Determination of the content of plant flavonoid compounds

Summary

Usually, we call a group of substances with C6-C3 C6 carbon structure as flavonoid compounds, including flavones, flavonols, flavanones, chai- cones, anthocyanins, etc. These compounds are widely distributed in all organs of plants and are related to plant growth and development. These compounds are widely distributed in various organs of plants and are related to the growth and development of plants, and in recent years they have also been found to be very beneficial to human health.

Principle

The basic principle of the determination of the content of plant flavonoids is that most of the flavonoids exist in the form of glycosides in plants, so the acidity of plants should be prevented from causing hydrolysis of glycosides during the extraction process, and a little _CaCO3 can be added during the extraction process _to avoid this. The solvent can be selected according to the nature of the compounds, alcohols are suitable for glycosides and compounds containing multiple hydroxyl groups, and if the compounds are highly methylated or non-glycosides, ethyl alcohol is more suitable. The content of flavonoids can be determined directly by spectrophotometric method, which uses the phenolic hydroxyl group on the structure of flavonoids and its reducing characteristics for color development, and determines the flavonoids at a specific wavelength. Commonly used reagents for color development are A1( _NO3)3, A1CL and other metal salts, AF+ can react with the hydroxyl group in the flavonoid molecule to form a colored metal complex.

Operation method

Determination of the content of plant flavonoid compounds

Principle

The basic principle of the determination of the content of plant flavonoids is that most of the flavonoids in plants exist in the form of glycoconjugates, so the acidity of plants should be prevented from hydrolyzing the glycoconjugates during the extraction process, and a small amount of CaCO3 can be added during the extraction process to avoid this. The solvent can be selected according to the nature of the compounds, alcohols are suitable for glycosides and compounds containing multiple hydroxyl groups, and if the compounds are highly methylated or non-glycosides, ethyl alcohol is more suitable. The content of flavonoids can be determined directly by spectrophotometric method, which uses the phenolic hydroxyl group on the structure of flavonoids and its reducing characteristics for color development, and determines the flavonoids at a specific wavelength. Commonly used reagents for color development are A1(NO3)3, A1CL and other metal salts, AF+ can react with the hydroxyl group in the flavonoid molecule to form a colored metal complex.

Materials and Instruments

Materials: citrus fruits, ginkgo biloba, lotus leaves, etc.
Materials: spectrophotometer, electronic balance, oven, water bath, soxhlet extractor, dispensing funnel.
Reagents:
①70% ethanol ethanol
②5% NaNO
2
②5% NaNO 2 solution
③10% A1(NO
3
)
3
solution ③10% A1(NO 3 ) 3 solution ④4% NaOH solution
④4% NaOH solution
⑤CaCO
3 solution ④4% NaOH solution ⑤CaCO
,100 昭・mL^芦丁溶液 (10 mg 芦丁用 70% 乙醇定容至 100 mL)。

Move

The basic procedure for the determination of the content of plant flavonoids can be divided into the following steps:

1. Plotting the standard curve: Dilute rutin solution with 70% ethanol to 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 Showa-mL "1, and put 1 mL of each solution into a test tube, add 1 mL of 70% ethanol, add 0.3 mL of 5% _NaNO2 solution, and then add 0.3 mL of 10% A1( _NO3)3 solution after 6 min, and add 2 mL of 4% NaOH solution to clarify the mixture, and measure the OD at 510 nm of spectrophotometer after 10 min. After 6 min, add 0.3 mL of 10% A1(NO3)3 solution, after 6 min, add 2 mL of 4% NaOH solution to make the mixture clear, after 10 min, the OD value was measured at 510 nm on a spectrophotometer. The OD value was measured at 510 nm of spectrophotometer after 10 min, and the standard curve of mass concentration-OD value was plotted.

2. Extraction of flavonoids: Take 1 g of ginkgo (or other plants) leaves and put it into a Soxhlet extractor, add 100 mL of 70% ethanol and a little _CaCO3, and extract for 6~8 h. Pour out the extract and concentrate under reduced pressure to evaporate the ethanol. The concentrated solution was washed 2~3 times with the same volume of ethanol in a separatory funnel to remove chlorophyll and wax paper, etc. Then the solution was diluted with 70% ethanol to 100 mL, and left to be measured. The leaves were weighed 10 g and baked in an oven at 105 笆to a constant weight to determine the moisture content.

3 . Determination of total flavonoids in the extract: Pipette 1 mL of the sample solution, measure the absorbance value according to the same procedure and method as above, and then find out the content of total flavonoids (expressed as rutin) in the sample from the standard curve (Mg- ^mL-1 ).

4 . Calculation of results
Total flavonoid content in dried leaves (seat-g7) = vxp
where:V-l g volume of extract made from dried leaves, mL;
p total flavonoid content measured in the extract - mL~l.

Caveat

1. The flavonoid compounds of different plants vary greatly, and different methods may be used for extraction.

2. If different color developing reagents are selected, the determination wavelength needs to be re-scanned.

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