Interaction Characteristics with Bovine Serum Albumin and Retarded Nitric Oxide Release of ZCVI4-2, a New Nitric Oxide-Releasing Derivative of Oleanolic Acid

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ZCVI4-2 is a newly developed furoxan-based nitric oxide-releasing derivative of oleanolic acid. It exhibited strong cytotoxicity against human hepatocellular carcinoma (HCC) in vitro and significantly inhibited the growth of HCC tumors in vivo. However, its low aqueous solubility and toxicity due to the fast release of nitric oxide (NO) in blood challenged its formulation. In the present investigation, the interaction characteristics of ZCVI4-2 with bovine serum albumin (BSA) were studied by fluorescence spectrometry, synchronous fluorescence spectra and Fourier transform-infrared (FT-IR). It was found that ZCVI4-2 concentration, temperature and pH had significant effect on the interactions. ZCVI4-2 was able to bind BSA with high affinity, low temperature and neutral pH favor the binding. The interaction exhibited to be a spontaneous and exothermic process. ZCVI4-2 was buried in the hydrophobic pocket in subdomain IIB of BSA and the exact binding site was around 3.83 nm in average from Trp212. The NO releasing characteristics of nanocomplexes were compared with ZCVI4-2 solution by Griess Reagent Method. It was found that the release of NO from ZCVI4-2/BSA nanocomplexes was retarded significantly, thus making ZCVI4-2 into a BSA-bound nanocomplexes had the great potential to lower the toxicity due to the absence of organic solvents and surfactants and meanwhile the sustained release of NO.