Background: Envisaging the poor solubility (56 ngml1) and permeability of tetrahydrocurcumin
(THCC), it was formulated into lipidic nanostructures to enhance its bioavailability
upon topical application to promote the healing process for skin inflammatory disorders. Lack of literature
on a suitable method for determining THCC per se and nanoformulations prompted us to develop
an RP-HPLC method to detect the drug in its nanostructures and in pig ear skin post dermatokinetics.
Objective: The present investigation aimed to develop a simple, precise and RP-HPLC method for
the quantitative estimation of THCC in prepared lipidic nanostructures, its ointment, and in skin homogenate
obtained post dermatokinetic study.
Methods: THCC encapsulated nanostructures and ointment were formulated using a modified
emulsification method and embedded into an ointment base to enhance its spreadability and improve
patient compliance. A fast and sensitive reverse-phase high-performance liquid chromatography
method was developed using a Hypersil BDS reverse phase C18 column (4.6 mm × 250 mm, 5
μm) with mobile phase comprising tetrahydrofuran (THF) and 1 mgmL-1 citric acid (4:6), at a flow
rate of 1.0 mLmin-1 with a run time of 20 min.
Results: THCC nanostructures were successfully prepared using the spontaneous microemulsification
method. THCC was detected at 282 nm and revealed two peaks which were attributed to the
keto-enol tautomerism in the molecule with retention times of 6.23 min and 11.06 min, respectively.
The assay of THCC in nanostructures and ointment was found to be 98.30 % and 99.98 %, with
an entrapment efficiency 77.00±2.74 %. The dermatokinetic studies revealed sufficient release of
THCC from its ointment up to 24 hr with a concentration of 1382 μgcm-2, for causing a therapeutic
Conclusion: The method was found to be reproducible and robust, as shown by the low coefficient
of variation and a constant analyte/IS ratio. It was successfully employed for the estimation of
THCC assay in nanostructures and its ointment and dermatokinetic analysis in the skin.