灵芝提取物β-1,3-葡聚糖含量测定及多糖成分分析

Determination of β-1,3-glucan content and analysis of polysaccharide composition from Ganoderma lingzhi extract

采用酶法试剂盒检测法和苯胺蓝荧光检测法对不同结构多糖中β-葡聚糖含量进行测定,结果表明,两种方法对高纯度β-1,3/1,6-葡聚糖的含量检测均较为准确,但含有葡萄糖的杂多糖和多分支连接的β-葡聚糖均会对酶法试剂盒检测产生干扰,苯胺蓝荧光法检测β-1,3-葡聚糖专一性较好。通过比较不同灵芝提取物中β-1,3-葡聚糖的含量和得率可知,热水提取物和KOH提取物中β-1,3-葡聚糖的含量较高,分别为20.52%和45.86%,β-1,3-葡聚糖得率分别为0.27%和1.27%,占β-1,3-葡聚糖总提取得率的88%。HPSEC分析结果显示不同提取物中多糖的分子量分布不同,热水提取物中主要包含2个组分,分子量分别为2.835×10~6Da和9.587×10~4Da,KOH提取物中主要包含分子量分布在1×10~5–1×10~6Da范围内的3个组分。各提取物中多糖的单糖组成均以葡萄糖为主,水提多糖中含有少量半乳糖,酸碱提取多糖中含有少量木糖和甘露糖。本研究结果显示,分步提取中沸水和KOH碱溶液提取β-1,3-葡聚糖效率较高。

Enzymatic assay kit and the aniline blue fluorometric method were used to determine the β-glucan content of polysaccharides with different structural characteristics. Results indicated that both two methods were accurate for pure β-1,3/1,6-glucan fraction determination. However, the heteropolysaccharide containing glucose residues and branched glucan with β-1,4 and β-1,6-linked residues as main chain interfered in the determination. The aniline blue fluorometric method demonstrated good selectivity for β-1,3-glucan determination. Comparison of the content and yield of β-1,3-glucan from different extracts of Ganoderma lingzhi showed that hot-water extract and KOH extract possessed higher β-1,3-glucan content reaching 20.52% and 45.86%, respectively. The yield of β-1,3-glucan from these two extracts were separately 0.27% and 1.27%, accounting for 88% of the total yield of β-1,3-glucan. HPSEC analysis showed that polysaccharides from different extracts possessed different molecular weight distributions. Hot-water extract mainly contained two fractions with molecular weight of 2.835×106 and 9.587×10^4 Da. KOH extract consisted of three fractions with the molecular weight ranging from 1×10^5 to 1×106 Da. Monosaccharide composition analysis showed that all polysaccharides from the extracts were mainly composed of glucose. A small amount of galactose was detected in water extract while xylose and mannose were also detected in acid and alkaline extracts. Hot-water and KOH alkaline solution were efficient in sequential extraction for extracting β-1,3-glucan from the fruit bodies of G. lingzhi.