Abstract
Citrus grandis (L.) extract was extracted with petroleum ether, ethyl acetate, chloroform, ethanol and aqueous solvents. The extracts were tested against clinical pathogens viz., Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Penicillium sp., Mucor sp., Aspergillus niger and Candida albicans using disc diffusion method. The ethyl acetate extract showed maximum zone of inhibition against Pseudomonas aeruginosa (15.0±0.1) and Candida albicans (11.0±0.2). On the other hand chloroform extract had no effect against Escherichia coli and none of the extract showed inhibitory activity against Aspergillus niger except for aqueous extract. The observed antimicrobial activity could be due to the presence of alkaloids, flavonoids, saponins, terpenoids, steroids, tannins, cardioglycosides, aminoacids and proteins. Further analysis with Fourier Transform Infrared (FTIR) spectrum revealed the presence of OH stretching for hydroxyl (3408.41 -3352.28 cm-1 ), C=O stretching for carbonyls (1734.01 cm-1 ), C-O stretching for alcohols (1076.28 cm-1 ), C-H stretch for alkane (1249.82-2933.33 cm-1), -C-H bending for alkane (1452.4 cm-1), -C=H bending for alkene (634-850 cm-1), -C=H stretching for alkene (3012.81 cm-1), C=C stretching for alkene (1618.28-1645 cm-1), -C=C- stretching for alkyne (2368.59 cm-1), N-H stretching for amine (3292.49-3300 cm-1 ), C-N stretching for amine (1253.73-1616.35 cm-1), C-O stretching for esters (1049.2 cm-1 ), C=C stretching for aromatic (1402.28-1598.98 cm-1 ), nitro compounds for N-O stretching (1369.46 cm-1). The presence of functional groups indicate the occurrence of alcohol, alkane, amines, aromatics, aldehydes, phenols, esters and nitro compounds in leaves of Citrus grandis (L.) extracts and showed potent antimicrobial activity.
