Centella asiatica
1、 Standard of snow herb       This product is the dried whole grass of Centella asiatica (L.) urb., an Umbelliferae plant. Harvest in summer and autumn, remove sediment and dry in the sun.
      [character] this product often curls into a mass. The root is cylindrical, 2 ～ 4cm long, 1 ～ 1.5mm in diameter; the surface is light yellow or grayish yellow. The stem is slender and curved, yellowish brown, with fine longitudinal wrinkles, and the nodes often have whisker like roots. The leaves are mostly shrunk and broken, and the intact ones are nearly round or kidney shaped after flattening, with a diameter of 1-4cm; they are grayish green and have thick blunt teeth on the edge; . Umbels axillary, short. The double hanging fruit is oblate, with obvious raised longitudinal edges and fine reticulation, and the fruit stem is very short. The air is weak and the taste is light.
      [identification] (1) cross section of the stem of this product: the epidermal cells are round or nearly square. Below, there are 2-4 rows of pachytene cells. 6-8 outer tough vascular bundles; The outer side of phloem is microlignified fiber group, the cambium in bundle is obvious, and xylem vessels are arranged radially. The medulla is larger. .
      Leaf surface view: the upper and lower epidermal cells are polygonal; Stomatal inequality or infinitive, with less upper epidermis and more lower epidermis.
      (2) Take 1g of the product powder, use 25ml of ethanol, heat and reflux for 30 minutes, filter, evaporate the filtrate, add 20ml of water to dissolve the residue, shake and extract with water saturated n-butanol twice, 15ml each time, combine the n-butanol solution, wash with 15ml of water saturated with n-butanol, discard the water solution, evaporate the n-butanol solution, add 1ml of methanol to dissolve the residue, and use it as the test solution. In addition, take asiaticoside reference substance and hydroxyasiaticoside reference substance, add methanol to make a solution containing 1mg per 1ml, which is used as the reference solution. . In the chromatogram of the test sample, spots with the same color appear at the corresponding position of the chromatogram of the control sample.
      [inspection] the moisture content shall not exceed 12.0% (the second method of general rule 0832).
      .
      Acid insoluble ash content shall not exceed 3.5% (general rule 2302).
      [extract] according to the hot leaching method under the alcohol soluble extract determination method (general rule 2201), using dilute ethanol as solvent, it shall not be less than 25.0%.
      [content determination] determine according to HPLC (general rule 0512).
      Chromatographic conditions and system suitability test octadecylsilane bonded silica gel was used as filler; ; The detection wavelength was 205nm. The number of theoretical plates should not be less than 5000 according to asiaticoside peak.
      Preparation of reference solution take an appropriate amount of asiaticoside reference and hydroxyasiaticoside reference, weigh accurately, add methanol to make a solution containing 0.2mg per 1ml.
      Preparation of the test solution take about 0.5g of the powder (passing the second sieve), accurately weigh it, place it in a corked conical flask, precisely add 20ml of 80% methanol, close the stopper, weigh it, sonicate (power 180W, frequency 42khz) for 30 minutes, cool it, weigh it again, make up the lost weight with 80% methanol, shake it well, centrifuge, and take the supernatant.
      The determination method is to precisely suck 10 μ l of the reference solution and 10 ～ 20 μ l of the test solution, inject them into the liquid chromatograph, and determine.
      The total amount of asiaticoside (c48h78o19) and hydroxyasiaticoside (c48h78o20) in this product shall not be less than 0.80% according to the dry product.
      Decoction pieces
      [processing] remove impurities, wash, segment and dry.
      This product has irregular sections. The root is cylindrical with light yellow or grayish yellow surface. The lotus is thin, yellowish brown, with fine longitudinal wrinkles, nodes can be seen, and whisker like roots often grow on the nodes. The leaves are mostly shrunk and broken, and the intact ones are nearly round or kidney shaped after flattening, grayish green, with thick blunt teeth on the edge. Umbels short. The double hanging fruit is oblate, with obvious raised longitudinal edges and fine reticulation. The air is weak and the taste is light.
      [content determination] the total content of asiaticoside (c48h78o19) and hydroxyasiaticoside (c48h78o20) in the same medicinal material shall not be less than 0.70%.
      [identification] (except for the transverse section of the stem) [inspection] [extract] is the same as that of medicinal materials.
      [nature, taste and meridian tropism] bitter, pungent and cold. It belongs to the liver, spleen and kidney meridians.
      [functions and indications] clearing heat and dampness, detoxifying and detumescence. It is used for damp heat jaundice, heatstroke diarrhea, stone drenching and blood drenching, carbuncle, swelling and sore poison, falling and flapping injury.
      [usage and dosage] 15 ～ 30g.
      [storage] put it in a dry place.


2、 Chemical constituents of Centella asiatica
It contains a variety of triterpenoid components of α - geraniol type, includingAsiaticoside(Asiaticoside)、 Thankuniside, isothankuniside,Hydroxyasiaticoside(Madecassoside)， Brahmoside, brah minoside, and Brahmic acid, as well as madasiatic acid. In addition, it also contains meso inositol, centellose, wax, carotenoids, chlorophyll, andKaempferol、quercetin And flavonoid glycosides of glucose and rhamnose. . Triterpenoids haveAsiatic Acid(asiatic acid)、Hydroxyasiatic acid(brahmic acid)、 Isobrahmic acid and betulinic acid. Triterpenoid saponins haveAsiaticoside(asiaticoside,madecassol)、Hydroxyasiaticoside(madecassoside)、 Brahmoside and brahminoside are also called thankuniside and isothankuniside. In additionKaempferolandquercetin And its glycosides, asiaticine, inositol, centellose, sitosterol, vitamin CAlpha carotene、Beta carotene, green volatile oil and resinous substances.

3、 Standard of snow herb
1. central action: the glycosides contained therein have sedative and sedative effects on mice and rats, and this effect is mainly on the cholinergic system in the central nervous system. The alcohol extract has no analgesic effect.
2. effect on skin tissue: asiaticoside can treat skin ulcers, such as intractable trauma, skin tuberculosis, leprosy, etc. Intramuscular injection or subcutaneous implantation in mice, guinea pigs and rabbits can promote skin growth, local leukocytosis, connective tissue vascular network proliferation, mucus secretion increase, hair and tail growth acceleration, etc. .
3. antibacterial effect: the water extract of buds has antibacterial effect. Asiaticoside can treat leprosy. Some people believe that its role is to dissolve the wax film of bacteria, which can be eliminated by other drugs or body defense functions.
4. other effects: the alcohol extract can relax the isolated ileum of rats. Glycosides can reduce the tension and contraction amplitude of isolated ileum in rabbits and rats, and slightly inhibit the effect of acetylcholine. For anesthetized dogs, intravenous injection can slightly excite breathing, slow heart rate and moderately reduce blood pressure, and the latter two cannot be blocked by atropine. Asiaticoside has been reported to have a therapeutic effect on leprosy.