Glucuronic acid containing diacylglycerols (3-(O-α-d-glucuronopyranosyl)-1,2-diacyl-sn-glycerols, GlcA-DAG) are glycolipids of plant membranes especially formed under phosphate-depletion conditions. An analytical approach for the structural characterization of GlcA-DAG in red ripe tomato (Solanum lycopersicum L.) extracts, based on reversed-phase liquid chromatography (RPLC) coupled with electrospray ionization (ESI) and tandem mass spectrometry (MS/MS) using a linear ion trap, is described in this paper. At least 14 GlcA-DAG (R1/R2) species, including four regioisomers, containing three predominant fatty acyl chains C16:0, C18:2, and C18:3, were identified for the first time. Moreover, 29 GlcA-DAG acylated on the glucuronosyl ring (acyl-R3 GlcA-DAG) were discovered, alongside 15 acylated lyso-forms, i.e., acylated 3-(O-α-d-glucuronosyl)monoacylglycerols, abbreviated as acyl-R3 GlcA-MAG (R1/0) or (0/R2). Although many of these acylated lyso-forms were isomeric with GlcA-DAG (i.e., acyl chains with equivalent sum composition), they were successfully separated by reversed-phase liquid chromatography (RPLC) using a solid-core C18 column packed with 2.6 μm particle size. Tandem MS (and eventually MS3) data obtained from sodium adducts ([M + Na]+) and deprotonated molecules ([M - H]-) were fundamental to detect diagnostic product ions related to the glucuronosyl ring and then determine the identity of all investigated glycolipids, especially to recognize the acyl chain linked to the ring. A classification of GlcA-MAG, GlcA-DAG, and acylated GlcA-DAG and GlcA-MAG was generated by an in house-built database. The discovery of acylated derivatives emphasized the already surprising heterogeneity of glucuronic acid-containing mono- and diacylglycerols in tomato plants, stimulating interesting questions on the role played by these glycolipids.

中文翻译：

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通过反相液相色谱-电喷雾电离和串联质谱法表征葡萄糖醛酸-二酰基/单酰基甘油并在番茄脂质提取物中发现它们的酰化衍生物。

含有二酰基甘油的葡萄糖醛酸（3-（O-α-d-吡喃葡萄糖醛酸基）-1,2-二酰基-sn-甘油，GlcA-DAG）是植物膜的糖脂，尤其是在磷酸盐耗尽条件下形成的。基于反相液相色谱 (RPLC) 结合电喷雾电离 (ESI) 和串联质谱 (MS/MS) 的红熟番茄 (Solanum lycopersicum L.) 提取物中 GlcA-DAG 的结构表征分析方法本文描述了线性离子阱。首次鉴定了至少 14 个 GlcA-DAG (R1/R2) 物种，包括四种区域异构体，包含三个主要的脂肪酰基链 C16:0、C18:2 和 C18:3。此外，还发现了 29 个在葡萄糖醛酸环上酰化的 GlcA-DAG（酰基-R3 GlcA-DAG），以及 15 个酰化的溶酶形式，即，酰化的 3-(O-α-d-葡萄糖醛酸基) 单酰基甘油，缩写为酰基-R3 GlcA-MAG (R1/0) 或 (0/R2)。尽管这些酰化溶酶体中的许多与 GlcA-DAG 是同分异构体（即具有相等总组成的酰基链），但它们可以通过反相液相色谱 (RPLC) 使用填充有 2.6 μm 颗粒的实心 C18 柱成功分离尺寸。从钠加合物 ([M + Na]+) 和去质子化分子 ([M - H]-) 获得的串联 MS（以及最终的 MS3）数据对于检测与葡萄糖醛酸环相关的诊断性产物离子并确定所有研究了糖脂，特别是识别与环相连的酰基链。GlcA-MAG、GlcA-DAG 和酰化 GlcA-DAG 和 GlcA-MAG 的分类由内部建立的数据库生成。