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著者从日本信州大黄的根茎中分离出三个萘甙——甙A、B、C,并通过核磁共振、紫外、红外光谱确定了结构式.提取与分离:取新鲜的信州大黄根茎21.6公斤,用甲醇提取4次,甲醇提取物混悬在水里,并依次用1:1的氯仿——醋酸乙酯、醋酸乙酯和正丁醇提取,醋酸乙酯层水洗后进行干燥蒸发溶剂后,可得暗棕色提取物487g。取100g 反复在硅胶柱上层析(溶媒:氯仿——甲醇,醋酸乙酯——甲醇),得甙A 920mg 和甙C 246mg。另取醋酸乙酯提取物135g,连续用纤维素(水——甲醇)和葡聚糖凝胶(Sephadex LH—20)(甲醇)进行柱层析得粗品甙B,用硅胶进行制备薄层层析,精制可得甙B 80mg。分析:甙A 为无色针状形(甲醇),熔点150～152℃,〔α〕_D~(21)-109.0°(C=0.5,甲醇),分子式C_(20)H_(24)
The authors isolated three naphthoquinones, rhenium A, B, and C, from rhizomes of Rheum chinensis in Japan and determined the structural formulae by nuclear magnetic resonance, ultraviolet, and infrared spectroscopy. Extraction and separation: Take 21.6 kilograms of rhizome of fresh rhizoma Methanol extraction 4 times, methanol extract suspended in water, and sequentially with 1:1 chloroform - ethyl acetate, ethyl acetate and n-butanol extraction, ethyl acetate layer washed with water after drying solvent evaporation, available Dark brown extract 487g. Take 100g repeatedly on a silica gel column chromatography (solvent: chloroform - methanol, ethyl acetate - methanol) to obtain 920mg of A and 246mg of cesium C. Another 135 g of ethyl acetate extract was continuously subjected to column chromatography with cellulose (water-methanol) and Sephadex LH-20 (methanol) to obtain crude product B, and silica gel was used to prepare a thin layer. Analysis, refining available B 80mg. Analysis: 甙A is a colorless needle-shaped (methanol), melting point 150 ~ 152 °C, [α] _ D ~ (21) -109.0 ° (C = 0.5, methanol), molecular formula C_ (20) H_ (24)