Chemical composition and tyrosinase inhibitory activity of Cinnamomum cassia essential oil

Botanical Studies

Table 2 Inhibition constants of C. cassia essential oil (CC-EO), trans -cinnamaldehyde and cis -2-methoxycinnamic acid for mushroom tyrosinase

Inhibitor	CC-EO	*trans*-cinnamaldehyde	*cis*-2-methoxycinnamic acid
IC₅₀ (mg/mL)	6.16 ± 0.04^a*	4.04 ± 0.08^*	NS
K_i (mg/mL)	4.71 ± 0.09^*	2.38 ± 0.09^*	NT
αK_i (mg/mL)	15.50 ± 0.49^*	9.61 ± 0.47^*	NT
Inhibition type	Mixed	Mixed	NT

^aValues are presented as mean ± S.D. (n = 3). NS: tyrosinase inhibitory effect not shown; NT: not tested.
^*Means in the same parameter are significantly different (p < 0.05). K_i: dissociation constant for inhibitor binding with the free enzyme; αK_i: dissociation constant for inhibitor binding with the enzyme-substrate complex.