西南大学柑桔研究所李贵节副教授团队报道含氧杂环类次生代谢产物在柑桔果汁中的分布特征

2021-10-21作者:来源:西南大学责任编辑:食品界 字体A+AA-

近日,国际食品科技权威期刊LWT-Food Science and Technology在线发表了来自西南大学柑桔研究所加工课题组次生代谢产物与营养风味研究团队题为“Comprehensive identification and distribution pattern of 37 oxygenated heterocyclic compounds in commercially important citrus juices”的研究论文。该研究利用全新开发的分析方法,获取了具有重要经济价值的6大类柑桔(甜橙、宽皮橘、葡萄柚、柚、柠檬和莱檬)果汁中OHCs的分布图谱,为柑桔汁的健康与功能性评价提供了重要信息。西南大学柑桔研究所国家柑桔工程技术研究中心李贵节副教授为该论文第一作者和通讯作者,前国家“外专千人”Rouseff博士、程玉娇博士后、周琦硕士以及吴厚玖研究员参与研究。研究还得到了资源育种团队赵晓春教授、刘小丰博士和王福生博士等人的支持和帮助。本研究由重庆市自然科学基金(cstc2019jcyj-bshX0104)、国家柑桔工程技术研究中心开放项目(NCERC2019004)、中央高校基本科研业务费专项资金项目(XDJK2020C026)以及国家高端外国专家引进计划(WQ20135000161)等项目资助。

柑桔含氧杂环类化合物(oxygenated heterocyclic compounds, OHCs)是一大类次生代谢产物,其中既包含柑桔特有的多甲氧基黄酮,也包括高等植物中普遍存在的香豆素类物质。OHCs具有广泛的生物活性,能对人体健康产生功能作用。同时,OHCs均为桂皮酸途径的中下游产物,对其研究也有助于进一步明确柑桔中该途径的精细过程,解析不同品种的次生代谢及其对应的功能基因表达的时空差异。然而,由于柑果中绝大多数OHCs含量很低,缺乏同时具备精确性和经济性的通用分析检测手段,人们对于其在可食部以及加工产品中的分布状况还不甚明确。

研究首先利用OHCs同时具有特征性紫外吸收和荧光发射光谱的性质,开发了一套基于固相萃取富集纯化、液相色谱高效分离和保留指数精准定位、二极管阵列串联荧光检测的分析解决方案[SPE-HPLC (LC-RI)-PDA-FLD],实现了对柑桔果汁中37种微量OHCs的同时分析。该方法兼具定性准确、定量灵敏和设备经济性,有望成为柑桔类样品中该类次生代谢产物的常规分析方法。


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利用上述方法分析了六大类50余品系共173个果汁样品。结果显示,本研究检出的含氧杂环类物质全面性较已有文献报道大幅提升(50%以上)。研究发现,5-去甲橘皮素、橙皮内酯和白芷属脑等OHCs分别为宽皮橘、柚和莱檬果汁的特异性标志物。利用多元统计分析还得出了六大类果汁的特征性OHCs,并利用其分布模式实现了柑桔大类间的相互区分。

香豆素中的呋喃香豆素亚类长期以来是影响柑桔鲜果和果汁消费的健康风险因素。对于罹患心血管疾病、正在服药控制的患者而言,呋喃香豆素能抑制小肠和肝脏细胞色素CYP酶系的活性,从而升高血药浓度,带来一定的风险。基于此,美国FDA将葡萄柚和柚类果实及果汁均列为心血管等疾病患者的饮食禁忌,这在一定程度上影响了我国柚子的出口。然而,本研究发现,以沙田柚为代表的柚类品种并不含呋喃香豆素,一刀切的风险管控有失偏颇,应予以进一步分析和修正。


Comprehensive identification and distribution pattern of 37 oxygenated heterocyclic compounds in commercially important citrus juices

Guijie Li, Russell Rouseff, Yujiao Cheng, Qi Zhou, Houjiu Wu

Citrus Research Institute, National Citrus Engineering Research Center, Southwest University, No. 15 Ganjucun, Xiema, Beibei District, Chongqing, 400712, China

Abstract

Oxygenated heterocyclic compounds (OHCs) are among the most biologically active components in citrus fruits which exert health benefits but also involve juice-drug interactions. However, current knowledge of OHC distribution in citrus juices is incomplete. By analyzing 173 samples from orange, mandarin, grapefruit, pomelo, lemon, and lime juices, this study constructed a comprehensive OHC (10 methoxyflavones, 12 coumarins, 15 furanocoumarins) compositional pattern of the six commercially important species. OHCs were determined using a newly developed high-resolution HPLC separation with UV and fluorescence detection. Identifications were based on matching an innovative combination of full UV and fluorescence spectra, multiwavelength fluorescence emission peak ratios, and alkyl aryl ketone retention index values with those of standards. Forty-six previously unreported OHC occurrences (12 methoxyflavones, 27 coumarins and 9 furanocoumarins) were identified in the six juice-species. Unique OHC markers were identified in mandarin (5-demethyltangeretin), pomelo (meranzin), and lime (heraclenol) juices. Orange and mandarin juices are characterized by two and five methoxyflavones respectively; pomelo and grapefruit by 5-substituted furanocoumarins and 7,8-disubstituted coumarins; lemon and lime by byakangelicin, 8-geranyloxypsoralen, and 5-geranoxy-7-methoxycoumarin. The greatly expanded and detailed OHC distribution pattern provides additional information for future epidemiological work investigating the relationships between citrus juice OHCs intake and health outcomes.