Complementary relationship between trans-cinnamaldehyde and trans-cinnamyl acetate and their seasonal variations in Cinnamomum osmophloeum ct. cinnamaldehyde

Cinnamomum osmophloeum ct. cinnamaldehyde is endemic to Taiwan. It has many bioactivities and is suitable for replacing commercial cinnamons (C. zeylanicum and C. cassia) due to the high content of trans-cinnamaldehyde (CAl) with extremely low content of coumarin. To expand its application, the main bioactive compound, CAl, should be consistent. This study investigates seasonal variations in the relative content (RC) of CAl in essential oil (EO) and the total content (TC) of CAl in leaf. Qualitative and quantitative analyses of EOs obtained monthly over a year were carried out using GC–MS and GC-FID. The RC of CAl in May dropped significantly to 32.2% of those in other months (> 76.3%), an obvious seasonal variation. Meanwhile, trans-cinnamyl acetate (CAc) became the major compound (65.4%) in EO. Moreover, the RC of CAc was complementary to that of CAl over a year. This complementary relation, however, was not observed in terms of the TC in leaf since the TC of CAl + CAc in leaf did not remain constant over a year (14.3–37.7 mg/g leaf). Seasonal levels in the TC of CAl in leaf were relatively stable (17.2–23.2 mg/g) over a year except in May (10.8 mg/g leaf). These results suggest that the trans-cinnamaldehyde-rich leaves of C. osmophloeum ct. cinnamaldehyde can be stably harvested except in May. This plant species consequently would be an ideal and renewable source of commercial cinnamons. © 2018 Elsevier B.V.