Plantain
1、 Standard of plantain herbal classic       This product is the dried whole grass of Plantago asiatica L. or Plantago depressa willd. Excavate in summer, remove sediment and dry in the sun.
      [character] plantain   The roots are tufted and whisker like. Leaves basal, long petiolate; The leaves are shrunk, oval or wide oval after flattening, 6 ～ 13cm long and 2.5 ～ 8cm wide; the surface is grayish green or dirty green, with 5 ～ 7 obvious arc veins; . There are several spikes with long flower stems. The capsule is covered with cracks, and the calyx is persistent. The smell is slightly fragrant and the taste is slightly bitter.
      ; The taproot is straight and long. The leaves are narrow, oblong or elliptic lanceolate, 5 ～ 14cm long and 2 ～ 3cm wide.
      [identification] (1) appearance of the leaves: plantain   The upper and lower epidermal cells are oblong, and the upper epidermal cells have keratinocytes. The stomata are indeterminate, with 3-4 accessory guard cells. Glandular hairs have 2 cells in the head, oval shape, and single cells in the stalk. Non glandular hairs are rare, with 2-5 cells, 100-320 μ m long, slightly thick walls, and slightly warty protrusions.
      ; Non glandular hairs are 3-7 cells and 350-900 μ m long
      (2) . In addition, take the reference substance of plantain and add methanol to make a solution containing 1mg per 1ml as the reference solution. Test according to thin-layer chromatography (general rule 0502), suck 10 μ l of each of the above two solutions, dot them on the same silica gel G thin-layer plate respectively, use ethyl acetate methanol formic acid water (18:3:1.5:1) as the developing agent, develop, take out, dry, and view under ultraviolet light (365nm). 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   Not more than 15.0% (general rule 2302).
      Acid insoluble ash   .
      [extract] according to the hot leaching method under the determination method of water-soluble extract (general rule 2201), it shall not be less than 14.0%.
      [content determination] determine according to HPLC (general rule 0512).
      Chromatographic conditions and system suitability test   ; The mobile phase was acetonitrile-0.1% formic acid solution (17:83); The detection wavelength was 330nm. The number of theoretical plates should not be less than 3000 based on the peak of plantain.
      Preparation of reference solution   Take an appropriate amount of plantain reference substance, accurately weigh it, put it into a brown measuring flask, add 60% methanol to make a solution containing 0.1mg per 1ml.
      Preparation of test solution   Take about 1g of this product powder (through No. 2 screen), weigh it accurately, place it in a corked conical flask, add 50ml of 60% methanol precisely, weigh it, sonicate (power 250W, frequency 40KHz) for 30 minutes, cool it, weigh it again, make up the lost weight with 60% methanol, shake it well, filter it, and take the filtrate.
      Assay   Precisely suck 10 μ l of the reference solution and 10 μ l of the test solution respectively, inject them into the liquid chromatograph, and determine.
      According to the calculation of dry product, the content of plantain (c29h36o16) shall not be less than 0.10%.
      Decoction pieces
      [processing] remove impurities, wash, segment and dry.
      This product is irregular. Rhizomelic or straight and long. The leaves are shrunken, mostly broken, with grayish green or dirty green surface and obvious veins. . The breath is slight, and the taste is slightly bitter.
      [identification], [inspection], [extract], [content determination] are the same as those of medicinal materials.
      [nature, taste and meridian tropism] sweet, cold. It belongs to the channels of liver, kidney, lung and small intestine.
      [functions and indications] heat clearing, diuresis promoting, gonorrhea relieving, expectorant, blood cooling, detoxification. .
      [usage and dosage] 9 ～ 30g.
      .


2、 Chemical constituents of plantain
1. the whole plantain containsUrsolic acid（ursolic acid）， N-hentriacontane,β - sitosterol（β-sitoserol），StigmasterolStig masterol, β - sitosteryl palmitate, stigmasteryl palmitate [1],Aucubin（aucubin）[2]， Plantainoside aPlantainB、PlantainC、PlantainD、PlantainE、PlantainF， ,Isoeugenol glycoside（isoacteoside），Eugenol glycoside（acteoside）， Leucosceptoside a,Isocantharide（isomartynoside）， Martynoside [3].

The aerial part contains plantaginin, rhamnosylisoeugenol, eugenol glycoside,Plantain（plantaginin）， Rhamnose isoeugenol, eugenol glycoside,Plantain（plantamajoside）， 7-hydroxy plantain (hellicoside) [4].

cycasin Aucubin[2] , plantain flavonoid glycoside [5], homoplanta ginin [6].

The root containsAucubin[2] , plantain glycosides [5], homoplantain [6].

The root contains stachyose, sucrose, Raffi nose and other sugars [7].

2. the whole grass in front of the crane containsoleanolic acid （oleanolic acid），β - sitosterol，Campesterol（campesterol）Stigmasterol，Luteolin（luteolin）， 6-hydroxyluteolin, eugenol glycoside, luteolin-7-o-glucoside, 6-hydroxyluteolin-7-o-glucoside [8], monoterpene iridoid glycosides aucubin, plantarenaloside, ixoroside,Chefolin（as-peruloside）， .

cycasin Fumarate（fumaric acid），Benzoic acid（benzoic acid），Cinnamic acid（cinnamic acid），Butyric acid（syringic acid），Vanillic acid（vannillic acid）， P-coumaric acid,Gentian acid（gentisic acid），salicylic acid（salicylic acid）， Tyrosol, 3,4-dihydroxycinnamic acid methyl ester, 3,4-dihydroxycinnamic acid ethyl ester, loliolide, digiprala ctone [11], baicalein,Alpine baicalein（scutellarein），Luteolin，Baicalin（baicalin），chlorogenic acid（chlorogenic acid），Neochlorogenic acid（neochlorogenic acid）[12]，Aucubin[13]，Plantain[14] And polysaccharide \u\u plantaglutide [15].

3、 Physiological effects of plantain herb

1. Antidepressant effects. Xu et al studied the antidepressant effect of the petroleum ether extract of plantain by using the learned help lessness model. They found that the number of mice that failed to escape after administration of plantain extract was significantly reduced, indicating that plantain has a significant antidepressant effect. [7] 
2. Scavenging effect of oxygen free radicals. Plantain decoction has a significant scavenging effect on oxygen free radicals. Many pathophysiological phenomena such as aging, tumor, inflammation and cerebral ischemia are closely related to excessive oxygen free radicals. The pharmacological effect of plantain against oxygen free radicals can be vigorously developed and utilized. [7]