Seed Biology, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853-1901, USA.
Carbohydr Res. 2013 Oct 18;380:130-6. doi: 10.1016/j.carres.2013.08.004. Epub 2013 Aug 20.
Three galactosyl cyclitols, digalactosyl myo-inositol (assigned the trivial name DGMI), trigalactosyl myo-inositol (assigned the trivial name TGMI), and trigalactosyl d-chiro-inositol (fagopyritol B3), were isolated from common buckwheat (Fagopyrum esculentum Moench) seeds. Structures of the three compounds were determined by 2D NMR spectroscopy. DGMI is α-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl-(1→1)-1l-myo-inositol, TGMI is α-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl-(1→1)-1l-myo-inositol, and fagopyritol B3 is α-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl-(1→6)-α-d-galactopyranosyl-(1→2)-1d-chiro-inositol. DGMI and TGMI are higher oligomers of galactinol, a major galactosyl donor in plant seeds. Fagopyritol B3 is a higher oligomer of the fagopyritol B series and one of six fagopyritols found in buckwheat seeds and in the bran milling fraction. Samples of TGMI and fagopyritol B3 also contained the compounds N-(β-glucopyranosyl)-nicotinic acid and β-d-apiofuranosyl-(1→6)-β-d-(1-O-methyl)-glucopyranoside.
三种半乳糖环糖醇，双半乳糖基肌醇（命名为 DGMI）、三半乳糖基肌醇（命名为 TGMI）和三半乳糖基 D-手性肌醇（荞麦戊醇 B3），从普通荞麦（Fagopyrum esculentum Moench）种子中分离出来。通过 2D NMR 光谱确定了这三种化合物的结构。DGMI 是α-D-半乳糖吡喃基-(1→6)-α-D-半乳糖吡喃基-(1→1)-1l-肌醇，TGMI 是α-D-半乳糖吡喃基-(1→6)-α-D-半乳糖吡喃基-(1→6)-α-D-半乳糖吡喃基-(1→1)-1l-肌醇，荞麦戊醇 B3 是α-D-半乳糖吡喃基-(1→6)-α-D-半乳糖吡喃基-(1→6)-α-D-半乳糖吡喃基-(1→2)-1d-手性肌醇。DGMI 和 TGMI 是植物种子中主要半乳糖供体半乳糖醇的高聚物。荞麦戊醇 B3 是荞麦戊醇 B 系列的高聚物之一，也是荞麦种子和糠磨制部分中发现的六种荞麦戊醇之一。TGMI 和荞麦戊醇 B3 的样品还含有化合物 N-(β-葡萄糖吡喃基)-烟酸和β-D-阿比呋喃基-(1→6)-β-D-(1-O-甲基)-吡喃葡萄糖苷。
