Effect of Skin Cryopreservation on in Vitro Transdermal Properties of Volatile Components from Cinnamomi Cortex

OBJECTIVE  To develop an HPLC determination method of coumarin, cinnamyl alcohol, cinnamic acid, cinnamaldehyde and 2-methoxy cinnamaldehyde in cinnamon oil, and compare the effects of in vitro skin cryopreservation on the transdermal properties of these components.

METHODS The transdermal absorption of cinnamon oil was examined using Franz diffusion cells with cryopreserved mouse skin as the permeation barrier. Simultaneously, skin vitality was monitored using MTT and CCK8 assays. An Agilent C₁₈ chromatographic column(4.6 mm×250 mm, 5 μm) with acetonitrile-0.2% phosphoric acid(30∶70) as the mobile phase at a flow rate of 1 mL·min⁻¹ was employed, detection was performed at 250 nm and 278 nm to simultaneously monitor the content changes of these 5 volatile components, the 24 h permeation regularities were analyzed over a period of 28 d.

RESULTS  Excellent separation of coumarin, cinnamyl alcohol, cinnamic acid, cinnamaldehyde and 2-methoxy cinnamaldehyde was achieved under the chromatographic conditions, good linear relationships(r>0.999) were observed within the concentration ranges of 0.0013−0.7414, 0.0043−2.3799, 0.0105−5.7974, 0.0389−44.5830, 0.0027−1.5224 μg respectively. The range of 24 h permeation rate changes of the above components was as followed: 1.64−6.43, 4.88−22.84, 3.76−60.40, 197.53−274.39, 8.20−12.60 μg·cm⁻²·h⁻¹. The vitality of cryopreservation skin decreased rapidly within the first 7 d then more gradually thereafter.

CONCLUSION  The proposed HPLC method offers a rapid and convenient means for determining the 5 volatile components in cinnamon oil, providing valuable insights for drug development. The vitality of cryopreservation skin in vitro continued to decline over 28 d. The variation patterns of 24 h permeation rates of the five components are different. Both CCK8 and MTT assays demonstrated similar trends in monitoring skin vitality.