Alisma orientalis
1、 Pharmacopoeia standard of Alisma orientalis       This product is the dried tuber of Alisma orientale (Sam.) juzep., a plant of Alismataceae. When the stems and leaves begin to wither in winter, they are dug, washed, dried, and the fibrous roots and rough skin are removed.
      [properties] the product is quasi spherical, oval or ovoid, 2-7cm long and 2-6cm in diameter. The surface is light yellow to light yellowish brown, with irregular transverse circular shallow grooves and most fine protruding fibrous root marks, and some at the bottom have tumor like bud marks. It is solid, yellowish white in cross section, powdery, and has many fine pores. The breath is slight, and the taste is slightly bitter.
      . There are many starch grains, single grain long oval, spherical or oval, diameter 3-14 µ m, umbilical point herringbone, short suture or trigeminal; Compound granules are composed of 2-3 fractions. The parenchyma cells are round like, with many oval pits and integrated pits. The vertical circumferential wall of endothelial cells is wavy, thick, lignified, and has sparse pore grooves. Most of the oil chambers are broken, and the intact ones are round, with a diameter of 54-110 µ M. sometimes oil droplets can be seen in the secretory cells.
      (2) Take 2G of the product powder, add 20ml of ethyl acetate, sonicate for 30 minutes, filter, add the filtrate to the alumina column (200-300 mesh, 5g, inner diameter of 1cm, dry packed column), elute with 10ml of ethyl acetate, collect the eluent, evaporate to dryness, add 1ml of ethyl acetate to dissolve the residue, and use it as the test solution. In addition, take 23 acetylalisol B reference substance and add ethyl acetate to make a solution containing 2mg per 1ml as the reference solution. According to the test of thin-layer chromatography (general rule 0502), suck 5 μ l of each of the above two solutions, dot them on the same silica gel h thin-layer plate, use cyclohexane ethyl acetate (1:1) as the developing agent, develop, take out, dry, spray with 5% silicotungstic acid ethanol solution, and heat at 105 ℃ until the spots are clear. In the chromatogram of the test sample, spots with the same color appear at the corresponding position of the chromatogram of the control sample.
      [check] moisture   .
      Total ash   .
      [extract] according to the hot leaching method under the determination method of alcohol soluble extract (general rule 2201), the use of ethanol as solvent shall not be less than 10.0%.
      [content determination] determine according to HPLC (general rule 0512).
      ; Octadecylsilane bonded silica gel was used as filler; Acetonitrile water (73:27) was used as mobile phase; .
      Preparation of reference solution   Take an appropriate amount of 23 acetylalisol B reference substance, accurately weigh it, add acetonitrile to make a solution containing 20 µ g per 1ml.
      Preparation of test solution   Take about 0.5g of this product powder (passing through No. 5 screen), weigh it precisely, place it in a corked conical flask, add 25ml of acetonitrile precisely, close the stopper, weigh it, sonicate (power 250W, frequency 50KHz) for 30 minutes, cool it, weigh it again, make up the lost weight with acetonitrile, shake it well, filter it, and take the filtrate.
      Assay   Precisely suck 10 µ l of the control solution and 10 µ l of the test solution respectively, inject them into the liquid chromatograph, and determine.
      Calculated as a dry product, the content of 23 acetylalisol B (c32h50o5) shall not be less than 0.050%.
      Decoction pieces
      [processing] Alisma orientalis   .
      This product is round or oval thick. The outer skin is yellowish to yellowish brown, and fine protruding fibrous root marks can be seen. The cut surface is yellowish white to light yellow, powdery, with many fine pores. The breath is slight, and the taste is slightly bitter.
      [check] moisture   No more than 12.0% for the same medicinal materials.
      .
      Alisma salina   Take Rhizoma alismatis tablets and fry them according to the salt water roasting method (general rule 0213).
      This product is shaped like Rhizoma alismatis tablets. Its surface is yellowish brown or yellowish brown, with occasional focal spots. It tastes slightly salty.
      [check] moisture   .
      Total ash   No more than 6.0% for the same medicinal materials.
      .
      [identification] (except for fine powder) [extract] is the same as that of medicinal materials.
      . Return to kidney and bladder meridian.
      [functions and indications] it can promote diuresis and dampness, relieve heat, remove turbidity and reduce lipid. It is used for adverse urination, edema and fullness, less diarrhea and urine, phlegm and dizziness, hot shower and pain, and hyperlipidemia.
      [usage and dosage] 6 ～ 10g.
      [storage] store in a dry place to prevent moths.


2、 Chemical constituents of Alisma orientalis
Tuber containsZeSialol a（alisol）、ZePurgative alcoholB、ZePurgative alcoholCAlisol a monoacetate, Alisol B monoacetate,Alisol c-23-acetate(Alisol C monoacetate) epialisol a,Alisma azulenol（alismol），Epoxy alisonene. It also contains choline, sugar, potassium, calcium, magnesium and other elements.

3、 Pharmacological action of Alisma orientalis
1. hypolipidemic effect: the fat soluble part of Alisma orientalis has obvious cholesterol lowering effect and anti atherosclerotic effect on experimental hypercholesterolemic rabbits. Alisol a, B and the acetate of Alisol a, B, C isolated from Alisol a, B, C, except Alisol B, have significant cholesterol lowering effect. Adding 0.1% to the diet of experimental hyperlipidemia rats can reduce blood cholesterol by more than 50%, among which Alisol a-24-acetate has the strongest effect. The ethanol extract of Alisma orientalis and the ethyl acetate extract of ethanol extract have hypolipidemic effects on experimental hypercholesterolemia rabbits and rats. Ethyl acetate extract and its residual part insoluble in acetic acid monohydrate had the strongest effect. Ethyl acetate extract, 1g/kg orally per day, also has obvious cholesterol lowering effect on normal rats fed with ordinary diet. The isoepitope labeling method proved that Alisol a had the ability to inhibit the esterification of cholesterol in the small intestine of mice, and could reduce the absorption rate of cholesterol in the small intestine of rats by 34%, but it did not affect the absorption of linoleic acid.
2. protective effect on liver: Alisol a acetate, Alisol B acetate and Alisol C acetate can protect the liver of mice poisoned by carbon tetrachloride, among which Alisol C acetate is the best.
3. effect on cardiovascular system: Rhizoma alismatis extract has mild hypotensive effect when injected intravenously into dogs and rabbits, which lasts for about 30 minutes. Alismatin has mild hypotensive effect on various experimental animals, and its hypotensive effect does not significantly affect plasma renin and ACE activities or aldosterone levels. The ethanol extract of Alisma orientalis has a slow relaxation effect on the conditioned contraction of isolated rabbit aorta induced by epinephrine in vitro. Alismatinol can inhibit the contraction of rabbit aortic strips caused by angiotensin, and its contractile effect is dose-dependent. Alismatin can reduce cardiac output, heart rate and left ventricular pressure, but it can increase coronary flow.
4. diuretic effect: saline loaded mice or rats are used for diuretic experiment. Subcutaneous injection of Alisol a acetate 100mg/kg in mice can increase the secretion of k+ in urine, but oral administration of the same dose is ineffective. When rats were given Alisol a acetate or Alisol B 30mg/kg orally, the secretion of Na + was significantly increased, compared with the control group p< 0.05 and p< 0.01.