Study On The Enhancement Of Antioxidation Activity Of Hydrophobic Flavonoids Using Cellulose Nanocrystals

Cellulose is the most abundant natural material,and has been widely used for many areas,such as paper,food,pharmaceutical,textile,and constructions.Cellulose nanocrystals(CNC)are a promising biomaterial that is extracted from cellulose fibers,such as wood,straw,cotton,which exhibits remarkable characteristics,including high mechanical strength,high stiffness,high aspect ratio and large surface area.Also,CNC shows great potentials in many fields because of its excellent characteristics,including biodegradability,biocompatibility,non-toxicity,abundant surface hydroxyl groups and negative charges.Flavonoids are natural polyphenolic compounds,exhibit desirable pharmacological and biological activities,such as anti-oxidation,anti-angiogenesis,anti-inflammatory and antibacterial,regulating estrogen and delaying apoptosis.However,the pharmaceutical application of many flavonoids is limited because of their poor water solubility.In this paper,CNC was used as carrier for hydrophobic flavonoids.The naringin,genistein and kaempferol,were nanonized through anti-solvent recrystallization and then loaded respectively onto the CNC to fabricate nanocomposites.The process conditions of the nanocomposites were also investigated.The surface morphology,chemical state and crystallization of the nanocomposites were studied by transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FTIR)and X-ray powder diffractometry(XRD).Finally,the dissolution and antioxidation activity of the nanocomposites were respectively evaluated by in vitro dissolution and in vitro hydroxyl or DPPH radical scavenging efficiency.The main conclusions of this work are as follows:(1)the process conditions for CNC/naringin were volume ratio of solvent and antisolvent,1:20;pH value,7.5;the naringin concentration,40 ?g·mL-1;and the crystallization temperature,0?.TEM demonstrated that CNC can significantly reduce the particle size of naringin and impart good dispersibility to naringenin.XRD and FTIR indicated that the naringin particles in CNC/naringin nanocomposite were in an amorphous state and bound together with CNC through electrostatic and hydrogen binding.The dissolution of naringin in CNC/naringin nanocomposite increased to 92.1%at 120 min.Compared with the original naringin(22.5%)and water/naringin(30.2%),the dissolution of naringin improved significantly.For CNC/naringin nanocomposite,the hydroxyl radical scavenging rate obviously increased to 43.3%at a concentration of 50 ?g·mL-1,compared with water/naringin(11.2%).(2)The process conditions for modifying CNC with CTAB were the mass ratio of CNC to CTAB,1:100;pH values,7.5;reaction time,30 min;and reaction temperature,50?.For CNC/CTAB/genistein nanocomposite,the modification of CNC with CTAB enhanced hydrophobic of CNC and compatibility between the CTAB-modified CNC and genistein,moreover,the genistein particles were loaded onto CNC evenly.The dissolution of the genistein in CNC/CTAB/genistein nanocomposite increased to 92.5%at 120 min,compared with that of the original genistein and water/genistein(0.85%and 14.2%).For CNC/genistein and CNC/CTAB/genistein nanocomposites,the hydroxyl radical scavenging rates obviously increased and were 46.4%and 68.5%at a 50?g·mL-1 concentration,respectively,which higher than original genistein(1.25%).(3)The dissolution of the kaempferol in CNC/CTAB/kaempferol nanocomposite increased were 88.5%at 120 min,while the original kaempferol had a limited dissolution,only 1.2%.The DPPH radical scavenging rate in vitro of CNC/CTAB/kaempferol nanocomposite reached to 91.6%.Compared with water/kaempferol(15.3%)and original kaempferol(6.6%),the DPPH radical scavenging rate of CNC/CTAB/kaempferol nanocomposite improved significantly.