Phytochemical screening and antibacterial activity of peel and seed extracts of Citrus limon

Abstract

Rapidly increasing antibiotic resistance is one of the greatest threats to global health. There is a growing demand today for naturally derived drugs and medicine in place of synthetic drugs that are more commercially available. This study was undertaken to screen for the phytochemicals and evaluate antibacterial activity of Citrus limon peel and seed extracts. Methanolic and aqueous extracts of the C. limon peel and seed were prepared. Qualitative phytochemical screening of the C. limon seed and peel extracts revealed a composition of Saponins, tannins, flavonoids and steroids. Glycosides were absent in the peel extracts. Antibacterial activity of Citrus limon peel and seed extracts was determined using agar disc diffusion assay. The bacterial isolate used was obtained from an environmental source. Inhibitory activity was observed for all the extracts except aqueous seed extract. Citrus limon methanolic seed extracts exhibited the largest zone of inhibition (19.83 ± 1.17) mm against the test bacterial isolate. Aqueous extract of C. limon seed showed no antibacterial activity against the test bacteria isolate. None of the inhibitory effects of the Citrus limon seed and peel extracts exceeded the zone of inhibition (28.50 ± 1.05) mm elicited by the standard positive control, Ciprofloxacin against test bacterial isolate. The presence of a zone of inhibition in the cultures inoculated with the C. limon seed and peel extracts indicated the potent antibacterial activity of these plant extracts. This research has thus provided scientific evidence confirming the efficacy of C. limon peel and seed extracts as natural antimicrobial agents. Further detailed studies should focus on identification, isolation, purification and quantification of the active compound (s) in C. limon seed and peel extracts that possess antibacterial activity.