第十章天然药物化学实验 11 3.To learn the method of preparation of silica gel thin layer plate. 4.To learn the chemical methods of detecting anthraquinones. 2.Experimental principles Rhubarb was recorded in Shen Nong's Herbal Classic.It has the effects of reducing internal heat.defaecation.cooling blood.detoxification.eliminating stasis.and dredging collateral channels.It is traditionally used for defaecation,promoting digestion,clearing heat,and detoxication as a folk medicine.Rhubarb is a famous plant purgating drug.and has been recorded early in pharmacopoeia of many countrys.All the roots and thizomes of Rheum palmatum L Rheum officnale Baill,and Rheum tanguticum Maxim.et Regll could be used as Rhubarb.Its chemical costituents contain various hydroxy-anthraquinones and their glycosides.The main anthraquinone aglycons are listed in the following table: Table 10-1 Characteristics of main anthraquinone aglycons Compounds Melt point() -H -COOH Rhein Yellow needle crystal 318-320 H Golden faky crystal Polnity of anhraquinone ycons indifferen because of th different structures.especially substitution groups.Their polarity.from strong to weak is in the sequence of Rhein.Emodin.Aloe-emodin.Physcion and Chrysophanol. The method of acid hydrolysis of Rhubarb Powder is used for higher aglycons' yield.The hydrolysis product,aglycon,is extracted with ethyl ether,and the ethyl ether extraction is separated by silica gel column chromatography according to their polarity. 3.Instruments and reagents 1.Experimental instruments Glass chromatographic column(21 mmx200 mm,24#),globe-shaped funnel (250 ml,24#),flask (100 ml),evaporating dish,test tube,glass thin layer plate(5x20 cm),filter paper,glassfunnel,iron support stand,absorbent cotton, round bottom flask,economical allihn condenser,thermostat water bath,Buchner fask,Busher funnel,ultraviolet lamp 2.Reagents and drugs Rhubarb Powder,silica gel (200-300 mesh).silica gel G.ethyl ether (AR). petrolum ether(60-90C,AR).ethyl acetate(AR),20%H2SO.0.5%CMC,1%alizarin 第十章 天然药物化学实验 11 3. To learn the method of preparation of silica gel thin layer plate. 4. To learn the chemical methods of detecting anthraquinones. 2. Experimental principles Rhubarb was recorded in Shen Nong's Herbal Classic. It has the effects of reducing internal heat, defaecation, cooling blood, detoxification, eliminating stasis, and dredging collateral channels. It is traditionally used for defaecation, promoting digestion, clearing heat, and detoxication as a folk medicine. Rhubarb is a famous plant purgating drug, and has been recorded early in pharmacopoeia of many countrys. All the roots and rhizomes of Rheum palmatum L., Rheum officnale Baill, and Rheum tanguticum Maxim. et Regll could be used as Rhubarb. Its chemical costituents contain various hydroxy-anthraquinones and their glycosides. The main anthraquinone aglycons are listed in the following table: Table 10-1 Characteristics of main anthraquinone aglycons R1 R2 Compounds Crystal form Melt point( ) ℃ -H -COOH Rhein Yellow needle crystal 318~320 -CH3 -OH Emodin Orange needle crystal 256~257 -H -CH2OH Aloe-emodin Orange needle crystal 206~208 -CH3 -OCH3 Physcion Brick-red needle crystal 207 -H -CH3 Chrysophanol Golden flaky crystal 196 Polarity of anthraquinone aglycons in Rhubarb is different because of their different structures, especially substitution groups. Their polarity, from strong to weak, is in the sequence of Rhein, Emodin, Aloe-emodin, Physcion and Chrysophanol. The method of acid hydrolysis of Rhubarb Powder is used for higher aglycons’ yield. The hydrolysis product, aglycon, is extracted with ethyl ether, and the ethyl ether extraction is separated by silica gel column chromatography according to their polarity. 3. Instruments and reagents 1. Experimental instruments Glass chromatographic column (21 mm×200 mm, 24#), globe-shaped funnel (250 ml, 24#), flask (100 ml), evaporating dish, test tube, glass thin layer plate(5×20 cm), filter paper, glassfunnel, iron support stand, absorbent cotton, round bottom flask, economical allihn condenser, thermostat water bath, Büchner flask, Busher funnel, ultraviolet lamp. 2. Reagents and drugs Rhubarb Powder, silica gel (200-300 mesh), silica gel G, ethyl ether (AR), petrolum ether (60-90 , AR), ℃ ethyl acetate (AR), 20% H2SO4, 0.5% CMC, 1% alizarin