Drugs derived from plants play a significant role in the prevention and treatment of human diseases. Psidium guajava L., Myrtaceae, is used widely in traditional medicine used for the treatment of diarrhoea, dysentery, gastroenteritis, stomach aches, and indigestion. The present study aimed at studying the antibacterial activity of the ethanolic extract of leaves of P. guajavaagainst the standard strains of bacterium and the antibiotics resistant clinical strains of bacterium. The extraction of the P. guajava leaves was carried out. The screening of the extracts for antibacterial activities was conducted by the disc diffusion method. The dried extracts were dissolved in dimethyl sulfoxide (DMSO) with a concentration of 0.1 g/mL. All the bacterial strains under study were inhibited. Staphylococcus aureus was most inhibited. The present study has shown that P. guajava leaf extract has excellent antibacterial activity against the drug resistant strains of both gram-positive and gram-negative bacteria.

Keywords: Psidium guajava, antibacterial activity, disc diffusion method.

1. Towers GH, Lopez A, Hudson JB. Antiviral and antimicrobial activities of medicinal plants. J Ethnopharmacol. 2001; 77:189–96.
2. Farnsworth NR. Ethno pharmacology and future drug development: The North American experience. J Ethnopharmacol. 1993;38:145–52.
3. Houghton PJ. The role of plants in traditional medicine and current therapy. J Alter Complement Med. 1995;1:131–43.
4. Runyoro D, Matee M, Olipa N, Joseph C, Mbwambo H. Screening of Tanzanian medicinal plants for anti-Candida activity. BMC Complement Altern Med. 2006;6: 11.
5. Shahidi BH. Evaluation of antimicrobial properties of Iranian medicinal plants against Micrococcus luteus, Serratia marcescens, Klebsiella pneumonia and Bordetella bronchoseptica. Asian J Plant Sci. 2004;3:82–6.
6. Reddy PS, Jamil K, Madhusudhan P. Antibacterial activity of isolates from Piper longum and Taxus baccata. Pharmaceutical Biol. 2001;39:236–8.
7. Maheshwari JK, Singh KK, Saha S. Economic Botany Information Service, NBRI. Lucknow: 1986. Ethno botany of tribals of Mirzapur District, Uttar Pradesh.
8. Dahanukar SA, Kulkarni RA, Rege NN. Pharmacology of medicinal plants and natural products. Indian J Pharmacol. 2000;32:S81–118.
9. Cowan MM. Plant products as anti-microbialagents. Clin Microbiol Rev. 1999;12:564–82.
10. Gutiérrez RM, Mitchell S, Solis RV: Psidium guajava: a review of its traditional uses, phytochemistry and pharmacology.   J Ethnopharmacol 2008, 117:1-27.
11. Dham SK. Treatment ofdiarrheal diseases.   In Diarrhoeal diseases: Current status, research trends and field studies Edited by: Raghunath D, Nayak R. New Delhi:  Tata McGraw-Hill Publishing Company Limited; 2003:245-254.
12. Abdel Wahab SM, Hifawy MS, El Gohary HM, Isak M. Study of carbohydrates, lipids, protein, flavonoids, vitamin C and biological activity of Psidium guajava L growing in Egypt. Egypt J Biomed Sci. 2004;16:35–52.
13. El Khadem H, Mohamed YS. Constituents of the leaves of Psidium guajava L: Part II: Quercetin, avicularin, and guajaverin. J Chem Soc. 1958;32:3320–3.
14. Arima H, Danno G. Isolation of antimicrobial compounds from guava (Psidium guajava) and their structural elucidation. Biosci Biotechnol Biochem. 2002;66:1727–30.
15. Seshadri T, Vasishta K. Polyphenols of the leaves of Psidium guava; quercetin, guaijaverin, leucocyanidin, amritoside. Phytochemistry. 1965;4:989–92.
16. Kandil FE, El-Sayed NH, Micheal HN, Ishak MS, Mabry TJ. Flavonoids from Psidium guajava. Asian J Chem. 1997; 9:871–2.
17. Murray MT, Pizzorno JE. Flavonoids-Quercetin, citrus flavonoids, and HERs (hydroxylethylrutosides) London: Harcourt Brace and company Ltd; 1999. Text book of Natural Medicine 2nd ed; pp. 745–50.
18. Mucsi I, Pragai BM. Inhibition of virus multiplication and alteration of cyclic AMP level in cell cultures by flavonoids. Experientia. 1985;41:930–1.
19. Kaul T, Middleton E, Ogra P. Antiviral effects of flavonoids on human viruses. J Med Virol. 1985;15:71–9.
20. Farkas L, Gabor M, kallay F, Wagner HI. New York: Elsevier; 1982. Flavonoids and Bioflavonoids; pp. 443–50.
21. Cowan MM. Plant products as antimicrobial agents. Clin Microbio Rev. 1999;12:564–82.
22. Rattanachaikunsopon P, Phumkhachorn P. Contents and antibacterial activity of flavonoids extracted from leaves of Psidium guajava. J Med Plants Res. 2010;4:393–6.
23. Gutierrez RM, Mitchell S, Solis RV. Psidium guajava: A review of its traditional, phytochemistry and pharmacology. J Ethnopharmacol. 2008;117:1–27.

Dr Beulah Edwin MD

Associate Professor, Dept of Microbiology, Tagore Medical College and Hospital, Chennai -600127, India

Email: This email address is being protected from spambots. You need JavaScript enabled to view it.