Phenolic Composition, Enzyme Inhibitory and Anti-quorum Sensing Activities of Cinnamon (Cinnamomum zeylanicum Blume) and Basil (Ocimum basilicum Linn)

Abstract

Cinnamomum zeylanicum and Ocimum basilicum are two plants used by many cultures for food and medicinal purposes. The phenolic composition of ethanol extracts of both plants were determined by HPLC-DAD. A total of seventeen compounds were identified in C. zeylanicum with trans cinnamic acid (179.90 +/- 0.45 mu g/g) and coumarin (84.50 +/- 0.41 mu g/g) as major constituents while ten compounds were detected in O. basilicum with rosmarinic acid (360.40 +/- 1.28 mu g/g) and vanillic acid (36.30 +/- 0.25 mu g/g) as major constituents. C. zeylanicum exhibited higher inhibition on AChE (54.30 +/- 0.97%) and BChE (66.43 +/- 0.84%) than O. basilicum with lower AChE (23.43 +/- 0.51%) and BChE (33.83 +/- 0.75%) inhibitions. Both extracts showed moderate inhibition of tyrosinase and urease enzymes. The quorum sensing (QS) inhibition of O. basilicum and C. zeylanicum was evaluated by two assays: violacein inhibition on Chromobacterium violaceum CV12472 and QS inhibition on Chromobacterium violaceum CV026. Excellent inhibition of violacein synthesis in CV12472 was exhibited by C. zeylanicum with 100% inhibtion at MIC to MIC/4 and further inhibitions of 48.0 +/- 2.0% (MIC.8) and 27.9 +/- 1.2% (MIC/16). QS inhibition diameter zones on C. violaceum CV026 at MIC were 13.0 +/- 1.0 mm and 10.5 +/- 1.0 mm for C. zeylanicum and O. basilicum respectively. Since both extracts could inhibit violacein synthesis in CV12472 and QS in CV026, they could block signal production and signal reception in QS mediated processes in bacteria. These results indicate that both plants can be used to remedy microbial resistance and Alzheimer's diseases.