College of medicine, Zhengzhou University, Zhengzhou 450001, PR China; Medical School, Huanghe Science & Technology University, Zhengzhou 450063, PR China.
Medical School, Huanghe Science & Technology University, Zhengzhou 450063, PR China.
Int J Biol Macromol. 2019 Sep 15;137:1002-1012. doi: 10.1016/j.ijbiomac.2019.06.191. Epub 2019 Jun 25.
Extracellular polysaccharide (EPS) produced by Pantoea agglomerans was purified for structural analysis and anti-UVB activity evaluation. The results showed that the EPS comprised of mannose and glucose in a ratio of 3:2. The molecular weight of EPS was estimated as 679 KDa. Fourier transform infrared spectrometry (FT-IR) showed that the EPS was composed of d-furanose without any substituent group. The structure of the EPS could be deduced as a repeated pentasaccharide arranged of three mannose molecules and two glucose molecules according to electrospray ionization mass spectrometry (ESI-MS) analysis and results mentioned above. The results also showed that the EPS attenuated UVB-induced cytotoxicity which was verified by morphology feature assay, down-regulated the expression of phosphor-JNK and active caspase3 significantly through MAPK pathway in UVB-irradiated HaCaT cells, and therefore protected the cells from apoptosis which could be identified by the lower apoptosis rate at low dose of UVB ray. In conclusion, the EPS as a macromolecule arranged by repeated pentasaccharide could protect HaCaT keratinocytes from UVB irradiation injury effectively, and the underlying mechanism may involve MAPK signaling pathway which contribute to apoptotic cell death. However, further studies on efficacy of the EPS in vivo are needed to determine.
聚生肠杆菌产生的胞外多糖（EPS）被纯化用于结构分析和抗 UVB 活性评价。结果表明，EPS 由甘露糖和葡萄糖以 3:2 的比例组成。EPS 的分子量估计为 679 kDa。傅里叶变换红外光谱（FT-IR）表明，EPS 由无任何取代基的 d-呋喃糖组成。根据电喷雾电离质谱（ESI-MS）分析和上述结果，EPS 的结构可推断为由三个甘露糖分子和两个葡萄糖分子组成的重复五糖。结果还表明，EPS 可减轻 UVB 诱导的细胞毒性，这通过形态特征分析得到验证，通过 MAPK 途径显著下调 UVB 照射的 HaCaT 细胞中磷酸化-JNK 和活性 caspase3 的表达，从而保护细胞免于凋亡，这可以通过低剂量 UVB 射线时较低的凋亡率来识别。总之，由重复五糖排列的 EPS 作为一种大分子可有效保护 HaCaT 角质形成细胞免受 UVB 照射损伤，其潜在机制可能涉及 MAPK 信号通路，有助于细胞凋亡死亡。然而，仍需要进一步研究 EPS 在体内的功效。
