EVALUATION OF ANTIMICROBIAL POTENTIAL OF ELAEOCARPUS SERRATUS L.

Received on 28 January, 2014; received in revised form, 29 March, 2014; accepted, 17 June, 2014; published 01 August, 2014

EVALUATION OF ANTIMICROBIAL POTENTIAL OF ELAEOCARPUS SERRATUS L.

Indhiramuthu Jayashree*, DH. Geetha and M. Rajeswari

PG and Research Department of Botany, Vellalar College for Women, Erode-12, Tamil Nadu, India

ABSTRACT: The in vitro antimicrobial activity of acetone, methanol and water extracts of leaf, stem bark and fruit of Elaeocarpus serratus L. (Elaeocarpaceae) was examined against four bacterial species (Shigella sonnei, Salmonella typhi, Staphylococcus aureus and Klebsiella pneumoniae) and a fungal species (Candida albicans) using the agar well diffusion method. Phytochemical screening was carried out for phenols, flavonoids and tannins. Results showed that the plant extracts exhibited a dose-dependent inhibition of microorganisms. The acetone and methanol extracts of leaf and stem bark of E. serratus displayed maximum antibacterial activity against all the bacterial species studied. The plant extracts also displayed high antifungal activity against Candida albicans especially, the acetone extract was found to be more active antifungal.  Generally, the lower concentrations of the extracts were susceptible to the fungal pathogen. E. serratus extracts contained phenols, flavonoids and tannins at varying levels. The ability of the crude extracts of the test plant to inhibit the growth of bacteria and fungi is an indication of its broad spectrum antimicrobial potential which may be employed in the management of microbial infections.

Elaeocarpus  serratus,  phytochemicals,  antimicrobial  activity,  agar  well diffusion method, zone of inhibition

INTRODUCTION: In recent years, multiple drug resistance in human pathogenic microorganisms has developed due to indiscriminate use of commercial antimicrobial drugs commonly used in the treatment of infectious diseases. This situation, coupled with the undesirable side effects of certain antibiotics and the emergence of previously uncommon infections are a serious medical problem ^{1, 2}. Therefore the scientists of the21st century are generally reviving our traditional knowledge and are screening various parts of plants scientifically used in the folklore medicine in search of newer lead compounds having antimicrobial efficacy ^{3, 4}.

Medicinal plants are known to produce certain bioactive molecules which react with organisms in the environment, inhibiting bacterial or fungal growth and protect the human body against pathogens ^{5, 6}.

Elaeocarpus is a genus of tropical and subtropical evergreen trees and shrubs belonging to family Elaeocarpaceae. Studies indicate that various Elaeocarpus species contain chemical constituent such as triterpenes, tannins, indolizidine alkaloids, flavonoids, and ellagic acid derivatives ^{7, 8, 9}.

Various speciesof Elaeocarpus have been known to possess anti-inflammatory ¹⁰,   antimicrobial ¹¹, analgesic ¹² and antihypertensive ¹³ activities. However, there is insufficient information regarding the antimicrobial activity of Elaeocarpus serratus L. In this paper, the antimicrobial property of crude extract of the leaf, stem bark and fruit of E. serratus L. has been studied as part of the exploration for new and novel bio-active compounds.

MATERIALS AND METHODS:

Plant materials and preparation of extract: The leaves, stem bark and fruits of Elaeocarpus serratus L. were collected from Upper Palani Hills of Western Ghats (Kodaikanal Forest Division), India and were authenticated at Botanical Survey of India (BSI), Southern Circle, Coimbatore, India and the herbarium of Voucher specimen number BSI/SRC/5/23/2011-12/Tech.  239 have been deposited at the Department of Botany, Vellalar College for Women, Erode (T.N), India. The plant materials were dried separately under shade and pulverized in a mechanical grinder and stored in a closed container for further use.

The air dried, powdered plant materials were extracted in the Soxhlet apparatus successively with different solvents in the increasing order of polarity [Acetone (56.5°C), Methanol (64.7°C) and Water (99.98°C)]. Each time before extracting with the next solvent, the powdered materials were dried in a hot air oven at 40°C. Finally, the materials were macerated using hot water with occasional stirring for 16 hours and the water extracts were filtered.

The different solvent extracts were concentrated, vacuum dried and weighed. The percentage yield was expressed in terms of air dried sample. The extracts were dried over anhydrous sodium sulphate, stored in sealed vials in refrigerator (5-8°C) until analysis¹⁴. All the reagents used were of analytical grade.

Test microorganisms: The test microorganisms used in this study (bacteria: Shigella sonnei MTCC 2957, Salmonella typhi MTCC 3216, Staphylococcus aureus MTCC 3381, and Klebsiella pneumoniae MTCC 3384; fungi: Candida albicans MTCC 183) were obtained from the culture collections of Manian Laboratories Pvt.  Ltd., Coimbatore, India.  Bacteria were cultured overnight at 37ºC in Mueller Hinton Broth (MHB) and fungi at 28°C for 72 hours in Potato Dextrose Broth (PDB) and used as inoculum.

Antimicrobial bioassay: The antimicrobial activity of the crude extracts was determined in accordance with the agar well diffusion methoddescribed by Sinclair and Dhingra,(1995)¹⁵. Bacteria were cultured overnight at 37ºC in Mueller Hinton Broth (MHB) and fungi at 28°C for 72 hours in Potato Dextrose Broth (PDB) and used as inoculum.

A final inoculum, using 100μl of suspension containing 108 CFU/ml of bacteria and 104 spore/ml of fungi were spread on Mueller Hinton Agar (MHA) and Potato Dextrose Agar (PDA) medium, respectively. Subsequently, using a sterile borer, well of 9 mm diameter was made in the inoculated media. Addition of 50, 100, 150 and 200 μl of 20 mg/ml each extract was aseptically filled into the well. Negative control was prepared using the same solvent employed to dissolve the extracts. Gentamycin (50 μg/ml) and Amphotericin (100 units/disc) were used as positive control. The test plates were incubated at 37°C for 24 hours depending on the incubation time required for a visible growth. The diameter of zone of inhibition (mean of triplicates ± SD) as indicated by clear area which was devoid of growth of microbes was measured.

Statistical evaluation: Each assay in this experiment was repeated thrice and the values were expressed as mean of triplicate analysis of the samples (n = 3) ± Standard Deviation (SD).

Preliminary phytochemical analysis: The extracts of the plant were screened for phenols, flavonoids and tannins using the following procedure:

Phenols: The extract (50 mg) was dissolved in 5 ml of distilled water. To this, few drops of neutral 5% ferric chloride solution were added. A dark green colour indicated the presence of phenolic compounds ¹⁶.

Flavonoids: Four milliliters of extract solution was treated with 1.5 ml of 50% methanol solution. The solution was warmed and metal magnesium was added. To this solution, 5-6 drops of concentrated hydrochloric acid was added and red color was observed for flavonoids and orange color for flavones ¹⁷.

Tannins: To 0.5 ml of extract solution 1 ml of water and 1-2 drops of ferric chloride solution was added. Blue color was observed for gallic tannins and green black for catecholic    tannins ¹⁸.

RESULTS AND DISCUSSION: The percentage yield of extracts and the phytochemical constituents of the plant are shown in Fig. 1 and Table 1, respectively. The maximum per cent yield was registered in the acetone  extract  of  leaf  of  E.serratus  (27.67%  ).The  methanol  extract  of  stem  bark  of E.serratus registered an yield percentage of 16.0% . Generally, the acetone and methanol extracts of plant parts contained more constituents than the water extracts. This might be due to the fact that phenolics are often extracted in higher amounts in more polar solvents such as aqueous methanol/ethanol as compared with absolute methanol/ethanol ¹⁹. This was in agreement with the findings of Shon et al. (2004)²⁰ who investigated  that  methanol  and  hot  water  were  more  efficient  to  extract  antioxidant compounds from Phellinus baumii. Similarly, Singh et al. (2010)²¹ showed that of all the solvents (pet ether, chloroform, ethanol and water) used, the ethanol extract of Elaeocarpus ganitrus had a maximum extractable value of 2.4% and chloroform had a minimum value of 0.5%.

FIG. 1: THE PER CENT YIELD OF DIFFERENT SOLVENT EXTRACTS OF ELAEOCARPUS SERRATUS

Plant sample:

AESL - Acetone extract of E. serratus leaf MESL - Methanol extract of E. serratus leaf WESL - Water extract of E. serratus leaf

AESB -   Acetone extract of E. serratus stem bark MESB - Methanol extract of E. serratus stem bark WESB - Water extract of E. serratus stem bark AESF -   Acetone extract of E. serratus fruit

MESF - Methanol extract of E. serratus fruit

WESF - Water extract of E. serratus fruit

TABLE 1: PHYTOCHEMICAL SCREENING OF DIFFERENT SOLVENT EXTRACTS OF ELAEOCARPUS SERRATUS

+   =   Present in small amount (concentration); ++ =   Moderately present; +++ =   Present in large amount

The antimicrobial activity of different extracts of E. serratus is shown in Table 2. The plant extracts showed a dose-dependent inhibition of micro-organisms.

Among the extraction medium, acetone and methanol extracts of leaf and stem bark of E. serratus displayed maximum antibacterial activity against all the bacterial species studied.  The water extracts of leaf, stem bark and fruit were found to be more susceptible to the bacterial species and showed no zone of inhibition except Shigella sonnei. The standard antibiotic gentamycin inhibited the growth of all the bacterial species effectively at a lower concentration of 50 μg/ml.

Generally, the inhibition of all the bacterial species (except Klebsiella pneumoniae) by the standard antibiotic gentamycin (50 μg/ml) was higher than the various solvent extracts of the test plant.

In the present findings, E. serratus extracts displayed high antifungal activity against Candida albicans.  The water extract of leaf and acetone extract of fruit of E. serratus produced the maximum inhibition zone of 18±1.05 and 18±0.92 mm at 200 μg/ml. On the whole, the various solvent extracts of the plant parts at higher concentrations (150 and 200 μg/ml) inhibited the fungal growth more effectively than the standard amphotericin which showed an inhibition zone of 11±0.02 mm at a concentration of 100 units per disc. Generally, the lower concentrations of the extracts were susceptible to the fungal pathogen.

TABLE 2:  ANTIMICROBIAL ACTIVITY OF DIFFERENT SOLVENT EXTRACTS OF LEAF, STEM BARK AND FRUIT OF ELAEOCARPUS SERRATUS

Values are mean ± SD (n=3)

Phenolics  and  polyphenols  present  in  the  plants  were  known  to  be  toxic  to  the microorganisms ²². Flavonoids have been reported to have both antibacterial and antifungal activities ²³. Tannins from Dichrostachys cinerea root bark possessed antibacterial activities ²⁴. In the present study, the phytochemical analysis of E. serratus solvent extracts revealed the presence of phenols, flavonoids and tannins at varying intensity. The phytochemical characteristics possessed by E. serratus may be attributed to its antimicrobial properties.

The high inhibitory potential of acetone and methanol extracts of leaf and stem bark of E. serratus might be due to the high solubility of the phytoconstituents in the organic solvents. The phytoconstituents might be present in higher concentrations in the leaf and stem bark along with some new microbicidal agents reflecting its higher bactericidal and fungicidal potential. Presence of these phytoconstituents in the leaf and stem bark pointed towards the pharmacological activities of this plant and supported the claim of the traditional users.

In support of the present study, the results of Nair and Chanda (2007) ²⁵ revealed that the ethanol extracts were more potent than aqueous extracts of all the plants studied. Similar trend was also noted by Ekwenye and Edeha (2010) ²⁶. According to them, the ethanol extracts of Citrus sinensis exhibited inhibitory activities that were found to be a little higher than aqueous extract on the bacterial species investigated. It can be therefore inferred that the active principles of the plant may be more soluble in ethanol than in water. Results of the present investigation agreed with the report of Arokiyaraj et al (2009) ²⁷.

According to them, Vitex doniana and Cajanus cajan acetone, methanol, ethanol extracts generally produced a clear inhibitory effect on the bacteria. The present findings were also supported by Singh et al (2010) ²¹ who evaluated the petroleum ether, chloroform, ethanol and water extracts of dried fruits of Elaeocarpus ganitrus for antifungal activity on different fungal strains. The chloroform and ethanol extracts were found to be more active antifungals.

CONCLUSION: It is inferred from the current findings that the phytoconstituents might be present in high concentrations in the leaf of Elaeocarpus serratus along with some new microbicidal agents reflecting its higher bactericidal potential. However, further studies are necessary to find out the active principles responsible for these activities which can be used as natural antimicrobial agents for human consumption and cure of infectious diseases.

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    How to cite this article:

    Jayashree I, Geetha D and Rajeswari M: Evaluation of antimicrobial potential of Elaeocarpus serratus L.. Int J Pharm Sci Res2014; 5(8): 3467-72.doi: 10.13040/IJPSR.0975-8232.5(8).3467-72

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