SUPERCRITICAL CARBON DIOXIDE IMPREGNATION/DEPOSITION OF NAPHTHOQUINONES IN MESOPOROUS SILICA PARTICLES

GAÑAN, NICOLAS ALBERTO; DIAS, ANA M. A.; ZYGADLO, JULIO ALBERTO; BRIGNOLE, ESTEBAN ALBERTO; BRAGA, MARA E. M.; SOUSA, HERMINIO C.

Cartagena

Congreso; 3rd Iberoamerican Conference on Supercritical Fluids (PROSCIBA 2013); 2013

Juglone, 1,4-naphthoquinone and plumbagin are three related naphthoquinones known for their toxicity, allelopathic activity and skin peeling effects. They naturally occur in several vegetable species, especially in walnut trees (Juglans spp.). In this work, these naphthoquinones are separately impregnated/deposited in mesoporous silica particles (SBA-15) using carbon dioxide as solvent in a static high pressure cell operating at 45ºC for 14 hs. Two pressure conditions (120 and 250 bar) and two depressurization rates (5 and 10 bar/min) were studied in order to determine their influence on impregnation/deposition yield. The total amount of impregnated naphthoquinones was determined spectrophotometrically by dissolution with ethanol, showing that best results were achieved at 120 bar and fast depressurization rate (10 bar/min). Controlled release kinetics in a mixture of physiological serum and ethanol (10% v/v) was also studied for a 48 h period at 32ºC and the corresponding release profiles were determined and compared. Preliminary permeation/diffusion profiles through a dialysis membrane (100 Da) were also determined in a Franz cell, using impregnated particles in suspension.