Proc Nutr Soc.; 63: 621-29.

9.       Lucy H, DaSilva EJ. 1999. Medicinal plants: A re-emerging health aid. Electronic J Biotech. 2: 56-70.

10.     Rabe T, Van Staden J. 1997. Antibacterial activity of South African plants used for medicinal purposes. J Ethnopharmacol. 56: 81-87.

11.     Koduru S, Grierson DS, Afolayan AJ 2006.. Antimicrobial activity of Solanum aculeastrum. Pharm Biol.; 44: 283-86.

12.     Okeke MI, Iroegbu CU, Eze EN, Okoli AS, Esimone CO.2001.Evaluation of extracts of the root of Landolphia owerrience for antibacterial activity. J Ethnopharmacol. 78: 119-27.

13.     Ebi GC, Ofoefule SI. 1997. Investigating into folkloric antimicrobial activities of Landolphia owerrience. Phytother Res 11:149-51

 

 

Received on 06.02.2011

Accepted on 17.02.2011     

© A&V Publication all right reserved

Research Journal of Pharmacognosy and Phytochemistry. 3(3): May- June 2011, 137-139