Anti-Alzheimer, anti-diabetic, skin-whitening, and antioxidant activities of the essential oil of Cinnamomum zeylanicum

Abstract

This study was designed to determine the anti-Alzheimer, anti-diabetic, skin whitening, and antioxidant activities of the essential oil of Cinnamomum zeylanicum (Blume) as well as the determination of antagonistic/synergic interactions of its major compounds. As a result of GC–MS analysis, 22 components were identified representing 99.79 % of the oil. (E)-Cinnamaldehyde (CAL) (81.39 %) and (E)-cinnamyl acetate (CAS) (4.20 %) were determined as the major compounds. The oil and the major compounds, CAL and CAS, showed over 78.0 % inhibitory activity on cholinesterases. In monoamine oxidase (MAO) A and MAO-B inhibition assay, both oil (96.44 % and 95.96 %, respectively) and CAL (96.32 % and 96.29 %, respectively) showed remarkable activity as high as rasagiline (97.42 % and 97.38 %, respectively). The oil also showed 57.78 % and 84.53 % inhibitory activity in self- and Cu2+ induced aggregation of Aβ1-42, respectively. The inhibitory activities of the oil, CAL, and CAS were found to be in the range of 7.29 %–21.30 % on α-amylase. In tyrosinase inhibition assay, CAL (83.75 %) and CAS (45.58 %) showed higher activity than that of the oil (18.08 %). In phosphomolybdenum and CUPRAC tests, the oil showed higher activity than the main components, whereas in FRAP assay the oil exhibited higher activity than CAS. In radical scavenging assay, the oil showed weak activity, whereas the main components remained inactive. In addition to the oil and the major compounds, activities of the samples prepared by mixing CAL and CAS in different proportions (CAL:CAS from 9:1 to 1:9) were also tested in order to analyse their antagonistic and/or synergistic interactions on each other.