Isolation, identification, and purification of cinnamaldehyde from<i>Cinnamomum zeylanicum</i>bark oil. An antibacterial study

Abstract

The present study was conducted to isolate the most important bioactive compound from Cinnamomum zeylanicum L. (Lauraceae) bark oil. The plant essential oil was extracted via steam distillation. Cinnamaldehyde was separated using a separating funnel and identified according to Tollen’s test followed by detection on TLC plates in comparison with standard cinnamaldehyde that served as positive control. Moreover, FTIR spectrometry and HPLC analysis were used to confirm the purity and identity of cinnamaldehyde. The isolated material was investigated for its antibacterial activity against six selected pathogenic bacteria. The Gram-positive bacteria were Staphylococcus aureus and Bacillus cereus; Gram-negative bacteria included Escherichia coli, Proteus mirabilis, Klebsiella pneumonia, and Pseudomonas aeruginosa. Cinnamaldehyde at different concentrations (1:1, 1:5, 1:10 and 1:20) was active against all tested bacteria and the highest inhibitory effect was observed against B. cereus (zone of inhibition: 25.3 mm) using the disk diffusion method. The minimal inhibitory concentration (MIC) of cinnamaldehyde was determined using a broth microdilution method in 96-well microtiter plates. MIC values ranged from 31.2 to 125.0 μg/mL. The most promising result was observed against B. cereus, while S. aureus, E. coli, and K. pneumonia ranked next (MIC: 62.5 μg/mL) followed by P. mirabilis and P. aeruginosa with a MIC of 125.0 μg/mL.