1、 Pharmacopoeia standard of Houttuynia cordata
This product is the fresh whole grass or dry aboveground part of Houttuynia cordata thunb., a plant of the three white grass family. Fresh products can be harvested and cut all year round; Dry products are harvested in summer when the stems and leaves are luxuriant and the flowers and ears are often cut. Impurities are removed and dried in the sun.
[character] the stem of fresh Houttuynia cordata is cylindrical, 20 ~ 45cm long, 0.25 ~ 0.45cm in diameter; the upper part is green or purplish red, the lower part is white, the nodes are obvious, and the lower part has fibrous roots, which are hairless or sparsely hairy. The leaves are alternate, heart-shaped, 3-10cm long and 3-11cm wide; the apex is acuminate, entire; The upper surface is green, dense glandular dots, and the lower surface is often purplish red; The petiole is slender, and the base is combined with the stipule to form a sheath. Spikes terminal. .
The stem of Houttuynia cordata Thunb is oblate, twisted, with yellowish brown surface and several longitudinal edges; . The leaves are folded and shrunk, and are heart-shaped after flattening. The upper surface is dark yellowish green to dark brown, and the lower surface is grayish green or grayish brown. Spikes yellowish brown.
[identification] (1) the powder of this product is grayish green to brown. The oil cells are round or oval in shape, 28-104 µ m in diameter, and contain yellow oil droplets. Non glandular hairs are 1-16 cells, with a diameter of 12-104 µ m at the base and a linear texture on the surface. The glandular hair has 2-5 cells in the head, containing light brown matter, with a diameter of 9-34 µ M. the leaf epidermis cells have wavy stripes on the surface, and the stomata are irregular. The diameter of calcium oxalate cluster crystals can reach 57 µ M.
(2) Take a proper amount of dried Houttuynia powder, put it in a small test tube, press it tightly with a glass rod, drop a small amount of magenta sulphite test solution until the upper powder is wet, place it for a moment, and observe from the side wall, the wet powder shows pink or red purple.
(3) Cut 25g of dried Houttuynia cordata (125g of fresh Houttuynia cordata), add 1ml of ethyl acetate according to the volatile oil determination method (general rule 2204), heat it slowly to boiling, and keep it slightly boiling for 4 hours, place it for half an hour, and take ethyl acetate solution as the test sample solution. . According to the thin-layer chromatography (general rule 0502), suck 5 µ l of the test solution and 2 µ l of the control solution, respectively dot them on the same silica gel G thin-layer plate, use cyclohexane ethyl acetate (9:1) as the developing agent, develop, take out, dry, and spray with dinitrophenylhydrazine test solution. In the chromatogram of the test sample, the same yellow spots appear at the corresponding positions of the chromatogram of the control sample.
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Acid insoluble ash (dried Houttuynia cordata) shall not exceed 2.5% (general rule 2302).
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Decoction pieces
[processing] remove impurities from fresh Houttuynia cordata.
Dry Houttuynia cordata to remove impurities, wash quickly, cut into sections, and dry.
This product is irregular. The stem is oblate cylindrical with reddish brown to yellowish brown surface and longitudinal edges. . Spikes yellowish brown. It tastes fishy and astringent when crushed.
[identification], [inspection], [extract] are the same as medicinal materials (dried Houttuynia cordata).
[nature, taste and meridian tropism] pungent, slightly cold. Return to lung meridian.
[functions and indications] it can clear away heat and toxin, eliminate carbuncle and pus, diuresis and relieve gonorrhea. .
[usage and dosage] 15 ～ 25g, should not be decocted for a long time; Double the amount of fresh product, and take it in water or mashed juice. For external use, apply proper amount, tamp or fry soup to fumigate and wash the affected area.
[storage] put dried Houttuynia cordata in a dry place; Keep fresh Houttuynia cordata in a cool and damp place.

2、 Chemical constituents of Houttuynia cordata

The aerial part contains volatile oil, decanoy acetaldehyde, lauric aldehyde, a-pinene andLinalool（linlool)， The first two have special odor. It also contains methyl-n-nonylketone, camphene, myrcene, limonene,Borneol acetate（bornyl acetate）， Caryophyllene. Houttuynin usually refers to the adduct of bisulfite pin of acetaldehyde decanoate. It also contains afzelin,Hyperin（hy-perin）, Rutin,chlorogenic acidas well asβ - sitosterol（β-sitosterol）， Stearic acid, oleic acid, linoleic acid. cycasin Quercitrin（qUercitrin）， Flowers and ears containIsoquercitrin（iso-quercitrin）。

3、 Pharmacological effects of Houttuynia cordata

. Rabbits were intramuscularly injected with Houttuynia cordata Thunb 8mg daily. After continuous administration for 3 days, the serum properdin was also significantly increased. Houttuynia cordata Thunb improved the rabbit epidemic force, which was of great significance for the treatment of sexually transmitted infections.

2. antibacterial effect: a yellow oil extracted from Houttuynia cordata has inhibitory effect on various microorganisms (especially yeasts and molds), and has obvious inhibitory effect on hemolytic streptococcus, Staphylococcus aureus, influenza bacillus, catarrhal coccus and pneumococcus. It also has effects on Escherichia coli, Shigella dysenteriae and Salmonella typhi. The synthetic decanoylacetaldehyde sodium bisulfite adduct is called synthetic houttuynin. . The concentration of Mycobacterium tuberculosis h37ry strain on the liquid culture medium was 16mcg / ml. On the modified Sutong's semisolid medium, it was 25mcg / ml, and its potassium salt was 12.5mcg / ml. The synthesized houttuynin isoniazid has a strong effect on TB bacilli, and its MIC is 0.78-3.1mcg / ml, which is effective on TB infected mice. It can significantly prolong the survival time. 1mg intraperitoneal injection per mouse can prolong the survival time of mice by 62 days, and the effect of mixed feeding is better.

. Zhuyutong reported that several non-volatile oil fractions were obtained by ethanol extraction. Among them, houttuynin Ⅲ has preventive protective effect on mice infected with influenza virus, but has no obvious effect on EMC and HSV Ⅱ. The derivatives of synthetic houttuynin also have strong antiviral effect. Houttuynia cordata extract (4G crude drug / ml) has obvious preventive and protective effects on mice infected with influenza virus. However, it has no obvious protective effect on encephalomyocarditis virus and herpesvirus type II infection. It was proved that the anti influenza virus component of Houttuynia cordata Thunb was not in the volatile oil part, but in the non-volatile matter.

. Its effect may be caused by organic matter. Potassium only plays an additional role of increasing diuresis. When it acts directly, it can weaken the activity of Leptospira - death - lysis, and also delay the onset of Leptospira in guinea pigs artificially infected.

. There was significant difference between the 0.75mg / ml houttuynin-7.5mg / mltmp compatibility group and the 7.5mg / mltmp group (t = 2.78) P < 0.01. It shows that the bacteriostatic effect of the combination of the two is better than that of the single use, and the two have synergistic effect. The 0.1ml / ml volatile oil of Houttuynia cordata Thunb had no antibacterial effect, and the 0.1ml / ml volatile oil of Houttuynia cordata thunb-7.5mg / mltmp compatibility group and 7.5mg / mltmp group had significant antagonistic effect compared with (t = 4.2) P < 0.001, indicating that the volatile oil of Houttuynia cordata Thunb can reduce the antibacterial effect of TMP. However, there are exceptions. The combination of the two can enhance the effect of anti paratyphoid fever and Shigella sonnei. Therefore, while affirming the antagonistic effect, we should not ignore the synergistic effect on individual strains.

6. other effects: Houttuynia cordata has analgesic, antitussive, hemostatic, inhibiting serous secretion, promoting tissue regeneration, wound healing, promoting the improvement of erythroderma and psoriasis, and houttuynine can stimulate skin foaming. .