1、 Pharmacopoeia standard of duckweed
This product is the dried whole grass of the duckweed Spirodela polyrrhiza (L.) schleid. Harvest from June to September, wash, remove impurities, and dry in the sun.
[properties] this product is a flat leaf shaped body, oval or oval, with a length of 2-5mm. The upper surface is light green to grayish green, with a small depression on the side, and the edge is neat or slightly curled. . It is light and fragile by hand. The air is weak and the taste is light.
[identification] (1) the powder of this product is yellow green. The vertical wall of the upper epidermal cells was wavy and curved, and the stomata were not fixed. The vertical wall of the lower epidermal cells is flat and straight without stomata. . Calcium oxalate clusters are smaller. Calcium oxalate needle crystals form bundles.
(2) . Another 1g of duckweed control medicine was taken and prepared into the control medicine solution by the same method. Test according to thin-layer chromatography (general rule 0502), suck 2 μ l of each of the above two solutions, dot them on the same silica gel G thin-layer plate, use ethyl acetate butanone formic acid water (6:3:1:1) as the developing agent, develop, take out, dry, spray 1% aluminum trichloride absolute ethanol solution, and inspect under ultraviolet light (365mn). In the chromatogram of the test sample, fluorescent spots of the same color appear at the position corresponding to the chromatogram of the control medicinal material.
[inspection] the moisture content shall not exceed 8.0% (the second method of general rule 0832).
[nature, taste and meridian tropism] pungent, cold. Return to lung meridian.
. For measles impervious, rubella itching, edema and less urine.
[usage and dosage] 3 ～ 9g. Apply appropriate amount externally and soak in decoction.
[storage] store in a ventilated and dry place to prevent moisture.

2、 Chemical constituents of duckweed

Azolla whole grass containsOrientin, luteolin-7-monoglycoside,Vitexin, apigenin-7-monoglycoside,Beta carotene，lutein, epoxy lutein, lutein and neoxanthin. It also contains 8% of lipids and 24.4% of proteins, and the fatty acids contained in lipids are mainly linolenic acid,palmitic acidAnd linoleic acid, in proteinl-leucine The content of glutamate accounted for 9.05%-9.79%, and the essential amino acid index was 52.2-52.7.
Duckweed contains trans-1,3-phytodiene, phytoene, sitosterol, phytol, 4 (R) - 4-hydroxyisophytol, (10R) - hydroxy-7z, 11e, 13z hexadecatrienoic acid, 11z hexadecenoic acid and 7z, 10z, 13z hexadecatrienoic acid.

3、 Pharmacological action of duckweed

1. diuretic effect: the diuretic components are potassium acetate and potassium chloride.

2. cardiovascular effects: Duckweed water extract has a cardiotonic effect on frog heart failure caused by quinine, which can be enhanced by calcium, and a large dose can stop the heart in diastole; And can constrict blood vessels to raise blood pressure.

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4. other effects: the antibacterial and antimalarial tests of duckweed were negative. It can kill Culex pipiens larvae and pupae in the laboratory and on site.