Validation of a spectrophotometric method to estimate the adsorption on nanoemulsions of an antimalarial oligonucleotide

Abstract

Recebido em 3/12/10; aceito em 22/3/11; publicado na web em 10/6/11This study describes the validation of a spectrophotometric method to estimate oligonucleotides association with cationic nanoemulsions. Phosphodiester and phosphorothioate oligonucleotides targeting Plasmodium falciparum topoisomerase II were analyzed at 262 nm. Linear response (r > 0.998) was observed from 0.4 to 1.0 nmol/mL, the relative standard deviation values for the intra-and inter-days precision were lower than 2.6% and the recovery ranged from 98.8 to 103.6% for both oligonucleotides. The association efficiency was estimated based on an ultrafiltration/centrifugation method. Oligonucleotides recovery through 30 kDa-membranes was higher than 92%. The extent of oligonucleotides association (42 to 98%) varied with the composition of nanoemulsions.

Phaeophytins from Thyrsacanthus ramosissimus Moric. with inhibitory activity on human dna topoisomerase II-α

“…Interest in compounds with inhibitory activity against the enzyme DNA-topoisomerase II-a has increased, [13][14][15][16][17][18][19][20] because intracellular levels of topoisomerase II-a (topo II-a) are elevated in a number of human tumors as compared to the respective normal tissues. Moreover, the development of drugs that can affect the DNA replication process by selectively interfering with the function of topo II-a continues to draw researchers' attention.…”

Investigation of the structural organization of cationic nanoemulsion/antisense oligonucleotide complexes

“…This +/-charge ratio is the theoretical ratio between the number of positive charges 4 from the cationic lipid in NE, and the number of negative charges from the phosphate groups 5 of the ON. The ON association was estimated by the ultrafiltration/centrifugation procedure 6 [20]. After separating a portion of the water phase using regenerated cellulose membranes at a 7 30 kDa cut-off (Millipore, USA), free ON was determined in the clear ultrafiltrate by 8 spectrophotometry at 262 nm (spectrophotometer Hewlett-Packard 8452A).…”