Yam
1、 Pharmacopoeia standard of Chinese yam This product is the dried rhizome of Dioscorea opposita thunb. After the stems and leaves wither in winter, dig them, cut off the root heads, wash them, remove the skin and fibrous roots, and dry them, which is commonly known as "Maoshan pill [1]"; Or remove the skin, cut thick slices while fresh, and dry, which is called "yam slices"; There are also dry yams that are plump and straight. Put them in clear water, soak them until they are dry and stuffy, cut both ends, rub them into a cylindrical shape with a wooden board, dry them in the sun, and polish them. They are commonly known as "smooth yams". [properties] Chinese yam is slightly cylindrical, curved and slightly flat, 15 ～ 30cm long and 1.5 ～ 6cm in diameter. The surface is yellowish white or light yellow, with longitudinal grooves, longitudinal wrinkles and fibrous root marks, and occasionally light brown skin remains. Weight, solid quality, not easy to break, white section, powder. It is light in breath, light in taste, slightly sour, and sticky when chewed. Yam slices are irregular thick slices, wrinkled and uneven, with white or yellowish white cut surface, hard and brittle, and powdery. It is light and sour. Guangshan yam is cylindrical, with both ends flush, 9 ～ 18cm long and 1.5 ～ 3cm in diameter. Its surface is smooth, white or yellowish white. [identification] (1) the powder of this product is white. The single starch granule is oblate ovoid, triangular ovoid, quasi round or rectangular round, with a diameter of 8-35 μ M. the umbilicus is punctate, herringbone shaped, cross shaped or short slit shaped, and laminar striations can be seen; . Calcium oxalate needle crystal bundles exist in mucus cells, with a length of about 240 μ m and a diameter of 2-5 μ M. The diameter of the marginal pitted conduit, reticulated conduit, threaded conduit and annular conduit is 12-48 μ M. (2) Take 5g of this product powder, add 30ml of dichloromethane, heat and reflux for 2 hours, filter, evaporate the filtrate, add 1ml of dichloromethane to dissolve the residue, and use it as the test solution. . Test according to thin-layer chromatography (general rule 0502), suck 4 μ l of each of the above two solutions, dot them on the same silica gel G thin-layer plate, use ethyl acetate methanol concentrated ammonia test solution (9:1:0.5) as the developing agent, develop, take out, air dry, spray 10% phosphomolybdic acid ethanol solution, and heat at 105 ℃ until the spots are clear. In the chromatogram of the test sample, spots of the same color appear on the corresponding position of the chromatogram of the control medicinal material. [inspection] the moisture content of crude yam and light yam shall not exceed 16.0%; Yam tablets shall not exceed 12.0% (method 2 of general rule 0832). The total ash content of Mao yam and Guang yam shall not exceed 4.0%; Yam tablets shall not exceed 5.0% (general rule 2302). The sulfur dioxide residue shall be determined according to the sulfur dioxide residue determination method (general rule 2331), and the content of Mao yam and Guang yam shall not exceed 400mg/kg; Yam tablets shall not exceed 10mg/kg. ; Yam tablets shall not be less than 10.0%. Decoction pieces [processing] yam remove impurities from crude yam or light yam, separate them into small and large ones, soak them until transparent, cut them into thick pieces, and dry them. The slicer is a thick round piece. The surface is white or yellowish white, brittle, easy to break, and the cut surface is white, rich in powder. [inspection] the total ash content is the same as that of medicinal materials, and shall not exceed 2.0%. [extract] the same as that of medicinal materials, not less than 4.0%. [identification] [inspection] (moisture and sulfur dioxide residue) are the same as that of medicinal materials. . It is irregular thick piece, wrinkled and uneven, with white or yellowish white cut surface, hard and brittle, powdery. It is light and sour. [identification], [inspection], [extract] are the same as that of medicinal materials. Stir fry yam with bran, take maoyam tablets or Guangshan tablets, and stir fry until yellow according to the method of stir frying with bran (general rule 0213). This product is shaped like Maoshan tablet or Guangshan tablet. Its cut surface is yellowish white or yellowish, with occasional burnt spots and a slight burnt aroma. [inspection] the moisture content is the same as that of medicinal materials, and shall not exceed 12.0%. [extract] the same as that of medicinal materials, not less than 4.0%. [identification] [inspection] (total ash and sulfur dioxide residues) are the same as those of medicinal materials. [nature, taste and meridian tropism] sweet and smooth. . [functions and indications] tonify the spleen and stomach, generate fluid and benefit the lungs, tonify the kidney and astringe essence. It is used for eating less due to spleen deficiency, diarrhea for a long time, asthma and cough due to lung deficiency, spermatorrhea due to kidney deficiency, vaginal discharge, frequent urination, and diabetes due to deficiency of heat. Stir fried yam with bran can fortify spleen and stomach. It is used for eating less due to spleen deficiency, diarrhea, loose stool, and excessive leucorrhea. [usage and use] 15 ～ 30g. [storage] store in a ventilated and dry place to prevent moths.

2、 Chemical constituents of yam
Yam tuber containsDiosgenin（diosgenin）0。 0.12%, dopamine, batatasinehydrochloride, polyphenoloxidase, allantoin and abscisin Ⅱ. It also contains glycoprotein, which is hydrolyzed to obtain: lysine, histidine, arginine, aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, leucine, isoleucine, tyrosine, phenylalanine and methionine. It also contains free amino acids including the above amino acids and cystine, γ -aminobutyric acid, as well as polysaccharides useful for reducing blood sugar, yam polysaccharides composed of mannose, glucose and galactose with a molar ratio of 6.45:1:1.26, and barium, beryllium, cerium, cobalt, chromium, copper, gallium, lanthanum, lithium, manganese, niobium, nickel, phosphorus, strontium, thorium, titanium, vanadium, yttrium, ytterbium, zinc, zirconium, as well as sodium oxide, potassium oxide, zirconium alumina, iron oxide, calcium oxide, magnesium oxide, etc. The rhizome contains dopamine, catecholamine, and cholesterol,Ergosterol（ergosterol），Campesterol（campesterol），Stigmasterol（stigmasterol），β - sitosterol（β-sitosterol）。 Mucus contains PHYTICACID, mannan IA, IB and IC; some people say that mucus contains 40% polysaccharide, 2% protein, 3% phosphorus and 24% ash, and the polysaccharide part is composed of 80% mannose and a small amount of galactose, xylose, fructose and glucose. Bulbil contains five distributive plant growth regulators, named batatasin Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ. It also contains arrestin, dopamine and a variety of sterols: cholestanol, (24R) - α - methylcholestanol [(24R) - α -methylcholestanol], (24s) - β - methylcholestanol [(24s) - β -methylcholestanol], (24R) - α - ethylcholestanol [(24R) - α -ethylcholestanol], cholesterol, campesterol, (24s) - β - methylcholestanol [(24s) - β -methylcholestanol], 24 methylene cholestanol (24-methylenecholesterol),β - sitosterol，Stigmasterol, isfucosterol, clerosterol, 24-emthylene-25-methylcholesterol, 7-cholesterol, 8 (14) - cholesterol [cholest-8 (14) -enol], (24R) - α - methyl-8 (14) - cholesterol [(24R) - α -methylcholest-8 (14) -enol], (24s) - β - methyl-8 (14) - cholesterol [(24R) - α -24s) - β -methylholest-8 (14) -enol], (24R) - α - ethyl-8 (14) - cholesterol [(24R) - α -ethyl-8 (14) -enol]. The tubers of the same genus of Dioscorea nipponica contain triterpenoid saponins, allantoin, choline, 17 amino acids (less γ - aminobutyric acid than the free amino acids contained in yam tubers) and inorganic compounds (less lanthanum than the inorganic compounds contained in yam tubers). It also contains Dioscorea polysaccharide a, B, C, D, e, f with hypoglycemic activity.

3、 Pharmacological action of Chinese yam
1. hypoglycemic effect
  1.1 can significantly reduce the blood glucose of normal mice and alloxan diabetic mice.

  1.2 can obviously resist the increase of blood glucose in mice caused by epinephrine.

  1.3 preventive administration of yam can resist the blood glucose rise in mice caused by alloxan.

  1.4 yam can resist the increase of blood glucose in mice caused by exogenous glucose.

2. regulate the body's response to non-specific stimuli. Yam can significantly prolong the survival time of mice, has a very significant atmospheric hypoxia resistance effect, can significantly reduce the damage of mouse organs by hypoxic environment, and improve the tolerance.

3. impact on immune function
  3.1 effect on the weight of immune organs. Yam can significantly increase the spleen weight of mice, but has no obvious effect on thymus.

  3.2 effect on carbon clearance in mice twelve Kunming mice were used. The experimental group received 0.2ml of yam water decoction (containing crude drug ig/ml) for 7 consecutive days, and the control group received 0.2ml of normal saline. 24 hours after the last administration, each mouse tail was IV treated with 0.1ml/10g of Chinese carbon ink (filtered with commercially available ink water, diluted three times). At 0.5 and 10 minutes after injection, 20ml of blood was taken from the posterior ocular venous plexus, dissolved in 21% NaHCO3 and left for 1 hour. The absorption value was measured at 650nm and the clearance index was calculated. Yam can significantly enhance carbon clearance in mice. Yang Zhonglin and others also studied the effects of raw yam, bran fried product and soil fried product on the non-specific immune function of mice by taking the carbon particle clearance experiment as the index. The results showed that there were very significant differences between the drug groups and the control group, and the raw product was stronger than the bran fried product and soil fried product, suggesting that it is appropriate to use raw yam for Invigorating Qi.

  3.3 effect on immunosuppression of cyclophosphamide. Yam polysaccharide can effectively resist the immunosuppressive effect of cyclophosphamide.

4. effects on small intestinal motility in mice. .

5. other nutrients are related to mucus and amylase. They are nourishing and can help digestion. . Expectorant.