铁皮石斛纳米粉与超微粉的物理特性和体外抗氧化活性比较研究

通过羟基自由基（·OH）、超氧阴离子（O2·- ）、亚硝酸根离子（NO2-）及DPPH自由基4种体外抗氧化模型，对铁皮石斛纳米粉和超微粉的体外抗氧化作用进行比较研究，对2种粉末的流动性、松密度、溶解性等物理特性，粒度及电镜扫描结构进行分析比较，并测定其悬浮液中多糖溶出速度及含量。结果表明：铁皮石斛纳米粉的多糖溶出速度及含量要高于超微粉；铁皮石斛纳米粉和超微粉水提取液对·OH、O2·- 、NO2-、DPPH自由基均具有较强的清除能力，且在一定范围内，清除率随浓度的增加而增大，呈现良好的量效关系；同一浓度时，纳米粉的清除率要明显高于超微粉，说明纳米粉具有更强的体外抗氧化能力；纳米粉的松密度、持水力、膨胀力、溶解性及水悬浮体系稳定性要高于超微粉，但流动性、润湿时间等参数不如超微粉；粒度及电镜分析表明纳米粉的细胞破碎程度更大，粒度更小，形状更不规则。

Physical Characteristics and Antioxidant Activity in vitro of Dendrobium candidum Nanometer Powder and Submicron Powder

The antioxidant effect of Dendrobium candidum nanometer powder and submicron powder was investigated and compared by hydroxyl radical(·OH), superoxide anion radical(O2·- ), nitrite ion(NO2-) and DPPH antioxidant experiments in vitro, the physical properties such as flowability, bulk density, solubility of the two kinds of powder were studied, and the particle size and scanning electron microscopy of the powder were analyzed, the polysaccharide dissolution rate and content in the suspension were also measured. The results showed that the polysaccharide dissolution rate and content of nanometer powder were higher than that of submicron powder; Both of D. candidum nanometer powder and submicron powder had strong scavenging activity of ·OH, O2·- , (NO2-)and DPPH, and within a certain range, the clearance rate of D. candidum powder increased with the increase of concentration, had obvious dose-effect relationship; In addition, the clearance rate of nanometer powder was significantly higher than that of submicron powder at the same concentration, the former had stronger antioxidant capacity in vitro; The bulk density, water-holding ability, expansibility, solubility and water suspension stability of nanometer powder were better than that of submicron powder, but the flowability and wettability were not as good as submicron powder; D. candidum nanometer powder had greater degree of cell disruption, smaller particle size and more irregular shape than submicron powder.