摘要
龙眼果肉营养丰富,含有多糖、蛋白质和维生素等多种营养成分。该研究旨在明确龙眼多糖的结构及其在小鼠体内的消化过程和吸收分布规律。通过高效液相色谱、离子色谱和核磁共振等方法发现龙眼多糖由葡萄糖、果糖、阿拉伯糖、半乳糖、半乳糖醛酸、木糖、甘露糖和鼠李糖组成,其摩尔比分别为28.94%、27.63%、19.13%、8.01%、6.71%、5.32%、2.40%和1.85%,并以1,6)-D-Fruf-(2→5)-L-Araf-(1→4)-D-Glcp-(1→3,6)-Glcp-(1→6)-D-Galp-(1→为主链的杂多糖。此外,采用荧光素Cy5.5标记龙眼多糖,观察龙眼多糖在小鼠体内的吸收与分布,结果表明龙眼多糖荧光信号主要积累在腹部,在1~4 h观察到强荧光信号,9~12 h荧光信号逐渐减弱,且龙眼多糖能进入大肠。研究结果将为龙眼多糖功能性食品的开发提供理论依据,对实现龙眼加工增值、资源高效利用和产业可持续发展具有重要意义。
Longan is one of the most valuable subtropical fruits in Southeast Asian regions.This fruit can also play an important role in the blood metabolism for neuropathic pain and swelling.Many studies have focused on the functional activity of longan polysaccharides(LP)in recent years.However,it is still unclear on the structural characteristics,as well as the absorption and distribution in vivo of LP.In this work,liquid chromatography,ion chromatography,and nuclear magnetic resonance spectroscopy(NMR)were employed to investigate the structure of LP.The results showed that the LP consisted of the glucose(Glc),fructose(Fru),arabinose(Ara),galactose(Gal),galacturonic acid(GalA),xylose(Xyl),mannose(Man)and rhamnose(Rha)with the molar ratios of 28.94%,27.63%,19.13%,8.01%,6.71%,5.32%,2.40%,and 1.85%,respectively.The Two-dimensional(2D)NMR spectra of HSQC,COSY,and HMBC revealed that the LP shared the following chemical shifts:δ,5.00/101.59,4.55/97.40,5.13/100.04,4.47/96.11,3.62/63.56,and 5.15/109.17,respectively.Moreover,these peaks were attributed to the H-1/C-1 signals of the A-F sugar residues.Ultimately,the LP was determined as a heteropolysaccharide with 1,6)-D-Fruf-(2→5)-L-Araf-(1→4)-D-Glcp-(1→3,6)-Glcp-(1→6)-D-Galp-(1→as the main chain.The microstructure of the LP was lamellar and stacked with a relatively smooth surface.There was the broad absorption peak near 3445-3440 cm^(-1),which was attributed to O-H stretching vibrations.The broad absorption peak near 2950-2945 cm^(-1) was attributed to C-H stretching vibrations.The peaks at 1623.11 and 1400.31 cm^(-1) were attributed to the carboxylate ion(COO−).The bonds at 1380.43 and 1360.52 cm^(-1) corresponded to C-O bending.The hump around 1200-1000 cm^(-1) confirmed the presence of a furanose sugar.The absorption at 1078.13 cm^(-1) was related to the C-O-C stretching vibrations,while the absorption peaks around 938-842 cm^(-1) indicated the simultaneous presence ofβandαconfigurations.In addition,the characteristic peaks at 1660 cm^(-1) and 1580 cm-1 were found in the FTIR spectrum of LP-Cy5.5,which belonged to the N-H bending vibrational bands of amide I and amide II,respectively.Meanwhile,the signals at 6.5-8.0 ppm belonged to the benzene ring of Cy5.5,compared with the 1H NMR of LP.As such,the successful synthesis of LP-Cy5.5 was realized after characterization.In addition,the LP with the near-infrared fluorescent dye Cy5.5 was selected as a fluorescent marker to assess the digestion and distribution of LP in mice.In vitro intestinal imaging revealed that there were fluorescent signals in all intestinal segments at the early stage.The fluorescence signal of LP-Cy5.5 was mainly distributed in the abdomen of mice.Particularly,the strong fluorescent signals of the LP-Cy5.5 were observed in the stomach,small intestine,cecum,and colon during 1-4 h of digestion,and then gradually disappeared afterward.It indicated that the LP was partially absorbed by the small intestine and then entered the large intestine,where it was utilized by the intestinal microbes.This finding can also provide a fundamental basis for the development of functional foods containing longan polysaccharides.Meanwhile,it is of great significance to obtain the valueadded and efficient utilization of resources in order to promote the sustainable longan industry.
作者
潘磊
章子豪
张凡
林雅晴
王琳
张怡
PAN Lei;ZHANG Zihao;ZHANG Fan;LIN Yaqing;WANG Lin;ZHANG Yi(College of Food Science,Fujian Agriculture and Forestry University,Fuzhou 350002,China)
出处
《农业工程学报》
北大核心
2025年第21期308-314,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
第四批国家“万人计划”项目(KRC19007A)
福建农林大学食品科学学院人工智能+专项培育基金
第二批福建省特殊支持人才“双百计划”项目(KRC16002A)。
关键词
龙眼多糖
结构
荧光标记
体内分布
消化过程
longan polysaccharide
structure
fluorescent labelling
in vivo distribution
digestive process
