Abstract
Purpose :
The aim of the study was to assess retinal PK profile of curcumin of three different oral formulations in rabbit. We also assessed the pharmacological effective concentration of curcumin using human retinal pigmented epithelial cells (ARPE-19) and human endothelial retinal cells (hREC).
Methods :
Products: a) curcumin formulation with a hydrophilic carrier (CHC; DiabecÒ-AlfaIntes); b) curcumin-phosphatidylcholine complex (CPC; NorfloÒ-EyePharma); c) curcumin + piperine (CPI; AVS RetinaÒ-SIFI). Retinal bioavailability of curcumin, after single oral administration was assessed in albino rabbits by LC/MS-MS [LLOQ=0.0002 ng/mg]. Efficacy of curcumin (from 1 to 100 µM) was evaluated in ARPE-19 cells exposed with oxidative stress (0.5 mM H2O2) measuring reactive oxygen species (ROS) production by DCFDA assay Kit and cell viability by ATP-lite assay. Further, we assessed TNF-α in hREC exposed with high glucose (40 mM) with or without curcumin treatment.
Results :
Curcumin was detected only in retina samples obtained by CHC-treated group (Cmax=0.036 ± 0.002 ng/mg Tmax= 6 h and AUC= 0.015 µg*min/mg retina). Retina curcumin levels after oral administration of CPC and CPI were below the LLOQ. Curcumin significantly (p<0.05) inhibited ROS production in RPE cells exposed to oxidative (even at the lowest concentration 1 µM). Furthermore, 10 µM (0.74 µg) curcumin significantly (p<0.05) decreased TNF-α levels in hREC exposed to high glucose.
Conclusions :
Curcumin levels detected in retinal tissue were pharmacological effective based on the results generated in vitro. Curcumin that reached the retina every minute was around 1 µg, which is higher to the lowest active concentration of curcumin in the in vitro study. Taken together, these data seem to indicate that curcumin formulation with a hydrophilic carrier (CHC) provides therapeutic levels of curcumin in rabbit retina suggesting that this formulation may be of value in clinical practice to manage retinal conditions.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.