Watermelon frost
1、         This product is made from the ripe fresh fruit and Tanner of Citrullus Lanatus (thunb.) matsumu.et Nakai, a Cucurbitaceae plant.
        [properties] this product is a quasi white to yellowish white crystalline powder. It has slight air and salty taste.
        [identification] (1) the aqueous solution of this product shows the differential reaction between sodium salt (general rule 0301) and sulfate (general rule 0301).
        (2) Take 2G of this product, add 15ml of 6mol/l hydrochloric acid solution, heat it in a boiling water bath and reflux for 2 hours, cool it, filter it, evaporate the filtrate to dryness, wash the residue and precipitated crystals with 20ml of 70% ethanol in several times, stir, filter, combine the filtrate, evaporate to dryness, dissolve the residue with 20ml of water, add it to 732 strong acidic cation exchange resin column (inner diameter is 1.5 ~ 2cm, column length is 8cm), elute with 200ml of water, discard the water, elute with 100ml of ammonia solution (concentrated ammonia solution 10ml → 100ml), collect the eluent, evaporate to dryness, add 1ml of 70% ethanol to dissolve the residue, and use it as the test solution.The. In addition, take glutamic acid reference substance and phenylalanine reference substance, add 70% ethanol to make a solution containing 0.5mg per 1ml each as the reference solution. According to the thin-layer chromatography (general rule 0502), suck 5 µ l of the test solution and 1 µ l of the control solution, respectively, dot them on the same silica gel G thin-layer plate, use n-butanol glacial acetic acid water (3:1:1) as the developing agent, develop, take out, air dry, spray 5% ninhydrin ethanol solution, 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.
        [inspection] heavy metals   Take 1.0g of this product and check according to law (the second method of general rule 0821). The content of heavy metals shall not exceed 10mg/kg.
        Arsenic salt   Take 0.20g of this product, add 23ml of water to dissolve it, add 5ml of hydrochloric acid, check according to the law (method 1 of general rule 0822), and the arsenic content shall not exceed 10mg/kg.
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        [nature, taste and tropism] salty, cold. Return to lung, stomach and large intestine.
        [functions and indications] clearing heat and purging fire, reducing swelling and pain. It is used for sore throat, throat obstruction and aphthous ulcer.
        [usage and dosage] 0.5 ～ 1.5g. Apply an appropriate amount externally, and blow on the affected area at the end of grinding.
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2、 Chemical constituents of watermelon frost
L-aspartic acid 、L-threonine、l-serine 、L-glutamine、L-Proline 、glycine、L-alanine、L-cystine、L-valine

3、 Pharmacological effects of watermelon frost