不同相对分子质量的黑根霉胞外多糖的生物活性

目的 探讨不同相对分子质量黑根霉胞外多糖的抗氧化、抗肿瘤和免疫调节活性。方法 通过分级醇沉从黑根霉的发酵液中分离得到3种不同相对分子质量的多糖，分别命名为RPS-1，RPS-2和RPS-3，检测3种多糖对DPPH、ABTS和羟自由基的清除活性。体外培养小鼠前胃癌细胞MFC、人非小细胞肺癌细胞A549和小鼠巨噬细胞RAW 264.7，给药48 h或24h后CCK-8法检测各组细胞存活率，一氧化氮试剂盒检测RAW 264.7细胞上清液中的NO水平，流式细胞仪检测3种多糖对A549细胞凋亡率的影响。结果 RPS-1，RPS-2和RPS-3均具有较好的抗氧化活性，中等相对分子质量多糖RPS-1对DPPH和ABTS自由基的清除活性显著高于RPS-2和RPS-3（P<0.05），低相对分子质量多糖RPS-3对羟自由基的清除活性显著高于RPS-1和RPS-2（P< 0.01）。3种多糖均能够抑制MFC细胞和A549细胞的增殖，激活巨噬细胞RAW 264.7，诱导A549细胞凋亡。高相对分子质量多糖RPS-2对MFC和A549细胞增殖的抑制活性高于RPS-1和RPS-3（P>0.05），RPS-2处理后A549细胞的凋亡率显著高于RPS-1和RPS-3（P<0.05）。高相对分子质量多糖RPS-2促进RAW 264.7细胞增殖的活性显著高于RPS-1和RPS-3（P<0.05），RPS-2处理后的RAW 264.7细胞释放的NO含量显著高于RPS-1和RPS-3（P<0.01）。结论 3种不同相对分子质量的多糖均具有抗氧化、抗肿瘤和免疫调节活性，低、中相对分子质量多糖RPS-1和RPS-3具有较好的抗氧化活性，高相对分子质量多糖RPS-2具有较好的抗肿瘤和免疫调节活性。

Assessment of biological activities of exopolysaccharides with different relative molecular masses extracted from Rhizopus nigricans

Objective To evaluate the antioxidant, anti-tumor and immunomodulatory activities of exopolysaccharides with different molecular masses isolated from Rhizopus nigricans. Methods Three polysaccharides with different molecular masses, namely RPS-1, RPS-2 and RPS-3, were separated from the fermentation broth of Rhizopus nigricans by fractional ethanol precipitation, and their capacity for scavenging DPPH, ABTS, and hydroxyl radicals was assessed. Cell counting kit-8 was used to analyze the changes in the viability of MFC, A549 and RAW 264.7 cells following treatments with the 3 polysaccharides; The level of nitric oxide in the supernatant of RAW 264.7 cells was detected using a nitric oxide detection kit, and the apoptosis rate of A549 cells was analyzed with flow cytometry. Results All the 3 polysaccharides had good antioxidant activities, and among them RPS-1 with a medium molecular mass exhibited the strongest scavenging capacity for DPPH and ABTS radicals (P<0.05) while RPS-3 with the lowest molecular mass had the best scavenging activity for hydroxyl radicals (P<0.01). All the 3 polysaccharides were capable of inhibiting the proliferation of MFC cells and A549 cells, activating the macrophages RAW 264.7 cells, and inducing apoptosis of A549 cells. RPS-2 with the highest molecular mass showed the strongest inhibitory effects against MFC and A549 cells (P>0.05), and RPS-2 had the strongest activity for inducing apoptosis in A549 cells (P<0.05). Compared with the other two polysaccharides, RPS-2 more strongly promoted the proliferation of RAW 264.7 cells and enhanced NO release from the cells (P<0.05). Conclusion The 3 polysaccharides all have antioxidant, anti-tumor and immunomodulatory activities, and among them RPS-1 and RPS-3 have better antioxidant activities, and RPS-2 has stronger anti-tumor and immunomodulatory activities.