Phytochemical Screening & Antibacterial activity of aqueous ... - IJGHC

E-ISSN: 2278-3229 

International Journal of Green and Herbal Chemistry 

Available online at www.ijghc.org 

Green Chemistry 

IJGHC; September-November, 2012; Vol.1.No.3, 211-216 

Research Article 

Phytochemical Screening & Antibacterial activity of 

aqueous & methanolic extract of Young & Mature 

leaves of Psidium guajava L. (guava) 

Meenakshi Vaidya 

Department of Botany, Mithibai College, Vile Parle (West), Mumbai 400 056. 

Received: 18 August 2012; Revised: 31 August 2012; Accepted: 11 September 2012. 

Abstract: Psidium guajava commonly called as guava belongs to family 

Myrtaceae. The leaf & the bark have lot of medicinal properties. Guava leaves 

especially have been a subject for diverse research in terms of pharmacological 

properties & its history in folk medicine. The leaves have been used in folk 

medicine as remedy for diarrhea & also for its antimicrobial properties. In the 

present study a comparative analysis of aqueous & methanolic extracts was done 

for both young & mature leaves. Phytochemical screening was carried out by 

standard biochemical tests, and to evaluate the possibility of novel 

pharmaceuticals having antimicrobial potential. The study revealed the presence 

of secondary metabolites like alkaloids, anthocyanins, carotenoids, essential oils, 

fatty acids, lectins, phenols, saponins, tannins etc. The microbial assay was done 

by agar cup method & MIC against the following microorganism- 

Staphylococcus aureus, Bacillus subtilis. 

Keywords: Psidium guajava, young & mature, Biochemical, antibacterial, 

MIC. 

INTRODUCTION 

Plants are reservoirs with healing powers. A renewed interest in screening of plants for biologically active 

compounds, particularly the ones which effectively intervene the human ailments. Even tens of thousands 

of antimicrobial compounds exist, the ability of microbes to develop resistance to even the most powerful 

antimicrobial compounds is amazingly rapid 1 .The most popular and attractive hypothesis is that vegetable 

and fruits contain bioactive compounds that have a protective effect. Plant based extracts can be extracted 

211 IJGHC; 2012, Vol.1, No.3, 211-216.

Phytochemical... 


from any part of plant like seeds, roots, leaves, barks, fruits etc. One of such plant used traditionally is 

Psidium guajava Linn. 

Psidium guajava Linn. is also known as guava , belongs to the family Myrtaceae which is widely 

distributed in tropical and warm temperature regions of the world 2 . P. guajava contains a number of 

phyto-constituents like tannins, essential oil, flavonoids, saponins, lectins, vitamins, fiber, fatty acids, 

alanine, oxalic acid, palmitic acid, quercetin, glutamic acid, d- galactose and histedine 3-10 The present 

work was carried out for phytochemical screening by following standard procedures and also finds out 

possible antimicrobial activities of the leaves of different maturity i.e. Young and mature with respect to 

methanolic and aqueous extracts with reference to Gram-positive bacterial strains using the agar cup 

diffusion method, MIC & to correlate the activity with the plant constituents present. 

MATERIALS AND METHODS 

The plant material for the current studies was collected from the campus of VIVA College, Virar (W) and 

which was authenticated (No. 105908).The plant material was washed, dried at 40 o C in oven for a period 

of seven days and then powdered. 

Preparation Of Extracts 

For Methanolic Extract: Ten grams of dried powdered material was first defatted with petroleum ether 

(60-80 o C) in Soxhlet apparatus for 2hr. It was then extracted with methanol for 6 h. the extract was 

filtered and the solvent was evaporated and reconstituted with DMSO (dimethyl sulfoxide) for further use. 

For Aqueous Extract: Water extract was prepared by adding ten grams of powdered plant material with 

distilled water in a beaker on water bath with constant stirring, filtered, concentrated. 

Test Organism: Staphylococcus aureus (NCIM 2654), Bacillus subtilis (NCIM 2195) were used to check 

for antimicrobial activity. The test organisms were sourced from NCIM, Pune. 

PHYTOCHEMICAL SCREENING 

The extracts were used for determination of phytoconstituents like alkaloids, anthocyanins, carotenoids, 

essential oils, fatty acids, lectins, phenols, saponins, tannins etc. 

Testing For Antibacterial Activity: The agar cup diffusion method was used to check the antibacterial 

activity of the extract. 0.2mL of standardized bacterial stock suspensions (10 8 - 10 9) colony forming units 

per mL was mixed with 20mL of sterile Mueller Hinton agar. The bulk seeded medium was poured into 

sterile Petri dishes and was left to set. For each testing organism three such plates were prepared and in 

each of these plates 4 cups, 8 mm in diameter were cut using a sterile cork borer and the agar discs were 

removed. The cups were then filled with 40 µL extract of different concentrations. Three replicates were 

carried out for each concentration of extract against each test organism, simultaneously addition of 

methanol & DMSO instead of extract were carried out as controls. The plates were then incubated at 37 o C 

for 24 hr in upright position. After incubation, the diameters of the results and growth inhibition zones 

were measured, averaged and the mean values were tabulated. 

MINIMUM INHIBITORY CONCENTRATION (MIC) 

The tube dilution method was used for determination of minimum inhibitory concentration. The extract 

was serially diluted to give different concentration range (based on results obtained for AST for each test 

organism). A set of 9 sterile test tubes containing 5 mL of sterile nutrient broth was prepared, 6 such tubes 

were inoculated with 100 µL of bacterial culture suspension and 1 mL of plant extract and remaining two 

tubes were inoculated with 100 µL of bacterial culture, one containing 1 mL of DMSO & the other 

containing Methanol. The last tube containing only sterile nutrient broth was used as negative control. The 

inoculated tubes were then incubated at 37 o C for 24 hrs (for bacterial cultures) and 25 o C for 2 days (for 

212 IJGHC; 2012, Vol.1, No.3, 211-216



fungal culture). After incubation, the tubes were screened for detecting the growth which were compared 

against negative control. The tube which did not show any growth was taken as MIC of the extract. 

RESULTS AND DISCUSSION 

Phytochemical Screening 

Phytoconstituent 

Result 

Tannins + 

Alkaloids + 

Flavonoids + 

Saponins + 

Essential oil + 

Fatty acids + 

Antimicrobial Susceptibility Testing (AST): methanolic & aqueous extract of Psidium guajava showed 

antibacterial effect on both the organisms. 

Table-1. Antibacterial activity of Psidium guajava leaf extracts 

1.1 Methanolic extract of young leaves 

Microorganisms 

Staphylococcus 

aureus 

Methanolic extracts of Psidium guajava(%) 

Mean inhibition zones (mm) 

10 9 8 7 6 5 4 3 2 1 DMSO Methanol 

19 

1 

7 

16 15 15 15 14 14 13 12 - - 

Bacillus subtilis 13 

1 

2 

12 11 - - - - - - - - 

1.2 Methanolic Extract of Mature leaves 



aureus 

Bacillus subtilis 



10 9 8 7 6 5 4 3 2 1 DMSO Methanol 

17 16 16 15 15 14 14 13 13 13 - - 

14 13 13 12 12 11 - - - - - - 




1.3 Aqueous Extract of Young Leaves 



aureus 


Methanolic extracts of Psidium guajava (%) 


10 9 8 7 6 5 4 3 2 1 DMSO Methanol 

13 13 12 12 11 11 - - - - - - 

13 12 12 11 - - - - - - - - 

1.4 Aqueous Extract of Mature leaves 



aureus 




10 9 8 7 6 5 4 3 2 1 DMSO Methanol 

14 14 13 13 12 12 11 11 - - - - 

13 12 12 11 - - - - - - - - 

‘-‘Indicates no inhibition (resistant to extract) 

Table-2.1 Minimum Inhibitory Concentration (Young leaves) 

Methanolic extracts (%) 

Microorganism 1 0.8 0.6 0.4 0.2 - DMSO Methanol -ve 


aureus 

- - + + + + + 

- 

Microorganism 7 6.8 6.6 6.4 6.2 6.0 DMSO Methanol -ve 

Bacillus subtilis - + + + + + + + 

- 

Table-2.2 Minimum Inhibitory Concentration (Mature leaves) 

Methanolic extracts (%) 

Microorganism 1 0.8 0.6 0.4 0.2 - DMSO Methanol -ve 


aureus 

- - - + + + + 

- 



- - + + + + + + 

- 





Aqueous extracts (%) 



- 

- - - + + + + + 

aureus 



- - + + + + + + 

- 


Aqueous extracts (%) 



aureus 

- - + + + + + + 

- 



- + + + + + + + - 

‘+’ indicates Growth of Bacteria (resistant to extract), 

‘-‘Indicates No Growth of Bacteria (sensitive to extract) 

DISCUSSION 

The study showed presence of phytochemicals like tannins, alkaloids, flavonoids, saponins, essential oil, 

fatty acids which were determined by standard procedures. Antibacterial activity was tested against 

S.aureus and B.subtilis and S.aureus was found to be more susceptible against both the extracts (young 

leaves showed better results in comparison to mature leaves) whereas B.subtilis showed moderate results 

for both the types of leaves for both extracts. Minimum inhibitory concentration was also carried out to 

find out concentration of extract causing inhibition of bacterial growth. Thus it can be concluded that 

maturity of leaves play an important role in determining its mode of action. 

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*Correspondence Author: Meenakshi Vaidya; Department of Botany, Mithibai College, 

Vile Parle (West), Mumbai 400 056. Email: minakshiv@yahoo.com

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