Nanocurcumin: a novel antifilarial agent with DNA topoisomerase II inhibitory activity

Objective: The aim of this study is to evaluate the antifilarial, antiwolbachial and DNA topoisomerase II inhibitory activity of nanocurcumin (nano-CUR). Methods: Nano-CUR formulations (F1-F6) were prepared using free radical polymerization and were characterized by particle size, morphology, encapsulation efficiency and in vitro release kinetics. Antifilarial potential was evaluated in vivo against Brugian filariasis in an experimental rodent model, Mastomys coucha, by selecting the formulation that maximized parasite elimination characteristics. Wolbachial status was determined by PCR and a relaxation assay was used to estimate DNA topoisomerase II inhibitory activity. Results: Nano-CUR (F3) having a 60 nm diameter and 89.78% entrapment efficiency showed the most favorable characteristics for the elimination of filarial parasites. In vivo pharmacokinetic and organ distribution studies demonstrate significantly greater C-(max) (86.6 +/- 2.56 ng ml(-1)), AUC(0-infinity) (796 perpendicular to 89.8 ng d ml(-1)), MRT (19.5 perpendicular to 7.82 days) and bioavailability of CUR (70.02%) in the organs from which the adult parasites were recovered. The optimized nano-CUR (F3) (5 X 5 mg/kg, orally) significantly augmented the microfilariciadal and adulticidal action of CUR over free CUR (5 X 50 mg/kg, orally) or Diethylcarbamizine (50 mg/kg, orally) against the Brugia malayi Mastomys coucha rodent model. The PCR results showed complete elimination of wolbachia from the recovered female parasites. Interestingly, nano-CUR was also found to be a novel inhibitor of filarial worm DNA topoisomerase II, Setaria Cervi in vitro. Conclusion: This study recognizes the beforehand antimicrofilarial, antimacrofilarial, antiwolbachial activity of nano-CUR (F3) over free forms and additionally its strong inhibitory action against the major target filarial parasite enzyme DNA topoisomerase II in vitro.