Acta Pharm. 54 (2004) 243-250

Antimicrobial activity of grapefruit seed and pulp ethanolic extract

ZDENKA CVETNIC ^1*  and SANDA VLADIMIR-KNEZEVIC²

zcvetnic@yahoo.com

¹Department of Microbiology, Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia
²Department of Pharmacognosy, Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia

Antibacterial and antifungal activity of ethanolic extract of grapefruit (Citrus paradisi Macf., Rutaceae) seed and pulp was examined against 20 bacterial and 10 yeast strains. The level of antimicrobial effects was established using an in vitro agar assay and standard broth dilution susceptibility test. The contents of 3.92% of total polyphenols and 0.11% of flavonoids were determined spectrometrically in crude ethanolic extract. The presence of flavanones naringin and hesperidin in the extract was confirmed by TLC analysis. Ethanolic extract exibited the strongest antimicrobial effect against Salmonella enteritidis MIC 2.06%, m/V). Other tested bacteria and yeasts were sensitive to extract concentrations ranging from 4.13% to 16.50% (m/V).

Keywords: Citrus paradisi (Rutaceae), grapefruit seed and pulp extract, antimicrobial activity