RESUMO
Thymoquinone (TQ), the most prominent constituent of Nigella sativa seeds, essential oil, is reported to possess an organ protective effect via Nrf2 expression and activation of Phase-II antioxidant enzymes. Haemorrhagic cystitis is the sudden onset of haematuria combined with bladder pain and irritable bladder symptoms are the known toxic effects of cyclophosphamide (CYP) chemotherapy. The objective of the present study was to investigate and compare the protective effect of thymoquinone (TQ) and thymoquinone nanoparticles (TQ-NP) in the kidney against CYP-induced haemorrhagic cystitis. Primarily, TQ-NP was fabricated by synthesis of N-acetylated chitosan and nanoparticle preparation by the ionic gelation technique. They were characterized by particle size, polydispersive index (PDI), zeta potential, entrapment efficiency (EE), SEM, and dynamic scattering calorimetry (DSC). Moreover, fluorescein isothiocyanate (FITC) labeled NPs were prepared for biodistribution studies. The protective mechanisms of TQ-NP included its anti-inflammatory activity, inhibitory effects on cytokine levels, and protection against the DNA damage in the bladder epithelium. The cystitis was induced in rats by orally administering 200 mg/kg of CYP. The dose-dependent protective effect of the TQ-NP was determined by intravenously administering 1, 2, and 5 mg/kg of the TQ-NP to CYP-treated rats. The present study revealed that the TQ-NP prepared by ionic gelation method provides kidney targeted delivery of TQ as compared to TQ solution. The mean particle size, PDI, and %EE of TQ-NP were 272.6 nm, 0.216, 70.81 ± 0.12% respectively. The zeta potential of thymoquinone-loaded nanoparticles was found to be -20.7 mV and - 22.6 mV respectively before and after lyophilization. SEM study also confirmed the small size and spherical shape. Pharmacokinetic studies revealed the improvement in half-life and prolonged action of the TQ-NP as compared to the TQ solution. Also, TQ-NP administration showed more protection against the characteristic histological alterations in the bladder in comparison to TQ solution. The present study indicates that TQ-NP exerts potent anti-oxidant, DNA protective and cytokine inhibitory activity at considerably lower concentrations as compared to plain TQ solution. The nano formulation of TQ using N-acetylated chitosan provides effective kidney targeted delivery of TQ, which in turn improves its retention and protective efficacy against CYP-induced haemorrhagic cystitis.