What Is Reserpine?

An indole alkaloid. It is found in many plants of the genus Ruffia. Colorless prismatic crystal. The melting point is 264 265 ° C (decomposed), and the specific rotation is -117.7 ° (chloroform, C = 1). Soluble in chloroform, dichloromethane, glacial acetic acid, soluble in benzene, ethyl acetate, and slightly soluble in dilute aqueous solutions of acetone, methanol, ethanol, ether, acetic acid and citric acid. The reserpine solution turned yellow after standing for a certain period of time, and showed significant fluorescence. The fluorescence was increased after adding acid and exposure. Reserpine is a weak base. Its hydrochloride is colorless crystals with a melting point of 224 ° C (decomposition); pyridine complex is yellow crystals with a melting point of 183 to 186 ° C (decomposition). Reserpine can reduce blood pressure and heart rate. It is slow, mild, and long-lasting. It has a long-lasting calming effect on the central nervous system. It is a good sedative.

Reserpine, or reserpine, is a kind of indole alkaloid drug used to treat hypertension and psychiatric diseases. It was originally extracted from the root wood of the genus Rutulinia. Nowadays, reserpine is no longer the first choice for treatment due to more side effects and better new drugs coming on the market. Catecholamines (belonging to monoamine neurotransmitters) play a great role in the regulation of heart rate, myocardial contractility and peripheral resistance. Reserpine's antihypertensive effect is achieved by consuming catecholamines in peripheral sympathetic nerve endings. . ^[2]

Method name: Reserpine API-Determination of Reserpine-Spectrophotometry.

Scope of application: This method uses a spectrophotometric method to determine the content of reserpine in the drug reserpine.

This method is applicable to the drug of reserpine.

Principle of the method: The test product was dissolved in chloroform, diluted with absolute ethanol to prepare a test solution, and a UV-visible spectrophotometer was pretreated, and the absorbance was measured at a wavelength of 390 nm to calculate its content.

Reagent:

1. Trichloromethane.

2. Anhydrous ethanol.

3. Sulfuric acid titration solution (0.25mol / L).

4. 0.3% sodium nitrite solution.

5. 5% ammonium sulfamate solution.

6. Methyl red-bromocresol green mixed indicator liquid.

7. Base anhydrous sodium carbonate.

Equipment: UV-visible spectrophotometer.

Sample preparation:

1. Sulfuric acid titration solution (0.25mol / L).

Preparation: Take 15mL of sulfuric acid, slowly inject an appropriate amount of water, cool to room temperature, add water to dilute to 1000mL, and shake well.

Calibration: Take about 0.75g of reference anhydrous sodium carbonate dried to constant weight at 270 ~ 300 , accurately weigh, add 50mL of water to dissolve, add 10 drops of methyl red-bromocresol green mixed indicator liquid, titrate with this liquid When the solution changes from green to purple, boil for 2 minutes, cool to room temperature, and continue titration until the solution changes from green to dark purple. Each 1mL of sulfuric acid titration solution (0.25mol / L) is equivalent to 26.50mg of anhydrous sodium carbonate. Calculate the concentration of this solution based on the consumption of this solution and the amount of anhydrous sodium carbonate taken.

2. Methyl red-bromocresol green mixed indicator solution.

Take 20 mL of 0.1% methyl red ethanol solution, add 30 mL of 0.2% bromocresol green ethanol solution, and shake well.

3. Preparation of reference solution.

Accurately weigh an appropriate amount of reserpine reference substance and make a solution containing about 20 mg per 1 mL according to the test solution preparation method to obtain the reference substance solution.

4. Preparation of test solution

Precisely weigh about 20mg of the test product, place it in a 100mL volumetric flask, add 4mL of chloroform to dissolve, dilute to the mark with absolute ethanol, shake well, take 5mL precisely, place in a 50mL volumetric flask, and dilute with absolute ethanol To the mark, shake well to get the test solution.

Note: "Precision weighing" means that the weighing weight should be accurate to one thousandth of the weighing weight. "Precision measurement" means that the accuracy of measuring the volume should meet the accuracy requirements of the volume pipette in national standards.

Operation steps: Precisely measure 5mL each of the reference solution and test solution, and place them in 10mL measuring flasks. Add 1.0mL of sulfuric acid titration solution (0.25mol / L) and 1.0mL of the newly prepared 0.3% sodium nitrite solution. Evenly, heat in a 55 ° C water bath for 30 minutes, cool, add 0.5mL of a fresh 5% ammonium sulfamate solution, dilute to the mark with absolute ethanol, shake well, and take 5mL each of the reference solution and the test solution Except that 0.3% sodium nitrite solution was not added, the same method was used to treat the corresponding blanks respectively, and the absorbance was measured at a wavelength of 390 nm according to ultraviolet spectrophotometry.

Note: The spectrophotometric method should be based on the same batch of solvent prepared as the test product, using a 1cm quartz absorption cell. The wavelength with the largest absorbance is used as the measurement wavelength. Generally, the error of the absorbance reading of the test product is between 0.3-0.7. The slit band width of the instrument should be less than half the width of the absorption band of the test product, otherwise the measured absorbance is low. The selection of the slit width should be based on reducing the absorption of the test article when the slit width is reduced. Because the absorption cell and the solvent may have blank absorption, the blank reading should be subtracted after measuring the absorbance of the test product, and the content should be calculated. ^[4]